SPEC Corp

Beautiful Tones - voted "World Leaders" for their Real Sound components from Japan
Our “Real-Sound” brings the true richness of music - Real-Sound” BRINGS THE BREATHS OF PERFORMER JUST IN FRONT OF YOU

The Sound SPEC targeted at our “Real-Sound” brings the true richness of music

How the joy of music would grow if the current mainstream speakers with wide range but low efficiency can reproduce higher-dimensional acoustic sound like the old vintage high-efficiency speakers.

In the development of our “Real-Sound” class-D amplifiers, we have tried to make it possible to reproduce a tone that is beautiful, rich and penetrating as if appealing directly to the human emotions, a real three dimensional field, and a musical sound full of dynamism !

On the belief that “ the joy of music is only found in ‘Real-Sound’”, we have been developing and marketing high-end audio products with the wish of communicating and sharing the sensations, also excitement of our “Real-Sound” music with our customers.

Through High End 2014 in Munich, we will demonstrate four integrated amplifier models including the RSA-F3EX, M3EX, V1EX and 717EX.

With extensive use of latest Class D solutions boosting revolutionary speaker drive power and advanced energy-saving performance these amplifiers deliver beautiful tones and fully dynamic sound, in a word true richness of music someone has never hear before.

And also REQ-S1EX, a phono equaliser amplifier fusing the latest semiconductor technology and matured analog technology, will allow the listeners of analog LP records to rediscover the fascination with “the ultimate high-resolution sound”.

Who is SPEC

SPEC designer Shirokazu Yazaki started his career with TEAC Japan, where he stayed for four years developing amongst other things the TEAC A-37300 reel-to-reel recorder, before he went to Pioneer for the following 17 years.
After a long stay in Indonesia he returned to Pioneer in Japan where he worked on the CT range of cassette recorders and the ‘legendary’ DV-AX10 DVD/CD/SACD player.

His interested in class D was aroused because his old Pioneer colleague Jun Honda works for International Rectifiers producing power management solutions and the pair co-operated in making modules for audio. Yazaki-San has been using single-ended triodes and horn loaded loudspeakers for decades, an enthusiasm inspired by a Jean Hiraga demonstration of Altec horn loudspeakers driven by a DA30 triode based amplifier in 1971.

From that moment Yazaki-San became fascinated with the DA30, which he prefers over a 300B, always trying to improve his own designs through listening and research with horn loaded loudspeakers from Altec, JBL and Onken.

History was written in February 2010 when the SPEC Corporation was formed by Shirokazu Yazaki and Jun Honda, to bring to the market class D amplifiers that are just as good or even better than the DA30 tube designs that had taken over 40 years to perfect.

Yazaki-San points out that the moving coil of a loudspeaker develops energy that returns to the output stage of an amplifier to influence the feedback circuit by creating distortion. In a class D amplifier this energy is absorbed not in a feedback circuit but in the power supply, where it is harmless. Which, he says, is one of the reasons why class D amplifiers sound so pure and clear.

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SC 03 AI RSA 717
SPECIAL PRICE: NZ$ 3,995.00 (incl. GST)
Original: NZ$ 6,995.00 (incl. GST)
Saving: NZ$ 3,000.00 (incl. GST)
1 OFF SPECIAL OFFER - REAL SOUND AMPLIFIER RSA-717EX - New concept in Class-D amplifiersA lot of people may tend to think Class-D means "digital", however, SPEC amplifiers, re "Class-D...
EXTENDED REVIEW (French / English translation) - SPEC is a young company , founded in 2010 by...

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Music / Media Network players, Streamers & Servers

Phono Stages

SC 02 PS REQ S1
NZ$ 16,995.00 ea (incl. GST)
REAL-SOUND” BRINGS THE TRUE RICHNESS OF MUSIC - You will rediscover an analog LP as the fascination of “Ultimate High-Resolution Sound”.                ...
A phono equaliser with extremely simple circuit configuration making full use of the latent ability...
 EXTENDED REVIEW: story began over a year ago when I prepared materials for our seventh...
CONCLUSION: Listening to music through the Japanese phono stage is like having a bath in essential...
Phono Stages

Integrated amplifiers

SC 03 AI RSA 717
SOLD
SPECIAL PRICE: NZ$ 3,995.00 ea (incl. GST)
Original: NZ$ 6,995.00 (incl. GST)
Saving: NZ$ 3,000.00 (incl. GST)
1 OFF SPECIAL OFFER - REAL SOUND AMPLIFIER RSA-717EX - New concept in Class-D amplifiersA lot of people may tend to think Class-D means "digital", however, SPEC amplifiers, re "Class-D...
EXTENDED REVIEW (French / English translation) - SPEC is a young company , founded in 2010 by...
Integrated amplifiers
SC 04 AI RSA G3
NZ$ 8,995.00 ea (incl. GST)
Integrated amplifiers
SC 04 AI RSA V1
NZ$ 10,995.00 ea (incl. GST)
REAL SOUND AMPLIFIER RSA-V1EX - Real, new-generation class-D amplifiers with latest highly accurate PWM switching device A lot of people may tend to think Class-D means "digital", however,...
SPEC Corporation is a very young company. They started in January 2010. The pretext for their...
Integrated amplifiers
SC 05 AI RSA M3
NZ$ 12,995.00 ea (incl. GST)
Here's an interesting observation: The new-generation class-D amplification modules developed by Mr. Honda-san for International Rectifier specifically for high-performance audio use were informed by...
EXTENDED REVIEW: As much as I love the Leben, I really think the SPEC is in a different performance...
Integrated amplifiers
SC 06 AI RSAF333
NZ$ 29,995.00 ea (incl. GST)
REAL SOUND AMPLIFIERS RSA-F333EX - Real, new-generation class-D amplifiers with latest highly accurate PWM switching devices. A lot of people may tend to think Class-D means "digital", however,...
EXTENDED REVIEW: I am one of those guys who is a regular reader of Jeff’s Place. It is always...
Integrated amplifiers
SC 07 AS RSR 1
NZ$ 1,795.00 ea (incl. GST)
Integrated amplifiers

Preamplifiers & Line-stages

SC 08 AS RPA P7
NZ$ 10,995.00 ea (incl. GST)

Power amplifiers (Stereo & Mono)

SC 08 AS RPA W7
NZ$ 7,995.00 ea (incl. GST)
The RPA-W7EX measures 13.7" wide by 3.7" high by 14.6" deep: not much bigger than a stack of three large notebook computers. Its case and chassis are made of steel—it looked svelte in my Salamander...
EXTENDED REVIEW: I'm a jazz lover. To be specific: I'm a lover of jazz on vinyl. I'm referring not...
SC 09 AM RPA W3
Price on application
NEW PRODUCT DUE FOR RELEASE END OF 2016

Miscellaneous

SC 10 SP RSP 901
NZ$ 1,200.00 pr (incl. GST)
You will recognize at once that the  PSP-901EX dramatically improves the sound quality of your system. The sound will be more clear and natural throughout entire range with 901EX. You will feel...
EXTENDED REVIEW: Mr. Yazaki-san also sent along a pair of the SPEC RSP-901 EX Real Sound Processors...
Miscellaneous

Turntables

SC 12 TT GMP8000
NZ$ 32,995.00 ea (incl. GST)
A thing of true beauty, supplied ready to accommodate your favourite 12" tonearm  (recommend IKEDA IT407) The merit of a string driven turntable system 
Turntables

Reviews

You may very well decide it is one of the best amplifiers out there regardless of price. At least that's my take on the SPEC, and I suspect it'll be yours too if you get a chance to give it a listen.
Jeff Day

REVIEW SUMMARY: From the first moment that I saw, touched, and powered my hi-fi systems with Yazaki-san's SPEC RSA-M3 EX Real Sound Amplifier I was deeply impressed with what he has accomplished. There is a certain irresistible 'sensuality' sonically, musically, and even visually to the SPEC RSA-M3 EX Real Sound Amplifier that makes it quite captivating amplifier to listen to music with.

The SPEC also threw a big 'they are here' style of soundstage into my room, with lots of natural detail, a voluminous sense of space, solid images that layered back into the soundstage nicely, and a relaxed live-like musicality that only the very best equipment can produce.

We talked about the SPEC and how its highs were spot-on perfect and natural sounding too, and Julie's vocals were stunningly natural, with absolutely no unnatural sibilance. The bass response was extended and full of nuance, and even though it was only 60 watts, the SPEC could really deliver the dynamic swings when called upon. The SPEC was deceptively powerful, and when loafing along it sounds only about as powerful as my 25 watt MC225, but when you really crank it up it never misses a beat and sounds astonishingly good, even at very loud 'blow out the windows' levels. In short, when we sitting there listening to the SPEC play music we came to the conclusion that it was one of the most perfectly voiced amplifiers we'd ever heard.

Everyone who has heard the SPEC Real Sound Amplifier, including Cindy, has made the comment of how rich and natural the SPEC sounds (in a timbral and tone colour sense), and Cindy added how it drew out many subtleties in the music, and had an ability "to remind you that recordings from your past are 'old friends'". I thought that the last was a particularly interesting comment, because the SPEC does indeed have an exceptional ability to portray music's emotional impact. It reminds you of how you felt when you heard the music for the first time, and it brings back all those feelings in a flood as you listen to the music.

The SPEC's is a very beautiful presentation of tone colour.
If you're interested in an amplifier with the beauty, tone colour, timbral naturalness, and rich stereoscopic musicality of the best vacuum tube designs in a non-fussy and classy solid-state design, I suggest that you listen to the SPEC RSA-M3 EX amplifier. You may very well decide it is one of the best amplifiers out there regardless of price. At least that's my take on the SPEC, and I suspect it'll be yours too if you get a chance to give it a listen.

EXTENDED REVIEW: Most regular readers of Positive Feedback know of my long-time passion for vacuum tube electronics. I've enjoyed the musical prowess and sonic chops of contemporary artisan-designed single-ended amplifiers with various output tubes, like the EL84, 45, 2A3, 300B, F2a, and 845 output valves; as well as inspired push-pull amplifiers using KT88, EL84, KT66, EL34, KT90 outputs, and probably some others I'm forgetting at the moment.

Lately I've been reveling in the musicality of vintage audio electronics with their classic circuits, like the McIntosh MX110Z tuner/preamplifier (27 vacuum tubes!), the McIntosh MC240 stereo and MC30 monaural amplifiers (6L6GC outputs), and McIntosh MC225 stereo amplifier (7591 outputs). Célébrer le tube à vide!

However, when I reviewed the ASR Emitter II Exclusive Version Blue solid-state amplifier from Germany back in Issue 66 I found out that valves weren't the only path to sonic nirvana, and that 'Big Blue's' sonics & musicality were superb on my equally big Duelund-crossover'd customized Tannoy Westminster Royal SE loudspeakers.

I learned the audio lesson that while parts choice does make an important difference in performance, it is the 'enlightened ear' of the talented designer that determines the ultimate musical performance of an audio amplifier, whether it contains vacuum tubes or solid-state devices.

The High-Fidelity Adventures of Mr. Shirokazu Yazaki
A case in point is the SPEC RSA-M3 EX Real Sound Amplifier from the 'enlightened ear' of Mr. Shirokazu Yazaki in Tokyo, Japan, that sounds shockingly good by any musical or sonic measure.

From the first moment that I saw, touched, and powered my hi-fi systems with Yazaki-san's SPEC RSA-M3 EX Real Sound Amplifier I was deeply impressed with what he has accomplished. There is a certain irresistible 'sensuality' sonically, musically, and even visually to the SPEC RSA-M3 EX Real Sound Amplifier that makes it quite a captivating amplifier to listen to music with.

Before I get too carried away telling you about the SPEC RSA-M3 EX Real Sound Amplifier, let me back up for just a moment and tell you about the man behind it, Mr. Shirokazu Yazaki (second from the left in the photo below). I have found the story of Mr. Shirokazu Yazaki's audio journey during our conversations to be quite fascinating, and I'm hoping I can relay that sense of intrigue to you, and why I think his story is important.

First of all, Mr. Shirokazu Yazaki has been a successful professional audio designer in Japan for over 40 years, and has been involved in the design of many fine audio components from some of the foremost Japanese electronics companies during that time. Yazaki-san fondly reminisces about a few component design high points he was involved with, like the TEAC A-7300 semi-professional open-reel tape recorder while he was at TEAC, or the Pioneer CT-95 / T-1100S cassette recorder as a design team leader & manager at Pioneer in their cassette recorder engineering department, or the Pioneer DV-AX10 universal disc player as the general manager for the Pioneer DVD engineering department.

Those of you with a detailed historical knowledge of audio will remember the highly regarded TEAC A-7300 reel-to-reel; the Pioneer CT-95 / T-1100S cassette recorder, which was considered superior to even the legendary Nakamichi Dragon; and the Pioneer DV-AX10, which was the world's first true universal disc player capable of playing CD, SACD, DVD and DVD-A with both high audio & video fidelity.

Towards the end of his career at Pioneer, Mr. Shirokazu Yazaki was put in charge of the Pioneer research & development center, where he first came into contact with a prototype class-D switching amplifier in 2006.

Now Back To The Beginning
Ok let's stop right here for a moment. Now we are going to journey back in time 40 years or so to 1971 when Mr. Shirokazu Yazaki first started his professional audio design career at TEAC, a young man fresh out of the university with a mechanical engineering degree.

There were events occurring during that time that would mark it as one of the defining periods of audio history, which would send ripples of inspiration through time to the future to spark an audio revolution that changed the way that many of us today think about what's possible in high-performance audio.

Over the years as an audio writer, it has been a great pleasure for me to interview a number of eyewitnesses who were involved from the beginning of that important period, like Mr. Shirokazu Yazaki, and to tell the story of how events unfolded, and how those events would come to shape the future of enthusiast audio, including my own enjoyment of music today.

While Japanese audio enthusiasts were familiar with the excellent American vacuum tubes from Western Electric, RCA, GE, etc., they didn't have a lot of access to European and British vacuum tubes until towards the end of 1960s, when a most important event occurred with French audio connoisseur Jean Hiraga (of L'Audiophile fame) starting to import European & UK vacuum tubes to Kobe, Japan.

Magazines like MJ and Radio Engineering were publishing do-it-yourself (DIY) articles about building vacuum tube amplifiers, including some using those 'new' European & UK vacuum tubes from Jean Hiraga, which were embraced by the creative 'underground' audio movement in Japan. There were a lot of really interesting designs taking shape around the vacuum tubes that were available from America, Europe, and the UK, and in particular around the ascension of directly heated single-ended-triode power (SET) amplifiers that were intended for use with high-sensitivity horn loudspeakers.

The Tokyo Audio Fair of 1971 featured a number of those vacuum tube amplifier designs, and notably the combination of DH-SET amplifiers driving high-sensitivity Altec A-5 loudspeakers, which wowed show goers with their superlative music-making ability, including our young Mr. Shirokazu Yazaki who had just started his career at TEAC.

Now the young Mr. Shirokazu Yazaki who went to work at TEAC was also an audio enthusiast & music lover who particularly enjoyed listening to jazz, so in 1971 when Yazaki-san went to the Tokyo Audio Fair he was impressed by the intense musical satisfaction that could be realized by listening to music with DH-SET amplifiers powering high-sensitivity Altec horn loudspeakers.

Excited by the possibilities of that 1971 Tokyo Audio Fair, Mr. Shirokazu Yazaki embarked upon what would become a life-long journey of assembling & refining his personal high-fidelity music system, first by constructing his own DH-SET amplifier, then by building and customising a Marantz 7 kit preamplifier, and over time developing his Altec & Onken-based horn loudspeakers.

In 1972 Yazaki-san began building his own SET amplifier after reading an article in the June issue of MJ magazine by a Mr. Anzai about building a simple GEC DA30 SET amplifier. Yazaki-san completed that first SET amplifier in early 1973, using the American Western Electric 310A as the driver, a Western Electric 274B as a rectifier, and the English GEC DA30 as outputs (the DA30 is less well known in the West, than say the 300B is, but it is held in extremely high regard by aficionados within the Japanese DH-SET scene, but they are rare and difficult to come by these days).

Mr. Shirokazu Yazaki told me that he has continuously improved his DA30 DH-SET stereo amplifier over the years, and the combination of Western Electric 310A driver, Western Electric 274B rectifier, and GEC DA30 outputs provides the most beautiful tonality he has every heard from an amplifier. Even though they were both capable of putting out 8-9 watts, Yazaki-san told me he selected the GEC DA30 over the Western Electric 300B for his amplifier because it had superior high-frequency response. He also went on to say that the oldest version of the Western Electric 310A, the 'mesh shield' that was produced in the 1930s & 1940s, was critical to getting the best sound. He thought that later versions of the WE 310As sounded rougher & less natural compared to the smooth & natural sounding original 'mesh shield' version. Yazaki-san also told me that the 1940s 'engraved' version of the Western Electric 274B rectifier expressed tonal colours better than all the other rectifiers he had experimented with. Compared to the 'engraved' version of the 1940s WE 274B rectifier, he found the Telefunken GZ34, Philips original GZ34, Mullard GZ37, GZ37 big bottle, RCA5R4GY, Western Electric 422A, etc., while excellent rectifiers, all bleached the tonal color to some extent.

The Western Electric 310A driver, Western Electric 274B rectifier, and the GEC DA30 outputs resulted in a rich midrange, beautiful tone, and a powerful upper bass that combined to give exceptional musicality.

Shortly after completing his DA30 DH-SET stereo amplifier Mr. Shirokazu Yazaki began building up his horn loudspeaker system. He started his loudspeaker system with a pair of 1960s vintage Alnico-magnet Altec 414A woofers in 1973, and then ordered Mr. Koizumi's Onken OS-NEW500MT drivers with matching SC-500WOOD wood horns in December of 1973, which were delivered in 1975. In 1977 Yazaki-san added Onken OS-5000T Esprit tweeter to complete his horn loudspeakers.

In 1979 when Marantz released the Marantz 7 in kit form, Yazaki-san bought the kit and built it up with better parts. Yazaki-san said he learned a lot about getting good tone modifying his Marantz 7 kit with different components, and he has made continuous improvements to it to the present day.

Mr. Shirokazu Yazaki described to me the sound of the audio system he built as being transparent, beautiful, rich, and dynamic, but most importantly it possessed "real stereoscopic sound full of musicality."

A Quick Lesson in Big DH-SET History
Now let me diverge slightly from Mr. Shirokazu Yazaki's story for just a moment so I can connect the dots of audio's 'big DH-SET history' for you by telling you how the Japanese DH-SET audio culture and Jean Hiraga's importing vacuum tubes to Japan would eventually trigger a change in Western audio culture, and then we'll get back to Mr. Shirokazu Yazaki's story and I'll explain how it all connects together.

Japanese audio enthusiasts like Mr. Yazaki-san who noticed how good DH-SET amplifiers were both musically & sonically started buying up vintage American & English vacuum tubes like the Western Electric 310A & 274B and GEC DA30, and vintage speakers that were designed to be used with low powered vacuum tube amplifiers (like the Tannoy series of Dual Concentric™ speakers and enclosures, and the Altec Voice of the Theatre loudspeakers (Altec was a spin off company of Western Electric incidentally)).

Those Japanese music lovers & fine audio constructeurs of vacuum tube circuits noticed how good those types of hi-fi equipment were at portraying the timbral & color aspects of the music, and like Mr. Shirokazu Yazaki, those enthusiasts continued to develop and refine those systems so that their presentation of music's timbral and color elements were truly profound, and their listening emphasis was expressed through equipment choices that maximized those qualities to result in a very different presentation of music than many listeners in the West were used to at the time.

However, once a fire is lit, you really can't keep it hidden for long, and word about the amazing musical realism attained by combining those highly refined DH-SET amplifiers with highly sensitive loudspeakers soon got out to those in the West who had ears to hear, like Jean Hiraga.

Due to his importing vacuum tubes to Japan, Monsieur Hiraga was among the first in the West to become aware of this new exotic DH-SET audio trend in Japan. He and his French enthusiast audio magazine L´Audiophile had discerned the importance of this aroma of music wafting in on the breeze from Japan and responded by opening a shop in Paris to do demonstrations of this new-old style of music listening.

In 1986 L´Audiophile demonstrated a 300B DH-SET amplifier at their store in France that signaled the birth of the DH-SET movement on French soil. The musical realism, the exquisite textures & colors, and the dynamic truths that L´Audiophile achieved so easily in their demonstrations using DH-SET amplifiers, Altec-Onken & Voice of the Theatre loudspeaker systems, and playing records on a Platine Verdier turntable, impressed a lot of people, and the SET, horns, and vinyl approach to musical nirvana started to go viral, working it's way into Germany.

The founder of Auditorium 23 in Germany, Keith Aschenbrenner, told me that after hearing the L´Audiophile system during this period, he thought that what Philippe, Jean, and Gerard were doing was remarkable, and their demonstrations marked a major milestone in musical realism in audio. Keith told me, "It was quite an education to hear that new 300B SET approach to amplification. When we got that first 300B SET amplifier in our shop, connected it to the Voice of the Theatre loudspeakers, it was just like a musical Christmas present. In the beginning, we handled it like Sunday shoes. The harmonic integrity and musical realism were astonishing. We went from using it for special demonstrations only to using it every day. Going back to our other equipment became so hard that we just gave up on it and stayed with the 300B."

A little while later the single-ended-triode virus made it to the North American audio scene when Noriyasu Komuru started building DH-SET amps, as did Gordon Rankin, and Don Garber. The DH-SET fires had begun burning in the consciousness of audio enthusiasts across North America, where whispers from the audio underground were heard to say "DH-SETs live again, and they can bring your music back to life." The SET resurrection fires raged on through time and place to a point where most contemporary enthusiasts now consider the DH-SET amplifier to be a normal part of the Hi-Fi scene.

Now Back To The Future
That's right, the DH-SET & horn loudspeaker revival around the world that many of us are enjoying today all started with the 'enlightened ear' of audio enthusiasts in Japan, like Mr. Shirokazu Yazaki, and others.

So now I want you to consider this intriguing scenario and its implications: In parallel over the last 40 years, Mr. Shirokazu Yazaki spent his workdays designing audio components professionally for two of the most influential Japanese audio electronics companies, TEAC and Pioneer, while during his personal time he was building & optimizing each component in his artisanal DH-SET & Altec-Onken horn loudspeaker audio system for his personal enjoyment of music.

Those two parallel audio themes in Mr. Shirokazu Yazaki's life intertwined & collided in time in October of 2006 when Mr. Nishimura-san from International Rectifier in Japan demonstrated a prototype class-D switching amplifier at the Pioneer research & development centre that Mr. Shirokazu Yazaki managed.

Mr. Yazaki-san told me that while the prototype class-D amplifier's sound quality was not as sophisticated as the best DH-SET vacuum tube amplifiers, he was shocked by its rich & musical sound, and he thought that those particular new class-D power devices it contained represented development & optimisation possibilities as exciting for audio enthusiasts as those during the time of the rise of the DH-SET culture in Japan back more than 40 years ago now.

Two months later, in December of 2006, Mr. Yazaki-san was in Los Angeles meeting with the designer of the prototype amplifier's impressive new generation of class-D power devices, Mr. Jun Honda, at International Rectifier. Mr. Honda-san was a former junior colleague of Mr. Yazaki-san's at Pioneer, and a personal audio friend, and after leaving Pioneer Mr. Honda-san had immigrated to the States where he went to work for International Rectifier (IR). Honda-san had been working at IR for about six years when he developed the new class-D power devices that Mr. Yazaki-san would hear in the prototype class-D amplifier that Mr. Honda-san & Mr. Nishimura-san had developed together, and which was then demonstrated by Mr. Nishimura-san at the Pioneer R&D center a few months before.

Impressed with the possibilities represented by the new class-D power amplifier developed by Mr. Honda-san & Mr. Nishimura-san, Mr. Yazaki-san began developing a class-D amplifier of his own based on Mr. Honda-san's new generation of class-D power modules, using his own artisanal Western Electric 310A, Western Electric 274B, and GEC DA30 DH-SET amplifier as the voicing reference.

His goal was to apply the same sort of attention to detail to the class-D amplifier he was building with Honda-san's new generation of class-D power modules that he did to his own DH-SET amplifier, desiring to approximate as closely as possible that amplifier's rich midrange, beautiful tone, and exceptional musicality.

Mr. Yazaki-san was so pleased with the way his class-D amplifier turned out he decided to build one for his good friend to enjoy, Mr. Nakamura-san. In 2009 Mr. Yazaki-san had Mr. Nakamura-san's new class-D amplifier finished and ready to go, and it turned out to be so impressive, that quickly on the heels of that, on February 6th, 2010, SPEC Corporation was founded.

A New Year's Eve to Remember
Mr. Yazaki-san enjoys building amplifiers for his friends, and he also built a beautiful pair of GEC DA30 monaural amplifiers for his good friend Mr. Ookubo-san (below left). Mr. Yazaki-san told me the story of the gathering of his audio friends on New Year's Eve to listen to the new monaural GEC DA30 amplifiers he built for Mr. Ookubo-san, and the class-D amplifier he had built for Mr. Nakamura-san

When Mr. Yazaki-san and his friends listened to the new GEC DA30 monaural amplifiers (below) they were all so moved by the music that it was truly a transcendent experience for them. He told me that what they experienced was so spectacular that it was hard for them to put into words, "We felt that the stereophonic sound we heard had reached an ultimate revel, and we were fascinated with and intoxicated by the music. The sound was transparent, beautiful, rich, and dynamic, and in the truest sense was "real stereoscopic sound full of musicality"."

Yazaki-san had told me that his good friend Mr. Ookubo-san had always enjoyed hearing his GEC DA30 amplifier in his system so much that he desired one of his own. "He loves so many kinds of music from classical to jazz, and had been so moved every time when he heard the sound of my old system with my aged DA30 stereo amplifier that I built up in early 1973, 40 years ago now, that he desired a DA30 amplifier of his own."

Yazaki-san told me that all the improvements he had made to his DA30 stereo amplifier over the years had resulted in a tonal quality that had reached an incredible level. He also told me he was a little worried about finding the exact tubes he needed to replicate that tonal quality, like the 1930s Western Electric 310A 'mesh shield' that he used for the inputs, or the 'engraved' early 1940s version of the Western Electric 274B for the rectifiers, which both had superior tonal color compared to later versions, but were really hard to find outside of a museum.

Mr. Ookubo-san was able to locate all of the best tubes Mr. Yazaki-san needed for the circuits, and he was able to start designing and building the monaural amplifiers. Mr. Yazaki-san also wanted to make Mr. Ookubo-san's monaural amplifiers as beautiful as they were good sounding, and he told me, "I thought that the appearance was an important matter for these amplifiers full of valuable vintage tubes. So I wanted to use and reproduce the beautiful color of "Altec Green" for the chassis, the same hammertone enamel paint used in my aged woofers' frames (the color used on the Altec 414A made in the 1960s), so I imported the paint from USA."

Mr. Yazaki-san developed the drawings of the chassis he desired for the amplifiers, and Mr. Yokoyama-san, a specialist from Valve's World, built them up for him using a combination of aluminum and wood. Mr. Yazaki-san told me, "Thanks to his artisanal approach to the chassis, everyone commented on how splendid the Altec Green colour was, how beautiful the monaural amplifiers turned out, and how fabulous the craftsmanship was."

Mr. Yazaki-san told me, "Of course Mr. Ookubo-san was thrilled with the extraordinary sound, musical performance, and the appearance of the monaural amplifiers. I'm also so happy that I could pour all of my skills and experiences from the last 40 years into building up these monaural amplifiers for Mr. Ookubo-san."

Mr. Yazaki-san went on to tell me that the maximum power output of his DA30 stereo amplifier was only in the range of about 8 to 9 watts, and he used it to drive his 105dB sensitive mid-horns and tweeters (Onken OS-NEW500MT drivers with SC-500WOOD horns, and Onken OS-5000T Esprit tweeters). To power his vintage Altec 414A woofers (500 Hz on down), Mr. Yazaki-san built a push-pull triode amplifier of his own design to complete the amplification of his Altec-Onken loudspeaker system.

He told me, "All those present for the New Year's Eve audio celebration felt that the combination of Mr. Ookubo-san's new DA30 monaural amplifiers (foreground below) and my old Altec-Onken horn speaker system was supreme."

Then they swapped out Yazaki-san's triode bass amplifier and substituted the class-D amplifier he had built for Mr. Nakamura-san (bottom right above). "We wanted to know how well the class-D amplifier would be able to drive the powerful vintage woofer, and how its tonal balance would compare to the tonal quality to Mr. Ookubo-san's new DA30 monaural amplifiers."

He went on to tell me, "The precise low-range control and vivid tone color of the mid to low-range really impressed us. We could not believe how good the sound was with the combination of these two very different types of amplifiers, one was the simple but oldest circuitry tube amplifier, and another one was new-design class-D amplifier. We couldn't believe how good this strange combination was, but it was a fabulous thing for us."

Mr. Yazaki-san told me how excited they were, "Because this demonstration had showed us that the newest class-D amplifier could be a real successor of vintage direct-heated single-ended-triode type of musical performance. We are all convinced that in the near future all music lovers who enjoy DH-SET type sound will enjoy the extraordinary fine tonal character and musicality of this newest design class-D amplifier, and at reasonable prices for an artisanal amplifier. Also, the additional power of the class-D amplifier with its precise control of the low-range is surely beyond any type of past amplifiers! My dream has come true!"

Why are these stories important?
You're probably wondering why I've taken so much time in this article to tell you in detail all about these interesting audio stories of Mr. Yazaki-san and his friends. After all, haven't class-D amplifiers been around for a while now, and aren't they already starting to proliferate? Well, yes they have, and yes they are.

In fact, I heard my first class-D amplifier back in 2004, and there were commercial high-performance audio offerings of class-D amplifiers in the USA as early as 2002, and maybe a little before that. I fondly remember listening to the little class-D Sonic Impact T-amp with my audio pals Pete Riggle, Bill Van Winkle, and TASmanian-devil Stephæn Harrell (Stephæn wrote for TAS before he wrote for 6Moons), when they had stopped by for an impromptu visit and listening session back in 2004.

We were/are all fans of vinyl front ends driving DH-SET amplification to power horn-loaded loudspeakers, and yet we were all quite astonished that a class-D 'toy' amp like the Sonic Impact T-amp could sound as good as it did. As I mentioned in my 6Moons T-amp article back then, my friend Bill Van Winkle is a sightless master piano restorer who lives the absolute sound. At the time, Bill was working on restoring a beautiful 100-year old walnut grand piano that was so gorgeous that I was tempted to empty out my life savings to buy it - and I don't even play piano! You know a guy like Bill has got his priorities straight when he has more pianos than he has audio components.

We had all been listening to the Yamamoto 45 SET and a variety of other single-ended amplifiers at the time. Imagine that you were there listening with us, and then I blindfolded you and slipped the class-D T-amp into the system and asked you to comment on its sound ... what do you think you'd say? I guess it'd be pretty close to what Bill Van Winkle said: "Its sonic signature reminds me most of the Yamamoto 45. It is clean sounding with lots of detail and decent rhythm and pace. Not quite as smooth and musical but very good."

I'd like to point out to you that Bill Van Winkle's reaction was similar to Mr. Yazaki-san's reaction upon hearing the prototype class-D amplifier at the Pioneer R&D facility in 2006. Those two very different approaches to class-D amplifiers evoked comparisons to DH-SET amplifiers in those two 'golden-eared' gentlemen when they heard them.

So what's the big difference between back in 2004, and now with other commercial class-D amplifiers, from what Mr. Yazaki-san is doing with class-D amplification today?

The class-D amplification environment of today is similar to the vacuum tube environment back 40 years ago or so when the DH-SET movement started in Japan. Really? Yes, really. Forty years ago there were commercial vacuum tube amplifiers available, and DH-SET amplifiers like the now legendary American Western Electric 91A (300B) had been around since 1935 (and the 92A even earlier).

So what were those Japanese audio enthusiasts doing that was so different in the sea of vacuum tube amplification that were available to them then that caused Monsieur Jean Hiraga to go "Whoa!" when he heard their hi-fi systems? What was it that was different about what they were doing compared to everything else out there at the time?

The Enlightened Ear
I believe that much of the difference boiled down to this: Japanese audio enthusiasts who were developing those DH-SET amplifiers 40 years ago were uniquely prepared by their culture to listen for different parameters of musical performance than was typical for most Westerners at that time, and they developed DH-SET amplification (and assembled audio systems) that optimized those musical elements.

I will point out that people in different cultures around the world listen to music differently, by placing more attention on listening to certain aspects of music's attributes than is common to other cultures. It might seem surprising, but the truth is that not everyone hears things the same way as you or I do when listening to the same piece of music.

For example, in most of Western culture, the conventional way of listening to and interpreting music is for the ear to focus in on pitch and harmony first. Yet in the traditional cultures of Turkey, Africa, and Japan, the listener's ear focuses in on the textures and colours of the music first—that's called 'timbral listening' by ethnomusicologists.

I think that those Japanese audio enthusiasts developing DH-SETs and building Altec-Onken horn loudspeaker systems were more discriminating when it came to listening for the timbral aspects of music because of the tradition of timbral listening in their culture, and those particular components they chose & refined excelled in reproducing those timbral traits. Those enthusiasts continued to develop and refine those systems so that their presentation of music's timbral and color elements were truly profound, and their timbral listening emphasis was expressed through equipment choices that maximized those qualities to result in a very different presentation of music than many listeners in the West were used to at the time.

So I think what happened as this new-old timbral way of listening to music was introduced to the West, was that it was mistakenly interpreted as being about the unique sound of horn loudspeakers combined with DH-SET amplification and vinyl front ends, but in reality it was an introduction to a beautiful expression of a particular culture's unique way of listening to music, timbral listening, and that when some of us in the West heard it for the first time it was a true 'aha moment' that changed the way we thought about listening to music.

The whole point of what I've been getting at by relaying these stories to you is that I think the same thing that happened 40 years ago with vacuum tubes & timbral listening in the development of DH-SETs in Japan is now happening again with the latest generation of class-D amplification devices & timbral listening in Japan. I think we may very well be living in another 'big' aha moment in audio history comparable to the one that happened with the DH-SET movement in Japan now over 40 years ago, but this time using class-D amplification devices.

I think that the superb tone colour and rich timbral texture presentations are part of the reason that vacuum tube Japanese audio equipment from Kondo or Shindo, for example, have generated such a dedicated following among music enthusiasts, and those same aesthetic musical sensibilities that have informed their designs are now present in class-D amplification from Mr. Shirokazu Yazaki. So while the 'media' of their art forms differs in the amplification devices used, the beauty, tone color, timbral naturalness, and rich stereoscopic musicality that informs their designs is present in abundance in the SPEC RSA-M3 EX amplifier of Mr. Yazaki-san just as it is in those esteemed vacuum tube designs.

So here once again we have the 'enlightened ear' of a talented audio designer that has recognised and refined the possibilities of a promising amplification device, and this time it is in the form of a class-D amplifier instead of a directly heated single-ended-triode.

Let the fun begin!

The SPEC Corporation
First let me introduce you to the people behind the SPEC RSA-M3 EX Real Sound Amplifier.

All of the members of the team contributing to the design of SPEC RSA-M3 EX Real Sound Amplifier use to work as part of the professional design team at Pioneer in Japan.

Mr. Yazaki-san told me, "Banno-san is not only a skilful engineer but also a musician who plays the piano, and is now learning the cello too. When he was working at Pioneer he was the authority of the optical disk player, such as the LaserDisk, DVD, and Blue-ray disk players. Banno-san and Yamakawa-san have very sensitive hearing. I'm so lucky for having such a good team!"

Mr. Banno-san is on the left in the photo above with Mr. Yoneda-san, whom about Mr. Yazaki-san says, "He is an expert engineer working in Nichicon, a very famous electrolytic condenser maker in Japan. His hearing is so sensitive that the sound of our products owes much to his development work for Nichicon. We are so lucky for getting the best capacitors in the world, Nichicon in Japan, and Arizona Capacitors, Inc. in the USA, and further more to the supremely good sounding Mica capacitor!"

Mr. Yazaki-san went on to say, "Honda-san has a genius for audio circuitry. He has immigrated to the USA with his family, his wife and three children, and has been working at International Rectifier since 2001. Honda-san developed the excellent new class-D solution, and the prototype amplifier with Nishimura-san, and now has launched a new audio business sector for IR, and is its director. When he lived in Japan, he used to come to my house and we enjoyed listening to jazz music together with my old tube and horn speaker system, so he has a lot of experiences of splendid direct heated single ended triode sound. We are still good friends even though he lives beyond the Pacific Ocean in Los Angeles, California."

                                                  The SPEC RSA-M3 EX Real Sound Amplifier

The SPEC RSA-M3 EX Real Sound Amplifier is a 60-watt (8 Ohms) per channel stereo integrated amplifier with three RCA inputs and one XLR input. With a flip of switch the SPEC RSA-M3 EX can also be used as a dedicated amplifier with a preamplifier. 

Here's an interesting observation: The new-generation class-D amplification modules developed by Mr. Honda-san for International Rectifier specifically for high-performance audio use were informed by that same sort of listening insight into tone color and timbral textures that he and Mr. Yazaki-san enjoyed while listening to jazz on Yazaki-san's DA30 DH-SET stereo amplifier and his Altec & Onken horn loudspeaker system.

Mr. Yazaki-san says, "By employing Mr. Honda-san's latest developed class-D amplifier devices, the power MOS-FETs achieve highly accurate current switching in the power stage, and a high-voltage gate driver IC with excellent time-axis control maximizes the ultimate PWM switching. The exceptional performance of these class-D devices ensures ultimate real sound with quality damping in the mid to low ranges even when driving low-efficiency speakers. Furthermore, the sweet and rich tonal character in the mid to high ranges of the amplifier is almost like the tone of the very best triode tube amplifiers."

The audio board in the SPEC RSA-M3 EX is located at the final stage of the amplifier just before speaker terminals, and consists of a low-pass filter and a snubber circuit (an energy-absorbing circuit used to suppress the voltage spikes when a switch opens). Mr. Yazaki-san told me, "This filter and the circuit are very important for the sound quality. In other words, M3EX's tonal quality depends largely on the parts used in these circuits."

"You can see two hermetic oil-filled capacitors on the audio board made for us by Arizona Capacitors, Inc. Yes, these capacitors are custom-made for us and each capacitor has a different tonal character. One has a beautiful mid-to-high end, and the other has a rich mid-to-low range like a vintage capacitor."

"And another special quality part are the two little black cubic boxes you can see on the audio board, which are custom Mica capacitors that are custom made for us in Japan, and they are one of the best sounding capacitors of all ages for a signal capacitor. These days Mica capacitors are so rare to have, but they are wonderful sounding, highly transparent like a blue sky. The clarity of the Mica capacitors combined with the rich sound of the oil-filled capacitors gives the really incredible deep tonal character to the SPEC RSA-M3 EX."

"The ideal sounding capacitor does not exist so we blend these different types of capacitors to get our favourite sound. The same is true for our power supply.

In our DC power supply we use the latest Silicon Carbide (SiC) Schottky diodes, which provide a powerful and noise-free sound. We select the diodes by ear for the best sound, and we choose only best ones, often only one out of ten that we listen to. The efficiency of class-D amplifier is far higher than any other semiconductor amplifier, and it runs up to 96% efficiency at full power. A traditional class-A or class-AB amplifier's final stage efficiency is only 20 to 30%. So these types of amplifier need big heat sinks. Our class-D amplifier is very sensitive to the quality of the power supply. Yes, we could say, the quality of the power supply determines directly the final sound quality. So we blended three types of capacitors, and this parallel connection of the capacitors reduces ESR (equivalent series resistance) in the entire range, which leads to a clear and also powerful sound. The oil-filled capacitors could compensate the mid to high range characteristic of electrolytic capacitors and bring out high speed, rich tonal character."

Our power switch is a type of switch used only for professional-use, for example in aircraft. It has high capacity and is very rugged."

I would also add that it is a very interesting power switch to use, and it has a very deluxe feel to it. It sure is a lot nicer than any of the switches in the old Cessna 150 aircraft I owned as a kid! To turn on the amplifier you first pull the spring-loaded locking switch out, and then switch it into position, and it locks in place. I've never encountered one like it before.

 "The selector switch is made in Japan for use in instruments for the communications industry." 

The wires are Belden 1503A, which we found in our evaluations to be one of the very best cables for inner signal use. The switch is hand-assembled by a technician, and is a higher-quality successor to the style of switch assembly used in the Marantz model #7 for input selection."

"The SPEC variable resistor is not your usual variable resistor, and no signal current flows in this variable resistor. It only works as a position-sensitive detector, and there is a very precise electronic volume device in our class-D amplifier unit that decides the gain of amplifier according to the information from this detector. We regard this variable resistor as very important for the tactile feeling of adjusting the volume, so we custom order it with a special curve and torque for just the right feel. The resistor is sealed for long-term reliability."

"The input selector and volume knobs are made for us in Japan."

The base of the RSA-M3 EX 's chassis is made of a solid laminated panel of European spruce from Austria. Mr. Yazaki-san says, "Spruce has long been used for the top plate of stringed instruments and the soundboard of pianos, and is known as a material with excellent sound quality that provides quick vibration transmission and moderate damping."

I thought that the spruce base for the RSA-M3 EX's chassis was intriguing, and I don't recall seeing anyone doing that before. My Gibson Advanced Jumbo guitar has an Adirondack spruce top and Brazilian rosewood back and sides (above), and it sure sounds fine. Also, in the photos of my listening / living room in my various articles at Positive Feedback Online you'll notice that all my audio equipment is on natural wood supports, like my solid walnut rack for my vintage McIntosh gear and turntable, including my Duelund external crossovers, and all the Sablon Audio Panatela speaker cables. Wood just makes audio gear sound better.

Mr. Yazaki-san, went on to say, "The combination of this material with the rigid steel chassis produces a rich and pleasant sound. The footers on the bottom of the wood base are a combination of pure painted maple from Hokkaido, Japan, and hickory from North America. Maple has excellent strength and is used in combination with spruce for the sides and backs of stringed instruments. Hickory is a hard material that absorbs impact well and is used for drumsticks, for example. The maple and hickory moderates the resonance of the spruce to help provide a rich musicality."

From the development of the class-D amplifier modules, to the selection of every single component that makes up the SPEC RSA-M3 EX Real Sound Amplifier, Mr. Yazaki-san and the entire SPEC team paid serious attention to voicing the amplifier to sound as musically satisfying as the transparent, beautiful tone colour, rich, and dynamic nature of the DA30 DH-SET reference amplifier.

                                                   The SPEC RSP-901EX Real Sound Processor

In addition to the SPEC RSA-M3 EX Real Sound Amplifier Mr. Yazaki-san also sent along a pair of the SPEC RSP-901 EX Real Sound Processors for me to listen to. The retail price for the SPEC RSP-901Real Sound Processors will be somewhere around $1000 USD a pair by the time they reach your dealer's showroom.

The SPEC RSP-901 EX Real Sound Processors are designed to reduce the fluctuations of loudspeakers' impedance over the frequency spectrum, while absorbing the return current from the speaker and its potentially deleterious effect on amplifier performance via a network of inductors.

The binding posts of an RSP-901 EX,onnects to the loudspeakers binding posts via a speaker cable 'pig-tail' (below on my Harbeth Super HL5s). 

Mr. Yazaki-san told me that using the RSP-901EX can result in a pretty dramatic improvement to the sound quality of a pair of loudspeakers, by making them sound more clear, natural, and musical throughout their range.

Inside the spruce enclosure are hand-picked components for the best sound quality: "…state-of-art hermetic seal oil-filled capacitor, named "Green Cactus" series made in USA, by Arizona Capacitors, Inc. …the resistor adopted… which has the smoother and more open air character…" and "…please pay attention to the appearance of RSP-901EX. It's like a jewelry box made of real spruce from North America with string instrument's color."

The idea for the RSP-910 EX came from an article in MJ magazine by Mr. Yasui in 1971 about impedance correction for loudspeakers. The relationship between a loudspeakers impedance variation with frequency, the resulting return electromotive force from the speaker to the amplifier, and the output of an amplifier driving the speaker based on the input signal, is a fairly complex relationship. It's a lot of variables for an amplifier to deal with, and a lot of things that an amplifier has to react to and get right for the best sound. Mr. Yazaki-san told me that solid-state amplifiers are more affected by this complex interaction than are vacuum tube amplifiers, but both can benefit from installing the RSP-910 EX, which minimizes the effects of the loudspeakers' impedance variation with frequency, and the resulting return electromotive force from the speaker, making life easier on the amplifier, so that it performs better.

Review Systems
For this review I used both of my current hi-fi systems, the smaller Harbeth Super HL5 and Leben based system I use in my listening/television room, and my Tannoy & vintage McIntosh system that I use in my larger living room space. They're both fantastic systems for the music lover!

In my small-room system I use Harbeth Super HL5 loudspeakers on Skylan 18-inch stands, Acoustic Revive Single Core speaker cables, the Leben CS-600 integrated amplifier, Acoustic Revive Single Coreinterconnects, the Leben RS-30EQ phono equalizer, an Auditorium 23 '103' style step-up transformer, Acoustic Revive Power Reference AC power cords, a VPI Classic turntable fitted with an EMT TSD-15 phono cartridge, an Oppo BDP-83 Blu-Ray player, an Apple TV & Roku for streaming duties, and a 42-inch Philips TV.

In my living room system I use Tannoy Westminster Royal Special Edition loudspeakers with Sablon Audio Panatela internal cabling, and the superb Duelund CAST external crossovers. Sablon AudioPanatela speaker cables connect to my restored vintage McIntosh MC225, MC30, and MC240 valve amplifiers, with Sablon Audio Panatela interconnects connecting the amps my restored vintage McIntosh MX110Z valve tuner-preamplifier, and a vinyl front end consisting of an Artisan Fidelity Statement Plinth in Macassar Ebony with Stillpoints Ultra isolation feet, a Classic Turntable Company modified Garrard 301 (Classic 301) with a brass platter, mounted with two of Thomas Schick's tonearms, one for mono with an Ortofon SPU Mono CG 25 Di MkII, and the other for stereo with an Ortofon SPU Classic GM MKII. Sablon Audio Gran Corona AC power cords connect my iMac & Mhdt Labs Havana USB DAC. A long pair of Acoustic Revive Single Core interconnects connects the Havana to my Mac preamp.

Listening Impressions
I listened to the SPEC RSP-901EX Real Sound Processor using my small room system, with the combination of my Harbeth Super HL5 loudspeakers and the SPEC RSA-M3 EX amplifier. I did not use the Real Sound Processors on the outboard Duelund crossovers on my Westminsters, as I would really need to use two pairs of Real Sound Processors, which I did not have access to.

Being unfamiliar technology, I wasn't really sure what to expect from the RSP-901EX Real Sound Processors, and I wondered if I'd even be able to hear a difference. In retrospect, I shouldn't have wondered, and I really liked what I heard them do with my Harbeths.

While I already mentioned the operational principles behind the SPEC RSP-901EX Real Sound Processors, let me summarise what Mr. Yazaki-san told me, and then briefly expand on the loudspeaker-amplifier frequency-impedance interaction that the RSP-901 EX is designed to improve. Basically, the RSP-901 EX is designed to provide an impedance correction for loudspeakers, whose impedance varies with frequency. There's a fairly complex relationship between an amplifier driving the speaker, and the speaker returning variable impedance based on frequency to the amplifier that it has to deal with while driving the loudspeaker. Minimising this interaction helps the amplifier perform better.

Right after listening to the SPEC RSP-901EX Real Sound Processors on my Harbeths, I had a conversation with my friend Siedy in the Netherlands, and the Dutch amplifier designer Jan Hut, who designed the 'Chaos' amplifier that Siedy uses to power his Westminster Royal loudspeakers, that has relevance for this topic.

Jan told me, "At the base of all amp designs stand engineers who learned to develop amplifiers the same way I did. That's because we all had teachers that think the same way on how you design amplifiers. Mostly they think that more is better, and a better measuring result will also be better to listen to music with. Even though measuring instruments do not know what better sound means, we think they do. The problem occurs in the feedback loop. An amp without feedback runs only one signal, the audio signal. It's not all that simple, but for now it will do. If you amplify that the right way it appears at the output, then goes to the speaker, and then back to the power supply. When you apply global feedback the amps sees more signals to work with. First the original input signal, and then the amplified signal that is sent back by the loudspeaker. The signal is passed along by the amp with a little delay and, and the amp has made little mistakes during the amplification process, which people try to compensate for by adding feedback, but then phase problems become an issue because the amp is comparing and compensating for these two signals. An average amp does not have any intelligence to do so, and it has no ears either, so new mistakes are made and enter the amp by the feedback and so on."

"The big bass signals are strong and stay rather unaffected, but the very small ones are affected, the ones that give us a part of the big spacious sound and three-dimensional picture. There is also another signal disturbing the audio signal when applying feedback, and that is the signal the speaker generates. The damping of the amp has to take care of that through the feedback loop also and so a third signal appears at the entrance of the amp and it tries to make the best of it. When you start adding even a small amount of feedback you can hear the spacious soundstage become smaller. So what we are asking is what's worse, letting the amp make a few mistakes we can't hear, or to introduce a lot of other signals by means of the feedback that the amp then has to deal with."

Jan's discussion was about the same phenomena that Mr. Yazaki-san told me about related to the complex interaction between the amplifier driving the loudspeaker, and the loudspeaker pushing back and 'driving the amplifier' which degrades the amplifier's performance by having to deal with multiple interacting signals. In Jan's case he told me about how he designs his amplifiers to minimize the deleterious effects of the loudspeaker-amplifier by using zero negative feedback designs, but Mr. Yazaki-san's idea is to introduce the SPEC RSP-901EX Real Sound Processor into the loudspeaker-amplifier relationship to help minimize the frequency-impedance variation interaction to improve the performance of any loudspeaker-amplifier combination. That's a cool idea.

Let me say that I listened to quite a lot of various types of music with the SPEC RSP-901EX Real Sound Processors installed on my Harbeth Super HL5 loudspeakers, and I found them to perform consistently & predictably across genres, but I'll limit myself to just a couple of examples to describe what I heard, then I'll move on and discuss the SPEC RSA-M3 EX Real Sound Amplifier.

On the Counting Crows' August and Everything After CD I swapped in and out the RSP-901EX Real Sound Processors while keeping the volume identical. The result was significant: the album's overall sound became warmer and richer, all of the images gained additional body & size and moved forward in the soundstage towards me, the sense of space in the soundstage became more expansive and 'darker'. On the emotive front, I thought the emotional connection was enhanced by the changes wrought by the RSP-901EX Real Sound Processors, the tone color became more intense, timbral textures became richer and more organic sounding, with the whole presentation of the music becoming less electronic sounding, and generally just more musically satisfying. Additionally, there was a more engaging 'feel' to the music, or maybe another way to say it was that the music felt more present in the room with me. The RSP-901EX Real Sound Processors worked as advertised, and I liked the improvement I heard from them when they were hooked up to my Harbeths.

On the Beautiful Dreamer Songs of Stephen Foster CD there's lots of great music by artists as diverse as Raul Malo, Allison Krauss, Yo Yo Ma, BR5-49, John Prine, Michelle Shocked, Mavis Staples, Roger McGuinn, and Ron Sexsmith, to name a few of the contributors. If there's ever an album that's begging to be released on 45RPM vinyl it's this one. Until then you can count on the RSP-901EX Real Sound Processors delivering the maximum emotional connection to the music from the CD, with rich tone, delicious timbral textures, a more natural presentation of vocal sibilants, an expansive sense of space, and an immersive 'in the room with you' presentation of the music.

Perhaps the most flattering thing I can say about the RSP-901EX Real Sound Processors' contribution to the performance of the Harbeth & SPEC RSA-M3 EX amplifier combination, is that when I had them hooked up to the Harbeths I tended to just get lost in the music more, and think less about the comparative listening process for the review. The RSP-901EX Real Sound Processors really let the emotional connection of the music shine through. The Harbeth Super HL5 loudspeakers & SPEC RSA-M3 EX Real Sound Amplifier combination sounds great, and it sounds even better when the RSP-901EX Real Sound Processors are hooked up to the Harbeths.

I replaced the SPEC RSA-M3 EX Real Sound Amplifier with my Leben CS-600 integrated amplifier, and did some more comparative listening with the SPEC RSP-901EX Real Sound Processors on & off the Harbeth Super HL5 loudspeakers.

Mr. Yazaki-san had mentioned to me that the magnitude of improvement the SPEC RSP-901EX Real Sound Processors provide was greater for solid-state amplifiers than it was for tube amplifiers, so I was expecting to hear a more modest improvement with my Leben CS-600 in the system. However, contrarily I found that the magnitude of improvement from the SPEC RSP-901EX Real Sound Processors was much greater with the Leben CS-600 than it was with the SPEC RSA-M3 EX Real Sound Amplifier. Perhaps the SPEC amplifier is already designed in such a way to minimize this loudspeaker-amplifier interaction?

The resulting changes from the SPEC RSP-901EX Real Sound Processors with the Leben CS-600 were of much the same nature (albeit greater in magnitude) as with the SPEC RSA-M3 EX Real Sound Amplifier: the overall sound became warmer & richer, the images gained additional body & size and moved forward in the soundstage, the sense of space in the soundstage became more expansive and 'blacker', with the whole presentation became less electronic sounding and more natural sounding, and generally just more musically satisfying.

I particularly recommend the RSP-901EX Real Sound Processors to my fellow Leben & Harbeth owners. If I may tickle your sense of intrigue a little, I think I can safely say that you haven't heard how good your Leben CS-600 integrated amplifier or Harbeth Super HL5 loudspeakers can sound until you've heard them with a pair of RSP-901EX Real Sound Processors helping them along. The SPEC RSP-901EX Real Sound Processors are one of those no-brainer products that can you buy, install in your system, marvel at the result, and never look back.

The Leben CS-600 & SPEC RSA-M3 EX Comparison

I think a lot of people will be interested in the comparison between the 'gold standard' Leben CS-600 vacuum tube integrated amplifier (my long time integrated amplifier reference) and the SPEC RSA-M3 EX class-D integrated amplifier. There is a bit of a price mismatch between the two, with the Leben CS-600 being around $6,500 USD, and the SPEC RSA-M3 EX being in the neighbourhood of $9,500 USD. However, the Leben has a reputation of being a giant killer, so lets check out how it fares against the exotic SPEC RSA-M3 EX Real Sound Amplifier.

The Leben CS-600 vacuum tube integrated amplifier really turned my head when I reviewed it back in 2007, and it has been a constant fixture in my small-room system since then. The Leben CS-600 also wowed a lot of people with its superb performance at the Salon & Image Show in Toronto in the years following that review, including the cast of excellent Stereophile writers like Stephen Mejias, John Atkinson, Robert Deutsch, John Marks, and Art Dudley, who heaped praise upon it.

If I were to blindfold you and play a little music for you on my Harbeth Super HL5 loudspeakers based system with both the Leben and SPEC integrated amplifiers, and then asked you which amplifier was the vacuum tubed amplifier, I bet 8 out of 10 of you would pick the SPEC RSA-M3 EX as the tube amplifier.

That's right, in an intriguing morphing of perceived reality the solid-state SPEC RSA-M3 EX sounds more like I think most people would imagine a vacuum tube amplifier to sound than the actual vacuum tube Leben CS-600 integrated amplifier does


The Leben CS-600 and the SPEC RSA-M3 EX amplifiers have considerably different voicing when it comes to their overall sonics & musicality, yet both of these integrated amplifiers are eminently musical devices that I think anyone would be overjoyed to own.

Using a broad brush, the SPEC RSA-M3 EX sounds tonally richer, warmer, darker, smoother, has a more relaxed & colorful presentation, and sounds more timbrally natural than the Leben CS-600.

The Leben CS-600 and SPEC RSA-M3 EX are both capable of throwing a wide & deep soundstage, and they both present a similar sized soundstage for a given recording, but what I heard within the soundstage was very different for these two amplifiers.

If the SPEC RSA-M3 EX Real Sound Amplifier's sound was a photograph, the slider for 'structure' would be set to the middle 'natural' position, with nothing added or taken away from the natural level of detail your eyes would perceive in the images contained within the photograph. The SPEC indeed does have 'real sound' just like the name says, but 'real' in the sense of how your ears hear 'real live music' in life, with natural levels of brightness, detail and micro-contrast, as opposed to the enhanced sense of 'structure' that the Leben CS-600 has.

The Leben CS-600 has the sonic 'structure' slider moved a little to the right of natural, being brighter, with more fine details that pop out, and with micro-contrasts that are more pronounced. The Leben's is not an unpleasant portrayal of the musical 'film' but it is more than you would usually hear at a concert in life, and not quite as natural sounding as the SPEC RSA-M3 EX's level of structural detail.

Staying with the Viveza analogy let me talk about the 'brightness' slider that controls the overall lighting level in a photograph. If you slide the brightness slider to the right the overall image gets brighter, and if you slide it to the left the overall image gets darker. In this context, the soundstage through the Leben CS-600 was brighter, like someone turned up the lights on the stage. The SPEC RSA-M3 EX was just the opposite, and it was like someone turned down the stage lights, giving a darker presentation of the same expansive soundstage. In aural terms this gave the Leben CS-600 a shimmering quality—a sort of 'glamor glow'—to the sense of space within the soundstage. Listeners who enjoy an enhanced sense of space from a recording will like that sonic feature of the Leben CS-600. I will point out that when you listen to live music that you don't really hear this enhanced 'sense of space' effect, it's something that comes from recorded music that doesn't exist to any extent in real life, rather it's a pleasant artifact from the recording process. Through the SPEC RSA-M3 EX you get a more natural, but diminished, sense of space, and more like you hear in a concert with live music.

At the risk of wearing out my Viveza analogy, I will mention one final aspect related to 'contrast'. When you move the Viveza 'contrast' slider to the right you increase image contrast by making the darker tones deeper and lighter tones brighter. This makes darker colors look more deeply saturated and lighter colors look brighter, and the image looks a little darker but more colorful overall. If you move the contrast slider to the left the darker tones get lighter and the lighter tones get slightly darker, with the overall effect being that the image looks somewhat bleached out and less colorful overall. In this case the Leben CS-600's level of aural contrast is almost exactly in the middle, whereas the SPEC RSA-M3 EX has the contrast bumped up a bit to the right, resulting in deeper tonal colors, and a darker and more contrasty overall aural presentation of the music. The SPEC's is a very beautiful presentation of tone color.

Now let me put all those comments about structure, brightness, and contrast into context as to how they affect overall resolution, transparency, soundstaging, sense of soundspace, and imaging.

The Leben CS-600 has more resolution compared to the SPEC RSA-M3 EX, and it gives a more detailed representation of a recording than does the SPEC. The SPEC RSA-M3 EX has less resolution than the Leben CS-600, yet it is more comparable to the amount of detail I actually hear when listening to live music, and in that sense it is more accurate and realistic.

Both the Leben and the SPEC have similar levels of aural transparency back into the depths and widths of their soundstages, and they both present similar recorded width & depth for a given recording. I found that a little bit counterintuitive given the more brightly lit presentation of the Leben, as I thought that would allow me to hear more deeply into the soundstage, but it did not. They have roughly equal transparency even though the Leben is brighter and the SPEC is darker overall.

As I mentioned earlier, the Leben CS-600 has an enhanced sense of soundspace compared to the SPEC, which gave the Leben CS-600 a shimmering quality—a sort of 'glamor glow'—to the sense of space within the soundstage. Listeners who enjoy an enhanced sense of space from a recording will like that sonic feature of the Leben CS-600. This is a sonic 'enhancement' on the Leben's part, albeit an enjoyable one, but the SPEC actually comes closer to sounding like a normal acoustic signature you hear when listening to live music in a natural acoustic setting.

The way images are presented on the soundstage for the Leben and SPEC differ quite a lot. The first difference is in image size, where the SPEC consistently delivered larger sounding images than the Leben. It's a little bit like the difference I see when I use a 35mm lens on my Leica M9 camera compared to a 50mm. The 35mm lens puts images further from me so they look smaller. The 50mm lens puts images closer to me so they look bigger, and for some reason the 50mm images look more like I see images with my unaided eyes. Likewise, the SPEC's images sound more life-sized to me, with the Leben's images being somewhat more miniaturised in comparison, so the SPEC seems more naturally life-like to me in the way it images.

The images on the soundstage with the Leben were more holographic, and the edge outlines of the images were more defined. The SPEC's images had more diffuse edge outlines, but were more solid in a natural flesh & blood sort of way, and the Leben's holographic images were a little more transparent and a little more 'ghost-like'. So on the imaging front I think the SPEC produces images that are more like I hear when I listen to live music, yet the Leben's presentation of images can be quite enchanting in an audiophile sonics sort of way.

Ok, up until now I've been mostly talking about how these two integrated amplifiers are voiced from an audiophile-style 'sonics' perspective, but lets take a closer listen to how they handle the actual fabric of the music, from a 'timbral realism' perspective in the context of textures, colors, and tones & overtones of the music; and also in the way they handle tempo, melody, harmony, rhythm, dynamics, and loudness.

If you've read between the lines in my descriptions above you've already guessed that the SPEC's voicing provides more 'timbral realism' than does the Leben CS-600, and I think that instruments sound more like themselves through the SPEC. The Leben resolves more information, and that can be interesting, but it gives more timbral information than you'd usually hear in a concert, so the timbral textures aren't quite as convincingly natural as the smoother & richer, more texturally accurate presentation of the SPEC. The result is that the SPEC's combination of rich, smooth, dark, colourful tone is more like I hear in life, while the Leben's more detailed and more tonally neutral presentation makes it easier to pick instruments out of the recording's mix.

When it comes to dynamics I think the Leben CS-600 is the more dynamic of the two, and that it infuses melodies with an extra little bit of pep as they move along. Tempo-wise, I think the Leben CS-600 sounds more energetic, and it highlights the differences in the speed of tempos to a greater extent, which makes it exciting to listen to, particularly on music with faster tempos. The SPEC is smoother and more relaxed sounding than the Leben, and while you can definitely tell the difference in tempos, the difference is not as pronounced as with the Leben. The increased resolution of the Leben makes harmonies more obvious, but not necessarily as realistic sounding as the SPEC, whose smooth, rich, colourful presentation blends harmonies beautifully together in a very naturally lifelike and sonorous fashion.

One area that the SPEC clearly trounces the Leben is in its ability to play loud. As volumes increase the Leben CS-600 is less composed than the SPEC RSA-M3 EX, which sails along unperturbed through loud passages that leave the Leben sounding a little strained and 'shouty' in comparison. The rich, smooth, colourful & darker balance of the SPEC really becomes an asset as the volume levels go up, and it makes listening at loud levels very gratifying.

Well that's enough of picking apart the performance of these two superb integrated amplifiers in my Harbeth Super HL5 based hi-fi system. While I feel obligated to delve into the details of their performance and to try to articulate it for you to give you a better idea of what makes them tick, it is in some ways a disservice to both of these integrated amplifiers, because a reductionist approach to aural analysis hints that the complexities of these amplifiers performance is nothing more than the sum of their sonic & musical parts, which is in fact rather grossly misleading.

There's a reason that the Leben CS-600 has won so many accolades from the audio press, and that it has remained my gold standard for an integrated amplifier for so many years, as it is a ridiculously good amplifier that is a blast to listen to music with. The strengths of the Leben CS-600's voicing is that it has an articulate, almost delicate, charming sonic palette, with a brightly lit enhanced sense of space, a sweet presentation of enhanced detail, a lively sense of tempo, and a bright, bubbly, upbeat presentation of melodies that makes music very compelling to listen to. You can also entertain yourself for a lifetime swapping in and out a broad variety of different vacuum tubes to tailor its overall sound to your tastes. If the Leben were a wine, it would be superb champagne, with bubbles tickling your tongue, and a clean, crisp, delicious flavor, whose presence makes every day life feel like a celebration. The Leben CS-600 on its own is a winner, plain and simple, and if you own one you should pat yourself on the back for making such a wise choice.

Hang onto your hat though, as I really, really, liked what I heard from the SPEC RSA-M3 EX on my Harbeth Super HL5 loudspeakers, it too is a spectacularly good sounding integrated amplifier, and I liked it even better than my Leben CS-600, and by quite a bit. I think the SPEC RSA-M3 EX sounds more like live music does in real life than the Leben does. The SPEC is easy on the ears too with its rich, naturally detailed timbral textures, its dark & warm sound, and its deeply beautiful tone color. The SPEC has a laid back and relaxed presentation, which conveys an emotional wallop like the laidback romanticism of a late night jazz club, but can still crank out the volume when it needs to. To extend the wine analogy, the SPEC is like a really superb Pinot Noir that is full of elegance & refinement, an exotic bouquet, velvety texture, and a flavor infused with hints of ripe red fruit, cherries, chocolate, and spices. It's delicious, and I think it rewrites the book of what you can expect sonically & musically from an integrated amplifier's performance. The SPEC RSA-M3 EX really does deliver on a DH-SET style of sound that is beautiful, rich, colourful, with great tone, and with intense musicality.

Did I like the SPEC better than my Leben CS-600 on my Harbeths? Yes I did. At $9500 USD for the SPEC RSA-M3 EX you would expect it to outperform the Leben CS-600 at $6500 USD, and it did. My Leben CS-600 isn't going anywhere though, I still love it, and I plan to continue using it as a reference for a good long time to come.

The Tannoy Westminster Royal Special Edition loudspeakers and the SPEC RSA-M3 EX

Now lets talk about the performance of the SPEC RSA-M3 EX Real Sound Amplifier driving my TannoyWestminster Royal Special Edition loudspeakers, which have been hot-rodded with the ultra-performance Duelund Coherent Audio CAST external crossovers, and wired internally with the superbSablon Audio Panatela cabling.

I've really been enjoying the combination of my restored vintage McIntosh MX110Z tuner/preamplifier and McIntosh MC225 stereo amplifier powering my West's, and the musical results I'm getting from that vintage Mac duo with the WRSEs has been the best I've ever heard, in spite of the vintage Mac pairing's relatively modest price.

Yves Beauvais restored and hand-voiced my little MC225 stereo amplifier. Among Yves' talents are the production of record albums, like the collected Ornette Coleman recordings on Atlantic, Beauty is a Rare Thing, Jorma Kaukonen's Blue Country Heart, and many more. So Yves really knows the whole recorded music process from recording to playback, and the way he voiced my little vintage McIntosh MC225 really highlighted his talents with its astonishingly natural musicality.

You can use the SPEC RSA-M3 EX as an integrated amplifier or as an amplifier only with the flip of a rear panel switch, so I flipped its switch and put it in its 'amplifier only' mode, and dropped it into the system in place of the beguiling little McIntosh MC225 stereo vacuum tube amplifier.

The SPEC RSA-M3 sounded natural and transparent, with lifelike tempos & melodies, and with a sense of space, holographic imaging, treble 'sparkle' and tactile presence of fingers on instruments, that came close to that of my hand-voiced MC225. The SPEC didn't have that extra little bit of 'glamour glow' effect that my vacuum tube MC225 did, but it sounded very, very, good.

A short listen to the SPEC RSA-M3 EX on my Westminsters told me that it was a world-class amplifier, but it was also clear to that its performance was held back by my MX110Z tuner-preamplifier. So while the SPEC RSA-M3 EX worked well in its amplifier-only mode, it was clearly at its best with my big Westminsters when used as an integrated amplifier.

For the rest of the review I partnered the SPEC RSA-M3 EX with the New Valve Order SPA-II phono equalizer for vinyl duties with my Garrard Project 2015 player system (feature article to come), consisting of an Artisan Fidelity Statement Plinth in Macassar Ebony with Stillpoints Ultra isolation feet, a Classic Turntable Company modified Garrard 301 (Classic 301) with a brass platter, mounted with two of Thomas Schick's tonearms (one for mono with an Ortofon SPU Mono CG 25 Di Mk II, and the other for stereo with an Ortofon SPU Classic GM MKII). I connected the SPA-II to the SPEC with a pair of Acoustic Revive Single Core PC-TripleC RCA interconnects.

For digital duties I used my iMac with an Mhdt Labs Havana USB DAC, connected to the SPEC RSA-M3 EX with a very long pair of Acoustic Revive Single Core interconnects.

I absolutely adore listening to the superb Jazz24 stream, and I have it going almost all the time when I'm at home, while listening, lounging, or being a chef, and the fidelity is surprisingly good considering it's a stream. Jazz24 plays a broad selection of material too, from ancient crackly old jazz albums, all the way to jazz that is hot off the fretboard, and as such it gives me a lot of diverse material to quickly see how well a component performs across a wide range of music.

As an integrated amplifier the SPEC RSA-M3 EX really showed what it could do on the big Westminster Royal SEs. With the Jazz24 feed going directly into it, with no vintage McIntosh MX110Z tuner-preamplifier in the signal path before it, the sound was remarkably good, on par with—but not identical to—my vintage MC225 & MX110Z McIntosh combination, and from me that is high praise indeed.

The SPEC displayed superbly natural timbre & presence, with a smooth, rich, colorful, and musical presentation from material as diverse as 'Kathy's Waltz' from the Dave Brubeck Quartet's Time Outalbum, to '5-10-15 Hours' from Ruth Brown's Rockin' in Rhythm - The Best of Ruth Brown album.

The SPEC also threw a big 'they are here' style of soundstage into my room, with lots of natural detail, a voluminous sense of space, solid images that layered back into the soundstage nicely, and a relaxed live-like musicality that only the very best equipment can produce. In short, over the review period the SPEC impressed me with its sheer musicality and timbral realism that always made music enjoyable and edifying to listen to.

Ok, now that I have established that the SPEC makes digital media your friend, let's move on so I can tell you about what listening to vinyl records with the SPEC Real Sound Amplifier powering the big Westminster Royal SEs was like.

When I queued up the Analogue Productions 45RPM version of The Ray Brown Trio's Soular Energy on my Garrard Project 2015 player system I was immediately impressed by the sheer scale and presence of the music emanating from my Westminster Royal SE loudspeakers with the SPEC Real Sound Amplifier driving them. The images were totally life-size and had a 'they are here' reach-out-and-touch them presence in my living room that was really satisfying. On 'Easy Does It' the SPEC allowed Gene Harris' piano to positively sparkle with tone color and a compellingly vibrant melody line, with Ray's upright bass coming through with a lot of timbral realism, sounding just like an upright bass should in texture and tone, and Gerryck King's drum kit sounded realistic and tangibly present. On 'Mistreated But Undefeated Blues' the SPEC Real Sound Amplifier really gave the music swing & momentum, with a clear view into tempo and melody lines. Emily Remler's jazz guitar solo was superb, as was Red Holloway's sax solo, and they really had swing, momentum, and an engaging melody line. On Soular Energy the SPEC Real Sound Amplifier delivered music that was timbrally correct, full of color & life, and was intensely beautiful & emotional engaging.

The mono 45RPM Boxcar reissue of Julie London's Julie Is Her Name, Vol. 1, album, is beautifully done. The Boxcar reissue was mastered by Bernie Grundman from the original Liberty mono analog master on his all-tube disc cutting system, and pressed at RTI on two 180-gram records. I listened toJulie Is Her Name with the Ortofon SPU Mono CG 25 Di Mk II cartridge, which really brought out the considerable best in it (Thanks to Art Dudley for recommending this cartridge to me!).

On Julie Is Her Name, jazz guitar god Barney Kessel, and bassist Ray Leatherwood, accompanied Julie London to excellent effect. Through the SPEC Real Sound Amplifier Julie's vocal, Barney's guitar, and Ray's bass sounded astonishingly natural and 'real' on 'Cry Me A River'. The SPEC brought a high level of timbral realism and tone color to Barney's guitar and Ray's bass, and the sense of tempo and of the melody flowing along was just perfect. Natural, rich, beautiful presentation of tone color, musically engaging, and timbrally correct, describe the SPEC to a 'T'.

My buddy and vintage audio expert, Ron Barbee, stopped by for a visit while I was writing this up, and I put Julie Is Her Name on so he could hear the SPEC Real Sound Amplifier with the Garrard 2015 player system running the mono Ortofon. We ended up playing quite a few records, both mono & stereo, for some fun listening time. Ron's very familiar with my system, and I asked him what he thought of the SPEC in it. "It doesn't do anything wrong at all, and the SPEC's one of the best sounding amplifiers I've heard," said he. We talked about the SPEC and how its highs were spot-on perfect and natural sounding too, and Julie's vocals were stunningly natural, with absolutely no unnatural sibilance. The bass response was extended and full of nuance, and even though it was only 60 watts, the SPEC could really deliver the dynamic swings when called upon. The SPEC was deceptively powerful, and when loafing along it sounds only about as powerful as my 25 watt MC225, but when you really crank it up it never misses a beat and sounds astonishingly good, even at very loud 'blow out the windows' levels. In short, when we sitting there listening to the SPEC play music we came to the conclusion that it was one of the most perfectly voiced amplifiers we'd ever heard.

We also listened to the superb Cowboy Junkies' The Trinity Sessions. If you haven't yet experiencedThe Trinity Sessions I suggest you correct that oversight right now, as it's one great bit of music making, as well as being an audio benchmark of the sonic sorts. I love those good old mono records played back with good mono cartridges like the Ortofon, as they display amazing tone, timbre, and color, but listening to a record like The Trinity Sessions reminded me pretty quick that there are amazing aspects about great stereo records as well. The SPEC displayed the huge sense of space of the recording, filling my listening room with it, and the soundstage was at least triple the width of what you hear on even really good mono recordings. My take on things is that it's good to play back the mono vinyl you love with a dedicated mono setup to get the best out of that format, and to play back stereo masterpieces like The Trinity Sessions with a good stereo front end to get the best out of the stereo format, and to use a really great amplifier like the SPEC Real Sound Amplifier to get the best out of both of them.

One thing I really appreciated about the SPEC Real Sound Amplifier was that regardless of whether the source material was mono records, stereo records, or digital streaming, the SPEC drew the maximum amount of the music from them. A case in point is when musician, former model, and physicist friend Cindy dropped by, and I played her some of the same records I played for Ron. Cindy loves music, she's not an audiophile, but she readily hears what's going on with the music and the audiophile sonics. We started with a couple of nice mono records, Julie Is Her Name and Masterpieces by Ellington, and Cindy commented on the realistic and natural sound of the SPEC Real Sound Amplifier, and how good the recording of Duke's piano was on Masterpieces, and how good the SPEC was at delineating the tempo and time signatures. Cindy also noted that to get the most from a mono record you had to sit in the sweet spot evenly between the loudspeakers, but with stereo you had a much broader choice of seating position to get great sound.

Everyone who has heard the SPEC Real Sound Amplifier, including Cindy, has made the comment of how rich and natural the SPEC sounds (in a timbral and tone color sense), and Cindy added how it drew out many subtleties in the music, and had an ability "to remind you that recordings from your past are 'old friends'". I thought that the last was a particularly interesting comment, because the SPEC does indeed have an exceptional ability to portray music's emotional impact. It reminds you of how you felt when you heard the music for the first time, and it brings back all those feelings in a flood as you listen to the music. The SPEC infuses music with the same sort of intensity of emotions you experience when you sit down with an old friend to reminisce about past times, and the flood of emotions that comes with it.  

Summary & Conclusions

At the start of this article I mentioned that the SPEC RSA-M3 EX Real Sound Amplifier from the 'enlightened ear' of Mr. Shirokazu Yazaki in Tokyo, Japan, sounded shockingly good by every musical and sonic measure that I consider important when reviewing audio equipment.

Mr. Yazaki-san has artfully voiced the SPEC Real Sound Amplifier to be timbrally realistic, tonally colorful, evenly balanced from top-to-bottom, with sweet & natural high frequencies, a deliciously rich & liquid midrange, and a tight & tuneful bass. Tempos, time signatures, melodies, and harmonies were full of musical revelation in a very natural and 'live music' sort of way.

The SPEC Real Sound Amplifier has a way of making music your friend, whether it is mono or stereo vinyl, an FM broadcast, or a digital stream, and it has a rather unique ability to infuse listening to an old familiar music with the same sort of emotional intensity that reminiscing with an old friend evokes.

On my Westminster Royal SE loudspeakers, the SPEC Real Sound Amplifier provided some of the most musically satisfying and emotionally impactful musical performances I've ever heard coming from them.

Does the SPEC RSA-M3 EX Real Sound Amplifier sound like a direct heated single ended triode amplifier? Yes and no. It does have the rich musicality and beautiful tone colour of DH-SETs, but it easily outperforms most DH-SETs with its deep, tuneful, and articulate bass performance, and has even smoother, richer, and more natural high frequencies than all but a handful of the very best SET amplifiers. I think the truth is that the SPEC Real Sound Amplifier outperforms 99% of the vacuum tube amplifiers I've heard, and it is more powerful than many of them, so it's easier to match it up with a wide variety of loudspeakers and expect good results.

One thing I did learn about the SPEC during my time with it was to get the very considerable best out of it you need to get a good AC power cord on it. The stock AC cord is ok, and you can get by with it for a while, but if you want to hear what the SPEC Real Sound Amplifier is really capable of you need a good AC power cord, and the difference one makes is not subtle. I tried quite a number of power cords with the SPEC, and I found the two best with it were the Sablon Audio Gran Corona and Petit Corona (in that order).

The SPEC RSA-M3 EX Real Sound Amplifier is not cheap at an estimated US$9500 retail price, coming in a full US$3000 more than the superb vacuum tube Leben CS-600 integrated amplifier. As much as I love the Leben, I really think the SPEC is in a different performance category. A more appropriate comparator would be the hand-made, solid-state tour de force, ASR Emitter II Exclusive Version Blue amplifier from Herborn, Germany, that impressed me so much in Issue 66 when I reviewed it. It was simply awesome. Rather incredibly, the SPEC Real Sound Amplifier, while much less powerful at 60 watts, has all of the good performance attributes of Big Blue, but is even more timbrally realistic and tonally colorful, and the SPEC accomplishes that at slightly less than one-third of Big Blue's price of US$31,220 (excl tax). In that sense the SPEC RSA-M3 EX Real Sound Amplifier is a bargain.

I think that what we are witnessing here with the SPEC RSA-M3 EX Real Sound Amplifier may very well be the birth of something as musically significant as what happened with the advent of the DH-SET amplifier renaissance in 1960s Japan, but this time it is with a class-D amplification device from the 'enlightened ear' of Mr. Shirokazu Yazaki.

If you have been put off by the quirky nature and low power of DH-SETs, this could be your chance to check out that ol' SET magic with a thoroughly modern amplifier that is capable of driving a broad range of modern loudspeakers, and it could very well be your big 'aha' moment, just like it was for Jean Hiraga with DH-SETs way back when, and change the way you think about listening to recorded music.

The superb tone color and rich timbral textures that are normally the purview of fine vacuum tube designs are now present is this class-D amplifier from Mr. Shirokazu Yazaki. If you're interested in an amplifier with the beauty, tone color, timbral naturalness, and rich stereoscopic musicality of the best vacuum tube designs in a non-fussy and classy solid-state design, I suggest that you listen to the SPEC RSA-M3 EX amplifier. You may very well decide it is one of the best amplifiers out there regardless of price. At least that's my take on the SPEC, and I suspect it'll be yours too if you get a chance to give it a listen.

I found the SPEC RSP-901EX Real Sound Processors to be fascinating devices, and the premise that they can help minimise the frequency-impedance variation interaction of any loudspeaker-amplifier combination to improve their performance is a really cool idea. With my Harbeth Super HL5s and the Leben CS-600 / SPEC RSA-M3 EX Real Sound Amplifier the overall sound became warmer & richer, the images gained additional body & size and moved forward in the soundstage, the sense of space in the soundstage became more expansive and 'blacker', with the whole presentation became less electronic sounding and more natural sounding, and generally just more musically satisfying. The SPEC RSP-901EX Real Sound Processors are the real deal and worth their asking price, and one of those no-brainer products that can you buy, install in your system, marvel at the result, and never look back.

I would like to thank Mr. Shirokazu Yazaki for letting me interview him, listen to and write about his SPEC RSP-901EX Real Sound Processors and SPEC RSA-M3 EX Real Sound Amplifier, it was truly a privilege, and an enjoyable experience all the way around. I suspect we will be hearing much more about Mr. Shirokazu Yazaki and his designs for the SPEC Corporation in the near future.

 I would also like to thank the ever-gracious Mr. Yoshi Hontani for making arrangements for this review.

The SPEC RSP-901EX Real Sound Processors are one of those no-brainer products that can you buy, install in your system, marvel at the result, and never look back.

REVIEW SUMMARY - Excerpt out of a fuller review including SPEC RSA-M3EX Integrated amp:
The resulting changes from the SPEC RSP-901EX Real Sound Processors with the Leben CS-600 were of much the same nature (albeit greater in magnitude) as with the SPEC RSA-M3 EX Real Sound Amplifier: the overall sound became warmer & richer, the images gained additional body & size and moved forward in the soundstage, the sense of space in the soundstage became more expansive and 'blacker', with the whole presentation became less electronic sounding and more natural sounding, and generally just more musically satisfying. I think I can safely say that you haven't heard how good your Leben CS-600 integrated amplifier or Harbeth Super HL5 loudspeakers can sound until you've heard them with a pair of RSP-901EX Real Sound Processors helping them along. The SPEC RSP-901EX Real Sound Processors are one of those no-brainer products that can you buy, install in your system, marvel at the result, and never look back.

EXTENDED REVIEW: Mr. Yazaki-san also sent along a pair of the SPEC RSP-901 EX Real Sound Processors for me to listen to. The retail price for the SPEC RSP-901Real Sound Processors will be somewhere around US$1000(excl tax) a pair by the time they reach your dealer's showroom.

The SPEC RSP-901 EX Real Sound Processors are designed to reduce the fluctuations of loudspeakers' impedance over the frequency spectrum, while absorbing the return current from the speaker and its potentially deleterious effect on amplifier performance via a network of inductors.

The binding posts of an RSP-901 EX,onnects to the loudspeakers binding posts via a speaker cable 'pig-tail' (below on my Harbeth Super HL5s). 

Mr. Yazaki-san told me that using the RSP-901EX can result in a pretty dramatic improvement to the sound quality of a pair of loudspeakers, by making them sound more clear, natural, and musical throughout their range.

Inside the spruce enclosure are hand-picked components for the best sound quality: "…state-of-art hermetic seal oil-filled capacitor, named "Green Cactus" series made in USA, by Arizona Capacitors, Inc. …the resistor adopted… which has the smoother and more open air character…" and "…please pay attention to the appearance of RSP-901EX. It's like a jewelry box made of real spruce from North America with string instrument's color."

The idea for the RSP-910 EX came from an article in MJ magazine by Mr. Yasui in 1971 about impedance correction for loudspeakers. The relationship between a loudspeakers impedance variation with frequency, the resulting return electromotive force from the speaker to the amplifier, and the output of an amplifier driving the speaker based on the input signal, is a fairly complex relationship. It's a lot of variables for an amplifier to deal with, and a lot of things that an amplifier has to react to and get right for the best sound. Mr. Yazaki-san told me that solid-state amplifiers are more affected by this complex interaction than are vacuum tube amplifiers, but both can benefit from installing the RSP-910 EX, which minimizes the effects of the loudspeakers' impedance variation with frequency, and the resulting return electromotive force from the speaker, making life easier on the amplifier, so that it performs better.

Review Systems

For this review I used both of my current hi-fi systems, the smaller Harbeth Super HL5 and Leben based system I use in my listening/television room, and my Tannoy & vintage McIntosh system that I use in my larger living room space. They're both fantastic systems for the music lover!

In my small-room system I use Harbeth Super HL5 loudspeakers on Skylan 18-inch stands, Acoustic Revive Single Core speaker cables, the Leben CS-600 integrated amplifier, Acoustic Revive Single Coreinterconnects, the Leben RS-30EQ phono equalizer, an Auditorium 23 '103' style step-up transformer, Acoustic Revive Power Reference AC power cords, a VPI Classic turntable fitted with an EMT TSD-15 phono cartridge, an Oppo BDP-83 Blu-Ray player, an Apple TV & Roku for streaming duties, and a 42-inch Philips TV.

In my living room system I use Tannoy Westminster Royal Special Edition loudspeakers with Sablon Audio Panatela internal cabling, and the superb Duelund CAST external crossovers. Sablon AudioPanatela speaker cables connect to my restored vintage McIntosh MC225, MC30, and MC240 valve amplifiers, with Sablon Audio Panatela interconnects connecting the amps my restored vintage McIntosh MX110Z valve tuner-preamplifier, and a vinyl front end consisting of an Artisan Fidelity Statement Plinth in Macassar Ebony with Stillpoints Ultra isolation feet, a Classic Turntable Company modified Garrard 301 (Classic 301) with a brass platter, mounted with two of Thomas Schick's tonearms, one for mono with an Ortofon SPU Mono CG 25 Di MkII, and the other for stereo with an Ortofon SPU Classic GM MKII. Sablon Audio Gran Corona AC power cords connect my iMac & Mhdt Labs Havana USB DAC. A long pair of Acoustic Revive Single Core interconnects connects the Havana to my Mac preamp.

Listening Impressions

I listened to the SPEC RSP-901EX Real Sound Processor using my small room system, with the combination of my Harbeth Super HL5 loudspeakers and the SPEC RSA-M3 EX amplifier. I did not use the Real Sound Processors on the outboard Duelund crossovers on my Westminsters, as I would really need to use two pairs of Real Sound Processors, which I did not have access to.

Being unfamiliar technology, I wasn't really sure what to expect from the RSP-901EX Real Sound Processors, and I wondered if I'd even be able to hear a difference. In retrospect, I shouldn't have wondered, and I really liked what I heard them do with my Harbeths.

While I already mentioned the operational principles behind the SPEC RSP-901EX Real Sound Processors, let me summarise what Mr. Yazaki-san told me, and then briefly expand on the loudspeaker-amplifier frequency-impedance interaction that the RSP-901 EX is designed to improve. Basically, the RSP-901 EX is designed to provide an impedance correction for loudspeakers, whose impedance varies with frequency. There's a fairly complex relationship between an amplifier driving the speaker, and the speaker returning variable impedance based on frequency to the amplifier that it has to deal with while driving the loudspeaker. Minimising this interaction helps the amplifier perform better.

Right after listening to the SPEC RSP-901EX Real Sound Processors on my Harbeths, I had a conversation with my friend Siedy in the Netherlands, and the Dutch amplifier designer Jan Hut, who designed the 'Chaos' amplifier that Siedy uses to power his Westminster Royal loudspeakers, that has relevance for this topic.

Jan told me, "At the base of all amp designs stand engineers who learned to develop amplifiers the same way I did. That's because we all had teachers that think the same way on how you design amplifiers. Mostly they think that more is better, and a better measuring result will also be better to listen to music with. Even though measuring instruments do not know what better sound means, we think they do. The problem occurs in the feedback loop. An amp without feedback runs only one signal, the audio signal. It's not all that simple, but for now it will do. If you amplify that the right way it appears at the output, then goes to the speaker, and then back to the power supply. When you apply global feedback the amps sees more signals to work with. First the original input signal, and then the amplified signal that is sent back by the loudspeaker. The signal is passed along by the amp with a little delay and, and the amp has made little mistakes during the amplification process, which people try to compensate for by adding feedback, but then phase problems become an issue because the amp is comparing and compensating for these two signals. An average amp does not have any intelligence to do so, and it has no ears either, so new mistakes are made and enter the amp by the feedback and so on."

"The big bass signals are strong and stay rather unaffected, but the very small ones are affected, the ones that give us a part of the big spacious sound and three-dimensional picture. There is also another signal disturbing the audio signal when applying feedback, and that is the signal the speaker generates. The damping of the amp has to take care of that through the feedback loop also and so a third signal appears at the entrance of the amp and it tries to make the best of it. When you start adding even a small amount of feedback you can hear the spacious soundstage become smaller. So what we are asking is what's worse, letting the amp make a few mistakes we can't hear, or to introduce a lot of other signals by means of the feedback that the amp then has to deal with."

Jan's discussion was about the same phenomena that Mr. Yazaki-san told me about related to the complex interaction between the amplifier driving the loudspeaker, and the loudspeaker pushing back and 'driving the amplifier' which degrades the amplifier's performance by having to deal with multiple interacting signals. In Jan's case he told me about how he designs his amplifiers to minimize the deleterious effects of the loudspeaker-amplifier by using zero negative feedback designs, but Mr. Yazaki-san's idea is to introduce the SPEC RSP-901EX Real Sound Processor into the loudspeaker-amplifier relationship to help minimize the frequency-impedance variation interaction to improve the performance of any loudspeaker-amplifier combination. That's a cool idea.

Let me say that I listened to quite a lot of various types of music with the SPEC RSP-901EX Real Sound Processors installed on my Harbeth Super HL5 loudspeakers, and I found them to perform consistently & predictably across genres, but I'll limit myself to just a couple of examples to describe what I heard, then I'll move on and discuss the SPEC RSA-M3 EX Real Sound Amplifier.

On the Counting Crows' August and Everything After CD I swapped in and out the RSP-901EX Real Sound Processors while keeping the volume identical. The result was significant: the album's overall sound became warmer and richer, all of the images gained additional body & size and moved forward in the soundstage towards me, the sense of space in the soundstage became more expansive and 'darker'. On the emotive front, I thought the emotional connection was enhanced by the changes wrought by the RSP-901EX Real Sound Processors, the tone color became more intense, timbral textures became richer and more organic sounding, with the whole presentation of the music becoming less electronic sounding, and generally just more musically satisfying. Additionally, there was a more engaging 'feel' to the music, or maybe another way to say it was that the music felt more present in the room with me. The RSP-901EX Real Sound Processors worked as advertised, and I liked the improvement I heard from them when they were hooked up to my Harbeths.

On the Beautiful Dreamer Songs of Stephen Foster CD there's lots of great music by artists as diverse as Raul Malo, Allison Krauss, Yo Yo Ma, BR5-49, John Prine, Michelle Shocked, Mavis Staples, Roger McGuinn, and Ron Sexsmith, to name a few of the contributors. If there's ever an album that's begging to be released on 45RPM vinyl it's this one. Until then you can count on the RSP-901EX Real Sound Processors delivering the maximum emotional connection to the music from the CD, with rich tone, delicious timbral textures, a more natural presentation of vocal sibilants, an expansive sense of space, and an immersive 'in the room with you' presentation of the music.

Perhaps the most flattering thing I can say about the RSP-901EX Real Sound Processors' contribution to the performance of the Harbeth & SPEC RSA-M3 EX amplifier combination, is that when I had them hooked up to the Harbeths I tended to just get lost in the music more, and think less about the comparative listening process for the review. The RSP-901EX Real Sound Processors really let the emotional connection of the music shine through. The Harbeth Super HL5 loudspeakers & SPEC RSA-M3 EX Real Sound Amplifier combination sounds great, and it sounds even better when the RSP-901EX Real Sound Processors are hooked up to the Harbeths.

I replaced the SPEC RSA-M3 EX Real Sound Amplifier with my Leben CS-600 integrated amplifier, and did some more comparative listening with the SPEC RSP-901EX Real Sound Processors on & off the Harbeth Super HL5 loudspeakers.

Mr. Yazaki-san had mentioned to me that the magnitude of improvement the SPEC RSP-901EX Real Sound Processors provide was greater for solid-state amplifiers than it was for tube amplifiers, so I was expecting to hear a more modest improvement with my Leben CS-600 in the system. However, contrarily I found that the magnitude of improvement from the SPEC RSP-901EX Real Sound Processors was much greater with the Leben CS-600 than it was with the SPEC RSA-M3 EX Real Sound Amplifier. Perhaps the SPEC amplifier is already designed in such a way to minimize this loudspeaker-amplifier interaction?

The resulting changes from the SPEC RSP-901EX Real Sound Processors with the Leben CS-600 were of much the same nature (albeit greater in magnitude) as with the SPEC RSA-M3 EX Real Sound Amplifier: the overall sound became warmer & richer, the images gained additional body & size and moved forward in the soundstage, the sense of space in the soundstage became more expansive and 'blacker', with the whole presentation became less electronic sounding and more natural sounding, and generally just more musically satisfying.

I particularly recommend the RSP-901EX Real Sound Processors to my fellow Leben & Harbeth owners. If I may tickle your sense of intrigue a little, I think I can safely say that you haven't heard how good your Leben CS-600 integrated amplifier or Harbeth Super HL5 loudspeakers can sound until you've heard them with a pair of RSP-901EX Real Sound Processors helping them along. The SPEC RSP-901EX Real Sound Processors are one of those no-brainer products that can you buy, install in your system, marvel at the result, and never look back.

This is typically the kind of amplifier that can address different profiles, positioning itself as a first foray into true High Fidelity or as an ultimate amplifier for the one that favours the spontaneity and consistency in everything else
Joel Chevassus

REVIEW SUMMARY - (French / English translation) I tested the RSA SPEC-717 EX on 5 pairs of speakers and different systems. I admit that the small built-Japanese was never unworthy and positioned itself as a credible challenger against amplification priced more expensive. Whether on my Vivid K1, the Lawrence Audio Violin, the Sonus faber Guarneri Evolution, Pascal Louvet Isis or small SA2K, the RSA-717 EX has made the show.

On extracts busiest in instruments such as the New World Symphony by the CSO under the baton of Fritz Reiner or Georg Solti, the RSA-717EX never becomes rough as you might fear the light of the modest power claimed. In contrast, the strong are perfectly mastered without this unconditional clarity can be assimilated as too clinical or artificial dilation. There is always an organic side in the result issued by the SPEC.,

EXTENDED REVIEW (French / English translation) - SPEC is a young company , founded in 2010 by respectable samurai of Japanese hifi who cut their teeth in venerable houses like Pioneer and Teac, and have been for many years.

I met my part for the two founders, Messrs Yazaki and Banno, a year ago at the Munich salon. They are lovely people, both humble and passionate, in short everything that makes for me the charm of the Nippon audio tradition.

The company Archipelago began by launching an integrated amplifier called RSA-F1, "RSA" is short for "Real Sound Amplifier". They also launched in the wake of a filter for passive speakers called RSP-101 (Real Sound Processor - 101).

Since then the range has been extended with a number of integrated amplifiers, the latest RSA-717 EX, the subject of this short test and whose realization was possible thanks to the French François Gourdain importer Synergy boss -Esoteric.François is in my opinion one of the few French importers (rest assured there are others) that still work exclusively in heart stroke. There is a year and a half we talked about Lumin, and there's less than a year of SPEC. We tested these two brands a common enthusiasm without flaws. François Gourdain, which I describe as "rare pearl diver" and kindly gave me the opportunity to test for a smallest integrated month range, called the RSA-717 EX. So back to the subject that concerns us, namely amplifiers manufacturer Nippon SPEC ...

The amplifiers available in the manufacturer's catalog now number 4, all developing a power of between 50 and 60 watts into 8 ohms: RSA-F3EX, the RSA-M3EX, the RSA-V1DTEX and of course RSA- 717EX.

The circuit of amplifiers SPEC was designed by the chief designer Koichi Yazaki, which in addition to its long experience as a mechanical engineer and Teac Pioneer, is a passionate amplifiers based 300B. He served as the best achievements in 300B to design an amplifier scheme that can approach it sound qualities while being able to take more ambitious and complicated loads than those normally assigned to the triode. From this research was born the concept of the original SPEC amplifiers, to reach this fullness of sound and the natural dynamics, the main idea was to combine the best analog components with the latest generation of class amplifier modules D Pulse Width Modulation (PWM in English for Pulse Width Modulation) International Rectifier Manu.

All SPEC integrated work well on the very principle of class D modules surrounded by analog components, some like oil capacitors are replicas of OUR components (West Cape) and manufactured directly on specifications by Arizona Capacitors in the United States. The food is traditional and therefore also completely linear, except for one exception, the RSA-717 EX, which implements a so-called switching power supply "audiophile quality". Finally, each amplifier is integrated in an aluminum frame resting on a wooden base of various species, allowing to combine the aesthetic function (decreasing the chassis resonance frequency, and avoiding extraneous vibrations disrupt circuits amplification and pre-amplification). Class D modules enable a very broad picture and generate more power with astonishing insensitivity to acoustic loads associated with them.

Like his elders, the RSA-717 EX youngest adopts a minimalist appearance. Nothing is there to do in my face, the ostentatious: it is undeniably in the Nippon sobriety with obvious care taken in the manufacture of the object including stunning wooden cheeks acting foot, gives it an audiophile chic look the best for those who have known the line of prestigious Pioneer exclusive series, Luxman Marantz Esotec or even Sony ES. As for me, I just love ...

On the front , a source selector and a volume control knob are the main functions available to the user. Always in front, a type Aret power switch "safe power", taking the design of the switches found in aircraft cockpits, and a switch to disable the speaker outputs when you want to change or add a connection on the back panel.The LED system inserted directly into the switches is both elegant and very readable.

At the rear, there are four isolated terminals WBT more traditional, three entries asymmetrical lines and an XLR input. A plug connector for optional remote control box is also there in case. The optional remote control is nevertheless proving to be a gain control and does not control the volume knob. She adds also notoriously the selling price of all and only the irreducible "all from my sofa" may be tempted to take the plunge ...

Inside the housing of the amplifier, there is a scheme articulated around a controller IC and the latest generation of two Mosfets of from International Rectifier. The circuit is ultra-compact, like many amplifiers class D, and with very short connections. This plays on the natural dynamics and although eventually these characteristics have not always been present in some class D achievements I've tried.

This time by cons, the engineers at SPEC decided to opt for a switching power supply to see what they could learn compared to a linear power supply. They took the opportunity to inaugurate a new diode bridge acquired from Silicon Carbides.Include a qualitative approach in the selection of components with electrolytic capacitors, oil capacitors and other top quality mica, the implementation on the circuit also provides a vibration treatment. Finally critics compartments of the box are isolated with a shield Mu-metal to limit any harmful electromagnetic radiation.

As for performances , the power developed by the small SPEC is hardly impressive, since it develops 2 x 50 Watts into 8 ohms and exactly twice into 4 Ohms. But they are real watts available and this modest power already allows many association with speakers of all sizes.

The technical information provided by the manufacturer are quite limited in number, but we note the frequency response, rather wide, measured at + 1dB (6 ohms, 1 watt) over a range of 10Hz to 30kHz. The harmonic distortion (THD) is given to 0.02% at 1 kHz and 80% of maximum power.

The input sensitivity of 300 mV rms and the gain on the unbalanced inputs at maximum volume and an average impedance of 6 ohms is measured to 37.3 dB (1 kHz).

The amplifier is a real lightweight since it weighs only 7 kg, which radically changes the face of the amplifiers that I could handle my house lately ...

Finally, the dimensions make it a more liveable device easily into any piece of furniture: 35 cm wide and 37.5 cm deep with a height of 9.5 cm.

Although the advertised power is relatively modest for a class D amplification of this type (I could also compare to other integrated class D sold a little cheaper but claiming a much higher power), I was amazed never detect power limiting, somewhat in the same style as the little Trends TA-10.2, but with a refinement operation in no way comparable. Indeed, this small integrated proved even more surprising about loads low return on the speakers you would have thought the easiest and therefore likely to better suit him. I would not say as much for the little SPEC does not work well on good performance speakers, but it comes into its own, responding now where we do not necessarily expect, in terms of demanding pregnant power and why we tend to focus a lot beefier amp.

Where Micromega AS-400 seemed quite flat , lacking life and extension at the top as in the low end, SPEC RSA-717 EX appeared hyper-tonic come, high contrast with sharp 300B of more realistic than my little class T, and superbly authoritarian in the extreme low as very few much more expensive and more powerful amps have previously been able to convince me.

I want to say that to date, I remember the small built-SPEC as the only Class D amplifier that has really attracted me and convinced. Never Rotel 3DLAB, NAD, Bel Canto, Primare, Flying Mole, NuForce, and others made me think I could find my happiness in Class D. Only small Trends had impressed me but remained in an envelope budget and in a format that matchbox bridled in their absolute undeniable qualities in relation to the prices at which they were offered. SPEC RSA-717 EX is for me the only device working in this amplification class, and I was given a try, coming within a dimension of high-end, real upscale.

Its holding in the bass and treble quality is really excellent for the price and you quickly forget the Spartan side of the object reviling in its sound capabilities. I do not know what actually equivalent in these price ranges in class A or AB could compete with this newcomer. Some candidates values that I could confront him as the LFD NCSE are able to offer a valid alternative listening.

The LFD NCSE nevertheless a little too overweight in the low end and more generosity in the midrange with an incredible density but lack of ventilation and expansion in the treble. So, this makes it a very attractive proposition to hear jazz club or pop rock fashion requiring a great seat and extent, with a very powerful rhythm. The integrated LFD has an incredible opening. SPEC, which is nevertheless not left, yet can almost pass for a wise child. But it is mostly neutral and versatile than the LFD offers a more distinctive, more crude even if it is particularly addictive final ...

I tested the RSA SPEC-717 EX on 5 pairs of speakers and different systems. I admit that the small built-Japanese was never unworthy and has positioned itself as a credible challenger against amplification priced more expensive. Whether on my Vivid K1, the Lawrence Audio Violin, the Sonus faber Guarneri Evolution, Pascal Louvet Isis or small SA2K, the RSA-717 EX has made the show. I found it surprisingly also sensitive to the quality of cables areas. At more than 96% efficiency (at full power), we can also understand that the quality of the current sector is of importance ...

Only the middle register (especially lower midrange) and dissociation plans benefit from being more developed. This is where my Luxman M800a couple made the hole Coincident with the preamp. But how many times the price? And when I compare them to all the other criteria: extension, held in the grave, fluidity, openness, depth scene ... I am surprised by the beam qualities inherent in the entry level of SPEC Corporation. Indeed, the RSA-717EX its balanced input holds a candle to many high-end amplifiers. Of course, looking good, we'll find some other advantages to Luxman, but I would not risk a confrontation listening blindly betting on the fact that I would be able to distinguish each time. That is to say that beyond a slight lack of heat and thick, the performance displayed by the small built are really impressive. This is in any case which leads me to think that we can finally hope for any better in terms of sound performance Class D, not only from the point of view of energy balance ...

Listening to the first instalment of Roberta Gambarini "Easy to Love", the chiseled voice of the soprano and the Italian stamps impressive clarity. It's very nice to enjoy an image both large and extremely focused. And this small built on the Vivid Audio K1 holds the grave with a seat and a speed which is not common. The rhythm of the bass immediately arouses membership and we begin to listen to the whole album in one go without scroll through the songs.

On extracts busiest in instruments such as the New World Symphony by the CSO under the baton of Fritz Reiner or Georg Solti, the RSA-717EX never becomes rough as you might fear the light of the modest power claimed. In contrast, the strong are perfectly mastered without this unconditional clarity can be assimilated as too clinical or artificial dilation. There is always an organic side in the result issued by the SPEC .ss in the lower midrange.

On flamenco guitar and the album Jazzpaña II (Gerardo Núñez), attacks of notes are really frank and well clipped instruments without anyone feels at any moment an impression of hardness or ear fatigue. The rhythm and stamps are ideally transcribed and never have I had the feeling that the sound could become chaotic. The extinction of notes are perhaps not so marked that with my Luxman couples, but there is a very fine yarn in the treble and reverb recording out very clearly.

This is also a character all terrain reveals that Japanese integrated amplifier because it also feels comfortable on pop than classical. It has an emergency case and immediacy that makes the sound finally very natural. No frills or pretence with RSA-717EX, it makes you jump right into the music.

Conclusion:

In conclusion, I would say that the primary qualities of the small built-SPEC remain its opening, its intelligibility and exceptional vivacity. Let's add-y impressive stability and ultimately its very sweet to have a good idea of his abilities. The RSA-717EX is in some ways the theory of the right wire, and undoubtedly a superb exercise in style. But it's also a machine that distills lot of listening pleasure, the easy way! This is typically the kind of amplifier that can address different profiles, positioning itself as a first foray into true High Fidelity or as an ultimate amplifier for the one that favours the spontaneity and consistency in everything else .
..
….. Joel Chevassus

My Shindo Haut-Brion didn't match the Spec for ultimate resolution or upper-treble purity, nor did it meet that overachiever's low noise floor and startling micro-dynamics.
Ken Micallef

REVIEW SUMMARY: The Spec RPA-W7EX Real-Sound proved its worth as a benevolent truth teller, consistently wowing me with how well it wrested the last bit of information from every LP I played. Its first-rate resolution and seemingly nonexistent noise floor made possible many late nights of discovering new sounds from old LPs.

Everyone I've invited to my penthouse pad to hear the RPA-W7EX has been enchanted by its superbly detailed reproduction of music: never clinical or mechanical, yet consistently natural. 

The Spec's sound flowed. Its fast release of notes, and subtle but powerful tonal and rhythmic abilities, revitalised my LP collection. 

Regardless of the volume level or the recording's inherent dynamics, the Spec's remarkable resolution, first-rate imaging, and spot-on tonal colours remained constant, and the amplifier was never flustered by wide dynamic range or steep power demands.  Playing jazz, boogie-woogie, or electronic gumbo, the Spec provided the kind of natural bass frequencies any music lover could hope for.

The Spec RPA-W7EX expresses the colourful soul and vivid textures of a tubed amplifier with the unfaltering resolution, vanishingly low noise floor, and power of the best class-D switching amplifiers. While it isn't cheap, Spec's RPA-W7EX Real-Sound has made a big crack in the kings' imperial fortress.

EXTENDED REVIEW: I'm a jazz lover. To be specific: I'm a lover of jazz on vinyl. I'm referring not to my sexual proclivities but to 331/3rpm LPs from such venerable labels as Blue Note, BYG Actuel, Contemporary, ECM, ESP-Disk, Impulse!, Prestige, and Riverside. Nothing hits the sweet soul spot of this former jazz drummer and devout jazz head harder than Tony Williams's riotous ride-cymbal beat, Hank Mobley's carefree tenor-saxophone shouts, Charles Mingus's gutbucket double-bass maneuvers, or Bill Evans's haunting piano explorations. Jazz and vinyl both may constitute narrow slivers of music sales, but millions of us around the globe are on a constant hunt for exceedingly rare, grail-like jazz LPs, which we spin on our turntables with an equally holy reverence for the musicians' achievements.

My love of jazz and jazz vinyl has strongly informed my choice of playback gear: a Kuzma Stabi S turntable (known informally as "the pipe bomb"—a reference to its brass-rod chassis) with Kuzma Stogi tonearm and Denon DL 103 cartridge, Shindo Laboratory tubed preamp and power amp, and DeVore Fidelity Orangutan O/93 full-range speakers. This collection of wood, metal, glass, and wire has helped me experience sensory and musical bliss. Tubes rule. Life without Sylvania, Telefunken, and Mullard is life lacking proper aural nourishment.

Probably like you, I've worked for years to refine my audio system, perched in my bachelor pad high above the bridge-and-tunnel-crowd din of Greenwich Village. I've spent as many years collecting LPs, and purchasing, ripping, and selling CDs—and listening, listening, and more listening. My choices of tubed over solid-state, analog over digital may not be yours, but I hope we can agree that what dictates the choices of all of us is the music—or, at least, that it should.

Many a listener has gone from solid-state to tubed amplification, including Spec Corporation founders Shirokazu Yazaki and Tsutomu Banno. Combine a mad audio DIYer (Yazaki) with an adventurous circuit designer/engineer (Banno)—they respectively helmed technological breakthroughs at TEAC/Pioneer Japan and International Rectifier—then let them share their wisdoms in novel class-D amplifier designs, and . . . the Spec RPA-W7EX Real-Sound amplifier is ready for show time 

Description

The RPA-W7EX Real-Sound is the only stereo power amplifier in Spec's USA product line, which includes integrated amplifiers, a turntable, Real-Sound speaker attenuators, and Mica capacitors. As with most amplifiers based on class-D circuits, Spec claims for the RPA-W7EX high resolution, an exceedingly low noise floor, extremely efficient heat dispersion, abundant power, and the ability to drive practically any speaker. Shirokazu Yazaki has had more than 40 years' experience in building and refining audio products for his own use, including a single-ended tube amplifier built around a GEC DA30 directly heated triode, which drives a horn speaker system comprising Altec 414A woofers, Onken OS-500MT mid/high drivers, and matching SC-500 wooden horns. However, he envisioned something unique for Spec's first class-D stereo power amp.

Like all class-D designers, Yazaki and Banno worked to overcome class-D's typical problem of brittle, bass-deficient sound—what Michael Fremer has described as "all outer shell, very little creamy center." Yazaki's solution began with the choice of capacitors used in the RPA-W7EX's low-pass filter—the exit point in a class-D amplifier's output stage. Yazaki is well-versed in the sounds of various capacitors: In the early 1990s, he used vintage Black Beauty and Black Cat caps to upgrade his own Marantz 7K, a '70s-era kit preamplifier that has long impressed him with its musicality (footnote 2). He also experimented with West Cap's oil-filled capacitors in his homebrew DA30-based SET amplifier, and in his early class-D prototypes. West Cap eventually became Arizona Capacitors (footnote 3), some of whose paper-in-oil capacitors are used in various Spec products; Yazaki says they have a "gorgeous and rich mid-to-low range" and a "pure and beautiful mid-to-high end."

Other noteworthy choices in the RPA-W7EX's design include Tsutomu Banno's "ground-plane branching" circuit-board layout, mica-dielectric capacitors sourced from India, and Tepro-Vamistor resistors. Fast-recovery ROHM/Schottky silicon-carbide (SiC) diodes were, in Banno's words, used to "eliminate" the high-frequency noise generated by class-D pulse-width-modulation (PWM) switching, a perpetual problem in class-D designs. Additionally, while many class-D amps have a single amplifier module, Banno used in the RPA-W7EX a hybrid two-in-one approach, integrating the driver and DirectFET MOSFET of International Rectifier's AUDAMP4 with a PowIRaudio IR4301 module. As a result, the RPA-W7EX can output up to 100Wpc into 4 ohms.

The RPA-W7EX measures 13.7" wide by 3.7" high by 14.6" deep: not much bigger than a stack of three large notebook computers. Its case and chassis are made of steel—it looked svelte in my Salamander rack, felt lighter than its 13.6 lbs, and seemed to produce no heat at all. This is evidently what made it possible for mechanical engineer Yasuhiro Yamakawa to use large slabs of natural wood for the side panels and footers, effectively sealing the RPA-W7EX in a sleek, minimalist cocoon.

"The switching operation doesn't produce heat," Banno explained in an e-mail exchange, "so using a wood base is effective for creating natural, REAL SOUND [his emphasis]. In addition, because there is no heat we can fully enclose the case. No dust enters the unit. No heat leads to long reliability because cyclical heat is not good for parts and solder.

"Wood dampens vibrations and resonates with the audio signal. Accordingly, the tone becomes more natural, rich, and melodious because of the wood. Intriguingly, I think of it like a musical instrument. [Banno is a cellist.] After many experiments, we found that the combination of spruce and maple worked best. In the RPA-W7EX the wood is of three-layer construction: spruce for damping the main chassis, maple and spruce for the three footers."

I popped the RPA-W7EX's lid, uncovering five circuit boards connected by tidy, all-copper wiring. On the largest board was the International Rectifier AUDAMP4 class-D amplifier module, which contains four large Nichicon caps, a small potted IRAUPS3 transformer (or choke), and a tiny, side-mounted circuit board. On the second board—directly connected to the RPA-W7EX's power receptacle, fuse, and on/off switch—are smaller Nichicon caps, a Talema potted toroidal transformer, and a single Arizona C50309-6223K Blue Cactus capacitor. The third board comprises many large and very small caps, two inductors, numerous diodes, and two tiny elevated boards, all wired directly to the amp's speaker terminals, input-selector switches, and RCA and XLR jacks. All in all, it's a beautifully constructed amplifier, inside and out.

Engraved on the center of the front panel is Spec's logo, which seems to depict the sun rising low on the left flank of a Fuji-like mountain—or maybe it's just a lower-case d and an upper-case A, representing the designer audio slogan that Spec puts on many of their products . . . ? At the far right is an inch-long, On/Off Power toggle, sourced from the aircraft industry. To power up the RPA-W7EX, you gently pull the spring-loaded toggle, then snap it into its up position. The red Off LED flashes for a second or two, and then the green On LED glows steadily, to confirm power engagement. The switch operation felt professional and elegant—as if I were powering up my own personal Learjet.

On the Spec's rear panel are, from left to right: the power receptacle, a fuse plug, and a mini-plug input for Spec's H-VC1 hardwired external volume control ($400). To the right of that jack is a gain switch with three positions: maximum gain, –6dB, and the setting for use with the H-VC1. In my system, the maximum setting provided way too much gain—I couldn't turn the volume knob on my Shindo Allegro preamp, itself a high-gain device, past 7 o'clock!—and the –6dB setting didn't provide enough attenuation: The H-VC1 was practically a necessity.

Then come two pairs of banana speaker terminals made by Aec Connectors Co., Ltd., of Taiwan, and a three-position switch for choosing between normal stereo operation, mono operation with the same signal appearing on both pairs of output terminals (useful for biwiring a system with two RPA-W7EX amplifiers), or strapped monoblock operation, with signal on only one pair of terminals. Finally, on the far right are Aec RCA and XLR input jacks, with a three-position selector switch for choosing between single-ended inputs (RCA), balanced inputs (XLR, with pin 2 hot), and balanced inputs with –6dB attenuation.

Listening

New York City provides ample diversion for the LP collector. With new vinyl-only stores opening practically every month, even a hardened jazz collector like the late writer and cartoonist Harvey Pekar would have had a great time searching for sides. Pekar swore off collecting LPs long before he became famous for his wonderful American Splendor comics and the film of that title. Like the pre-Hollywood Pekar, I visit my favorite vinyl vendors weekly. After cleaning my new sides, I often invite friends over to listen to them.

Yazaki, Banno, and Spec mechanical engineer Yasuhiro Yamakawa seem to have chosen the RPA-W7EX's parts wisely and well. The amplifier had sonic qualities I usually associate with tube amplification: sweet 'n' saturated tonal colors and palpable instrumental textures, coupled to startling microdynamics that left me slack-jawed in wonder, enjoying LPs anew for hours on end. Disc after disc, I felt I was experiencing fresh musical truths. Sometimes, as with ca-1962-'66 Blue Note "New York USA" LPs such as Wayne Shorter's Night Dreamer (LP, Blue Note 84173) or Andrew Hill's Compulsion!!!!! (LP, Blue Note 4217), the revelation was as simple as hearing greater definition and more pronounced dynamic distinctions between instruments. Other times, as when playing Artur Rubinstein's set of Chopin's Scherzos (LP, RCA Living Stereo LSC-2368), the flow of the notes, the resonance of the recording studio, the percussiveness of the piano's hammers, and Rubinstein's mastery of touch and interpretation, all made for a new experience of heart and mind.

The Spec RPA-W7EX was unforgiving of lesser recordings, but when presented with a well-recorded album, such as Sonny Rollins's soundtrack music for Alfie (LP, Impulse! A-9111), or doomed jazz singer Beverly Kenney's Come Swing with Me (LP, Royal Roost RLP 2212), this modest-looking amplifier was positively surgical in its retrieval of low-level information—yet it achieved the not-so-easy feat of doing so without sounding sterile or clinical. With every LP and digital file I sent its way, the Spec exposed the recording's unique tonal, dynamic, and textural elements with natural spirit and a practically feminine touch.

To answer the nagging question "Can the Spec bass-boogie or not?," I turned to seminal Krautrock terrain: Kraftwerk's 1974 album, Autobahn (LP, Vertigo VEL-2003). Fabled recording engineer Rudy Van Gelder may have been the master of capturing the double-bass sonorities of Paul Chambers, Ron Carter, and Reggie Workman, et al, but for bass reproduction without borders, analog synthesisers reign supreme. The motorik grooves of this album's title track sounded delicate and precise via the Spec, yet lacked that last degree of low-end dread. Yet musically, the track was a full-on rave, its humming, forward momentum and sleek sounds rumbling delightfully by.

I then opted for the contemporary bass-synth warfare of Brandt Brauer Frick's super-percussive Mr. Machine (2 LPs, K7! K7286LP). On this exquisitely recorded album, Frick plies various percussive and melodic instruments in configurations that challenge the categories of electronic, funk, and contemporary classical music. "Mi Corazon" begins with a lone bass drum pulsing 4/4, soon joined by madly pitching timpani, triangle, piano, and squirming synth bass. The Spec portrayed all of this track's graphic qualities, establishing instrumental images with sharply defined leading edges on a vividly present soundstage. Synth-bass notes buzzed under my feet like angry wasps, the Spec resolving the last iota of gasping baritone air, which recalled steam rising from a Manhattan manhole.

Not totally sated, I played a disc that goes even further in conjuring bass'n'rhythm fury from growling synths: Loscil's Sketches from New Brighton (LP, Kranky 171). "Second Narrows" is serene in a ghostly way, like slow-moving sea creatures in a death dance. Highly detailed, grain-free (another consistent Spec quality), and rather slimy, its bass notes dipped down with superior decay and sustain, hovering before me like the summer sun, all heat and glare. The Spec outlined Loscil's unctuous bass blobs with macrodynamic precision, but the images lacked ultimate depth and weight. Resolution of this dynamic track was solid, though I didn't feel enveloped in sound. But the spectral soul of "Second Narrows" was convincing, its visceral grip on my ears and brain a thrill.

We were talking jazz, right? There is no greater mid-1960s jazz recording than Hammond B3-slaying organist Larry Young's Unity (mono LP, Blue Note 4221). Young innovated a unique, modal style of organ jazz that has yet to be matched. "Zoltan" highlights Young's scorching technique, accompanied by tenor man Joe Henderson, trumpeter Woody Shaw, and drummer Elvin Jones. The Spec presented Young's glowing Hammond organ pedals with ferocity and power, and, as with every recording I played through it, each instrumental line was easy to follow, regardless of the volume or the complexity of the arrangement. Even given its unparalleled resolution, the Spec's spatial depiction of this mono disc was oddly shrunken. Individual sounds were spatially well defined, with sharp leading edges, but those elements were smaller in scale than I'd heard before in my system.

Results were similar with Workin' with the Miles Davis Quintet (LP, Prestige 7166). The Spec re-created Davis's lyrical trumpet with the sweetest tone and quickest delivery I've ever heard, and did the same for John Coltrane's rangy tenor, Red Garland's effervescent piano, and Philly Joe Jones's drum set. The sound of Philly Joe's ride cymbal had incredible stick definition, good cymbal body, and harmonic overtones—again, all as I'd never heard before from my rig. I realized that the Spec's tonal signature, while largely true to the source, was somewhat dark, lending a burnished feel to brasses, bass, and reeds. Paul Chambers's chugging double bass was warm and clear, but also rather soft and a mite thin.

Moving forward in the last century, Norwegian electric guitarist Terje Rypdal's self-titled 1979 album, with bassist Miroslav Vitous and drummer Jack DeJohnette (LP, ECM 1125), proffers an excellent example of producer Manfred Eicher's atmospheric approach: brilliantly recorded instruments on an expansive soundstage. The Spec purveyed every detail of DeJohnette's hyperactive drumming and Rypdal's sky-strafing guitars. Sustain and decay were superb within a swirling, stormy soundstage. As with the other recordings I'd listened to, the Spec's consistently superb retrieval of upper-register transients was thrilling.

Comparison

My Shindo Haut-Brion didn't match the Spec for ultimate resolution or upper-treble purity, nor did it meet that overachiever's low noise floor and startling microdynamics. 

On the last day I did any listening for this review, I received from Jonathan Halpern of Tone Imports, Spec's US distributor, the Spec AP-UD1 Analog Disc Sheet: a disc of aluminium coated in a "soluble resin." Compared with the Mooo, the Sheet focused the midrange, seemed to lower the noise floor, and increased resolution. The sound became purer, more spacious, and more liquid—definitely more enjoyable. Could this be an easier way to get Spec's Real-Sound? Time will tell.

Conclusion

The Spec RPA-W7EX Real-Sound proved its worth as a benevolent truth teller, consistently wowing me with how well it wrested the last bit of information from every LP I played. Its first-rate resolution and seemingly nonexistent noise floor made possible many late nights of discovering new sounds from old LPs.

Everyone I've invited to my penthouse pad to hear the RPA-W7EX has been enchanted by its superbly detailed reproduction of music: never clinical or mechanical, yet consistently natural. 

The Spec's sound flowed. Its fast release of notes, and subtle but powerful tonal and rhythmic abilities, revitalised my LP collection. 

Regardless of the volume level or the recording's inherent dynamics, the Spec's remarkable resolution, first-rate imaging, and spot-on tonal colours remained constant, and the amplifier was never flustered by wide dynamic range or steep power demands.  Playing jazz, boogie-woogie, or electronic gumbo, the Spec provided the kind of natural bass frequencies any music lover could hope for.

The Spec RPA-W7EX expresses the colourful soul and vivid textures of a tubed amplifier with the unfaltering resolution, vanishingly low noise floor, and power of the best class-D switching amplifiers. While it isn't cheap, Spec's RPA-W7EX Real-Sound has made a big crack in the kings' imperial fortress.
......... Ken Micallef
 

Footnote: Later that decade, Yazaki led the design team that created one of the first universal SACD/DVD-A/DVD-V players, the Pioneer DV-AX10, thus the old Marantz 7K played a role in voicing one of the most noteworthy products of 2000.

I am going to keep „901” for myself because it is simply the best one in what it does.
Wojciech Pacuta

REVIEW SUMMARY: we know how they work, what's the scientific background, and yet hearing them work still comes as a surprise. It's even more so because they change an already good performance into even better, more refined, more dynamic, smoother and yet offering even more information in the top end and lower bass. Each version of a Real-Sound Processor works very well, but each one delivers even better performance then its predecessor. Now I don't have a problem with selling „101” and „501” and let them serve other music fans. I am going to keep „901” for myself because it is simply the best one in what it does.

EXTENDED REVIEW: There is not too many people like Mr Shirokazu Yazaki. I was tempted to write something like: are extremely rare, but I managed to hold myself back. He is an engineer with impressive education and immense practical experience with both, analogue and digital devices. He created such a remarkable devices like TEAC A-7300 reel-to-reel, high quality cassette recorders including Pioneer CT-95, he is also behind the best multi-format DVD-Audio/SACD Player, Pioneer V-AX10. What's more, he's also a brilliant manager who lead large teams and large companies for years as he did for 17 years for Pioneer Corporation where he was in charge as a group leader or a manager in the engineering department of mainly cassette tape recorder, and later as the general manager of DVD engineering department. He shared the story of his life with „High Fidelity” Readers in the article My private history of audio. And on top of all that Mr Yazaki is a music “addict”.

Want more? - No problem: in his private life Shirokazu-san is a great fan of tubes, SET amplifiers and horn speakers. To share his experience about the wonderful sound of extremely rare tubes with a wider group of music lovers he decided to build, together with his friend Honda-san, class D amplifiers that would sound like the best tube ones. Let me remind you that both gentlemen worked together for Pioneer, but beginning 20th century Honda-san left with his family for USA, where he took up the job in International Rectifier, a manufacturer of semi-conductors. He developed a class D amplifier for this company. Soon after a third engineer joined these two - Banno-san, today a chief engineer of SPEC Corporation, they found proper oil coupling capacitors and finally designed and manufactured the class D Real-Sound Amplifier.

I was lucky to reviewed the first unit that came to Europe and ever since I couldn't shake the memory of this immensely dense, rich sound and how wonderful music sounded when played via this amp. It was the first time when I saw something more in the “switching-mode ” amplifier – its sonic signature truly offered a resemblance to very expensive tube amplifiers, thus realizing the main goal formulated by its designers. Today company offers three integrated amplifiers: RSA-F33EX, RSA-M3EX, RSA-V1EX and the latest, RSA-717EX, phonostage RSQ-S1EX, and a fascinating turntable GMP-8000. So one could build almost a complete system with SPEC devices. SPEC does not offer their own loudspeakers. They use (I dare to take some credit here) Kaiser Acoustics and Amphion ones.

The line-up is completed with oil and mica capacitors of the MC-DA line which is quite unusual for a manufacturer of very modern components. But once we realize that Shirokazu-san loves tube amplifiers all become clear. As he told me finding right capacitors was a key to realizing his concept of Class D amplifiers sounding like best tube ones. He chose oil caps, once produced by WEST-CAP, and presently offered by Arizona Capacitors.

These capacitors became sort of a central element of the whole design of a new product, I haven't even mentioned yet - Real-Sound Processor. I was the first non-Japanese who had a chance to try this product out in his own system and it took me quite some time to realize what this small box did for the sound. Falling in love with it was in fact only a matter of time. RSP-101 http://www.highfidelity.pl/@numer--40&lang= is a small, wonderfully made wooden box with a pair of speakers posts. And that's it. One connects it with loudspeakers posts in parallel with speaker cables. Once I did it, what I heard took me by surprise and forced me to give it a serious thought. I repeated this experiment again some time later, when I received a newer version, model RSP-501EX. I was truly honored by a fact that I received the first pair ever produced, with serial numbers 0001/0002. And again – impact on sound was even greater.

Mr Shirokazu Yazaki describes Real-Sound Processor as „Impedance Compensator” that works in a similar way as loudspeaker's crossover. But unlike them it is a more versatile product, as it might work well with many different speakers and amplifiers. In theory it should do a good job for all solid-state amplifiers, including those in Class D and loudspeakers with “difficult” impedance curve. But experience shows that it always works. As my reference power amplifier I use Soulution 710 that offers uniquely high damping factor and a very fast signal risetime. M40.1 loudspeakers, my personal favorite, offer relatively (at least in theory) friendly impedance curve. And yet the RSP-501EX, that I've been using for quite some time now, turned out to be a fantastic, natural partner for this duo. More about this “magical box” in its latest incarnation called RSP-901EX directly from Mr Shirokazu Yazaki.

A few words with Shirokazu Yazaki - SPEC CORPORATION | Director/Engineering

I’m so happy to have the chance for talking about the latest Real-Sound Processor, RSP-901EX, because that it is not only our new product but also might be the ultimate improved model I have ever developed and I hope it would be a good news for all of music lovers live in overseas.

The operating principle of “Real-Sound Processor” had been made in public on the Japanese specialized magazine named MJ, “AUDIO TECCHNOLOGY” by Mr Yasui throughout 1971. He just drought out this concept as “ Impedance Correction” for speaker. Yasui-san was a senior amateur researcher and a person of authority of semiconductor linear amplifier. At that time he got into the conclusion that only the pursuit of improving the static characteristic of power amplifier could never bring the superior sound. And also he set up the importance of amplifier’s dynamic characteristic including the actual movement of speaker to get musical sound. But still right now, after more than 40 years passed I regard his view point as an excellent insight and much further a relevant challenge for the present “audio-technology”. Sorry to say, I should recognize we only know the improving the dynamic characteristic of the system consisted of amplifier and speaker might be an extremely important factor for getting superior sound quality.

For that matter, we are not able to reach at an effective measuring method to be fixed the dynamic behaviors and also expose the real relations between the characteristic and our hearing. I suppose, so many reasons might exist. But one of the major difficulties of analysis of the dynamic characteristic would be speaker itself. Needless to say, speaker is the transducer which converts some electric energy to kinetic motion. But if I were to say frankly, this transducer would be a collective of imperfect characteristic for being driven by amplifier. How fluctuant the impedance frequency characteristic is, you know. Yes it might be quite simply the hard load of amplifier. But also you should remind one more thing, “Counter-electromotive Force” of speaker. The motion of speaker is started in the magnetic circuit or voice-coil of the unit by the current be flowed from amplifier on Fleming's left-hand rule and at the same time this motion raises up counter-electromotive force in the voice-coil by Fleming's right-hand rule. It is true that amplifier drives speaker, but would be the fact that speaker affects amplifier by this counter-electromotive force. And this counter-electromotive current returns to the amp via the speaker cord, making it difficult to drive speaker in accordance with the input signal. And this current causes negative effect especially on the traditional semiconductor linear amplifier. 

Since the transfer function of semiconductor is poor in linearity compared to tube, this type of amplifier inevitably needs correct the static characteristic by performing negative feedback circuitry. But this negative feedback makes the amplifier stage vulnerable to the counteraction, counter-electromotive current from speaker, causing complicated phase delays inside of amplifying stage. Needless to say, this physical phenomenon hurts the sound quality of the audio system including amplifier and speaker.

Because again, our “Real-Sound Processor” has two major functions, one is making an improvement to reduce the fluctuations of speaker’s impedance frequency characteristic. The other is absorbing that counter-electromotive current from speaker including network composed of some inductors. Accordingly, the processor makes amplifier possible to drive the speaker more faithfully for sound source, improving the sound resolution and the start-up, also reproduces natural resonances. Above all you could find out the deep, rich and fascinating tonal characters you have never experienced before and also agree how amplifier could drive speaker easily!!

I had tried so long time to seek out improving the sound quality of “Real-Sound Processor” and learned that only the tonal or the sound quality of the parts, resistor and capacitor decide the sound itself. You should recognize that the perfect characteristic resistor and capacitor has never existed at all ages and countries. For example, capacitor is consisted of mainly capacitance, small quantity of resistance and inductance. Also we should remind the matter of material’s physicality. Sometimes when I make hearing tests for capacitor, I feel the unique tonal character of dielectric material or electrode itself. 

But fortunately early 2014, I met up with the outstanding quality parts. It was the highest quality and state-of-art hermetic seal oil-filled capacitor, named “Green Cactus” series made in USA, by Arizona Capacitors, Inc. This type of capacitor could make it possible to get the live and natural sound of new “Real-Sound Processor”. And in this summer we released RSP-701 for our domestic market. And now thankfully, 701 is the successful product in the field of audio-accessories.

By the way, language above all Japanese is far away from European language. 

They say that Japanese is vowel sound but compared to this Japanese, major European language is made of consonant. And this consonant is surely consisted of high frequency spectrum. So I supposed that European might have more sensitive hearing for high range than ordinary Japanese and determined to change to another “Green Cactus”, it reproduces much finer mid-to-high range. And also I converted the resistor adopted in 701 to another one which has the moother and more open air character. 

As well, please pay attention to the appearance of RSP-901EX. It’s like a jewelry box made of real spruce from north America with string instrument’s color. And 901EX’s box is produced by famous “Shirakawa Co., Ltd” at Hida-Takayama, beautiful historic town. You will see also woodworking is the Japanese traditional handicrafts. I believe firmly that RSP-901EX could bring out the full potential of your system and you could fully enjoy the “Real-Musicality” through “Real-Sound” of 901EX!!

TESTING METHODOLOGY

Test was performed as an A/B/A comparison, with A and B known. There were few stages of this test. First I compared RSP-901EX with two previous versions: RSP-101 (No 0029/0030) and RSP-501EX (No 0001/0002). Then I listened to my system with and without RSP-901EX. The boxes were connected with speakers using short (around 60cm) runs of Oyaide Tunami speaker cable and were placed on Harbeth M40.1 bases. To even better decouple them from the ground I placed them on small Acoustic Revive TB-38H platforms; I use one of these under my power strip – it really works! For the test I used following power amplifiers: Soulution 7100 Accuphase E470, Acuphase A-70, SoulNote SA7300 Chord SPM1200 MkII and Audio Reasearch Galeo GS150.

SOUND

No matter how “crazy” or “snake-oil-like” such products might look like to skeptics, they are usually based on a solid scientific knowledge and measurements. Especially when it come to Japanese products. Over the years I learned that Japanese manage to combine solid facts, modern technologies with things that, at least at the first sight, seem to belong to the world of magic. An example? How about Mr Ken Ishiguro, chief of Acoustic Revive, who made a quartz crystal one of key elements of his products. And as one can easily check, all his products are supported with serious scientific research and measurement's results.

Despite the facts lots of hardheaded engineers treat such products as snake-oil that won't help, nor harm any audio system. But they are simply wrong! Knowledge gained through experiments plays a great role in audio. Which is obvious once one starts to use such a fantastic product as RSP-901EX. Product created by such an unusual person as Mr Shirokazu Yazaki. No matter what one thinks about such product one has no ground to doubt competency of Mr Yazaki as a skilled, experienced engineer.

Real-Sound Processor” introduced to the sound depth and serenity. Smoothness and richness. These changes I mentioned are not limited only to tonality, or dynamics, or resolution of the presentation (although how much more resolving presentation becomes might be easiest to recognize). In fact it introduces deep, structural changes to the sound, reconstructing its very fabric from inside. All these superficial differences, I mentioned, very easy to notice. But I think that these changes are different from what other amplifier, source or loudspeakers introduce to the system. It reminded me of what a complex approach to the problem of vibration in the system, by using high quality anti-vibration rack, placing each component on a platform and so on, can give user in terms of system's performance.

The impact on sound of the first version of RSP, model „101”, I perceived as the sound getting darker. Each time a newer model replaced older, so when I changed „101” to „501”, and now „501” to „901”, this effect was getting stronger. I noted this aspect in particular because it shows how complex system our hearing is, and how insufficient, how simple is our vocabulary when it comes to describing it. Why would I say that? Because the easiest way to describe Mr Shirokazu's “correctors” would be to say that they change frequency range by limiting the top extreme, the treble. That's what subjectively listener feels like at the beginning. But the more experienced one, given it some time, would realize soon that there is in fact more information in the top end, not less. With „901” much more!.

It is an extraordinary experience – comparing sound of my system with and without „101” I could easily recognize that the level of background noise was lower and thus there was more information in the sound. „501” worked in the same way and the results were even better. „901” is another step in the same direction, or maybe even a huge leap which makes it sound like a totally different product and not just an enhanced version.

It results in a much better differentiation of events on the soundstage. Everything happening deeper into the stage becomes more clear, more distinct. Drum sticks hitting drums echoed somewhere in the back of the hall on Milt Jackson's album, which became much clearer with “901” in the system. Thelonious Monk's piano seemed even bigger, more three-dimensional than usually because of a more audible response of the surrounding environment. The Solo Monkalbum seems to be recorded in a very direct way, with microphones placed almost inside piano's body. And maybe that's how it actually was recorded, but with „901” presentation included also more information from outside the body. In the Welcome To My Worldopening Depeche Mode's album Delta Machine there is some short reverb added to Dave Gahan's voice. One can hear it even without Japanese boxes but when one lets them do their job one finally realizes why this reverb was added – it was done to create sort of a “buffer” around the voice – this way voice didn't have to be loud to be well heard. Without SPEC device vocal was placed deeper in the mix and it wasn't so well defined.

The latest version of RSP enriches the sound, makes it deeper. Listener has an impression of much, much more controlled presentation. But, to be fair, sound without RSP seems more direct, with more powerful attack phase. Once we connect RSP-901EX to our speakers we quickly realize that without it presentation is “simplified”, not to use the term “ordinary”.

I'd like to point out that I truly like the sound of my system. I think it performs really well even without these “processors”. But any improvement in our system becomes obvious when we compare it with something else – that's the best way to find ways to improve what we think is already great. So please, remember that everything I described is a result of comparison “WITH” and “WITHOUT”, and not description of sound itself. In this particular case good systems with be still good both “WITH” and “WITHOUT”, but do not count on these processors to turn a not so good system into a fabulous one. This product's job is not to compensate for flows of a system, but rather to let it sound even better.

SUMMARY

Exactly on the day when I took photos for this text and wrote the summary we had a partial (3/4) Sun eclipse in Poland. In Cracow it started at 9.44 A.M., the maximum eclipse was at 10.53, and it ended at 12.04. Photos I took are time-stamped at 11.00 and there is my daughter on one of them looking at the Sun through an X-ray photo. There is something mystical about how drown we all are to the star that gives us life. Already the Ancients knew that and today we know it even better as we know much more about how it all works. If today such an ordinary (in a cosmic scale) event initiates such a huge, almost primal emotions, how powerful these had to be for our ancestors?!

It works in a similar way with accessories like RSP-901EX: we know how they work, what's the scientific background, and yet hearing them work still comes as a surprise. It's even more so because they change an already good performance into even better, more refined, more dynamic, smoother and yet offering even more information in the top end and lower bass. Each version of a Real-Sound Processor works very well, but each one delivers even better performance then its predecessor. Now I don't have a problem with selling „101” and „501” and let them serve other music fans. I am going to keep „901” for myself because it is simply the best one in what it does.

........Wojciech Pacuta

I tend to think most of us would simply want to hunker down and forget about the world for a while. If that's you, the REQ S1-EX will perfectly suit.
Wojciech Pacula

REVIEW SUMMARY: Listening to music through the Japanese phono stage is like having a bath in essential oils, resting on silk sheets, sipping caffé latte somewhere in sunny Italy, drinking a mug of Paulaner in a small bar in the center of Munich. It's about an excellent balance between individual parts, a conscious choice about sound, clear views on technical matters and last but not least a fantastic man behind it all which makes listening to the REQ-S1 EX like meeting an old friend: a bit of nostalgia mixed with curiosity and a renewed sense of security. 
Sounds modelled by this preamplifier are never unpleasant. It’s also an obvious departure from objective neutrality. Nevertheless it doesn't alter the heart of the matter, the value and naturalness of the presentation. Thanks to it all albums recorded and mixed in the analog domain (especially of acoustic instruments) come out great. Others sound a bit worse for this treatment but never bad. Their inferiority is a technical issue of their producer and label, not SPEC's or ours. But perhaps such distinctions are academic. They really only arise from the reviewer's need to talk of differences. While it's possible to get superior resolution, I'm unsure whether anybody really needs it. I tend to think most of us would simply want to hunker down and forget about the world for a while. If that's you, the REQ S1-EX will perfectly suit.

 EXTENDED REVIEW: story began over a year ago when I prepared materials for our seventh annual Japanese issue of HighFidelity. I asked Mr. Yoshi Hontani for help whom I wrote of in the past. Together with his son Elia he made a few appointments for me with manufacturers from his home country which were completely unknown to me and thus full of secrets. This is how I first came across Audio Replas, fo.Q, SAEC, Air Cable (Okutsu Denko Co.) and the signature product from SPEC Corp., their RSA-V1 amplifier reviewed. A few months after that review I received a very nice letter from Mr. Shirokazu Yazaki, chief SPEC designer, thanking me for my accurate observations and sharing his experiences. He also sent me a brief report of a New Year's Eve meeting during which he and others had auditioned his latest design, a tube amplifier based on very exotic Western Electric tubes he crafted for a friend. Thus began our e-mail friendship. It's unusual to find a person separated from us by thousands of miles, by a completely different culture and by a very different professional background yet with whom we clearly share similar sensibilities, tastes and views. After a while the idea of a phono reference preamplifier began to crystallise. But first some background on the company and its boss. This is how Yoshi Hontani first introduced Mr.Yazaki to me:

"Mr.Yazaki of SPEC is a very interesting engineer. He loves the sound of 300B single-ended amplifiers and has been continuously upgrading his own 300B SET across 38 long years whilst aiming for the ultimate sound. To solve the only disadvantage of his 300B SE amp—insufficient power to drive today's low-efficiency speakers—he finally decided to replace his 300B output tubes with the newest highest-grade PWM switching devices supported by a linear power supply and West Cap-type vintage oil caps. This means that whilst the output tubes were replaced by switching transistors, the basic theory remains that of a valve amp. Although the ultimate target sound should be the same, the sound of these amplifiers is different at this stage. It means that neither tube nor solid-state amps are perfect but there currently seems no solution for further improvements. Some Japanese audio journalists commented already that these latest SPEC amplifiers could be the future of audio amplifier design." - Yoshi Hontani


Here is how Mr.Yazaki sketched out his own background: "My own committed audio hobby started in 1971 when I had just graduated from university and joined TEAC as a mechanical engineer. At the time they were one of the most famous tape recorder makers in the world. I'd been interested in audio products already, especially the dynamic motion of open-reel tape transports. But I suppose at the bottom of it I was basically just another music lover fond of instrumental and vocal Jazz.

"As a tube amplifier fan I became terribly excited when fine European tubes first started to arrive in Japan by the early 1970 thanks to Jean Hiraga. He started a business importing mainly vintage British tubes to Kobe in Japan. I was so stimulated by DIY articles on how to make your own tube amplifiers with vintage European glass from specialised monthly magazines like MJ or Radio Engineering. I'd never before actually heard the sound of such a tube amplifiers. I'd only read about them to imagine both beautiful sonics and exotic cosmetics. But finally I could experience them and became deeply impressed by the superb and very real sound of single-ended direct-heated triode power amplifiers coupled to high-efficiency Altec A-5 horn speakers at the Tokyo Audio Fair of 1971. This experience became the impetus which would actually spur on and shape my own audio career.

Here is how Mr.Yazaki sketched out his own background: "My own committed audio hobby started in 1971 when I had just graduated from university and joined TEAC as a mechanical engineer. At the time they were one of the most famous tape recorder makers in the world. I'd been interested in audio products already, especially the dynamic motion of open-reel tape transports. But I suppose at the bottom of it I was basically just another music lover fond of instrumental and vocal Jazz.

"As a tube amplifier fan I became terribly excited when fine European tubes first started to arrive in Japan by the early 1970 thanks to Jean Hiraga. He started a business importing mainly vintage British tubes to Kobe in Japan. I was so stimulated by DIY articles on how to make your own tube amplifiers with vintage European glass from specialised monthly magazines like MJ or Radio Engineering. I'd never before actually heard the sound of such a tube amplifiers. I'd only read about them to imagine both beautiful sonics and exotic cosmetics. But finally I could experience them and became deeply impressed by the superb and very real sound of single-ended direct-heated triode power amplifiers coupled to high-efficiency Altec A-5 horn speakers at the Tokyo Audio Fair of 1971. This experience became the impetus which would actually spur on and shape my own audio career.

"About the horn speaker system, at the end of 1973 I first got a pair of used vintage Altec 414A woofers in good condition. It’s a 12-inch woofer but compared to the noted 15-inch 416A has more speed across its range. I thought it might prove better for home use. Now I had to decide between Altec, JBL and Onken drivers for the horn. I finally decided on the latter for its exceptionally flat response and the organic natural tonal character of the wooden horn with its amazing Japanese craftsmanship. I ordered the mid-high Onken OS-NEW500MT driver and matching SC-500WOOD wood horn in December of 1973 but didn't receive them until early 1975. It took much time to make these drivers due to the craftsmanship Mr. Koizumi insists on to deliver perfection to his customers. In 1997 I added the OS-5000T Esprit tweeter and the structure of my high efficiency horn speaker system was complete.

"I should also say something about my Marantz 7 preamp. In 1979 Marantz Japan released the kit form of the Marantz 7 as the Marantz 7K. I had adored the Marantz 7 because of its legendary musicality and beautifully balanced design. So I built up the kit but with better parts. I learned so much about how we can get fine musical tone from building that kit. Of course I made continuous improvements to my Marantz 7 up to the present. That means this Marantz 7 really was a good professor for me on audio technology.

"I don’t have sufficient time to describe my professional career over the last 40 years in detail. I would simply like to mention a few memorable products which I either developed on my own or as manager or general manager of an engineering department. I worked with TEAC as mechanical engineer for about 4 years designing open-reel tape recorders. Here I think I learned everything important about tape-transport technology. I drew countless plans for mechanical parts for their TEAC A-7300, a high-performance 2-track 38cm/sec semiprofessional tape recorder. After these 4 years I moved on to Pioneer where for the next 17 years I was team leader or manager of the engineering department for mainly their cassette recorders. At this time I was already an expert in designing high-performance dual-capstan mechanisms. My interest and task was how to reduce their wow & flutter. Each year through the '80s my team developed many models such as the CT-A1, CT-A9, CT-91 and CT-93. By 1992 we released the ultimate cassette deck named Pioneer CT-95 or T-1100S for the Japanese market. Combined with my reference master mechanism, the newly developed Dolby S system, a precise automatic tape tuning system and many other improvements, the CT-95 won the highest ratings from various German hifi magazines. They felt that the CT-95 surpassed even the famous Nakamichi Dragon. This was my secret medal and private delight.

"One more impressive model to mention would be the Pioneer DV-AX10. This was the world’s first real universal player capable of playing CD, SACD, DVD and DVD-A. Not only was the DVD video quality remarkable but also the CD sound was full of musicality. The DV-AX10 garnered the gold medal of Japan's HiVi monthly magazine from amongst all of 1999's A/V products reviewed in Japan. As a general manager of the DVD engineering department I felt delight and honour. And here I met one fabulous engineer, Mr. Banno who struggled to manage an engineering team of about 40 and chased a breakthrough across a range of tough issues. And would you believe it, 10 years later Mr. Banno and I each day are in hot pursuit of a good-sounding D-class amplifier here at SPEC Corp. He and I experienced so many types of sound during the AX10's R&D and it seems to us that those experiences led directly to the development of our D-class amplifiers.

"Around the end of the 1990s and by the beginning of the millennium, Pioneer had reached its zenith where we thus could enjoy the rare opportunity to develop as high-end a DVD player as the AX10. We also had a well-designed spacious listening room and could select high-priced speakers, preamps and power amplifiers as reference for our development of the AX10. I remember that I bought a pair of B&W801, then the reference of specialist audio shops in our domestic market. Of course B&W 801 were driven by high-power semiconductor amplifiers of various famous domestic and foreign brands. Yet Mr. Banno and I were never moved by the sound of this high-end audio system. The sound was like watching miniature paintings. We could hear all the details but were never touched by the music. We felt the sound was very precise but one-dimensional and lacked any real dynamics or rhythm. When I returned home and listened to music over my old high-efficiency system, I was once again intoxicated by the playback which was so transparent, natural and organic. I felt that the difference came from the distinction of certain dynamic characteristics of these two systems, not merely specific static qualities. Yet at the time I couldn’t clearly understand the reasons for my dissatisfaction with the standard approach.

"It was unexpected but my career in the engineering department was over by the spring of 2000 when I was transferred to a subsidiary production company at Semarang/Indonesia for management reconstruction as their director. I thus had to leave behind the sound of my old system and experienced many hardships about all aspects of expat life in an equatorial foreign country. I think those hardships, unfamiliar circumstances or the nature of the rainforest fostered some inner strengths and musical hearing abilities. In any case Indonesia has since become my second home.

"Getting back to Japan, toward the end of my career at Pioneer I was put in charge of their R&D centre. I could choose a good sound system with an amplifier and speakers of my own preference. I well remember one day in October 2006 when I had opportunity to attend a demonstration of new D-class power devices and a prototype amplifier which used them. I was very impressed with the sound. It was only a prototype so the sound wasn't truly sophisticated yet its rich mid to low ranges made it feel like a good tube amplifier with very similar musicality. I noticed an obvious difference to the sound of traditional transistor amps. On another business trip on December 9th, 2006, I had the chance to talk to the person who had developed that amplifier in Los Angeles. As a matter of fact he turned out to be my junior colleague from Pioneer and a personal audio friend.

"Mr. Honda had emigrated to the US with his family and found a job with International Rectifier, a semiconductor company specialising in a power management technique called IR. After around 6 years working there, he had developed new D-class devices. I felt he was not only a nice guy but also a brilliant engineer with a certain genius for audio circuitry so a joint dinner at a seaside restaurant became a true delight. We talked about our private lives and of course hifi, especially his new parts. It was a great night for both of us and this meeting became the start of my search for the full musical potential of these brilliant IR class D devices. On February 6th 2010 we started our new company SPEC Corporation.

"I already had a lot of know-how on how to work with such parts to improve their musicality. There are two major areas for tweaking. One is the low-pass filter in the final stage of the D-class circuit, the other major determinant is the quality of the power supply. Today I'd like to focus on the low-pass filter. The role of this filter is very important for switching amplifiers because it filters out the PWM switching carrier frequency of about 400kHz in an efficient manner to pass along pure analog current to the speakers. This circuit is ultra simple—composed of a single inductor and capacitor—but the quality of the analog current and its sound quality depends most highly on the quality of these two basic parts. Here I must add that the switching abilities of these new IR amplification devices are near perfect. IR states power transfer efficiency approaching 96%. So yes, here we have a new generation of audio power parts. I firmly believe this is very good news for music lovers around the world.

"I would like to get back at the low-pass filter. By the end of 2009 I had reached the conclusion that the best capacitor to use in this filter was the vintage oil-filled capacitor marked 'hermetic seal' from WEST CAP, part N°. CPV09 0.47/600 made for the US military in 1967. Of course as coupling capacitor it also remarkably improved the sound of my old DA30 non-feedback SET. Its sound gained in musicality and deep bass with no trace of grain in the mid and higher ranges. But we couldn’t use these NOS parts for our new D-class amplifier. It was hard to find a solution for this vexing problem, so hard in fact that I can only explain the ensuing find as divine intervention. It turned out that the original capacitor manufacturer had survived in Tucson, Arizona. They'd changed their name from West Cap to Arizona Capacitors Inc. in the early '90s. Arizona Capacitors took over from West Cap huge production facilities and endless engineering drawings. As their Japanese distributor our company has worked together with Arizona Capacitors selling quality custom oil-filled capacitors since the summer of 2011. Japanese tube amplifier fans remember the name of lovely sounding vintage caps from Sprague and West Cap. Our distributing business has grown because of the high tonal quality of these oil-filled capacitors. And finally we were able to adopt these custom oil-filled capacitors for all our amplifiers. This was a real miracle and I thank the Lord for having blessed me so many times by coming across these tonally pure parts.

"If I were to say something about the true potential of D-class amplifiers, I'd say that it's important how they control the inevitable back electromotive force from the speakers. In D-class amplifier the current of the back EMF is directed back at the power supply whereas in a traditional solid-state amplifier the current forcibly enters their feedback loop. That disturbs the precise phase transmission of dynamic music signals. That's why our RSP-101 improves the sound and helps protect amplifier circuit precision especially of solid-state amplifiers with deep feedback." - Shirokazu Yazaki. About today's review subject, he had this to add: "With the REQ-S1 we improved our domestic REQ-77S version to let you hear the performer's very mind and soul. We also adopted the very latest parts of ultra low-noise high-gain op amps within very simple circuitry whose very simplicity means that we more easily hear the quality differences between passive parts like capacitors and resistors. This fact is the same as for our class-D amplifiers and the RSP-501EX. Put simply, the experience of developing the class-D amplifiers RSP-101, 301 and 501EX led us directly to the REQ-S1. For its power supply we have adopted the newest SiC (silicon carbide) diodes. These are also in the RSA-M3EX. They are free from switching noise and have an excellent sonic character of a very transparent mid to high end with rich and powerful mid to low registers."

The REQ-77S launched for sale in Japan in March 2013 and its European version followed in April. Our review unit with serial number 0001 would be a world premier. At Munich HighEnd 2013 SPEC Corp. showed its new mass-loaded AP-5 turntable [the speaker end of that system is shown below - Ed].

Sound - a selection of recordings used during these auditions: Bill Evans, Selections from Live at Art D'Lugoff's Top Of The Gate, Resonance Records, HLT-8012, Limited Edition #270, blue wax 10” LP (2012); Cannonball Adderley,Somethin’ Else, Blue Note/Analogue Productions, AP-81595, “The Blue Note Reissues, 45 RPM Special Edition #2468”, 45rpm 180g 2xLP (1958/2008); Clifford Brown and Max Roach, Study In Brown, EmArcy/Universal Music Japan, UCJU-9072, 180g LP (mono); Depeche Mode, Delta Machine, Columbia, 460631, 180g 2xLP (2013); Eva Cassidy, Songbird, Blix Street Records/S&P Records, S&P-501, 180g LP (1998/2003); Keith Jarrett, The Survivors’ Suite, ECM Records, ECM 1085, LP (1977); OMD, Dazzle Ships, Virgin Records, 205 295-320, LP (1993); Talk Talk,Spirit of Eden, Parlophone/EMI, PCSDX 105, 180g LP+DVD 24/96 (1988/2012); The Cure, Disintegration, Fiction Records, 532 456-3, 180g 2xLP (1989/2010); The Montgomery Brothers, Groove Yards, Riverside/Analogue Productions, AJAZ 9362, 'Top 100 Fantasy 45 Series', 45rpm 180g 2xLP (1961); Tingvall Trio, Skagerrak, Skip Records, SKL 9057-1, Limited Edition, 180g LP (2006); Tommy Schneider & Friends, The Hidden Port, Kolibri Records, No. 12001, 180g LP (2012); Wes Montgomery & Wynton Kelly Trio, Smokin’ At The Half Note, Verve/Universal Music K.K. [Japan], UCJU-9083, 180g LP (1965/2007); Yaz, Upstairs at Eric's, Warner Bros. Records/Mobile Fidelity, MOFI 1-020, Silver Label, Special Limited Edition No. 2044, 150g LP (1982/2012); Zakir Hussain, Making Music, ECM 1349, LP (1987). 

Shirokazu Yazaki is a man who knows exactly what he wants. In his work as chief designer he is guided by a logic which he presumably learnt at college but unlike many of his colleagues also in Europe, he is not its slave. Rather logic adapts to conditions and whatever material he deals with. This material being music, it requires thinking outside the box and going beyond the confines of academic knowledge which is quite often dull when it comes to coping with things difficult to measure that ultimately need to be worked out with that most sensitive instrument of the human ear.

In their pursuit of a music truth or an internal logic, designers are doomed to work out compromises and make choices. This is how it was, is and will be. No invention or technology can change that. Mr.Yazaki knows this well. I can hear it using his products. I can feel it listening to them. I can hear and understand it. The reference sound for this Japanese designer are tube devices from the Western Electric days and its more exotic types though 300B are included. This is how he tunes his class D amplifiers. This is also how he tuned the REQ-1S EX phono stage.

If we were to distance ourselves from the music and concentrate just on its sound, this one would seem quite warm and in ultimate terms of limited selectivity. In short this isn't a microscopic tool with which to analyse various pressings and versions of the same record. Although it uncovers much relevant information, these data arise along the way and in the background. These elements are audible, they occasionally even manifest themselves but never do so in the foreground and never are comparable to or confused with the main presentation.

The first example about this is how the machine renders recordings somewhat similar by rounding over attacks and saturating colours. These two features generate the impression of warmth. Yet there is no actual warmth because it's hard to claim that any part of the frequency range is emphasised. Vocals and instruments operating across a similar range are not brought forward or exposed. The mix is always even, the distance from the listener, the perspective of a given instrument primarily dependant on the mastering engineer. Despite the fact that by comparison to an RCM Audio preamplifier the SPEC did sound warm and not terribly selective, all through the audition it was obvious that it had an inclination towards or a sort of weak spot for records pressed from analog not digital masters - even when the latter were of 24/96 or even 24/192 resolution. The difference between them was not clear at first. It was not about colour or resolution, at least not directly. Good productions of digital remasters such as ECM's Making Music by Zakir Hussain, the new reissue of Talk Talk's Spirit of Eden and The Doors box set sounded surprisingly convincing in fact. They had fullness and depth with no trace of sharpening or brightening as can occasionally happen on an overly dry playback system.

But it merely took listening to something fully analog like the reissue of Groove Yard by The Montgomery Brothers andSomethin 'Else by Cannonball Adderley from Analogue Productions; or Study in Brown by Clifford Brown and Max Roach and Smokin 'At The Half Note by Wes Montgomery on 200g Japanese vinyl to immediately feel what it was about. I got a much deeper smoother slightly less muffled sound. The muffling here doesn’t refer to a rolled-off withdrawn treble. It's simply SPEC's signature. It occurs on all recordings no matter what. It's thus something deeper and more intrinsic. It is a sense of suppressing all the upper registers. I recognised it from speakers with poorly crossed-over drivers or an incorrect amount of internal damping. The vocal delivery of Talk Talk’s front man Mark Hollis was warm, full and sensual but also slightly nasal. Ditto for Alison Moyet's voice on the reissue of Upstairs At Eric'sfrom Mobile Fidelity or the new 180-gram vinyl version of Disintegration by The Cure. The same pattern repeated itself. They all sounded surprisingly nice but depth and access to instruments was limited. But this wasn't the only scheme governing the sound. It simply demonstrated the priorities of SPEC’s designers. Another indicator would be played repertoire.

One hifi axiom is that the audio system should be universal. Audio equipment should sound as good playing a large symphony orchestra as it does with death metal. There's truth in that, the same kind that insists audio equipment should not interpret but show exactly what was recorded. In the real world where such axioms seem more abstract and idealized, a designer can choose between several equally attractive options on just one condition: it must lead to a better understanding of the music and enhance our experience.

And so we connect music playback to the people who design it with their peculiar preferences and beliefs. That applies both to the internal design—the engineering choices embedded in each component—and the external assembly of a complete system which music lovers build to suit their needs. Reviewing the REQ-1S EX I had no trouble knowing the answer. Yazaki-san looks for the truth in each musical performance. To explain that I must first spill some ink on the debate about the superiority of one truth over another, a debate far older than hifi itself. The question to answer is philosophical in nature. Should a designer attempt to bring the sound as close as possible to a live performance; or should he be concerned with a maximally accurate rendition of what was recorded? 

Although it may seem otherwise, these are two completely different paths. In the first recordings are somewhat homogenized as the character of the equipment imposes itself on them. In the second we have great differentiation between recordings but also more problems which carry over from the recording studio to our home. It would be best if the two were reconciled and in absolutely top systems we get something of a cease fire where both remain in a very delicate balance. In any other case one must choose sides!

The Japanese phono preamplifier joins the live event camp. It is best suited for albums which rely on acoustic instruments or electric ones recorded through stage amps. Then we get a brilliant marriage of emotion and technique very smooth and coherent. Unlike with albums converted from digital masters, the muffling of the upper midrange then is utterly nonexistent. In absolute terms however the treble is still soft and the whole rather warm. Yet this is perceived as an asset rather than flaw. Although live instruments are more open and a real live soundstage is more expansive, the REQ-1S EX guides our playback experience by a different set of rules to actually become richer and more human than technical.

Conclusion.

Listening to music through the Japanese phono stage is like having a bath in essential oils, resting on silk sheets, sipping caffé latte somewhere in sunny Italy, drinking a mug of Paulaner in a small bar in the center of Munich. It's about an excellent balance between individual parts, a conscious choice about sound, clear views on technical matters and last but not least a fantastic man behind it all which makes listening to the REQ-S1 EX like meeting an old friend: a bit of nostalgia mixed with curiosity and a renewed sense of security. 

Sounds modelled by this preamplifier are never unpleasant. It’s also an obvious departure from objective neutrality. Nevertheless it doesn't alter the heart of the matter, the value and naturalness of the presentation. Thanks to it all albums recorded and mixed in the analog domain (especially of acoustic instruments) come out great. Others sound a bit worse for this treatment but never bad. Their inferiority is a technical issue of their producer and label, not SPEC's or ours. But perhaps such distinctions are academic. They really only arise from the reviewer's need to talk of differences. While it's possible to get superior resolution, I'm unsure whether anybody really needs it. I tend to think most of us would simply want to hunker down and forget about the world for a while. If that's you, the REQ S1-EX will perfectly suit.

Review methodology.

The Japanese phono preamp was compared to the RCM Audio Sensor Prelude IC and fed from three different turntables: the Kuzma Stabi XL2 with Benz Micro Switzerland Ruby Z cartridge; the Dr. Feickert Blackbird equipped with a Reed 3P tonearm and Kansui and Zero cartridges from Miyajima Lab; and the Dr. Feickert Firebird with Dynavector DV509 MkII arm and matching XV-1 cartridge. The preamplifiers were placed directly on the Acoustic Revive RAF-48F isolation platform and the power supply unit on the RST-38. Power cords were Acrolink Mexcel 7N-PC9300. The review compared individual tracks and whole albums. I devoted a separate session to auditioning the preamp with the Phasemation EPA-007 balanced headphone amplifier and HifiMan HE-6 headphones in balanced mode. 

Design.

The full name of this component is the Designer Real-Sound Audio Phono Equaliser Amplifier REQ S1-EX. The first part refers to the product series, the second to a certain technique and philosophy, the third to the type of equipment and the fourth is the actual name. The unit splits into two enclosures for the amplifying and equalising circuit (PA-S1) and power supply (PU-S1). Both show meticulous workmanship and are made of steel plates with thick aluminium fronts. Underneath each enclosure is a screwed-on wood plinth forming an anti-vibration platform. This wood was prepared by Oak Village, a Japanese company specialising in wooden products in keeping with the country's 1.300 year-old tradition. The platform consists of a wooden plinth laminated from smaller pieces and three shallow footers. Two screw into the cut-outs, the third in the rear slips into a recess. It looks brilliant.

PA-1S.

On the unit’s front are four big toggles with small LEDs embedded in their tips. The first selects MM or MC. The second one activates a subsonic cut-off below 20Hz (7950µs). This is a modification of the 1972 RIAA curve often referred to as EIC RIAA which introduced a fourth correction point. The associated LEDs are green. The third switch activates a cartridge degausser. This sends a small current through the cartridge coil to demagnetize it. It is essential to insure that one's cartridge can undergo this process. Finally there is a mute switch on the far right. These two switches have red LEDs.

All connectors are Swiss Neutrik from Liechtenstein. There are separate inputs for MM and MC cartridges with two gold-plated ground connectors between them. Both have the same potential so we may use either. Apparently the designers’ idea was to enable connecting two cartridges at once or even more likely an MC cartridge and step-up transformer. Next to the MM input we have an input capacity switch with two positions for 100pF and 0pF, next to the MC input an input impedance switch for 20Ω and 200Ω. The output is on RCA and XLR. The output signal runs across quite long leads which suggests a balanced amplifying topology but the circuit is actually unbalanced to add a separate driver IC for the XLR output. Near the rear panel's left edge is the 7-pin XLR connector to connect the unit to its external power supply. All XLR connectors are gold-plated, the RCA connectors get rhodium plating. 

The electronic circuit mounts to a large PCB and a smaller auxiliary board hosts the relays and mute circuit. The ultra-simple circuit is based on ICs. The designer believes that only these operational amps are capable of matching the advantages of tubes which is a rather isolated view though Mr. Friedrich Schäfer from ASR champions something similar. The results speak for themselves. The assumption is that the cartridge should see the lowest possible impedance. Hence the MC input stage is based on op-amps using bipolar transistors which excel at working with low-Z low-level signal. The MM input stage features FET input op-amps optimal for high-impedance cartridges. That is why we have separate sections for MM and MC.

The first gain stage is based on Burr Brown OPA627AM for moving magnet and Linear Technology LT1115 for moving coil. According to SPEC the latter is the lowest noise op-amp currently in production. Then beautiful oil-coupled capacitors from Arizona Capacitors get us to the equalizing circuit. Up to this point the signal for MM and MC inputs was handled independently, the active input selected with an Omron relay. Frequency compensation is based on an RC circuit with the most beautiful resistors I've ever seen in audio equipment just like the accompanying capacitors again from Arizona Cap. The latter are manufactured to SPEC specification and bear their logo. These are bypassed with Bennic mica caps. The most important spec seems to be very tight tolerance. The final gain stage is built with two more op-amps, International Semiconductors LME49860 and Burr Brown DRV134. The latter is a balanced line driver for the XLR output. The coupling wires to the output connectors are quite long and like all internal wiring Belden. There are plenty of them run in bundles. Attention to star grounding is evident throughout. Wherever feasible parts are wrapped in vibration-damping materials. The entire inside surface of the top panel is also covered with a kind of vibration-damping mat which doubles as RF shield. 

PU-S1.

The power supply looks as good as the amplifying unit, features the same casing and a nice front panel with the anti-vibration platform to boot. The front sports just one switch but at that a locking toggle which looks superb. The rear panel features an IEC mains inlet, a fuse and a multi-pin Neutrik XLR power out. As visible from the inside, the IEC socket integrates a simple noise filter. As might have been expected and as I knew it from their integrated power amplifier, the power supply is extremely complex. It mounts on a large circuit board in the form of two separate sections for the left and right channels. These are powered by a large R-core transformer from Kitamura Kaiden. Next to it is a smaller transformer for the relays and LEDs in the main unit. The power supply for the main amplification circuit could easily drive a mid-sized power amplifier.

It features discrete SiC-type Schottky rectifying diodes and two large filter caps per channel. These are followed by Elna Silmic II capacitors and IC-based voltage regulators. There are more Elna caps in the output bypassed by large oil capacitors from Arizona Capacitors and Mallory. The latter brand is currently owned by Cornell Dublier, another American specialist whose capacitors show up with Manley geary. All oil capacitors are high-voltage types (400 and 600 V). What an excellent job! 
………. Wojciech Pacula

......it turns out that this could become our last amplifier - perhaps no the ‘best’ but definitely enough. And that is very much indeed.
Wojciech Pacula

REVIEW SUMMARY: The amplifier’s advantages can best be appreciated with classical music. Really? No, rather with Jazz. Actually, cough, it honestly sounded better yet with electronica. The Vangelis soundtrack to Blade Runner hadn’t sounded this good in a long time. Actually everything sounded great. As I see it now it’s difficult to pinpoint a particular musical style that would benefit the most provided we can accept certain perhaps—that’s what it looks like today—idiomatic limitations of class D. This is not an amplifier with the highest definition particularly at the frequency extremes. The midrange is outstanding however. The midbass can sometimes be too uniform and thus sound too similar across various CDs. The high treble is warmed up and slightly veiled but only in comparison to my Swiss reference amplifier. There aren't too many inputs. The amplifier is not budget-priced either especially at first glance. Yet the moment we see it and get a taste of its perfect design to spot the excellent components inside, we will change our minds. an unknown manufacturer, a no-frill design, nothing to stand out until we take a closer look and listen to well-matching speakers like Harbeth, Spendor, Castle & Co. Then it turns out that this could become our last amplifier - perhaps no the ‘best’ but definitely enough. And that is very much indeed.

SPEC Corporation is a very young company. They started in January 2010. The pretext for their launch was the RSA-F1 integrated amplifier known in specialist audio literature as real-sound amplifier as well as add-on RSP-101 loudspeaker filters called real-sound processors. I mentioned the latter in my editorial Small dreams in the 90th issue of High Fidelity. These little boxes have proven so cool that I kept them to partner my Harbeth M40.1.

I took great interest in reviewing this amp. When the Japanese get serious about anything, they usually approach it in a very unique way. And class D amplifiers definitely deserve serious consideration. However this review would not have happened had it not been for the stubborn help of Messrs Hontai Yoshi and son Elia. To introduce me to today's subject they sent me a brief list of the most important items I should know about the RSA-V1.

The electrical circuit was designed by a talented engineer working for many years at Pioneer who sought to come up with the best possible single-ended amplifier based on 300B tubes.

  • It uses the best available pulse amplifier system in a purely analog circuit (the power supply is linear and fully analog too).
  • The oil capacitors are a reproductions of the WEST-CAP NOS units.
  • The powerful amplifying system uses modules exceeding 90% efficiency so the amplifier generates almost no heat.
  • Due to high power it can effectively control almost all available speakers including those of low efficiency such as Kiso Acoustic HB-1. It's why Kiso Acoustic chose SPEC amps to demonstrate their HB-1 at trade shows.
  • Wooden base obtains as saturated a sound as possible.
  • Safe power switch as used in aircraft cockpits.

We came into this brand because we grew to love the sound of their amps. I believe you also will. We like the philosophy behind it too. Designer Koichi Yazaki is enthusiastic about 300B amplifiers. For 38 years he used a very good amplifier of this type to help him get closer to the ultimate sound with his own circuit which was to scale up power so it could also support speakers which the 300B couldn’t drive. To achieve his beautifully deep sound with high dynamics, he decided to combine analog with the latest generation PWM pulse power amplifiers. During exhibitions in Japan SPEC amplifiers are thus often confused with tube amps. - Yoshi Hontai

How can we sum this up? Perhaps like this: the SPEC amplifier is an analog switching design operating in class D adding NOS components and it is enclosed in a housing that combines wood and aluminium. It was intended to closely match the sound of 300B amplifiers but add scale and power. Let's see how this design brief translates to reality.

Sound.

A selection of recordings used during the auditions. Blade Runner soundtrack, Vangelis, Blade Runner Trilogy, 25th Anniversary, Universal, UICY-1401/3, Special Edition, 3 x CD (1982/2007); For Ever Fortune, Scottish Music In The 18th Century, Les Musiciens de Saint-Julien, Robert Getchell, Alpha, 531, CD (2012); Paganini for two, Gil Shaham, Göran Söllscher, Deutsche Grammophon/JVC, 480 246-5, XRCD24 (1993/2009); Diana Krall, All For You, Impulse!/JVC, 532 360-9, XRCD24 (1996/2010); Dominic Miller, Fourth Wall, Q-rious Music, QRM 108-2, CD (2006); Exodus, Supernova, Polskie Nagrania/Metal Mind Productions, MMP CD DG 0405, CD (1992/2006); Händel,La Maga Abbandonata, Simone Kermes, Maite Baumont, Il Complesso Barocco, Alan Curtis, Deutsche Harmonia Mundi/Sony Music Entertainment, CD 88697846212, CD (2003/2011). Jean Michel Jarré, Magnetic Fields, Epic/Sony Music, 488138 2, CD (1981/1997); Jean Michel Jarré, Téo & Téa, Aero Production/Warner Music France, 699766, CD+DVD (2007); Jimmy Smith and Wes Montgomery, Further Adventures of Jimmy and Wes, Verve/Universal Music [Japan], UCCV-9359, SHM-CD (1969/2008); Michael Jackson,Thriller, 25th Anniversary, Epic/Sony Music Japan, EICP 963-4, CD + DVD (1982/2008); Nosowska, 8, Supersam Music, SM 01, CD (2011); Sara K., Don’t I Know You From Somewhere?, Stockfisch, SFR 357.6055.2, CD; The Modern Jazz Quartet, The European Concert. Volume One + Volume Two, Atlantic/East West Japan, AMCY-1186-7, K2 CD (1960/2000); Wes Montgomery, Incredible Jazz Guitar of…, Riverside/JVC, VICJ-41531, K2 CD (1961/1999).

The SPEC amplifier is an ultra minimalist device. It features only a volume knob and input selector. There's no remote though you can optionally order one which is realised in a quite unconventional way. More on that in the final page. The RSA-V1 comes from a small specialised manufacturer known only to very experienced audiophiles. It is the result of a love for music which you can both see and hear. Its mechanical design combines a heavy metal enclosure with several types of wood. And finally it has a rather distinctive sound as though it had been especially designed to work with my Harbeths. Does that ring bells? How about the Lavardin Technologies IT-15? That review is an important reference point for today's assignment.

Generally speaking these two components appear to sound completely different. Decomposing their sound to a set of prime factors we arrive at a group of often contradictory elements. Yet after assembling it all back together and connecting amps to speakers from the likes of Harbeth or Spendor, we get a comparable musical message evoking similar emotions - although, let’s repeat it once more, by using a set of different tools.

I auditioned the SPEC RSA-V1 in two very different systems – my own and that of the Nautilus audio shop in Krakow, there with an Accuphase DP-510 CD player, Dynaudio Special 25 Signature Edition speakers and Purist Audio Design cables. With these two systems the amplifier sounded quite different. The Dynaudio/Accuphase setup proved that the amplifier delivers an extremely precise and exceptionally pure sound. I also very quickly realized that it seemed not to be limited by power restrictions because not only did it excel at deep dynamic bass but also well-differentiated dynamics. However all along I had the impression that this did not convey a completely coherent message - that all I saw was a frame on which the sound was built but not yet as a complete finished project. This only happened with my Harbeths.

As Mr. Hontai wrote, one of the companies that used SPEC amplifiers during their loudspeakers presentations was Kiso Acoustic. Was it coincidence that their HB-1 speakers garnered two awards from me based on my auditions during the High End 2011 show in Munich: Best Sound High-End 2011 and a Red Fingerprint award? I do not think so. It had been a well though-out system showing in which direction to proceed.

The sound I heard after hooking up the RSA-V1 to my Harbeth M40.1 was nothing short of spectacular. It probably—or almost certainly—was the first class D amplifier I knew where the technology not only failed to prevent it from achieving a high-quality sound but in many ways actually improved it to create such grandeur. With the Dynaudio speakers and Purist wiring I had the impression that it lacked some fullness in the lower midrange and that the upper midrange was a bit too forward. As is well known, class D amplifiers almost always are very sensitive to speaker cables and crossover designs. The latter in fact constitute a part of the reconstructive low-pass filter inside the output section of such amps. That’s perhaps why the amp’s audition at Nautilus floored me to some extent by its sheer power, clarity and precision but was not fully satisfactory. I did not buy into it.

With my Harbeth and Tara Labs speaker cables the Japanese amplifier played a different tune. It showed a beautifully saturated almost warm sound with a very strong solid bass foundation. It might for a moment have seemed that the treble was slightly withdrawn and softened as part of the classic class D trademark sound but after prolonged listening and a subsequent return to the reference system I found this hard to confirm. It was more like a foreboding shadow. Cymbals sounded very very convincing, both rich and full, somewhat ‘tube-like’ as heard from a good 300B amp and thus neither withdrawn nor warm but just right – natural in weight, texture and density.

But one does not immediately perceive cymbals thus because they appear as part of the midrange. And that’s the most impressive sub range of this amplifier not because it is limited to it but rather because the midrange is best differentiated to constitutes a true center from which we get the highest emotions. I mentioned this differentiation not without reason. Both treble (to a lesser extent) and bass (more so) do sound great—it’s hard not to like their color and dynamics—but when it comes to differentiating instruments within their ranges, showing clear textures is not their forté. The midrange though is a completely different story.

It is presented in a seemingly tube-like fashion as with interesting amps based on EL34s. I refer to a kind of saturation of sound, a maturity or even ‘over-maturity’. This manifests as vocals, guitars etc. moved in front of the speakers in a tangible very organic physical way for a truly energetic presentation. With albums like Sara K.’s Don’t I Know You From Somewhere? and Nosowksa’s 8 it was easy. Both actually encourage such a presentation. It also may have been expected from The Incredible Jazz of Wes Montgomery and Further Adventures of Jimmy and Wes but here the scale of this phenomenon—the sheer volume of sound—took me by surprise.

I did not hear small instruments suspended somewhere between the speakers. What I did hear were three-dimensional masses, entire sonic networks linked together into something greater. Superimposed on that was a brilliant texture of tape noise, the noise of air in the recording studio. The latter is nothing much but constitutes an integral part of these recordings. It's what ultimately gives them their specific sonic dimension. This noise was primarily centred in the midrange and not treble. This was thus not an amplifier to brighten up anything.

So the core sound exhibited similarities to an EL34 amp. But that was just a starting point. It was purer than any EL34 amp I’ve heard except perhaps for Linear Audio Research's IA-30T. As such it rather resembled good 300B amplifiers and to some extent the sound of my own Soulution 710 power amplifier which remains unrivaled in this respect. It was enough to listen to Simone Kermes’ La Maga Abbandonata album of Händel arias, especially the wonderful “Ombre pallida (Alcina)” to appreciate the combination of high power, purity and excellent midrange and treble color. These were exactly the same emotions I experienced while listening to the lady live some time ago fronting the Venice Baroque Orchestra during the Mtsteria Paschala festival. Simply beautiful and utterly splendid!

And so we come to the bass. It’s a good time to recapitulate what’s been said so far and, after adding a little, try to summarize. The bass was strong, full and slightly warm. I cannot imagine any speakers which would be problematic for this amp as long as speaker cables are properly matched. But it is here where you can hear a class D amplifier. With smaller speakers such as the above mentioned Dynaudio Special 25 Signature Edition and Kiso Acoustics HD-1, it will not be so obvious because they cannot render bass as low as my Harbeths. What I refer to is a slight sonic uniformity, a type of homogenization in the low bass. Dynamics and extension are outstanding but the differentiation of bass dynamics and color is not

To some extent the same applied to the treble. It was always pleasant and smooth but not exceedingly well defined though selective. As such it was the exact opposite of the Harbeths. The central and upper treble were slightly warm but if the recording lacked in this respect like Michael Jackson’s Thriller or some tracks from Nosowska’s 8, the SPEC would show it to some extent. It never sharpened or brightened up nor will it drown everything in uniform warmth however. 

The amplifier’s advantages can best be appreciated with classical music. Really? No, rather with Jazz. Actually, cough, it honestly sounded better yet with electronica. The Vangelis soundtrack to Blade Runner hadn’t sounded this good in a long time. Actually everything sounded great. As I see it now it’s difficult to pinpoint a particular musical style that would benefit the most provided we can accept certain perhaps—that’s what it looks like today—idiomatic limitations of class D. This is not an amplifier with the highest definition particularly at the frequency extremes. The midrange is outstanding however. The midbass can sometimes be too uniform and thus sound too similar across various CDs. The high treble is warmed up and slightly veiled but only in comparison to my Swiss reference amplifier. There aren't too many inputs. The amplifier is not budget-priced either especially at first glance. Yet the moment we see it and get a taste of its perfect design to spot the excellent components inside, we will change our minds. However our first impression is important. And that says that we don’t really know what we're paying for here.

I had exactly the same reaction to the Lavardin Technologies IT-15 amplifier - an unknown manufacturer, a no-frill design, nothing to stand out until we take a closer look and listen to well-matching speakers like Harbeth, Spendor, Castle & Co. Then it turns out that this could become our last amplifier - perhaps no the ‘best’ but definitely enough. And that is very much indeed.

Review methodology.

The amplifier was placed on the Base IV Custom Version rack and a wooden shelf. For some time it also sat on additional decouplers from Audio Repas (their OPT-30HG-PL/OPT-30HG-SC quartz insulators). The CD player was connected via XLR SAEC XR-4000 cables. 

The sound was better than over RCA. That result will largely depend on the CD player and the player/amp power cords. I used a Harmonix X-DC350M2R Improved Version cord. The test was an A/B comparison where both A and B were known. In addition to my reference amplifier, the RSA-V1 was compared to the Struss R150 and Hegel H200. Music samples were two minutes long

Design.

The first amplifier from this manufacturer was the RSA-F1. The reviewed RSA-V1 is a newer less expensive version with somewhat simplified housing and electronics but it was ‘dumbed down’ only to the point of making sense. It is an integrated amplifier based on analog amplification working in class D with newly designed power Mosfets. The amplifier comes without remote but may be ordered with a beautifully designed external receiver module and wand. That set is called the RSR-3 and you have to pay for it separately.

Front and back panels.

From the outside the amplifier is very simple but interesting. Its mechanical design is based on combining a steel casing with an integrated anti-vibration wooden plinth. According to the maker that plinth is what gives it its deeply saturated sound. The platform combines several components: solid oak wood with two feet in the front (the bar bears the Oak Village logo) and European Spruce ply cut in Austria with one footer in the back. These footers are Japanese maple from Hokkaido Island called hickory and were also recently used by Acoustic Revive in their RAF-48H and RST-38H anti-vibration platforms (the 'H' in their names derive from hickory). The front panel features only three parts - an input selector, volume knob and power switch. The volume knob illuminates blue but the backlighting may be turned off with a switch on the back panel. Both knobs are very solid aluminium and very attractive. The power switch is even cooler. Its design borrows from airplane cockpits. To switch the amp on or off you must pull the switch pin to release its latch. 

Next to this switch are red and green LEDs. The red one lights up when you turn the amp on and slowly dims when you switch it off. After turning off the amp the volume control backlighting also fades slowly – really cool. The quality lettering is beautifully silk-screened and the Designer Audio logo is engraved in the center. The back panel is quite simple. In the center we have two pairs of gold-plated rather plain binding posts. To the right we get three pairs of RCA and one XLR inputs. The RCAs are high-quality rhodium-plated issue. To the left we find the IEC mains socket, a switch controlling the volume knob back light and a small socket for the external remote control receiver 

The interior.

The interior divides into several sections carefully shielded with steel sheets. From the inputs the signal proceeds via Belden cables to the mechanical switch on the front panel and from there to the main circuit board with the power stage. The RSA-V1 is a power amplifier with adjustable gain. The latter isn't completely passive because it features an integrated 3310 IR01 circuit, a digitally controlled analog resistor ladder by JapaneseTachvonix which was apparently custom programmed

A quick check shows it to be the International Rectifier Japan version 01 of the CS3310/PGA2310 chip. The Japanese potentiometer on the front panel is only a driver that's not in the signal path. After the gain adjustment the signal goes straight to the small main board. That is a complete class D IRAUDAMP4 DB Rev.03 module from International Rectifier and as such the PWM modulator. This circuit is fully balanced so it is worth driving the amplifier from its XLR connectors. SPEC designed the output stage with newly developed Fets bolted to a tiny heat sink.

One of the most important components of a class D amplifier is its output filter which recovers the musical signal from the modulator signal. Its quality to a large extent determines the final sound. Here SPEC went all out and used special oil capacitors designed in collaboration with Arizona Capacitors Inc. The power supply is equally important. The Japanese usually don’t like switching power supplies and prefer linear designs. This amplifier is no exception. Under the shielding metal we find a very large powerful R-core transformer.

The rectifier features a bank of ultra-fast modern Schottky diodes and a number of filtering capacitors of various types. These include ‘Super Through’ and ‘Gold Tune’ Nichicons bypassed by oil capacitors from Arizona Capacitors bearing the SPEC Corp logo. It is a very clean well thought-out design. Although the amplifier is built around the stock heart from International Rectifier, it is supplemented by high-end custom designed components. 

........Wojciech Pacula

If you want what it does—mimic valve sound to this extent whilst throwing in modern power efficiency which SET-ish class A transistor amps certainly don't—then this could be the top game in town and play smack in the heart of your most desirable district.
Sarjan Ebaen


REVIEW SUMMARY: Were I a Spendor or Harbeth fan looking to maximise the known virtues of those warm Brit boxes, the RSA-M3EX could be it.

It really is about a powerful dose of classic valve sound. The big difference is cool running power; current-critical load happiness into low impedances; operational silence; and stable performance without the insidiously slow ageing of power triodes and its deleterious sonic effect.

With Boenicke Audio B10. speakers it was as fine a pairing as the eggs had been, extending lower without being plagued by ports for superior sealed bass, the ambient-rich sound favoured by Sven Boenicke—hence his penchant for lateral drivers—responded favourably to the amp's tonal weight. I really suspect Yazaki-San himself would have approved.

If Yazaki-San's results surprise us, it's only because none before have endeavoured to bend switching transistors quite so far in this direction. Henceforth SPEC marks that spot.

EXTENDED REVIEW: When a designer traces his audiophile lineage back some 38 years—to when Jean Hiraga first imported NOS tubes to Japan to promptly build himself a DA30-based SET with WE310A driver/274B rectifier followed by a vintage horn speaker system based on Altec 414A woofers, Onken OS-500MT mid/high drivers and matching SC-500 wooden horns—you just know his sonic north. When such a designer worked at Teac on their open-reel recorders as mechanical engineer and subsequently for nearly two decades at Pioneer where he was involved with more tape decks—the Nakamichi dragon-slaying CT-95 was a highlight—and the world's first true universal player whilst continuously evolving/upgrading his original SET... then you also know that despite newfangled technologies a love of vintage tube sound remained alive throughout.

When Shirokazu Yazaki joined forces with International Rectifier engineer Tsutomu Banno to launch SPEC Corp. on February 6th 2010, he had a most contrarious notion. He meant to advance his beloved valve sound with the very latest in ultra-efficient super high-speed switching power Mosfets which Banno had helped develop during his IR tenure. Yazaki-San is adamant that class D circuits are particularly vulnerable to the quality of their power supply and low-pass filter. With him the former becomes a massively overbuilt linear affair, the latter an ultra-simple inductor/cap circuit albeit based on rare custom parts. "By the end of 2009 I had reached the conclusion that the best capacitor to use in such a filter was the vintage oil-filled type marked 'hermetic seal' from West Cap, part N° CPV09 0.47/600 made for the US military in 1967. It turned out that the original capacitor manufacturer had survived in Tucson, Arizona. In the early 90s they'd changed their name to Arizona Capacitors Inc and from West Cap taken over huge production facilities and endless engineering drawings. As their Japanese distributor since the summer of 2011 we've worked closely with Arizona Capacitors to sell their quality custom oil-filled capacitors in our domestic market. We were thus able to adopt their fantastic capacitors for all our amplifiers. If I were to isolate something very important about the true potential of D-class amplifiers, it's how they control the inevitable back electromotive force from the speakers. In D-class amplifier the current of the back EMF is directed back at the power supply, not the feedback loop of traditional transistor amps where it undermines their phase integrity with dynamic music signal."

"The ultimate performance of a class D amp also depends on just how accurately it implements its pulse-width modulation switching. Here International Rectifier's DirectFet output device with a high-voltage invariant IC driver of excellent time axis performance really establishes new parameters. Other well-known class D advances are almost triple the efficiency of conventional semiconductor amps; instant current delivery; bidirectional energy transfer to regenerate back-electromotive forces in the power supply; and excellent linearity."

In the SPEC book this makes class D a 3rd-generation proposition preceded by the 1st generation of tube amps which were natural and rich of tone but of limited bandwidth and incapable of driving modern low-efficiency speakers; and the 2ndgeneration of traditional transistor amps which had high power, certain disadvantages based on their implementation of negative feedback plus wasteful energy consumption. Done right they believe that class D can combine the very organic presentation of tube amps with the raw drive power of transistor amps to become a best-of-both-worlds hybrid.

The use of specific tone woods for SPEC's metal enclosure plinth reminds us. Yazaki-San's audio background began in mechanical engineering. Just like his deliberate exploitation of NOS-type capacitor sonics*, this indicates strategic voicing or circuit tuning.

As such SPEC's approach to class D differs from Hypex/Ncore's Bruno Putzeys whose own blog contains comments like "...the fly in the ointment came as I slid our preamp proto (later baptized Makua) into a rack for one such demo. To understand my befuddlement you ought to know that said rack space had just been vacated by what I’d call a glorified variac but what was probably an 'autoformer-based passive preamplifier'. It had two big knobs, one for source (three positions) and one for gain (twenty-four 2dB steps). Rotating them took considerable force and both went alarmingly clunk as one did so. It was in other words esoteric. And its distributor had just asked me whether Makua had a remote control. Here’s the mistake I made not including one. When a product looks like it’s been designed in a basement decked out with Buddhist paraphernalia and the electrical circuitry—such as it may contain—is a highly intimate statement of one’s most personal artistic genius, nobody asks for a remote control. One doesn’t question High Art and demand that it be practical. But as soon as some degree of engineering is evident like the presence of an actual gain stage or the absence of distortion, the product becomes pedestrian and it’ll have to use the zebra crossing like anyone else."

The RSA-M3EX integrated combines the esoteric—tuned wood footers, tonewood plinth, vintage-style oil-filled caps—then crosses the zebra stripes with an optional costly remote executed differently once again as a wired wooden receiver box. That separation keeps this circuit and its potentially noisy display completely isolated from the main box. It also means that someone not into remote volume needn't pay for it.

Seeing how SPEC have four different integrated amplifier models—the RSA-717EX, F3EX, M3EX and V1EX—but little to distinguish them to the naked eye (the 717EX is smallest as the next photo shows on the top left-most rack), I asked Yoshi Hontani, English-speaking Japanese audio exporter for SPEC and other Japanese brands like Leben Hifi, to talk me through their specifics on behalf of Shirokazu Yazaki.

"We think of the M3EX as our main export model. It’s very important for us and thus much improved over the domestic M1 version. To clarify the differences between RSA-F3EX and M3EX, I should first point at their commonalities. The class-D amplifier module with IR output devices and R-core power transformer are exactly the same. Hence the power and sonic structure are the same too. But certain parts in the power supply, low pass filter and snubber circuit differ. And it is these differences which determine the particular sonic character of the F3EX and M3EX. In the M3EX power supply we changed the rectifier diode from an ultra-fast soft recovery type to the very latest SiC (silicon carbide) Schottky. 

"This SiC diode was first introduced last fall by ROHM, a semiconductor maker in Japan. We made our selection only after hearing 10 different types of SiC diodes during a ROHM presentation. As a result the winning unit has very powerful high-speed bass and a completely noise-free treble. Simultaneously we also evaluated high-capacity industrial soft-recovery versions used in the F1 and F3EX which are very detailed nuanced and rich.

"I felt that the sound of this diode performed much like a high-quality tube rectifier. At present I thus couldn't decide which was the better diode - the one in the M3EX or F3EX. The amps' actual sound character is directly related to this choice of diode. Both also adopt the Arizona Capacitors Inc hermetic-seal oil-filled caps and custom mica caps in their low-pass and snubber circuits. Because we developed a very close working relationship with this company for the last three years, we have access to two types of custom oil-filled caps. Our REQ-STEX phono preamplifier uses both of them. For our power amps we use the C85805 for the F3EX and the C30509 and C85805 for the M3EX. The F3EX connects two half-size caps in parallel in both the low-pass and snubber circuits to pare down equivalent series resistance. The M3EX uses the C50309 in the low-pass filter and the C85805 in the snubber circuit. Thus the sonic differences between these amps also relate a bit to this choice of capacitor. I myself have many experiences with many kinds of mil-spec vintage oil-filled caps. This eventually led to us Arizona Cap. not only for the low-pass filters, snubber circuits and power supplies of our class D amps but also for our speaker-impedance compensator boxes RSP-301 and 501EX. And I use Arizona caps in my old valve amplifiers coupling their driver and output tubes and in their power supplies.

"So I listen to music with Arizona caps every day at the office and in my home. I thus have some very specific opinions about their sound. The C85805 is a KP/AL/mineral-oil part, the C30509 a KP/MY/AL/mineral-oil type. Our chief engineer Mr. Banno and I appreciate and love them both. The C85805 has an extremely beautiful saturated midrange and treble to be perfectly matched to female vocals and stringed instruments like the violin. The sound is very graceful and pure. This comes from genuine-pulp Kraft paper dielectric. It's a material very close to nature and sounds sweet. The dielectric for the C30509 adds Mylar film. Its sound is almost perfectly balanced top to bottom but the most spectacular registers are the lower ones. Compared to the old vintage West Cap style this sound has better bass speed and a smoother treble to better fit today's broader bandwidth high-resolution music. Yet it retains the desirable warm vintage color of famous US caps like the Sprague 'Bumble Bee', 'Black Cat' and 'Vitamin Q'. I became convinced that the C30509 is the true successor to the famous West Cap vintage capacitors made in the US. I thus decided to distribute these caps in Japan for our domestic valve-amp fans in the summer of 2011. It took time but the nameArizona Capacitors has gradually become very familiar to Japanese DIYers. The common virtue of both types of Arizona caps is their extraordinarily natural sweet sound which gets even more so over prolonged use. Above all it's evidence of the real thing from my personal view on hifi parts.

"I should return to the sonic character we aimed for with the RSA-F3EX and M3EX which reflects the C85805 and C30509 capacitors. There also are the mica caps whose sound our catalog describes 'as transparent as a blue sky'. I feel that mica caps have the best reliability and HF performance. So it becomes the combination of our custom oil-filled and mica caps which exceeds the performance of any other type of signal-path cap I'm aware of. In the end it's this very strategic very well-researched combination of parts which defines our amplifier sound and especially the F3EX and M3EX models. Mechanically our RSA-F3EX as the top model also gets heavier aluminium panels which directly reflects in its higher price. Here we also added very special electrolytics to the power supply. Like magic this vastly improved ambient retrieval over the F1. The M3EX meanwhile benefits from the SiC rectifier to enrich its already powerful sound across the entire range. If one proposed two sides of the true meaning of enjoying the music, one would be delight, the other healing. In this sense the RSA-M3EX would be delight whilst the RSA-F3EX's tone would have some healing effects." 

So we have it in writing. Even its own designer doesn't consider the RSA-M3EX to be just neutral. For that he offers the more affordable V1EX.

What's wrong with just neutral? Wrong question. The V1EX covers that base. It'd be better to ask why Yazaki-San might hold a different personal preference; and why he believes others might join him in that costlier choice. For probable cause we refer back to an interview we published in a previous review of SPEC's phono stage. "Around the end of the 1990s and by the beginning of the millennium, Pioneer had reached its zenith. Our engineering team enjoyed the rare opportunity to develop as high-end a DVD player as the AX10. We also had a well-designed spacious listening room. We could select high-priced speakers, preamps and power amplifiers to be our reference for the development of the AX10. I remember that I bought a pair of B&W 801 which then was the reference of specialist audio shops in Japan. Of course B&W 801 were always driven by high-power semiconductor amplifiers of various famous domestic and foreign brands. Yet Mr. Banno and I were never moved by the sound of this high-end audio system. The sound was like watching miniature paintings. We could hear all the details but were never touched by the music. We felt that the sound was very precise but one-dimensional. It lacked any real dynamics and rhythm. When I returned home and listened to music over my old high-efficiency system, I was once again intoxicated by the playback which was so transparent, natural and organic. I felt that the difference came from the distinction of certain dynamic characteristics between these two systems, not merely specific static qualities."

In a later manifesto, Shirokazu put it this way: "With the mainstream of recent efforts pursuing audio quality based on the combination of low-efficiency speakers and high-power transistor amplifiers, what's really possible is merely a sound that expands on or behind the plane of the speakers by emphasising a feeling of elaborateness, wide frequency response and a rather thin tonal quality. Even if such a sound presents a high degree of perfection from the point of view of audio measurements, does it really bring us the joy and excitement of music?"

Shirokazu is far from alone questioning whether modern hifi hasn't made a bad turn somewhere to keep heading in the wrong direction. Zu's Sean Casey has long been on record on the same matter. So have various others. They all believe that in the pursuit of extreme resolution and parallel demands for ever smaller speakers of increased loudness and bass capabilities, something vital was lost. This view doesn't sugarcoat the fact that Western Electric-day systems had limited bandwidth and high distortion. It's not about returning to 50Hz-15kHz-3dB bandwidth and with it a wholesale elimination of modern music anchored in low bass. It's about maintaining legitimate gains made since whilst recovering aspects of valve tone and the easeful dynamics of vintage high-efficiency hornspeakers they feel have been sacrificed or diluted.

Means. Motive. Opportunity.

SPEC's solution bypasses the SET/horn revival which in Japan remains very active. They pursue conventional dynamic speakers of ±88dB efficiency to make a similar type of sound. For said purposes they harness the very latest in analog switching technology. That's admittedly somewhat radical. It's also quite in contrast again to our earlier mentioned Bruno Putzeys who applies very advanced math and error correction to obtain measurable neutrality and ultra-low distortion. SPEC actually treat their class D amps as valve circuits. They merely swap output devices. Tubes out, DirectFets in. That grossly oversimplifies things but points straight at the heart of the matter. A minor rebellion like Xalapas' El Candigato? Given the strategic component allocations hinted at above, should we assume that what primarily distinguishes the various SPEC amplifiers is different voicing? Shirokazu after all knows exactly how each part of their circuit contributes to the final sound and what to specifically change if one meant to shift sonics in a particular direction.

"The first SPEC model was the RSA-F1. It implemented our full technology with the highest-grade parts and components without regard to production cost. Based on this model we further improved the export version RSA-F3EX mainly by upgrading core power supply components. This made the sound even more graceful and sophisticated. Our second model became the RSA-V1 where intent was to reduce build cost with more affordable parts. The export version V1EX upgraded some of those again. The RSA-M1 was tuned specifically for JBL and Jazz lovers to increase dynamics in the mid to low registers and make the sound more active. The M1EX export version was further improved to cope with all manner of musical categories whilst maintaining the original sound signature.The RSA-717EX is a recent development to undercut the price of even the V1EX by applying a switch-mode power supply. This achieves similar sound to the RSA-V1EX and perhaps is superior for certain music. 

"Although the difference between F3EX and V1EX isn't double, the F3EX is the ultimate expression of our technology as implemented with the very best parts possible. Given this, if I had sufficient money to buy an F3EX, I might chose the F3EX over the M3EX to get the best even if I couldn't distinguish a clear sonic difference. If I couldn't afford the F3EX, I might convince myself that the M3EX was better for my favored music or that the difference was insufficient to pay double. We consider the V1EX our entry-level model. People who don't care about its SMPS will instead go for the 717EX whose sound exceeded our own expectations for it. In conclusion there are clear sonic differences between our three models (the 717EX is an exception). One final advantage of our amps are their superior linear power supplies. They convert over 95% of the wall power into actual output power. Usual transistor amps manage only about a 25% conversion margin. From this follows that our amps drive speakers three times as power hungry as our raw specs would suggest."

The published power ratings for the RSA-717EX/V1EX are 50/100wpc into 8/4Ω and 60/120wpc for the RSA-M3EX/F3EX. Following SPEC's math one should consider them actual 150/300wpc and 180/360wpc ratings versus conventional class A and A/B amps. Surprising perhaps in the maker's descriptions about their lineup is specific voicing, sometimes even for specific speaker brands or music styles; better export than domestic versions; and implied superiority of linear over switching power supplies even though the model with the SMPS is called "perhaps better for certain music" over its equivalent with the linear supply. Either these lines are blurrier and more ambiguous than good/better/best ideologies would wish; or like any loving parent Yazaki-San felt hard-pressed to be too specific about classifying his offspring. On price tiers SPEC hadn't officially begun exporting all models but tentative projections anticipate €18.000/$24.000 for the RSA-F3EX i.e. twice our review model; and €7.2000|$9.500 for the RSA-V1EX.

The remote option is most unusual. It obviously doesn't add a motor to the master knob. Thus having the latter fully counter clockwise can't produce any sound no matter how vigorously one presses the up button on the wand or in dying hope observes the LED confirmation of the display which shows received commands. That's because the remote only operates "within a ±10dB window against the level set by the main volume, i.e. in 4 steps up and 7 down. There's an additional 20-30dB of attenuation or full muting with the wand's attenuate button." The plastic casing with its IR circuitry sits inside the wooden box buffered by simple foam squares all around. This leaves some play. Shaking the wooden case thus elicits a bit of inner movement. To be blunt, €900/$1.200 for this strange and functionally crippled contraption with tiny 9V switch-mode power supply is excessive. It also looks odd and adds two cables to the usual spaghetti salad behind the gear. It does however allow the amp to be installed out of sight whilst retaining a modicum of volume control.

For the obligatory inside tour one has to move beyond the four strategic box shields. If one does here's what the bird's eye view on the main board would show which is usually concealed beneath the biggest internal case. 

Here we go straight to the 2-channel International Rectifier amplifier module. It piggybacks on SPEC's main board right in front of the low-pass filter air-core inductors and caps. The short flying leads from the main board to the output terminals leave via massive screw-down blocks. This termination method is far sturdier than the ubiquitous solder joints to a PCB. Its presence here indicates very high current flow at that precise juncture

The dual-mono IR module runs two clocks per channel. The main board contains a three-pole external clock switch (likely an assembly feature to fix the precision trim pot setting) and a socketed International Rectifier version of the Japanese Tachyonix Corp. 3310 volume controller chip. The heat-sinked module accommodates three 78M12CT voltage regulators.

As this inspection confirmed, the RSA-M3EX is very far from just another ICEpower, Hypex, PowerSoft, Abletec, AnaLight or Pascal affair. Just so that plain fact wouldn't safeguard it from being compared directly to such 'off-the-shelf' D-class competitors.

For modified Hypex UcD400 with linear power supply and Lundahl input transformer I had the $5.000/pr Aualic Merek monos on loan. For Pascal I had the modified S-PRO-based €3.250 Gato Audio DIA-250 with IR DirectFET output transistors like the SPEC. Both are from rather to very much more cost-effective. Both also offer considerably higher power. The Danish integrated even adds features like a 24/192 DAC with asynchronous XMOS-based USB, a beautifully legible dot-matrix white display and remote control over the amp's complete volume range.

Well prior to any listening yet, the gavel thus apeared to come down hard on the RSA-M3EX's price and its very peculiar also very costly add-on remote control. Nothing like a bit of competition to keep things honest. With that out of the way, how about sonics? For that assessment I'd use two very different speakers - the soundkaos Wave 40 and the AudioSolutions Rhapsody 200.

The first is a 92.5dB Raal ribbon-augmented German 8-inch widebander in a complex Swiss tone wood enclosure with very short line/scoop loading and low-order filters. This is the type of speaker conventionally mated to low-power SET amps (or in my own case Nelson Pass' SIT-1 transistor equivalent). The second is a typical 'muscle-amp' speaker by virtue of a challenging impedance curve and seriously underdamped dual-port bass alignment. It thrives on high damping factor i.e. low output impedance. As a 5-driver 3-way with higher-order networks, the dual-woofer floorstanders also responds well to power. To keep things honest against traditional amp topologies I'd use the aforementioned FirstWatt SIT-1 monos; Crayon Audio's CFA-1.2 which despite its medium power output handles the Rhapsody 200 beautifully and sonically can be thought of as a functionally and power-enhanced Bakoon AMP-12R; and the DC-coupled very affordable but boffo Job 225 which is a bit less refined but more powerful. You could say that the Japanese challenger had its work cut out for itself.

Round 1.

Wave 40. SPEC vs. FirstWatt. This system came conceptually closest to the designer's own vintage ideal of SET + horns even though my lower speaker sensitivity and lack of front-horn loading still differed significantly. On the one hand this made for a very typical low-power tube-friendly proposition vintage by design. On the other hand it didn't make for a scenario where at least traditionally we'd have expected a class D amp to do well. But times change. Take the forthcoming Greek Kalypso speaker from Rois Acoustics [right]. It will combine a whizzer-fitted Tangband 8-inch widebander with a folded rear horn and built-in PCM-to-PWM true digital amplification by Audio4Soul driven from either a USB or coax input. My recent DIA-250 review had shown how modern high-power class D amps can conjure up valve-reminiscent warmth and fullness into counter-intuitive loads well within the first-watt window. As such my Swiss soundkaos eggs were ideal to test Shirokazu Yazaki's claim that their approach to class D combines the best of traditional transistor and valve topologies. And so too were my simpler-than-triodes SIT1s ideal to juxtapose ultra-refined modern SET sound with specs better than equivalent valve amps. How would the RSA-M3EX strut its stuff in that context?

To simplify A/B/A swaps I wanted to run the RSA-M3EX in amp-direct mode preceded by the same Nagra Jazz preamp which drove the Nelson Pass monos and only subsequently compare the Nagra/SPEC combo to pure spec. Whilst the Jazz into the 35dB-gain Job 225 is dead quiet—the measured S/N ratio of my actual Nagra unit is 114dB—the SPEC in 20dB fixed mode was very noisy in the seat even when the Jazz was set to 0dB gain. In variable mode and with the Nagra set to unity gain, that noise disappeared. I thus would eliminate the Nagra from the go and only assess the RSA-M3EX as an integrated amplifier. In that mode and at the actual volume setting used, the SPEC was dead quiet whenever I paused my source.

The upshot of this juxtaposition against a €12.000 valve preamp + $10.000/pr single-ended transistor monos was a far from wildly dissimilar sound. My twice-priced separates were simply the more informative in the upper half of the sonic spectrum. This translated into more specific depth layering and related separation. I also had the more illuminated upper harmonics and subjectively greater speed with predictable outcomes on transient perception. The Japanese integrated played it darker, heavier and lusher. According to modern parlance and how we use the word 'resolution'—pixel count—it stepped that down. The emphasis instead shifted on something more sumptuous, languorous and rich. In tube terms it was in fact more vintage 300B (Western Electric or Sophia rather than Emission Labs) than the leaner quicker flavour of a 50 or 10Y.

If we drew a horizontal line with end points of fast/lean and relaxed/warm at the left and right respectively, the Bakoon AMP-12R would sit at the far left followed by the Crayon CFA-1.2. The Goldmund/Job 225 would sit between those two but a tier lower to indicate less refinement. The Jazz/SIT1 combo would take up the approximate midpoint. The SPEC then settled down rather farther to the right. How much farther I'd determine vis-à-vis the Gato DIA-225.

Quite a bit. I no longer had the DIA-400 on hand to determine whether that might overlap. That's because the big Dane had struck me as rather more fulsome and lush than its smaller sibling to walk our line way over to the right. With all that implies the RSA-M3EX sounded plainly louder than the DIA-250. It was chunkier. Meatier. At the same time it also projected more forward. This reduced depth and the Gato's more clearly walk-about stage. If we visualize a sea of violins—I was on a kick through various Louis Spohr clarinet concertos on the Hyperion label, with Michael Collins on blackwood—the Gato showed more white caps and ripples. More wind on the surface. The SPEC played it as a more homogenous mass. Less wind. For the clarinet's timbre the difference was akin to that between B-flat and A lengths. The longer instrument sounds darker and warmer.

This gets us directly at the live/playback dichotomy. As reported elsewhere, I'd recently attended our classical music fall festival in Montreux's Stravinski Hall. We'd heard the London Philharmonic under Charles Dutoit with Mussorgsky, Rachmaninov and, fittingly, Le Sacre du Printemps. Sitting in row 7 of the floor's left third the sound there was far closer to what the SPEC now proposed—massive, dark, with more wall-of-sound than vivisectionist staging—than what generally goes for high-resolution hifi sound. With the latter the obvious lack of actual visual data is replaced by quasi-visual playback cues like imaging, performer outlines, halos, pinpoint focus and heightened separation. None of that belongs with un-amplified live music. 1:0 for SPEC. Hurray!

But now we turn tables to inspect the average studio production. Microphones stare down throats and F-holes to capture impressions at pornographic proximities and massively paralleled. Unless we did a Van Gogh on a number of folks simultaneously, no human ears would ever duplicate that. Still with clarinet but now Eddie Daniels andNepenthe on the GRP label, this altered gestalt equalised the game 1:1 for everything left of the SPEC. Obviously close-mic'd multi-tracked recordings make up 95%+ of what we listen to. Now SPEC's readings diverge. They recalibrate such recordings to sound more like an acoustic live concert from a good distance. That's the very essence of this proposition from Japan

The question any buyer has to ask is whether this undeniably attractive makeover has their vote. It's the old beauty versus truth versus beauty is truth conundrum. Here writers must bail. How one decides is entirely personal. It relies on what one uses as reference, what one expects from a hifi and how one weighs tone mass vs. transient speed amongst various trigger points. Based on my exposure to class D sonics and using our earlier graph but now with Hypex Ncore at the center, I'd peg early NuForce well to the left and SPEC far to the right. Most current ICEpower falls between Ncore and SPEC but closer to the latter. Gato's DIA-250 slots between ICEpower and Ncore. AURALiC's Merak monos are the 'poor man's Ncore' to sit right next to NC1200 as I heard it in Acoustic Imagery's Atsah monos. Where does that put SPEC? As Anssi Hyvönen of Amphion put it who provided his speakers to SPEC's Munich HighEnd 2013 exhibit, "it sounded very liquid and for lack of a better word analogue". Spot on!

hat was my fix on the lay of this land. Up next would be the amp's behavior into my already SPEC-voiced Rhapsody 200 towers.

Round 2.

AudioSolutions Rhapsody 200. Using the prior sentence as lead-in segues straight into a predictive answer. Dark, warm, weighty, bassy—my usual brief for the AudioSolutions is "vintage Sonus faber voicing with US-style bass and high dynamics"—looked into the mirror. At lower levels this compounded even more. I wanted for the higher insight and twitchier reflexes of the Meraks. My very best option for the friendly Lithuanian lumberjacks really is the Crayon's whisper-level lucidity. The Bakoon and FirstWatt monos lack power and the latter won't control the underdamped twin ports. The SPEC clearly had no issues with the quite erratic phase/impedance angles of this load. No port boom, no mush. Its own voicing would simply have better complimented a far more neutral Amphion, the recently reviewed very quick Accuton-fitted Albedo Audio Aptica or an equivalent but big Mårten Design or Kharma tower.

Of course that statement betrayed personal bias. Were I a Spendor or Harbeth fan looking to maximize the known virtues of those warm Brit boxes, the RSA-M3EX could be it. Hence Polish contributor Wojciech Pacuła with his Harbeth M40.1 Domestic maxi monitors should be a perfect target-group spec(i)men. No wonder his review of their phono stage netted an award. If we distill our earlier introduction into the sound of vintage paper-in-oil caps, we have another confirmation. In our context none of it comes as a surprise then. 

The thing is, given class D's early criticisms—which haven't applied for a number of years now—it remains good form to reiterate that the breed's pendulum on a whole has since swung in the opposite direction. Whilst especially for Ncore it's swung back a bit again but moved to a higher level, with the M3EX it's stuck in the maximal counter position. As such Shirokazu Yazaki's stated goal has been met. It really is about a powerful dose of classic valve sound. The big difference is cool running power; current-critical load happiness into low impedances; operational silence; and stable performance without the insidiously slow ageing of power triodes and its deleterious sonic effect

With that pegged and the white towers too similar to veer more deeply into the same direction than suited my personal tastes—someone else could feel happily married however—I was curious. How would the Japanese get on with my Boenicke Audio B10? Where the Wave 40 are my Swiss eggs, the B10 are the Swiss slivers. Once you see their span-by-hand width you understand.

Round 3.

Boenicke Audio B10. Unlike the power-matched Crayon which eliminates signal-path capacitors and with it low-frequency phase shift (very good!) to produce a type of 'turbo' effect on these side-firing woofers (too much for my short-wall setup), the M3EX didn't upset the tonal balance. As had been the case on the white towers, woofer control was once again spot on. Whilst not lucid/quick like the Crayon and with rather less energy in the upper octaves, this was as fine a pairing as the eggs had been, extending lower without being plagued by ports for superior sealed bass, the ambient-rich sound favoured by Sven Boenicke—hence his penchant for lateral drivers—responded favourably to the amp's tonal weight. I really suspect Yazaki-San himself would have approved.

So would Kevin Scott, Living Voice designer and author of their superlative Vox Olympian horn speaker. Doubling as the UK's importer of Kondo Japan he favours succulent operatically dramatic sound to detest monochromatic tone colours. I seriously doubt Kevin would ever even consider class D. He's still a PC audio virgin. Just so the M3EX would surprise him just a tick. It really wears its tube lover's heart on the sleeve. As such it could only have been created by a devout SET fanatic. And perhaps the only country open-minded enough on hifi matters in the first place to pursue the strange arc of 300B direct-heated triodes to rapidly switching DirectFet transistors was Japan. So toss the rule book

Wrap.

SPEC's pricing too relies on open-mindedness. EJ Sarmento's mAMP monos are $1.800/pr. Gato Audio's all-in-one DIA-250 is €3.250. Merrill Audio's Hypex-based Thor monos get $4.000/pr. Here and in-between there's plenty of power and refinement to be had without overspending. Mola Mola does push the other direction. But they mean to recoup significant Ncore R&D investment funds. And—or so one imagines at least—they also wouldn't mind to simultaneously move up class D's general perception. Here SPEC sides with Bruno Putzeys. The latter has both name and track record. At least in the West Shirokazu Yazaki has neither. Yet. Being a merely 60wpc class D integrated with a very strange though optional remote makes the RSA-M3EX unapologetically pricey. But if you want what it does—mimic valve sound to this extent whilst throwing in modern power efficiency which SET-ish class A transistor amps certainly don't—then this sober nearly laboratory-named Japanese brand could be the top game in town and play smack in the heart of your most desirable district. In the end it reiterates a hifi leitmotif. It's not topology or parts choices. It's the designer's clear auditory vision which becomes the core determinant over the final outcome. That'swhat bends parts and topologies to its will. Vision is key then. Taken to heart, it becomes clear that class D couldn't be exempt from this rule. If Yazaki-San's results surprise us, it's only because none before have endeavoured to bend switching transistors quite so far in this direction. Henceforth SPEC marks that spot.

………. Sarjan Ebaen

Quality of packing: Very good.
Reusability of packing: Many times.
Ease of unpacking/repacking: A cinch.
Condition of component received: Flawless.
Completeness of delivery: Perfect.

The Leben CS-600 & SPEC RSA-M3 EX Comparison

REVIEW SUMMARY: Through the SPEC RSA-M3 EX you get a more natural, but diminished, sense of space, and more like you hear in a concert with live music.

The SPEC RSA-M3 EX has the contrast bumped up a bit to the right, resulting in deeper tonal colours, and a darker and more contrasty overall aural presentation of the music. The SPEC's is a very beautiful presentation of tone colour.the SPEC's images sound more life-sized to me, with the Leben's images being somewhat more miniaturised in comparison, so the SPEC seems more naturally life-like to me in the way it images.

The SPEC's voicing provides more 'timbral realism' than does the Leben CS-600, and I think that instruments sound more like themselves through the SPEC. The result is that the SPEC's combination of rich, smooth, dark, colourful tone is more like I hear in life, while the Leben's more detailed and more tonally neutral presentation makes it easier to pick instruments out of the recording's mix.

The SPEC is smoother and more relaxed sounding than the Leben,..... the SPEC, whose smooth, rich, colourful presentation blends harmonies beautifully together in a very naturally lifelike and sonorous fashion.

One area that the SPEC clearly trounces the Leben is in its ability to play loud. As volumes increase the Leben CS-600 is less composed than the SPEC RSA-M3 EX, which sails along unperturbed through loud passages that leave the Leben sounding a little strained and 'shouty' in comparison. 

Hang onto your hat though, as I really, really, liked what I heard from the SPEC RSA-M3 EX on my Harbeth Super HL5 loudspeakers, it too is a spectacularly good sounding integrated amplifier, and I liked it even better than my Leben CS-600, and by quite a bit. I think the SPEC RSA-M3 EX sounds more like live music does in real life than the Leben does. The SPEC is easy on the ears too with its rich, naturally detailed timbral textures, its dark & warm sound, and its deeply beautiful tone colour. The SPEC has a laid back and relaxed presentation, which conveys an emotional wallop like the laidback romanticism of a late night jazz club, but can still crank out the volume when it needs to. To extend the wine analogy, the SPEC is like a really superb Pinot Noir that is full of elegance & refinement, an exotic bouquet, velvety texture, and a flavor infused with hints of ripe red fruit, cherries, chocolate, and spices. It's delicious, and I think it rewrites the book of what you can expect sonically & musically from an integrated amplifier's performance. The SPEC RSA-M3 EX really does deliver on a DH-SET style of sound that is beautiful, rich, colourful, with great tone, and with intense musicality.

Did I like the SPEC better than my Leben CS-600 on my Harbeths? Yes I did. 

A listen to the SPEC RSA-M3 EX on my Westminsters told me that it was a world-class amplifier, but it was also clear to that its performance was held back by my MX110Z tuner-preamplifier. So while the SPEC RSA-M3 EX worked well in its amplifier-only mode, it was clearly at its best with my big Westminsters when used as an integrated amplifier.

Does the SPEC RSA-M3 EX Real Sound Amplifier sound like a direct heated single ended triode amplifier? Yes and no. It does have the rich musicality and beautiful tone colour of DH-SETs, but it easily outperforms most DH-SETs with its deep, tuneful, and articulate bass performance, and has even smoother, richer, and more natural high frequencies than all but a handful of the very best SET amplifiers. I think the truth is that the SPEC Real Sound Amplifier outperforms 99% of the vacuum tube amplifiers I've heard, and it is more powerful than many of them, so it's easier to match it up with a wide variety of loudspeakers and expect good results.

EXTENDED REVIEW: As much as I love the Leben, I really think the SPEC is in a different performance category. 

I think a lot of people will be interested in the comparison between the 'gold standard' Leben CS-600 vacuum tube integrated amplifier (my long time integrated amplifier reference) and the SPEC RSA-M3 EX class-D integrated amplifier. There is a bit of a price mismatch between the two, with the Leben CS-600 being around $6,500 USD, and the SPEC RSA-M3 EX being in the neighbourhood of $9,500 USD. However, the Leben has a reputation of being a giant killer, so lets check out how it fares against the exotic SPEC RSA-M3 EX Real Sound Amplifier.

The Leben CS-600 vacuum tube integrated amplifier really turned my head when I reviewed it back in 2007, and it has been a constant fixture in my small-room system since then. The Leben CS-600 also wowed a lot of people with its superb performance at the Salon & Image Show in Toronto in the years following that review, including the cast of excellent Stereophile writers like Stephen Mejias, John Atkinson, Robert Deutsch, John Marks, and Art Dudley, who heaped praise upon it.

If I were to blindfold you and play a little music for you on my Harbeth Super HL5 loudspeakers based system with both the Leben and SPEC integrated amplifiers, and then asked you which amplifier was the vacuum tubed amplifier, I bet 8 out of 10 of you would pick the SPEC RSA-M3 EX as the tube amplifier.

That's right, in an intriguing morphing of perceived reality the solid-state SPEC RSA-M3 EX sounds more like I think most people would imagine a vacuum tube amplifier to sound than the actual vacuum tube Leben CS-600 integrated amplifier does.

The Leben CS-600 and the SPEC RSA-M3 EX amplifiers have considerably different voicing when it comes to their overall sonics & musicality, yet both of these integrated amplifiers are eminently musical devices that I think anyone would be overjoyed to own.

Painting with a broad brush, I would say the Leben CS-600 is brighter, more resolving & transparent, more open sounding, more dynamic, more forward sounding, and it subjectively sounds more powerful than the SPEC RSA-M3 EX (even though it is not more powerful at 32 watts compared to the SPEC's 60 watts).

Using that same broad brush, the SPEC RSA-M3 EX sounds tonally richer, warmer, darker, smoother, has a more relaxed & colorful presentation, and sounds more timbrally natural than the Leben CS-600.

The Leben CS-600 and SPEC RSA-M3 EX are both capable of throwing a wide & deep soundstage, and they both present a similar sized soundstage for a given recording, but what I heard within the soundstage was very different for these two amplifiers.

If the SPEC RSA-M3 EX Real Sound Amplifier's sound was a photograph, the slider for 'structure' would be set to the middle 'natural' position, with nothing added or taken away from the natural level of detail your eyes would perceive in the images contained within the photograph. The SPEC indeed does have 'real sound' just like the name says, but 'real' in the sense of how your ears hear 'real live music' in life, with natural levels of brightness, detail and micro-contrast, as opposed to the enhanced sense of 'structure' that the Leben CS-600 has.

The Leben CS-600 has the sonic 'structure' slider moved a little to the right of natural, being brighter, with more fine details that pop out, and with micro-contrasts that are more pronounced. The Leben's is not an unpleasant portrayal of the musical 'film' but it is more than you would usually hear at a concert in life, and not quite as natural sounding as the SPEC RSA-M3 EX's level of structural detail.

Through the SPEC RSA-M3 EX you get a more natural, but diminished, sense of space, and more like you hear in a concert with live music.

At the risk of wearing out my Viveza analogy, I will mention one final aspect related to 'contrast'. When you move the Viveza 'contrast' slider to the right you increase image contrast by making the darker tones deeper and lighter tones brighter. This makes darker colours look more deeply saturated and lighter colours look brighter, and the image looks a little darker but more colourful overall. If you move the contrast slider to the left the darker tones get lighter and the lighter tones get slightly darker, with the overall effect being that the image looks somewhat bleached out and less colourful overall. In this case the Leben CS-600's level of aural contrast is almost exactly in the middle, whereas the SPEC RSA-M3 EX has the contrast bumped up a bit to the right, resulting in deeper tonal colours, and a darker and more contrasty overall aural presentation of the music. The SPEC's is a very beautiful presentation of tone colour.

The way images are presented on the soundstage for the Leben and SPEC differ quite a lot. The first difference is in image size, where the SPEC consistently delivered larger sounding images than the Leben. It's a little bit like the difference I see when I use a 35mm lens on my Leica M9 camera compared to a 50mm. The 35mm lens puts images further from me so they look smaller. The 50mm lens puts images closer to me so they look bigger, and for some reason the 50mm images look more like I see images with my unaided eyes. Likewise, the SPEC's images sound more life-sized to me, with the Leben's images being somewhat more miniaturised in comparison, so the SPEC seems more naturally life-like to me in the way it images.

The SPEC's images had more diffuse edge outlines, but were more solid in a natural flesh & blood sort of way, and the Leben's holographic images were a little more transparent and a little more 'ghost-like'. So on the imaging front I think the SPEC produces images that are more like I hear when I listen to live music, yet the Leben's presentation of images can be quite enchanting in an audiophile sonics sort of way.

If you've read between the lines in my descriptions above you've already guessed that the SPEC's voicing provides more 'timbral realism' than does the Leben CS-600, and I think that instruments sound more like themselves through the SPEC. 

The result is that the SPEC's combination of rich, smooth, dark, colourful tone is more like I hear in life, while the Leben's more detailed and more tonally neutral presentation makes it easier to pick instruments out of the recording's mix.

The SPEC is smoother and more relaxed sounding than the Leben, and while you can definitely tell the difference in tempos, the difference is not as pronounced as with the Leben. The increased resolution of the Leben makes harmonies more obvious, but not necessarily as realistic sounding as the SPEC, whose smooth, rich, colourful presentation blends harmonies beautifully together in a very naturally lifelike and sonorous fashion.

One area that the SPEC clearly trounces the Leben is in its ability to play loud. As volumes increase the Leben CS-600 is less composed than the SPEC RSA-M3 EX, which sails along unperturbed through loud passages that leave the Leben sounding a little strained and 'shouty' in comparison. The rich, smooth, colourful & darker balance of the SPEC really becomes an asset as the volume levels go up, and it makes listening at loud levels very gratifying

The Leben CS-600 on its own is a excellent, plain and simple, and if you own one you should pat yourself on the back for making such a wise choice.

Hang onto your hat though, as I really, really, liked what I heard from the SPEC RSA-M3 EX on my Harbeth Super HL5 loudspeakers, it too is a spectacularly good sounding integrated amplifier, and I liked it even better than my Leben CS-600, and by quite a bit. I think the SPEC RSA-M3 EX sounds more like live music does in real life than the Leben does. The SPEC is easy on the ears too with its rich, naturally detailed timbral textures, its dark & warm sound, and its deeply beautiful tone colour. The SPEC has a laid back and relaxed presentation, which conveys an emotional wallop like the laidback romanticism of a late night jazz club, but can still crank out the volume when it needs to. To extend the wine analogy, the SPEC is like a really superb Pinot Noir that is full of elegance & refinement, an exotic bouquet, velvety texture, and a flavor infused with hints of ripe red fruit, cherries, chocolate, and spices. It's delicious, and I think it rewrites the book of what you can expect sonically & musically from an integrated amplifier's performance. The SPEC RSA-M3 EX really does deliver on a DH-SET style of sound that is beautiful, rich, colourful, with great tone, and with intense musicality.

Did I like the SPEC better than my Leben CS-600 on my Harbeths? Yes I did. 

A listen to the SPEC RSA-M3 EX on my Westminsters told me that it was a world-class amplifier, but it was also clear to that its performance was held back by my MX110Z tuner-preamplifier. So while the SPEC RSA-M3 EX worked well in its amplifier-only mode, it was clearly at its best with my big Westminsters when used as an integrated amplifier.

As an integrated amplifier the SPEC RSA-M3 EX really showed what it could do on the big Westminster Royal SEs. With the Jazz24 feed going directly into it, with no vintage McIntosh MX110Z tuner-preamplifier in the signal path before it, the sound was remarkably good, on par with—but not identical to—my vintage MC225 & MX110Z McIntosh combination, and from me that is high praise indeed.

The SPEC displayed superbly natural timbre & presence, with a smooth, rich, colourful, and musical presentation from material as diverse as 'Kathy's Waltz' from the Dave Brubeck Quartet's Time Outalbum, to '5-10-15 Hours' from Ruth Brown's Rockin' in Rhythm - The Best of Ruth Brown album.

The SPEC also threw a big 'they are here' style of soundstage into my room, with lots of natural detail, a voluminous sense of space, solid images that layered back into the soundstage nicely, and a relaxed live-like musicality that only the very best equipment can produce. In short, over the review period the SPEC impressed me with its sheer musicality and timbral realism that always made music enjoyable and edifying to listen to.

I was immediately impressed by the sheer scale and presence of the music emanating from my Westminster Royal SE loudspeakers with the SPEC Real Sound Amplifier driving them. The images were totally life-size and had a 'they are here' reach-out-and-touch them presence in my living room that was really satisfying.

he SPEC Real Sound Amplifier has a way of making music your friend, whether it is mono or stereo vinyl, an FM broadcast, or a digital stream, and it has a rather unique ability to infuse listening to an old familiar music with the same sort of emotional intensity that reminiscing with an old friend evokes.

On my Westminster Royal SE loudspeakers, the SPEC Real Sound Amplifier provided some of the most musically satisfying and emotionally impactful musical performances I've ever heard coming from them.

Does the SPEC RSA-M3 EX Real Sound Amplifier sound like a direct heated single ended triode amplifier? Yes and no. It does have the rich musicality and beautiful tone colour of DH-SETs, but it easily outperforms most DH-SETs with its deep, tuneful, and articulate bass performance, and has even smoother, richer, and more natural high frequencies than all but a handful of the very best SET amplifiers. I think the truth is that the SPEC Real Sound Amplifier outperforms 99% of the vacuum tube amplifiers I've heard, and it is more powerful than many of them, so it's easier to match it up with a wide variety of loudspeakers and expect good results.

In terms of amplifier/speaker matching, we found the Spec to be very tolerant: it sounded fabulous with all the speakers we tried, irrespective of their impedance

REVIEW SUMMARY: The Spec also showed its mettle on the moody intro to ‘State of Mind’ where drums and bass dredge the depths of the sonic melange, before the tortured sound of a synth interrupts the croaked lyric and ethereally-echoed backing voices. The resulting fat, multi-layered sound was delivered perfectly by the Spec RSA-717EX, with the amplifier never losing the thread of the musical performance, or failing to reveal any of the layers.
The simple but effective bass lines played by Michael Meagher were delivered with the classic ‘steel fist in velvet glove’ feel by the Spec in such a way that they were pervasive but never dominating,
On ‘Seeing Me Round’, all the musicians get a brief shot at the spotlight, so we enjoyed deliciously natural, realistic sound from acoustic and electric guitars, synths, organs… you name it, 

EXTENDED REVIEW: Spec Corporation is something of a rarity: a newly-founded (2013) high-end audio company that manufactures its products in Japan. Of course some might say that because Spec is a Japanese company (founded by Syuzou Ishimi), manufacturing its products in Japan makes perfect sense.

EQUIPMENT

The company’s product line is a little eclectic, because although it includes stereo amplifiers and a phono preamplifier, it also ranges a string-driven turntable, also a device called a ‘PSP-901EX Real Sound Processor’ that says it ‘absorbs back-emf from speaker systems’, and a range of mica capacitors that electronics technicians can use to replace or bypass the standard capacitors in valve amplifiers made by other manufacturers.

The company places more importance than most on the design and manufacture of the capacitors used in its products. One example of this is the fact that it uses not only its own mica capacitors in its products, but also ‘paper-in-oil’ capacitors manufactured by Arizona Capacitors (US) to the specifications of capacitors originally made by West Cap. It also uses SiC (Silicon Carbide) Schottky diodes rather than standard silicon types, due to their lower reverse leakage current and higher reverse voltage (two of the reasons they’re specified for use in aerospace applications). And in common with all other amplifiers made by Spec, the RSA-717 EX is equipped with a Class-D ‘digital’ output stage manufactured by Californian outfit International Rectifier.

Chief designer at Spec is none other than Koichi Yazaki, who joined Spec after working at Teac and Pioneer, but we wonder if he ever worked for Japan Airlines, because the power switch on the front panel is like nothing we’d ever seen before and, according to Craig Johnstone, of local Australian Spec distributor Audio Heaven, they’re used in aircraft cockpits in applications where it’s essential that a switch can’t be inadvertently ‘bumped’ from one position to another.

Although the power switch looks like a standard (well perhaps not-so-standard!) two- pole toggle switch, you can’t just flick the switch lever up and down. In order to move the lever, you need to grasp it firmly, then pull it outwards at the same angle the toggle is pointing. Once this is done, the switch can be moved up or down, after which a spring pulls it back in towards the front panel where it locks, after which it cannot be moved without repeating the same operation (in reverse).

The ‘On’ LED immediately adjacent to the power switch glows green when the amplifier is on, as you’d expect, but the ‘Off ’ LED has a rather strange action. When the amplifier is turned on it glows red for a short period, then pulses and turns off. When the amplifier is turned off, the red LED glows brightly, then once again pulses on and off weakly before extinguishing completely.

Although it’s also a toggle, the speaker switch is a standard toggle switch, without a safety lock. Well, once again, perhaps it’s not quite standard: the switch has a tiny ‘chameleon’ LED built into its end which, so far as the RSA-717EX is concerned, glows green when the speaker output is active, and red when the speaker output is off. A feature of both switches is that ‘Off ’ is the downwards position of the switch, and ‘On’ is the upwards position, which may be the convention in Japan and North America, but is the ‘wrong way around’ for Australians.

The volume control appears (and feels) as if it’s a standard analogue potentiometer, but it’s not: it’s a rotary encoder that instructs a solid-state volume circuit in order that, according to Spec “audio quality is not affected depending on the volume (level adjustment knob) position”.

The input selector has only four positions, all of which are line-level: there is no phono input. Line 1, 2 and 3 are all unbalanced inputs (via RCA sockets), while Line 4 is balanced (via XLR sockets). Although four inputs should be sufficient for most applications, some might find an extra one or two handy. There is no balance control either, which could help compensate for poor recordings and/or for speaker level compensation.

As you can tell from our photograph, although the Spec RSA-717 EX has a headphone socket, it’s a small 3.5mm phone type. We have always preferred full-sized phone jacks, as they’re physically and electrically more robust and need no adaptor when using professional- grade headphones, but we admit there is these days the opposite argument that most headphones now have minijack plugs, so would require an adaptor for the larger socket. The rear panel of the RSA-717EX has just a single set of high-quality speaker terminals. All the RCA input terminals are gold-plated, though the XLR terminals are not.

The Spec RSA-717EX is a ‘non-standard’ size, somewhat smaller than usual, measuring just 375mm wide, 350mm deep and 95mm high. The aluminium chassis is beautifully finished with an attractive anodised coating, and wood panels at either end made from a combination of Japanese spruce and Japanese maple. These panels are said to be made “by craftsmen in the historic town of Hida Takayama in Japan.” Spec claims that the use of these two timbers “cut off vibration effectively from the outside”.

The Spec RSA-717EX can be controlled by remote, but the remote control is not included with the amplifier — indeed the circuitry for remote operation isn’t built into the amplifier at all. It’s available only by separate purchase, and it costs $750, because you’re buying not only the remote control itself, but also a separate output ‘receiver’ that plugs into the ‘remote’ jack on the rear panel, and a power supply for that receiver. We’re so accustomed to remote control ourselves that we’d factor this in, but if you’re happy to set and forget, this could be a useful saving.

PERFORMANCE

It seemed appropriate to kick off the listening sessions with Sydney-based hip-hop artist Tuka’s latest album ‘Life Death Time Eternal’, and this certainly proved a good choice to demonstrate the Spec RSA-717EX’s many sonic strengths. The simple but effective bass lines played by Michael Meagher were delivered with the classic ‘steel fist in velvet glove’ feel by the Spec in such a way that they were pervasive but never dominating, particularly notably on ‘My Star’ which also offers classic electric guitar sound by Counterbounce (Pip Norman) and backing vocals that include infectious unison whistling.

The Spec also showed its mettle on the moody intro to ‘State of Mind’ where drums and bass dredge the depths of the sonic melange, before the tortured sound of a synth interrupts the croaked lyric and ethereally-echoed backing voices. The resulting fat, multi-layered sound was delivered perfectly by the Spec RSA-717EX, with the amplifier never losing the thread of the musical performance, or failing to reveal any of the layers.

It was an altogether cleaner sound when we switched to Josh Ritter’s new album ‘Sermon on the Rocks’, but the greater use of real instruments allowed us to better evaluate the tonal qualities of the Spec, and we can report that designer Koichi Yazaki has nailed it, such that the company’s ‘Real Sound’ catch-phrase certainly rings true. The clarity of Ritter’s vocal rang through as life-like as a live performance and Zac Hickman’s acoustic bass was as woody and natural as you’d expect.

The transients of the percussive sound, courtesy Matt Barrick’s drum kit, were delivered brilliantly by the Spec. On ‘Seeing Me Round’, all the musicians get a brief shot at the spotlight, so we enjoyed deliciously natural, realistic sound from acoustic and electric guitars, synths, organs… you name it, including a lyric for the ages. Rolling Stone magazine said Sermon was “awash with biblical imagery and mythological Americana”. True enough, but also awash with great music.

In terms of amplifier/speaker matching, we found the Spec to be very tolerant: it sounded fabulous with all the speakers we tried, irrespective of their impedance. If you routinely listen at loud to very loud levels we think you’ll find that the RSA-717EX will, however, work best when it’s paired with high-efficiency loud- speakers — those with sensitivity ratings of 89dBSPL or more: it just seemed to sound more dynamically unrestrained with these higher-efficiency designs when playing at these volume levels. If you’re not listening at high levels, and/or you have a smaller room, lower- sensitivity speakers will suit just as well.

CONCLUSION

An auspicious debut for this quirky little Japanese amplifier. The exterior finish is unique and the amplifier has a lovely, natural sound quality that makes it very easy on the ear. #

Listening Adventures with Tannoys with the Wonderful SPEC Amps - SPEC RSA-M3EX & SPEC RSA-F33EX
Siedy Abee

REVIEW SUMARY: Wow, Jeff was really impressed by this amp. It performed very impressively on his big Tannoy Westminster Royal SE loudspeakers. Based on his review I informed one of my best friends, Piet de Vries. I knew Piet was thinking about starting a company who is specialized in selling very nice audio equipment.  In line of what Mr. Yazaki-san (of the SPEC company) calls ‘Real Sound’. I told Piet about the SPEC amps. To put a long story in short words: Piet is now importing the SPEC amps! Wow! He started immediately with the whole range, including the RSA-F33EX!

EXTENDED REVIEW: I am one of those guys who is a regular reader of Jeff’s Place. It is always a great pleasure to open up Jeff’s website and to read about his newest adventures.

I had never heard about the SPEC RSA-M3EX before, and I started reading with interest about Jeff’s first listening experience with the SPEC RSA-M3EX. This is the middle model in the range of SPEC amps.

Wow, Jeff was really impressed by this amp. It performed very impressively on his big Tannoy Westminster Royal SE loudspeakers. Based on his review I informed one of my best friends, Piet de Vries. I knew Piet was thinking about starting a company who is specialized in selling very nice audio equipment.  In line of what Mr. Yazaki-san (of the SPEC company) calls ‘Real Sound’. I told Piet about the SPEC amps. To put a long story in short words: Piet is now importing the SPEC amps! Wow! He started immediately with the whole range, including the RSA-F33EX!

Yes, this was all inspired by Jeff!

Piet is also now the dealer for the Netherlands for Harbeth loudspeakers, Pennaudio loudspeakers and network-players from Lumin. Piet invited us to have a listen at his place. He lives very nice. He lives nearby the German border in a very rural area. Very quiet & lovely. The equipment we did the listening to and with:

Together with Jan Hut (the designer and maker of my Chaos mk2 integrated tube amp, cables, interlinks and who modified my beloved Philips CD 104 player) and Stefan we started listening to set 1.

Set 1.
Tannoy 15 DMT Mk2 speakers
Linn LP 12 – full Linn version
ASR Emitter 2 Exclusive version blue, with Accupower
SPEC RSA-F33EX
SPEC RSA-M3EX

We started with the mighty ASR Emitter 2 Exclusive amp. The sound was fine and we liked the way the Emitter was controlling the Tannoy 15 DMT. It was just the way an Emitter should sound, with a huge soundstage combined with lovely voices and an non-aggressive sound. As always it was as if we were listening to an nice tube amp with real-world power and slam.

After this Piet installed the SPEC RSA-F33EX. It is a bit strange to put an amp on the huge Emitter but there was no other place.  After a short time of warming up for the SPEC Piet hit the play button for the Lumin, and we were all quite shocked! This SPEC amp sounded very different compared to the Emitter. It sounded more spacious and holographic and at the same time very transparent & open, and it brought into the room a new sense of energy and musicality. How is this possible? We don’t know.

In a certain way I was sad about this. I do really love the sound and the looks of the Emitter, and now here was just a 1-box integrated amp (the Emitter has four boxes) that was outperforming the Emitter. After some discussion we concluded that the bass of the Emitter was perhaps somehow a bit more dominant, but only slightly. After listening to this awesome good sounding SPEC we turned it off and installed the SPEC RSA-M3EX.

After a nice cup of coffee and some delicious cake Piet turned up the volume and hit the play button. Immediately we could hear that this amp had the ‘SPEC family sound’. The same energetic, dynamic and tubelike sound as his bigger brother. The difference where not all that big! Be sure, when you have heard the F33EX you know that it is the way to go – end of story. But the F33EX is almost double the price of the M3EX. Is that worth the money? If you can live with 95% of the performance of his bigger brother than is the answer NO, if you want to have it than you have to buy the ‘bigga brotha’.

So, after these amazing listening experiences Piet brought us a nice beer. It tasted good!

Than we changed over to set 2.

Set 2.
Tannoy 215 DMT Mk2 speakers
Lumin D1 Network Player
SPEC RSA-M3EX

The sound was very nice and very like the sound of set 1. Although a bit less dynamic and holographic. Note: in later listening sessions we discovered that the 215 DMT Mk2 was not as precise as the 15 DMT Mk2. The soundstage was more diffuse compared to the 15 DMT, and not so pin-point in imaging. Overall we could hear also now the same fine musical sound as with set 1: very lifelike, organic, holographic and very musical! We really could hear what Yazaki-san means with “Real Sound’ reproduction.

After this Piet invited us to change our chairs again, so we could listen to set 3. 

Set 3.
Penaudio Sara SE speakers
Lumin D1 Network Player
SPEC RSA-717EX

A set with a lot of ‘Real Sound’ components! The cables were all from Western Electric. Piet did not warn us when he let the music play! WOW! What a nice sound! How was this possible! How could such a fine bass be produced by such a little speaker? It really sounded very musical and muscular! The sound was almost around us, as if were listening to 3D sound produced by a 2D set. The combination of this very nice speaker, little SPEC amp (the ‘717’), and the WE cables blew our minds! The big Tannoys produced a really big sound, and the sound of the Dual Concentric tulip wave unit was very precise and holographic, but listening to this more room friendly set-up was really nice.

This listening session was very involving, and we all want to thank Jeff that he inspired Piet to contact Yazaki-san of the SPEC Corporation! (You are welcome! Yazaki-san is a treasure! – Jeff)

In a later session Piet brought the SPEC RSA-F33EX with him to my house. Also on the Westminster Royal SE the sound was very involving. A very precise and controlled sound with spades of musicality and lifelike dynamics and again a very holographic sound. I could happily live with the SPEC amp! 

I often get the impression that Japanese high end products have a soul, a part of the designers aura stays under the hood. The SPEC is among these products, Shirokazu Yazaki has me under his spell.
René van Es

REVIEW SUMMARY: The RSA-M3EX.... creating an enormous virtual stage for musicians to excel in solos against other band members or in front of an orchestra. The image reaches from one side wall to the other, and from floor to ceiling, with a back wall that’s no longer audible and a more forward moving sound. But the music doesn’t slam you in the face, the stereo image the RSA-M3EX creates is the one you have been looking for so many years. Time after time instruments and vocalists perform and there seems to be no preference for a particular genre. 
Small jazz combo’s benefit from a system with speed and transparency. The Bobo Stenson Trio’s album Cantando is a good example. Percussion forms an important part of this music and the RSA-M3EX loves it. The drum kit is hit hard, Glockenspiel tingles into the room and cymbals sizzle. Smaller and bigger drums exchange places in an organised barrage. A plucked bass follows the line and piano stands out playing its own solo. The musicians seem to enjoy what they play and the SPEC projects this feeling towards the listener and very soon my feet tap out the rhythm. It makes me realise how natural, rich, pure and musical the sound of this class D amplifier is. The SPEC RSA-M3EX is the first amplifier without the specific class D character that bores me over time, a colouration that turns music into a technical exercise. No manufacturer has overcome this until now, and in advance of a formal conclusion I dare to state that this is the first and only amplifier of this kind that I could live with.

EXTENDED REVIEW: I am always curious about what new brands and/or technologies have to offer, so when I got the chance to hear a SPEC amplifier at home I didn’t say no. I picked the Real Sound Amplifier RSA-M3EX, the middle model in the range. I had not heard of the brand or the designer so took a look on the internet to see what they had to offer, this piqued my interest and in my enthusiasm I changed my normal writing procedure. Usually I start with a description followed by the listening impression, but when a product is very good I start with the sound. Well, the SPEC RSA-M3EX is just such a product.

Matching

Trying to find the best possible match between components is a part of the review process that’s not often told in detail, but sometimes it’s interesting enough to go into. My first set-up was in a smaller room with a pair of Harbeth P3ESR loudspeakers. Playing music was not as spectacular as promised by the distributor and the company leaflets. In fact I could not relate the high price with the performance although I could hear that something special was trying to get out. I missed power, speed and low end energy. Music sounded nice and full of detail, but drums were slow, there were no rumbling bass notes and electronic music had none of its impact. Only the stereo image was very well defined and full of space, putting the accent on the midrange and thus voices. After extended listening I reached the conclusion the speed was not an issue at all and the lack of bass notes had more to do with the chosen loudspeakers than anything else. The Bass might not have been overwhelming, but they came out tight and pure. More pure than results with other amplifiers in the same room and set-up. The perceived lack of drive changed into an admiration of the pure and open sound. With every listening session I got more and more convinced that the SPEC needed far bigger loudspeakers with a higher efficiency to prove its worth.

Who am I, not to move the amplifier into my main listening room and connect a pair of PMC fact.12 transmission line speakers? I enjoyed the SPEC before but this was a new era and I never looked back. The power I missed was there in spades, listening to the sound effects used in movies it was now possible to feel the fear. Bass engulfs the room whilst remaining surprisingly tight, the grip on the loudspeakers showing just how much power this amplifier has to offer. Speed is no longer an issue and drums explode into the room. All my initial reservations about the RSA-M3EX were blown away and it was time to further investigate the real beauty of this integrated amp. The PMC speakers seem to disappear from the room given a decent source and a nice amplifier, there’s no need to close your eyes for that. But the room acoustics and the setting of the speakers in a room that doubles as a space for the family make it a lot harder to create a deep stereo image. Like so many listeners I moved my loudspeakers into a position to get the best compromise and to create a good environment to judge audio components in. In my experience some amplifiers and sources cannot create a deep and wide soundstage in this room, but the RSA-M3EX is just the opposite, creating an enormous virtual stage for musicians to excel in solos against other band members or in front of an orchestra. The image reaches from one side wall to the other, and from floor to ceiling, with a back wall that’s no longer audible and a more forward moving sound. But the music doesn’t slam you in the face, the stereo image the RSA-M3EX creates is the one you have been looking for so many years. Time after time instruments and vocalists perform and there seems to be no preference for a particular genre. Searching for minor limitations I notice that on a CD like Live In The O2 Arena by Katie Melua my own amplifier shows a little more of the atmosphere from the large hall. At the same moment I realise that the combination of speaker and amplifier is one, as slave and master in start/stop behaviour. Some amplifiers tend to create another illusion of space by being a little slower, so which one is right? I do not know and the differences are small.

More music

Small jazz combo’s benefit from a system with speed and transparency. The Bobo Stenson Trio’s album Cantando is a good example. Percussion forms an important part of this music and the RSA-M3EX loves it. The drum kit is hit hard, Glockenspiel tingles into the room and cymbals sizzle. Smaller and bigger drums exchange places in an organized barrage. A plucked bass follows the line and piano stands out playing its own solo. The musicians seem to enjoy what they play and the SPEC projects this feeling towards the listener and very soon my feet tap out the rhythm. It makes me realize how natural, rich, pure and musical the sound of this class D amplifier is. The SPEC RSA-M3EX is the first amplifier without the specific class D character that bores me over time, a colouration that turns music into a technical excercise. No manufacturer has overcome this until now, and in advance of a formal conclusion I dare to state that this is the first and only amplifier of this kind that I could live with.

‘The Bug’ by Dire Straits explodes with hammering percussion, Mark Knopfler in front of the band, drums behind him, guitars to the left and right of the soundstage and backing vocals between the singer and the band. Fast sounding and lacking only a bit of the weight more powerful amplifiers can offer. The RSA-M3EX is about purity, musicality and minimal distortion rather than being a power plant. High efficiency loudspeakers with or without minimalist damping like a pair of Russel K. Red 100 would turn your hi-fi system into a high quality PA system for instance, while my PMCs love and need more power. A Loreena McKennitt performance for German radio called ‘Troubadours On The Rhine’ is extremely well recorded. The dynamic expression within her voice shows the range of the SPEC, shows how low the dynamic noise floor is. Lesser amplifiers modulate the noise with the loudness of the music, making music tiring and restless. The acoustic instruments in the band and McKennitt herself add to the atmosphere and pureness that the RSA-M3EX creates, grabbing the listener’s attention time after time. When the track finishes and the public in the studio applauds a “thank you” from Loreena sounds uncannily real. Unique? No, maybe not, but good proof of the designer’s craftsmanship.

Luo HaiYing sings in Chinese with backing from big drums. These drums need power, despite the SPEC’s 60 Watt rating this is no problem thanks to a heavy power supply and large capacitors, and it produces a wonderful stereo image. Musica Antique Nova by Rachel Podger is even better, her violin almost sings in the listening room. The words subtle, rich and pure come to mind. There’s absolutely no stress in this amplifier, you simply enjoy the performance without any reference the to technology inside the box. It’s hard to listen to what the amplifier does, much easier to enjoy the results. Music is the winner, especially when Dame Kiri Te Kanawa starts singing ‘Madame Butterfly’ accompanied by a large orchestra, the amp’s capabilities seem limitless. Looking for specific class D shortcomings I cannot find any, no matter how hard I try. Is this amp the best ever or do I still want more? Naturally the SPEC does not have the limitless power and authority that my 250 Watt class AB amp delivers, and a bit more air around the musicians would be welcome, just a bit. Why am I looking for shortcomings? Because I do not want to be tempted to buy a SPEC to be honest. Dreaming away again with a piano concert from Mozart played by Kristian Bezuidenhout, it’s a luxury to imbibe music this way.

RSA-M3 EX

The SPEC looks simple with just source, volume and a nice power switch on the front, and inputs, speaker terminals, a switch to illuminate the volume control and a small switch to use the RSA-M3EX as power amp on the back. A 3.5mm bus is available for the two part remote control; receiver and a handset. The bottom of the amplifier is made of wood with integrated feet. The aluminium housing with the spruce base and its maple and hickory feet makes an attractive combination. The amplifier delivers 60 Watts into 8 Ohms and the frequency range resembles that of a tube amplifier, 10Hz – 30Khz ±1dB (6Ω, 1W). Under the hood the SPEC differs from most other class D amplifiers, it has a PWM engine triggering MOSFET switching power transistors, a technique developed by International Rectifier in the US. The power supply has a big R-core transformer and silicon-carbide Schottky diodes. Capacitors are used in a carefully matched mix of electrolytic and paper-in-oil types of different values for the best audio results. The output filter uses a coil specially developed for audio by listening and a combination of paper-in-oil plus silver-mica capacitors, especially made for SPEC by Arizona Capacitors Inc. As SPEC states, the RSA-M3EX is actually made like a tube amp but with class D modules instead of tubes.

Who is SPEC

SPEC designer Shirokazu Yazaki started his career with TEAC Japan, where he stayed for four years developing amongst other things the TEAC A-37300 reel-to-reel recorder, before he went to Pioneer for the following 17 years. After a long stay in Indonesia he returned to Pioneer in Japan where he worked on the CT range of cassette recorders and the ‘legendary’ DV-AX10 DVD/CD/SACD player. His interested in class D was aroused because his old Pioneer colleague Jun Honda works for International Rectifiers producing power management solutions and the pair co-operated in making modules for audio. Yazaki-San has been using single-ended triodes and horn loaded loudspeakers for decades, an enthusiasm inspired by a Jean Hiraga demonstration of Altec horn loudspeakers driven by a DA30 triode based amplifier in 1971. From that moment Yazaki-San became fascinated with the DA30, which he prefers over a 300B, always trying to improve his own designs through listening and research with horn loaded loudspeakers from Altec, JBL and Onken. History was written in February 2010 when the SPEC Corporation was formed by Shirokazu Yazaki and Jun Honda, to bring to the market class D amplifiers that are just as good or even better than the DA30 tube designs that had taken over 40 years to perfect. Yazaki-San points out that the moving coil of a loudspeaker develops energy that returns to the output stage of an amplifier to influence the feedback circuit by creating distortion. In a class D amplifier this energy is absorbed not in a feedback circuit but in the power supply, where it is harmless. Which, he says, is one of the reasons why class D amplifiers sound so pure and clear.

Finally

After an enthusiastic review the conclusion can only be positive for the SPEC RSA-M3EX amplifier. I had to get used to the amp, it first seemed a little plain and underpowered compared to my own amplifiers. An opinion that soon needed adjustment and turned 180 degrees into appreciation of its pure, delicate and undistorted sound quality. Deep bass notes might seem to lack power at first, but soon I found out that bass is so tight, fast and uncoloured that it only attracts less attention. This was even clearer after changing from small monitor speakers to large transmission lines. Also consider the near perfect stereo image of the RSA-M3EX, the spatial sound and the purity of the reproduced music. Every class D amplifier I have heard had a specific class D signature that I could never get used to, I always returned to more conventional designs with a preference for class A. That is until I listened to the SPEC RSA-M3EX, an amplifier that makes me forget the technology and sounds so good that I would like to own one. It’s my first encounter with class D technology that offers high end sound quality in the true sense. I realise I probably make more enemies than friends with these words, so be it. A final word: I often get the impression that Japanese high end products have a soul, a part of the designers aura stays under the hood. The SPEC is among these products, Shirokazu Yazaki has me under his spell.

.......René van Es

This obscure Japanese-made Class D amp is a velvet fist in a velvet glove - 5/5 STARS
ASHLEY KRAMER

REVIEW SUMMARY: It does everything the designer intended it to do and it does it all well. It’s no modern efficient Class D wonder, pumping out enough iron fisted grunt to drive even a set of Apogee panel speakers within an inch of their lives; rather it’s a far more subtle offering, a velvet fist in a velvet glove if you like, but with real strength in its grip. This isn’t a criticism – matched to the right speakers, the RSA-V1 can more than hold its head up alongside its competitors at this lofty price point. It’s obscure, eccentric, scarce and totally worth a listen if you’ve got around ten gorillas to spend on a high-quality amplifier. It really deserves some matching equipment that’s at least as talented, so don’t be shy when you’re putting a system together around it. You won’t be sorry. 

EXTENDED REVIEW: WHAT SOUND IS this? That’s the title of a song from the new Verlaines album Untimely Meditations, a rather strange track, yet one that I enjoy immensely. It’s also a question I found myself repeatedly asking about the Spec RSA-V1 integrated amplifier while trying to get to grips with its sonic characteristics.

This Japanese-made amp is something of an odd creation, conceived by a gentleman who spent a great deal of time working on single ended valve amplifiers using the mighty 300B valve. Sages tell us that sometimes a change is as good as a holiday, so out of left field, this guy designed a range of Class D amplifiers that sound nothing at all like you’d expect a Class D amplifier to sound. But more on that later.

Construction and Features

The RSA-V1 is a very good-looking piece of kit, with a restrained design aesthetic that speaks more of a grass roots company origin than a megacorporation. From a looks point of view, it could well have been built by any one of the many small UK-based audio companies, right down to those all too familiar Letraset style fonts on the front panel – but this approach is all part of the charm.

The satin silver chassis is nicely finished, and although the top and side panels are made with one piece of bent heavy gauge metal, the result is both solid and good looking. Internally, the various sections of the amp are isolated from each other with metal sheets. There’s a wooden bottom section that looks like a separate isolation platform but it’s very much attached to the amp, forming three footers. There’s more to this than meets the eye – the combination of wood and metal is a deliberate choice to reduce vibration. In fact, the wooden section is made up using multiple types of wood including solid oak from Hokkaido and Canadian sitka spruce. Even the three-point footer design is specifically made using harder solid wood to cut the transmission of external vibrations.

The Class D nature of the beast might lead one to expect a lightweight box mostly filled with air, a circuit board and a small switch-mode power supply. You’d be in for a shock, as I was when I collected the RSA-V1 from the local dealer, because the 15-kilogram weight indicates that there’s a substantial transformer in there, a shielded R-core unit to be precise. What the weight doesn’t tell you is that the designer uses reproduction NOS parts (copies of old oil capacitors recreated by Arizona Capacitors Inc, for example), ultra short signal paths and the highest specification PWM switching amplifier modules he could find – the same modules that are in the range topping Spec RSA-F1 amp.

The amplifier’s topology is interesting – according to the diagram below from the Spec website, it’s a dual-mono design, with the audio signal running into digital volume controls, then into the PWM controller and switching FETs before getting passed through a low pass filter consisting of a simple circuit made up of a toroidal coil, condenser and specifically ordered capacitors usually used in valve amps. The whole ensemble has been tweaked and fine-tuned by careful listening. Even the inbound power has been carefully attended to with selected high quality components in the power supply including newly developed ultrafast soft-recovery diodes and electrolytic capacitors specially designed for this amplifier.

This isn’t one of those 1000 watt into 4 Ohms Class D amps, rather it generates a reasonable 50 watts into 8 Ohms, which neatly doubles into 4 Ohms according to the manufacturer. So there’s enough power to drive most speakers easily unless they’re really inefficient power hungry hogs. There are four rhodium-plated line level inputs round back (three RCA and one balanced XLR) controlled by a chunky rotating knob on the front panel. The speaker binding posts are solid enough and there’s the obligatory IEC power socket, which promptly had my Nordost Shiva power cable plugged in, where it remained for the duration of the review.

The power switch is a very cool locking number that could easily be found on the instrument panel of a vintage aircraft. The big volume control is illuminated by a subtly glowing blue LED, which can be turned off. Beware the little switch that cuts out the LED: flick it up and it turns off the glow but a click down switches the RSA-V1 into its power amplifier mode, and if it’s getting a 2-volt signal from a CD player at that point, your speaker cones (and ears) may be less than impressed.

There’s no wireless remote control supplied (its an optional extra) but in an odd touch, there’s a socket round back that accepts a cable running to a huge, but lovingly crafted wooden receiver for the optional metal-bodied RSR-3 remote. There’s no phono stage, no DAC, no pre-amp outputs or sub outs and no headphone socket; this is a bare bones integrated amplifier sans frills, besides the audio quality that is, which as we’ll see, is quite something.

Sound Quality

So what sound is this? It doesn’t take long to recognise that there’s something very interesting happening here, but it does take a little longer to put the pieces of the puzzle together. Once I did I figured out exactly what I was hearing – this is a Naim power amp aspirated by a very good valve preamplifier, with only the best aspects of both making it through this uncommon but oh so blessed union.

There’s no English page on the Spec website for the RSA-V1 amplifier (has been since updates to include English) but there is one for the similar looking flagship RSA-F1 model. That page, along with some dogged persistence with Google Translate got me the gist of the manufacturer’s attitude to audio, which basically comes down to exactly what I heard, the “natural and beautiful tone of a tube amp, the driving force of the semiconductor amplifier”. I just didn’t expect it to be quite this good.

There’s the same foot-tapping immediacy and pace that one gets with Naim gear, so listening to the RSA-V1 without getting deeply involved is tough. In fact, forget tapping feet, it got me off my feet more than once. [You levitated? – Sarcastic Ed]. However, beyond the speed grip, and intensity, there’s barely a hint of solid-state character here. Instead, you get a midrange that can only be described as liquid in the sense that’s usually only seen in valve amps. It’s not overly warm, nor does it drown the music in cloying syrupy sweetness, but it is fluid, effortless and so suave as to defy the Class D or PWM origins of the signal.

I had the same Living coice Avatar floor stand speakers that I used for the Shindo review and they proved an excellent match for the RSA-V1, and along with my Marantz SA-8260 SACD player and a cryogenically treated Slinkylinks cable loom and Nordost power cables, the sound was a beguiling combination of fire and silky smoothness that suited pretty much all kinds of music.

Cue up the mellow stylings of ‘House of Valparaíso’ from Calexico’s superb Carried to Dust album of 2008 and the sound is simply entrancing. The speed of the instruments in the intro is sharply noticeable, the percussion sounds like it’s coming from the hollow depths of an actual drum kit thanks to the abundance of textural information on offer, and the vocals come across like they’re being reproduced by some kind of magical smoothness generator powered by 21-year- old single malt Scotch. Instruments are nicely separated in the mix and the dynamic range is extended, with an easy sense of scale.

Switch to ‘Karmacoma’ from Massive Attack’s Protection and the RSA-V1 has the vocals placed dead centre and well behind the speakers with that commanding bass line throbbing out into the room. Here the Living Voice speakers deliver more bass weight and impact than they did with the Shindo pre/power combination in front of them but the bottom octave is still AWOL, as expected from the frequency extension figures. However, what is there is taut and locked down with no looseness. The overall quality of the bass is very good, and while I’ve seen feedback in other reviews stating that the bass seemed a little homogenised, I had minimal reservations, except perhaps that the midrange is so fabulous that it could well be seen to be making the bass seem less nuanced.

I worked through much of ZZ Top’s Six Pack compilation via the Spec and while this recording has been criticised as lacking in bass quality compared to the original releases, the RSA-V1/Living Voice pairing made it a lot of fun – I’d spin that big volume knob to about one o’clock and settle in for a long session with Gibbons, Hill and Beard, loving the big sound of tracks like ‘El Diablo’, where the bite and distortion of the guitars sound much like I’d imagine the guitar amps to sound in the first place. This is another track where the head-nodding and foot- tapping is mandatory if you’re alive; if there’s no movement, then you may have a rather serious problem.

Incidentally, with these 94dB sensitive speakers, one o’clock on the volume knob is all I ever needed (or wanted), even in a big room. The RSA-V1’s sound is so crisp and clean, with a low noise floor that it always sounds quieter than it actually is. It’s only when I wandered downstairs and heard just how loud the music upstairs was that I twigged how clear and easy the RSA-V1 is to listen to.

I occasionally thought that I was being taken for a ride by an evil conspiracy, that the silver-tongued and totally unfatiguing top end just had to come from valves, along with the midrange, but that’s not the case. This system is beautifully balanced right to the very top, especially with the help of that rather nice silk tweeter in the Avatar II’s. Cymbals rattle and crash off into the far end of the audible spectrum with nary a trace of harshness and zero roll off, just effortless extension. Allied to that midrange, it’s a pleasure that demands more and more listening time.

Wild Beasts’ ‘The Fun Powder Plot’ from the epic Two Dancers album was a track I had to hear through the RSA-V1. With my turntable out of action, I pressed the 320kbps download that came with the vinyl into service via my iPod Classic and Pro-Ject Dock Box Fi iPod dock. Result? Hell yes! My listening note is short and sweet: “Bloody marvelous!” The speed of the drumming here is magic, the falsetto vocals strong, sweet and packed with reams of detail and textural touches not heard on lesser systems. All in all, this is something close to brilliant, especially via this humble source. The terrible cliché of pace, rhythm and timing just has to be invoked here, because the amp emulates the original hero of that realm (Naim) but adds an entirely new level of refinement and enjoyment.

Detail levels are very high, courtesy of that low noise floor no doubt, but the RSA-V1 is just one of those amps that cuts a layer or two (perhaps three) of grime from the performance, sounding high res but not like typical hi-fi – the lovely valve-like sound elevates it beyond that. Soundstaging and imaging are unfailingly precise, with a real sense of depth behind the plane of the speakers and tight control of the placement of performers and instruments. Funnily enough, the soundstage height was somewhat taller than when I had the Shindo gear in place.

My only quibble with the RSA-V1 is that it needs a bit of a warm up before it can be heard at its most stunning, which is ironic as it runs as cool as any amplifier I’ve ever used – after hours of use, there’s no heat in the chassis at all, just a faint warmth around the power switch on the front panel. Still, it starts off sounding good but marginally lean, but after half an hour or so, the midrange warms up just a tad and the balance is perfect. No big deal, many amps display the same characteristic but it’s worth noting.

Conclusion

What then of the question I asked in the beginning of this review: “What sound is this?” Listening to the dissonant yet bizarrely enjoyable Verlaines track on this amplifier is an experience. I’m usually tempted to turn it down on other systems and especially on headphones because of the merciless rasp of the horns but here, it’s a roller-coaster excursion into alien territory at high volume, and it’s a great deal of fun. The harshness vanishes, but not because the RSA-V1 is plastering over the cracks, it’s just such a smooth yet insightful amp with something of a unique sound that seems to make me reach for more volume, not less.

It’s versatile too. I tried everything from Eminem to Tony Joe White, and Diana Krall to Nirvana on this system and never felt inclined to hit the skip button because the amp wasn’t doing justice to the music. Quite the opposite actually – CD goes in, CD plays to the end. If I had to make a call, I’d say that the quality of the midrange marginally flatters the kind of acoustic music I like more than it does hard rock or rap but not to a degree that would worry me, because the pace and speed keep the RSA-V1 honest with harder music.

I mentioned the thought of being taken for a ride, that there had to be valves under the hood. At times I wondered if I’d see a Naim power amp stashed in there too if I cracked the hood. This ongoing comparison to both Naim kit and to high-end valve gear is high praise – the Naim sound is one I like a lot but it can be a bit lean and dry at times, particularly with the wrong speakers in the loop. The Spec RSA-V1 gives the best of both worlds with none of the negatives, bar perhaps a lack of outright power, but then again, neither valve amps nor Naim amps are known for big power, except for a few high-end valve monsters. This sounds like a hybrid amp of note, despite not really being a hybrid at all.

You don’t get many of the bells and whistles that feature on a lot of modern integrated amplifiers but this is an addictive stereo component. The rarity of the brand, and the idiosyncratic construction and architecture make it a genuinely interesting proposition, but the superb sonics make it an entirely compelling piece of high-end hi-fi gear
...........ASHLEY KRAMER

Awards

SPEC REAL SOUND - REQ-S1EX PHONO STAGE WINS RARE - 6MONS RED FINGER PRINT AWARD

REAL-SOUND” BRINGS THE TRUE RICHNESS OF MUSIC - You will rediscover an analog LP as the fascination of “Ultimate High-Resolution Sound”

CONCLUSION: Listening to music through the Japanese phono stage is like having a bath in essential oils, resting on silk sheets, sipping caffé latte somewhere in sunny Italy, drinking a mug of Paulaner in a small bar in the centre of Munich. It's about an excellent balance between individual parts, a conscious choice about sound, clear views on technical matters and last but not least a fantastic man behind it all which makes listening to the REQ-S1 EX like meeting an old friend: a bit of nostalgia mixed with curiosity and a renewed sense of security.

Sounds modelled by this preamplifier are never unpleasant. It’s also an obvious departure from objective neutrality. Nevertheless it doesn't alter the heart of the matter, the value and naturalness of the presentation. Thanks to it all albums recorded and mixed in the analog domain (especially of acoustic instruments) come out great. Others sound a bit worse for this treatment but never bad. Their inferiority is a technical issue of their producer and label, not SPEC's or ours. But perhaps such distinctions are academic. They really only arise from the reviewer's need to talk of differences. While it's possible to get superior resolution, I'm unsure whether anybody really needs it. I tend to think most of us would simply want to hunker down and forget about the world for a while. If that's you, the REQ S1-EX will perfectly suit.

Testimonials

These Japanese SPEC engineers have certainly created a LOVELY, SMOOTH, TUBE SOUNDING, SOLID STATE INTEGRATED AMPLIFIER that is a PLEASURE to LISTEN to.
Hello Terry,
Thank you so much for the loan of your SPEC RSA-M3EX Integrated amplifier to listen and evaluate in my system over the weekend.

It just slotted into my system as though it had always been there and the remote control was such a pleasure to use. The blue light around the volume control knob was a very nice aesthetic touch.

I was most impressed with its sound especially when listening to CDs. It was warm, rich and lush yet detailed and I found it very ADDICTIVE to listen to for long hours into the night. 

I was also  delighted to find it had a Preamp-In function and I was able to enjoy records via my preamplifier/phono through it as well.

I would venture to say that it is one of the most MOST TUBE SOUNDING OF ANY SOLID STATE GEAR I have listened to in a long time, as you know listening to music though valve gear has been my choice for over 30yrs.

The sound stage did lack a bit in depth compared to my tube gear however it was very wide and I particularly enjoyed the sound of female singers with voice detail that was STUNNING AND OH SO CLEAR AND DETAILED .

The BASS weight was there in SPADES and the MID range was SUPERB.

I would have liked to hear a bit more air and treble and perhaps different interconnects or speaker cables would produce this result.

To Summerise:  

These Japanese SPEC engineers have certainly created a LOVELY, SMOOTH, TUBE SOUNDING, SOLID STATE INTEGRATED AMPLIFIER that is a PLEASURE to LISTEN to. 

It is a wonderful way to capture the music that is hidden in a CD collection and a real a REAL MUSICAL TREASURE.

……. Paul