KEF LS50W wireless 200w active monitor speakers Omni-Q driver array

KF 03 SS LS50W
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KEF

Our brand promise is 'Innovators in Sound'. This is a summation of our company direction as well as our whole work ethic and the underlying culture at KEF.

Special

What Hi-Fi? Awards 2018 winner. All the performance of a top traditional system in a smart "All-In-One" package... 

VERDICT
These KEF Wirelesses are way more than just active versions of the award-winning LS50s. They’re a complete system wrapped in a neat and brilliant package

FOR
Impressive clarity and insight
Taut bass and strong dynamics
Features and excellent build
Neat package

OVERVIEW - all of the acoustic features and innovations that set the LS50 apart from every other speaker in its class remain. 
The FEA-designed cabinet with its constrained layer damping bracing and precision engineered curved baffle, the Uni-Q driver and the elliptical flexible port all work in concert to prevent cabinet vibration and resonances that produce unwanted sound coloration – putting you that much closer to how your favourite music was intended to sound. 
To get the most out of your music, every note should arrive at your ears at exactly the right time. Before KEF perfected our Uni-Q technology, this perfect time alignment could only be experienced in a small 'sweet spot,' leaving listeners outside of the ‘sweet spot’ with a less than ideal listening experience. 
Uni-Q changed that, opening up the optimum listening space to practically every spot in your room. The LS50W employs an advanced time correcting DSP crossover which takes that awesome achievement to the next level by correcting for inherent time delays introduced in the crossover stage. 
Amazing sound dispersion matched only by a live music performance is now attainable in virtually every room. This incredible achievement cannot be reproduced by any other active speaker.

With Spotify Connect and Tidal built in, all the music you love is at your fingertips. Stream from the cloud, or directly from a NAS drive or a computer through DLNA fully wirelessly at 48kHz/24bit resolution (or 96kHz/24bit using optional wired connection). Or simply use Bluetooth.

 

 

Features

Specifications

Reviews

Videos

Features

Every Spot is Sweet - Uni-Q
Get a three-dimensional sound image wherever you sit, for a sweet spot listening experience anywhere in a room using KEF's patented Uni-Q technology. Now in its 11th generation, it places the tweeter in the acoustic centre of the bass/midrange cone, allowing LS50 Wireless to create a more detailed, accurate and beautifully integrated three-dimensional sound image.

Crossover Timing Correction
High and low frequencies should hit your ears at exactly the right time. This perfect time alignment was only an ideal case in theory previously, and perfectly accurate sound could only be experienced within a small 'sweet spot'. With LS50 Wireless’ advanced time correcting DSP crossover and the unique sound dispersion abilities of Uni-Q, time corrected accurate sound can be achieved in different types of rooms. This is a feat that cannot be reproduced by any other active speaker.

Audiophile Grade System Configuration
Audiophile-grade sound means audiophile-grade technologies. LS50 Wireless delivers this with an array of sophisticated components built in. Through expert audio engineering, LS50 Wireless includes an end-to-end 192kHz/24-bit high-resolution digital signal path, dedicated DAC per channel, streaming pre-amplifier, and a 230-watt x2 amplification in a bi-amp dual mono configuration. All factory-optimised.

End-to-End High-Resolution
Every piece of information from a high-resolution music source is reproduced fully and accurately through an end-to-end 192kHz/24-bit high-resolution digital signal path. This creates a signal path from the input to the amplifiers that is completely digital and high resolution.

A standard RJ45 termination for the interconnect cable between speakers and a Cat 6 shielded cable improves bandwidth and performance headroom while rejecting noise and electromagnetic compatibility, ensuring LS50 Wireless sound is consistently high-quality.

Simplicity meets Sophistication
The beauty of the LS50 Wireless is its effortless combination of simplicity and elegance. It is easy to set up and use, yet offers sophisticated sound fit for audiophiles through inspired audio engineering and the Uni-Q driver.

Specifications

AMPLIFIER OUTPUT POWER - LF: 200W HF: 30W
OUTPUT - Subwoofer output

INPUTS
2.4GHz/5GHz Dual-band Wi-Fi network
Bluetooth 4.0 with aptX® codec
USB Type B
TOSLINK Optical RCA
Analog Line Level Input 10/100 Mbps
RJ45 Ethernet (For network and service)

DIMENSIONS - 300 x 200 x 308 mm

Reviews

Overall, these speakers have the insight to unravel a recording yet never go so far as to tear the music apart. They’re informative but always musical with it.

OUR VERDICT
These KEF Wirelesses are way more than just active versions of the award-winning LS50s. They’re a complete system wrapped in a neat and brilliant package

FOR
Impressive clarity and insight
Taut bass and strong dynamics
Features and excellent build
Neat package

AGAINST
Some small usability issues

What Hi-Fi? Awards 2018 winner. All the performance of a top traditional system in a smart package...

When someone says the words ‘hi-fi system’, what do you think of? If you’re anything like us, you’ve just pictured a combination of separates comprising source – maybe a streamerCD player or record player – an amplifier and a pair of speakers.

If we could go back 40 years and ask the same question, we suspect any enthusiast would have given a very similar answer - minus the digital sources, of course.

While hi-fi has certainly improved and been developed over the decades, on a fundamental level, arguably, it’s barely evolved at all.

Active speakers, while nothing new, could be a building block for an alternative solution.

On a purely technical level they have clear performance benefits, and they certainly reduce the box count. But many enthusiasts don’t like the lack of easy upgradability or the low perceived value - active speakers are, inevitably, always far more expensive than their passive relatives due to the cost of the power amplification inside. And, of course, a pair of active speakers only goes so far - you still need to add a preamp and a range of sources too.

But what if you didn’t need to add those extras? Imagine active speakers with preamp functionality; something that includes digital and analogue inputs.

Such a device would certainly need Bluetooth, and perhaps even streaming services such as Tidal built-in. You know what would also be nice? A streamer, so that any music stored on a NAS unit or computer connected to your home network could be replayed.

Such well-equipped active speakers would not only get rid of the clutter of traditional hi-fi but also, if done properly, could potentially deliver a performance broadly equivalent to a similarly priced separates rig.

The good news (as you may have guessed...) is that such a product does now exist: KEF’s LS50 Wireless.

Build

While we’ve reviewed powered and actives options from the likes of  Dynaudio, Dali and Meridian before, none of them has combined such a wide range of features in such an elegant two-box format.

Those that offer a range of inputs usually add an extra connection hub that transmits the signal wirelessly to the speakers. That’s not the case here. There are just the two fully active speaker boxes, arranged in a master and slave configuration. All sources connect to the right (master) speaker, which is then linked to the left by means of a supplied ethernet cable.

As is usually the case, 'wireless' doesn’t actually mean wireless. While these KEFs are better than most, you still have two mains leads – one for each speaker – and the connecting lead between them. Still, they remain a neater solution for getting high-quality sound into the home than traditional separates.

It will come as no surprise to any regular reader that the Award-winning passive LS50s are the basis for this design. The drive units remain unchanged.

These speakers use a Uni-Q array, where the 25mm aluminium dome tweeter sits in the centre of a 13cm magnesium/aluminium mid/bass cone.

This arrangement helps to produce an even dispersion of sound and improves integration between the two drivers. What looks like a grille in front of the tweeter is, in fact, a waveguide that improves its performance.

That beautifully built and finished enclosure is the same as the passive version too, bar a couple of centimetres of additional depth to accommodate the electronics and heatsinking. There are three cabinet options: the Titanium of our review samples, gloss black and gloss white. Each option comes with a contrasting colour on the Uni-Q driver array.

That curved front panel still looks unusual and is made of DMC (Dough Moulding Compound: a polyester resin combined with glass fibre and calcium carbonate). DMC was chosen for its inertness and ability to be shaped.

The rest of the enclosure is made from MDF. It’s heavily braced and strongly damped to minimise any resonances. We don’t tend to talk much about ports, but the one here is unusual in that it’s flexible in a bid to reduce distortion.

Features

These are true active speakers where each drive unit has a dedicated power amplifier. A 30W Class A/B circuit feeds the tweeter while a 200W Class D module powers the mid/bass unit.

The Class D design was chosen for its combination of high power and low heat output – heat generation is an important consideration in a product as crammed as this.

KEF has taken advantage of the internal DSP by phase correcting the crossover and using the software to allow the speakers to play loud and true while minimising distortion.

The digital signal path is 24-bit/192kHz capable and there’s a dedicated DAC for each drive unit. Only the optical input is limited to 96kHz signals, but that’s not unusual.

Take a look at the back of the right speaker and you’ll find stereo analogue, optical and USB Type B connectors. You’ll also find a subwoofer connection, in case you want to add more low frequency output, and an Ethernet socket for connecting to your network.

Normally we’d recommend sticking to the wired network option for greater stability but we used the twin-band (2.4gHz/5GHz) wireless option for most of our test without issue.

There are also controls for adjusting the sound for different speaker placements with options for close-to-wall or free space positioning as well as the choice between desk or stand supports. These choices can be made from the dedicated iOS/Android app too.

That app looks nice, is well laid out and easy to use. It controls the streaming (DLNA as well as Tidal) functionality and allows plenty of scope to fine-tune the speaker’s performance in a given environment. There is room for improvement, though. It’s a little glitchy and feels unresponsive at times.

We also don’t like the sliding volume control. It doesn’t change the volume until you lift your finger, so you don’t know how loud the sound is going to be until you hear it. It can shock on occasion.

It’s important to note that the app doesn’t switch between physical inputs, as it only operates the KEFs in streaming mode. To change input, you need to use the supplied remote or the touch controls on the master speaker.

This swapping around of controllers gets a little annoying if you switch sources a lot, particularly as the app has to reconnect with the LS50s every time you switch back, rather than just working straight away.

It would also be nice to be able to see an indication of the input chosen when sitting at the listening position – the only indicator is out of sight on the right speaker’s top panel. So if you’re using the remote to change input there’s no way (apart from counting clicks) to know what input the LS50 has settled on.

None of these things are anywhere near serious enough to be deal breakers for us, but they make living with the speakers a fussier experience than it should be. Make no mistake; you will want to live with them.

Why? To our ears they sound at least as good as the best comparably featured separates combinations available for similar money. Remember, here there are no extra electronics to house or cables to hide, just a pair of beautifully built speakers on (ideally) a pair of stands. Neat.

Sound

We start off with Arvo Part’s Tabula Rasa and are deeply impressed by what we hear. The LS50 Wirelesses sound clean and precise. They dig up so much detail and deliver it in an organised and stable manner. We’re struck by the KEF’s subtlety and their ability to generate strong dynamic shifts without stress.

These are small speakers but they manage to fill our medium sized listening room with high volume levels. KEF claims a maximum sound pressure level of 106dB, which should be loud enough for most people in most circumstances.

Positioned with care, a little away from the rear wall and with a touch of toe-in towards the listening position, they render a lovely, expansive soundstage that’s neatly layered and nicely defined.

We try the LS50s in less optimised positions and manage to use the app to make the results sound balanced. They’re never quite as good as the optimal position in terms of outright clarity or stereo imaging, but tonally we still get a balanced presentation.

Once set-up properly we think KEF’s engineers have struck a really nice tonal balance. It’s even-handed yet refined enough to make the most of less than optimal recordings or sources.

Moving onto Massive Attack’s Angel shows the LS50’s impressive bass performance. These aren’t big speakers so you won’t get really deep floor shaking bass, but they generate low frequencies that are taut, articulate and punchy.

For a speaker that stands 30cm tall and has a mid/bass unit that’s just 13cm in diameter, it’s an impressive result. The good news continues higher up the range with a transparent and fluid midrange and insightful highs.

Vocals are delivered with passion while percussion comes through with bite and composure.

The LS50 Wirelesses are rhythmic too, delivering the song’s unmistakable momentum with determination. They never sound too pushy either, allowing the song’s natural flow to come through.

Overall, these speakers have the insight to unravel a recording yet never go so far as to tear the music apart. They’re informative but always musical with it.

We play a whole range of music from the heartfelt grit of Bruce Springsteen’s Terry’s Song and sparse electronica of xx’s Stars right through to large scale symphonies from the likes of Stravinsky and Beethoven; these speakers take it all in stride. It takes a broad range of talents for this to happen.

Verdict

KEF has done a terrific job here. It has taken the award-winning LS50s and made them an even better proposition.

That price tag looks pretty hefty for such compact speakers, but remember that money also buys you a dedicated streamer, a Bluetooth module, 24-bit/192kHz DAC, preamp and four power amplifiers with a total of 460W of output.

Is this what the hi-fi system of the future should look like? We certainly hope so.

The LS50W has all of those characteristics but to each one it adds a significant extra level of quality and ability. It may be a hi-fi speaker, but it’s a brilliant little nearfield monitor too.  
Phil Ward

SUMMARY: the LS50W is one of those monitors — simply because it sounds so natural and uncoloured — for which there’s not a great deal to say. The mid-range, especially on voices, offers great clarity, yet still has warmth, and the high frequencies from that coincident tweeter are detailed and delicate, yet there’s still HF power when it’s needed. The stereo imagery and portrayal of depth effects is absolutely among the best I’ve heard. I hate to fall into the trap, because the basic principle of a dual-coincident design is coherence, but the whole performance just hangs together in a way that simply sounds right.

EXTENDED REVIEW: although primarily a hi-fi brand, KEF have strong links to some classic monitor designs — and in this new compact speaker, it shows...

I suspect I know what you’re thinking. You’re thinking, “Why are Sound On Sound reviewing what is clearly a consumer product”? And it’s a reasonable question because despite KEF’s close links to numerous BBC-designed studio monitors of old, the company always have been primarily a hi-fi brand, with little availability through pro audio retailers or distributors. And, well, hi-fi speakers and pro monitors require different characteristics... don’t they? Well, no. To my way of thinking, and echoing Duke Ellington’s famous thoughts on music, there are only two kinds of speaker: good ones, and “the other kind”. There’s also no escaping the fact that the most iconic nearfield monitor out there, the Yamaha NS10, began life as a hi-fi speaker, and one of the most iconic h-fi speakers, the BBC LS3/5A, began life as a nearfield monitor (although it would be a while after its arrival before the term ‘nearfield’ was coined).

But, if we’re going to review a ‘hi-fi speaker’ as a nearfield monitor, why the KEF LS50 Wireless? Why not a Bowers & Wilkins model or a Mission, or a Monitor Audio? Well, regular readers of my reviews will perhaps have picked up on the occasional mention that one of my favourite speakers for nearfield monitoring is the original, passive version of the KEF LS50. It’s the one I use when there are no review monitors either side of the workstation, and when there are review monitors in place, it’s the one I use as a benchmark reference. I think the LS50 is one of the best (if not the best) compact and reasonably affordable speakers ever made (I bought my pair, previously loved. So, when KEF announced a wireless active version, that also happens to incorporate a raft of electroacoustic advances over its predecessor, it was of huge interest and, I think, impossible to ignore here on planet pro-audio.

Wi-Fi System

To begin with, however, a bit of description and background. The LS50 Wireless (to be written henceforth as LS50W) is a compact and classy-looking speaker with connection panel, heatsink and reflex port on the back and a touch control panel on the top of the right-channel speaker. The LS50W is wireless in so much as it can connect to a Wi-Fi network and play audio streams. The ‘wireless’ title, however, is not entirely accurate because each speaker of the pair needs mains power, and a network-style cable is used to connect the pair together so that they can talk to each other. The LS50W can also connect to conventional wired input signals. The right-channel speaker is by default the ‘master’ and carries the control panel, configuration switches and input sockets. The left speaker is the ‘slave’ (the right/left master/slave default can be switched). The left speaker rear panel carries just the pairing network socket, its mains input socket and a rotary balance control. I’m sure there’s a good reason why the balance control is on the left speaker, but I’m not sure what it is. I didn’t use it anyway.

Along with providing power for the internal A-D, DSP and D-A conversion, those mains inputs also, of course, provide power for a couple of power amplifier channels in each speaker. Interestingly, while the bass/mid amps provide 200 Watts of Class-D power, the tweeter amps provide 30 Watts of Class A/B. The discrepancy between bass/mid and tweeter amplifier power ratings arises partly because the tweeter is more sensitive than the bass/mid driver (so needs less power), and partly because headroom is required on the bass/mid amplifier to enable LF equalisation to be applied. The decision to use Class A/B for the tweeter was taken on sound quality grounds.

The LS50 cabinet is constructed from a rounded and gloss-finished MDF carcass attached to a gently curved and matte-finished, dough-moulded composite front panel. The curve and soft edges of the front panel will help to minimise the smearing effect of edge diffraction. The cabinet is comprehensively braced and damped internally and KEF make quite a play of the FEA (Finite Element Analysis) simulation techniques used to optimise its design in order to minimise panel resonance. It certainly sounds dead to the high-tech knuckle tap. The previously mentioned reflex port exits through the amplifier heatsink on the rear panel and is somewhat more sophisticated in design than the simple plastic tubes I sometimes find myself describing. The tube is elliptical in section, with generous flaring on both entrance and exit, but most unusually, it is constructed internally from a flexible material that’s designed to help suppress the ‘organ pipe’ resonant mode that reflex ports often display. The clean and resonance-free curve in Diagram 1 illustrates the success of the KEF port design in those terms.

Quelle Coincidence

The most distinguishing feature of the LS50W is the matte-copper-finished, dual-concentric — or, more correctly, dual-coincident — compound driver. The difference between the ‘dual-concentric’ and ‘dual-coincident’ terms distinguishes the KEF-style driver from earlier compound driver designs, such as the classic Tannoy unit developed by Ronald Rackham in 1948. Rackham’s Tannoy driver located the tweeter on the same central axis as the bass/mid diaphragm, but at a position behind the magnet, so it’s laterally displaced. In contrast, the KEF-style compound driver places the tweeter right at the apex of the bass/mid diaphragm, so not only is it on the same central axis, it’s effectively at the same position in space — hence ‘coincident’. The voice coils of the bass/mid driver and tweeter are both laterally and axially aligned, so their effective acoustic source positions are the same.

KEF introduced their first dual-coincident driver in the mid 1980s. It was was made possible by the development of high-power NeFeB (Neodymium-Iron-Boron) magnetic materials, which made it possible to build a dome tweeter compact enough to fit on the end of a bass/mid driver pole-piece. Patents were granted to KEF that protected the dual-coincident technology and were mostly effective in restricting competitors from exploiting similar ideas for a couple of decades. Even after the original patent protection had lapsed, later KEF patents covering refinements to the basic idea continue to limit the scope for other manufacturers to compete. This could well be one reason why the compound driver in the Pioneer RM monitors has its tweeter mounted slightly forward of the bass/mid diaphragm apex.

But what, you might by now be asking, are the advantages of the dual-coincident format? Firstly, at a stroke, it fixes a fundamental problem of conventional multi-way speakers with displaced drivers: their phase relationship changes with listening position. It’s simply a matter of geometry: move your head, and the relative distance from your ears to the bass/mid driver and tweeter (in a conventional two-way system) changes. This means that in the crossover region where the output from the two drivers overlaps, the frequency response of the direct sound varies significantly as the relative phase of the outputs from the two changes. Putting a time-domain slant on this, dual-coincident means that the signal arrival time from bass/mid driver and tweeter is the same at all listening positions. This is illustrated in Diagram 2, showing the step response of the LS50W (literally, the response to a simple step change input signal) compared to the step response of a conventional two-way monitor).

Secondly, the dispersion discontinuity that typically occurs in two-way speakers, where the relatively narrow dispersion of the bass/mid driver towards the top end of its range joins the much wider dispersion of the tweeter, is avoided. In a dual-coincident arrangement, the dispersion of the tweeter is defined by the dimensions and profile of the bass/mid diaphragm. When KEF first launched their dual-coincident technology, they christened it ‘Uni-Q’, ‘Q’ being an acoustician’s term for directivity. This consistency of directivity from, effectively, a point source is, I think, particularly suited to nearfield listening. Diagram 3 illustrates the dispersion consistency of the LS50W.

KEF have now been developing their dual-coincident technology for over 30 years and, in contrast to the relatively primitive early Uni-Q drivers, the compound driver fitted to the LS50W is decidedly high-tech. In fact there are not too many drivers out there in either pro or hi-fi sectors that have it beaten in terms of engineering and technology. Its bass/mid element is a 130mm magnesium/aluminium-alloy diaphragm driven by a 50mm-diameter voice coil. The diaphragm is unusual not only for its material but also for its radially reinforced profile and radially pleated rubber surround. Rather than to play a role primarily in bass/mid driver performance, the last of these features is actually designed to present less of a diffraction-causing discontinuity to the tweeter radiation than would a conventional half-roll surround.

Tangerine Dream

And speaking of the tweeter, it’s a 25mm, rear-vented, reinforced-aluminium dome device driven by a NeFeB magnet, but perhaps its most interesting aspect is the ‘tangerine’ waveguide and short horn. The tangerine waveguide is designed to compensate for a fundamental technical aspect of acoustic radiation from a dome that, while obvious when you think about it, mostly goes unappreciated.

Imagine a dome moving axially backwards and forwards. Acoustic radiation will be proportional to the velocity along the axis of movement. However, the profile of the dome, increasingly sloped towards its outside, means that the perpendicular axial velocity effectively falls towards the periphery (the inverse is true for a cone diaphragm). So the dome output level reduces across its radius. The action of the tangerine waveguide is to increase the acoustic impedance presented to the dome towards its periphery and so compensate for the drop in output. It’s as if the dome operates as a direct radiator at the centre and morphs towards a compression driver model at the outside. It’s a neat solution to the problem and one you probably won’t see elsewhere because, of course, it’s patent protected.

Around the outside of the tangerine is a ‘horn’ profiled wave-guide section that extends a significant distance into the bass/mid diaphragm and smoothly integrates the tweeter with the diaphragm profile. The effective integration of the tweeter and bass/mid driver radiation is an area of Uni-Q technology that has developed significantly over the decades and is fundamental to the way KEF have optimised the dual-coincident concept. I wrote earlier that one of the benefits of the dual-coincident format is that it consolidates the dispersion characteristics of the bass/mid and tweeter diaphragms, and it does. Optimising the phenomenon, however, falls into the ’easier said than done’ category. In order to make it work well there’s a number of conflicting factors to be resolved. Firstly, the bass/mid diaphragm profile that works best in terms of that driver’s mechanical/acoustic performance might not be the profile that works best in terms of tweeter radiation and dispersion. So perhaps the stiffening ‘creases’ of the LS50 bass/mid diaphragm are present partly to enable a little more latitude in its physical profile to suit tweeter radiation demands.

Secondly, the bass/mid driver diaphragm, unavoidably, isn’t stationary and this is potentially a problem in terms of intermodulation distortion. Intermodulation distortion occurs when, as the name suggests, one signal modulates another, resulting in the generation of sum and difference signals not present in the input. Speakers generally are prone to it, there being a number of mechanisms that can potentially result in intermodulation. But with movement of the bass/mid diaphragm in very close proximity to the tweeter dome, dual-coincident systems have a potential intermodulation mechanism that conventional speakers don’t. So part of the role of the horn section around the tangerine waveguide on the KEF driver is, I suspect, to constrain the radiation of the tweeter and minimise the potential for intermodulation.

Primal Stream

Moving away from the dual-coincident driver, the LS50W is an unconventional beast in other respects too. This is primarily because it’s a consumer hi-fi speaker aimed mainly at users who have fully embraced the contemporary digital, networked and streamed audio paradigm. The most obvious aspect of its unconventional nature is in the complement of inputs provided. Along with conventional unbalanced analogue and S/PDIF optical digital inputs, the LS50W can play Spotify and Tidal streams wirelessly, play from DLNA-compatible servers and over Bluetooth, and operate as a USB device (so DAW apps will see it as an audio output). It also ships with a remote control and has an iOS/Android app for setup and control.

The lack of balanced analogue audio inputs and the addition of touch-panel, handset or app-based volume control left me scratching my head a little over the best way to integrate the LS50W into my DAW setup (Pro Tools with, currently, a second-generation Focusrite Scarlett 18i20). Though not ideal (being unbalanced), the analogue inputs worked perfectly well and it was possible to set the volume of the LS50W at, or near, maximum (although frustratingly, there’s no indication of volume on the speaker itself or in its app) and treat them as conventional active monitors with volume control on the interface. However, the LS50W incorporates internal DSP, so analogue input signals go through an entire A-D/D-A process, and a signal chain incorporating that extra conversion round trip doesn’t seem ideal. Using the LS50 as a USB output device in the DAW also worked perfectly, and to my ears, sounded better than the analogue inputs, however as soon as the DAW job in hand leaves ‘the box’ and requires inputs or outputs, or even a pair of headphones or a second pair of monitors, it’s no good if the monitors have exclusive use of the DAW interface.

By default, the right speaker acts as the ‘master’, and is where the speaker EQ controls, analogue and digital audio inputs, and Ethernet link output socket are located.

A solution to this conundrum came to me in the form of a TC Electronic BMC-2 DAC/monitor controller (for which I’ve promised to thank KMR Audio for the loan). The BMC-2 provides three digital inputs and well-implemented digital volume control, so by taking an optical output from the Scarlett interface I could connect the LS50W digital optical input to the BMC-2 and have both a fully digital monitoring chain and convenient desktop volume control. Conveniently, the BMC-2 can also drive a second pair of monitors from its analogue outputs so I could simultaneously connect my passive LS50s (given a clean bill of health following a technical once-over by KEF) and be able to directly compare the active LS50W and the passive LS50.

Before I get to how that comparison panned out there’s just one more aspect of the LS50W to describe. I’ve mentioned a couple of times that the LS50W incorporates some DSP, but haven’t explained why. There’s effectively four elements to it. Firstly, the 2.2kHz crossover between the bass/mid and tweeter is done in the digital domain, and secondly, the DSP provides analysis of the input signal so the trade-off between low-frequency bandwidth and volume level can be optimised. It means that the diaphragm displacement-limited power handling can be maximised, which is decidedly useful on a speaker with a relatively small LF radiating area.

The Small Phases

The third DSP function is to compensate for the phase (time) changes that occur over the mid to HF frequency band, the most obvious of course being those introduced by the crossover filters and driver voice-coil inductance. A linear-phase response throughout the audio band has long been a holy grail of speaker design and while a few monitors claim to achieve it, in reality it’s not truly possible on multi-way speakers with physically displaced drivers. You can have linear phase at discrete positions in space where the driver-to-ear flight time is equal but, as mentioned earlier, as soon as you move your head, it’s gone. With a dual-coincident driver, however, it’s very much worth equalising phase because the distance between each ear and the two drivers remains constant. The step response in Diagram 2 shows clearly how the two drivers of the KEF LS50 are time-coincident (the LS50W DSP helps here too of course, and it’s also the case that if I’d moved the measuring microphone, the conventional speaker step response in Diagram 2 may well have looked better).

The final LS50W DSP function is to provide some environmental EQ — accessible from push switches on the back of the right speaker or, more conveniently, via the app. Variable ‘desk’, ‘wall’ and high-frequency EQ functions are provided along with three LF extension options. For what it’s worth, in my room, a little desk and wall attenuation worked well and I preferred the less extended LF option.

Passive Resistance

So how did the comparison between the old passive and new active LS50W go? It went extremely well as it turns out. The LS50W sounds unmistakably like my passive LS50, only more so. I played both familiar and unfamiliar material from Pro Tools sessions and CDs, but also, thanks to the range of inputs the LS50W offers and its network-connected nature, hi-res streams from servers and slightly less hi-res streams from Spotify came into play. One advantage of the ‘consumer’ nature of the LS50W in a pro environment is that it provides such easy access to as wide a range of audio sources as it’s possible to imagine. If your monitoring setup is occasionally required for ‘entertainment’ listening rather than work, the LS50W makes a decidedly strong case for itself.

Being compact and consequently relatively limited in terms of both maximum volume level and low-frequency extension, the LS50W will never be fully in its comfort zone playing the role of a main or midfield monitor, but it’s actually able to play surprisingly loud, and in my room never sounded as if it was up against its limits. Having said that, its fundamental quality and revealing nature meant that there was little to be gained in monitoring terms by pushing the volume level too far. Listening to familiar mixes and material I was immediately comfortable with the tonal balance while at the same time impressed that I could hear easily down into the layers of the mix so that details, both good and bad, were more apparent and so easier to either work with and emphasise, or deal with and suppress.

Nifty Fifty

I mentioned previously that I preferred the less extended LF options of the three that the LS50W offers, and that to some extent reflects my only concern over its performance: its reflex-loaded bass. KEF supply foam bungs with the passive LS50 to block the ports and that’s how I normally use them, the more explicit bass detail and more secure sense of timing being of greater worth to my ears than wider bandwidth. There are no port bungs supplied with the LS50W, but using the LS50 bungs and selecting the ‘Extra’ LF EQ option produced what I felt was the best result, although it was a very close-run thing with the less extended EQ option without bungs. In the grand scheme of things though, the LS50W reflex-loaded bass is very far from a deal breaker and in comparison to many reflex-loaded speakers the negative influence of the port is subtle.

Moving further up the band, the LS50W is one of those monitors — simply because it sounds so natural and uncoloured — for which there’s not a great deal to say. The mid-range, especially on voices, offers great clarity, yet still has warmth, and the high frequencies from that coincident tweeter are detailed and delicate, yet there’s still HF power when it’s needed. The stereo imagery and portrayal of depth effects is absolutely among the best I’ve heard. I hate to fall into the trap, because the basic principle of a dual-coincident design is coherence, but the whole performance just hangs together in a way that simply sounds right.

I’m going to conclude by referring back once again to the passive LS50 for a moment. The qualities it delivers so effectively are a combination of neutrality in terms of tonal balance, dispersion consistency for nearfield listening, pin-sharp imaging, and the hear-through clarity that comes from minimal enclosure character, low distortion and, of course, time-domain coherence. The LS50W has all of those characteristics but to each one it adds a significant extra level of quality and ability. It may be a hi-fi speaker, but it’s a brilliant little nearfield monitor too.

I was … well…BLOWN AWAY. These do NOT have the all out gusto and power or bass output and in your face sound of the Phantom Golds but dare I say, they sound more delicate, more focused, more complete, more cohesive, more open when compared side by side.

SUMMARY: I was … well…BLOWN AWAY. These do NOT have the all out gusto and power or bass output and in your face sound of the Phantom Golds but dare I say, they sound more delicate, more focused, more complete, more cohesive, more open when compared side by side. No chest thumping shaking bass and no warm sound but it was just right. A shade or hair to the right of neutral into warm and with the detail and imaging I was hoping for, the same imaging and depth I heard from the passive versions but now they came to life with the extra bass extension and power. The way these speakers deliver music is quite special and spellbinding. Put on some acoustic guitar, piano, vocals or a mic of all and you will be shocked at the realism of the vocals and midrange. Best I have heard since my old Guarneri Evolutions and these may even be better in many ways (Guarneri can be very warm depending on amp or room and this can hinder the details and open-ness of the speaker) . The KEF’s are More accurate but also throaty and husky when needed.

EXTENDED REVIEW: Wow. Just Wow. Audio tech just continues to move forward, and here we are in 2017 with a myriad of new tech waiting for us audio nuts to try. Me, I am now a huge believer in the “wireless” speakers…well, more so “Active” speakers for 2016/2017. So far this year I have tested the modest Klipsch Sixes which are also a set of powered active speakers. I really enjoyed them and for the money, the Klipsch’s are tough to beat but at the end of the day, the build or sound of those Klipsch are not nearly up to the levels of Devialet Phantoms, Dynaudio or KEF Active speakers. The Sixes, I consider “Mid Fi” as they just do not deliver the Audiophile experience with soundstage, air and imaging yet they are very good for playing good old fashioned party music, and they sound damn good and fill a room. But what we have here in the KEF LS50 Actives is something entirely different and on a different level. IN A GOOD WAY.

Let’s back up a tad…

About a year or two ago I owned a pair of standard passive KEF LS 50’s and had them set up and stand mounted in my listening room, which is SMALL. 12X13 and most speakers in this room sound like magic somehow..almost all, but not all. Normally a room like this would be a nightmare, or so I am told but anyone who has heard my audio systems in this room has told me how amazing it sounded. Rich, full yet with all of the audiophile tricks included. ; ) I truly love my room, as what I hear inside of these walls has beaten demos of high end speakers in shops and others I have heard that cost much more than what I normally have in here.

When I had the standard passive LS50’s in this room though, which are notoriously hard to match an amp to, I ran them with three integrated amps. One was a $10,000 McIntosh Ma8000, one was a McIntosh Headphone amp and the other was an Audio research 75WPC amp. None really drove those original LS50’s to my satisfaction, or..what I should be saying is, the LS50’s while being amazing with layering and detail fell flat for the lower end. They had almost no real solid room filling bass, and while they were as open as can be, had a nice wide soundstage and had gobs of detail, the high end irritated me too much so I got rid of them and sold them at a $300 loss after a few months. They never grew on me and yet I tried, and I did love them for what THEY COULD DO, just not what they could not do. This is why I never reviewed them as well. I do not review what I do not like ; )

After they were sold I somehow missed that layering and detail they gave with some vocals. In some situations, they did deliver amazing spooky real vocals. When I saw KEF was releasing “wireless” active versions of the LS50’s with four amps inside of two speakers that matched the drivers perfectly (200 WPC for the mid/bass and 30WPC Class A/B for the tweeter) as well as its own 24/192 dacs and all the inputs I would need…I knew I had to give them a test. The word on the street was that these new Active versions upped the game and brought these speakers to life and the bass now extended lower, into the 40’s. WHAT?!?! If so, I would be getting that sweet detail of the KEF’s and some of the bass that was missing from the passive versions! Hmmmm.

I ordered Black with Blue drivers but you can also get these in White with Copper Drivers or a Grey with Red Driver (would have been my 2nd choice) as that color combo matched my listening room perfectly. When they arrived I moved out the Klipsch Sixes and was ready to be BLOWN AWAY! All of the reviews of these speakers praised them as amazing. When I put them in, I was a little let down as they sounded thin and flat. The Klipsch Sixes I reviewed recently were pumping out LOUD, LIVE sounding music with an effortless ease and these were..well..NOT. Now, due to the power cords and cables needing to be plugged into the each speaker, I could not fit them on my stands (same with the Sixes) so I set them where I had placed the Klipsch speakers.

As the music played I notice the same thing as I had with the passive LS50’s. They seemed thin and a tad bright. Hmmmm. Something had to be off..it had to be. I soon found out that yes indeed, something was off.

I have a Sonos going into these with an audioquest Diamond optical cable. I also have my Marantz TT15 Turntable going into a Tube phone stage (Vincent) and then into the analog ins of the speakers. As they played I decided to read the instructions, lol.

When I set them up I set the controls on the back to them being on a desk and away from the wall. When I changed the settings to being close to the wall, they came to life in the bass dept. THERE IT WAS. BASS. It was rich, never boomy, and solid/tight and fast. Wow. What a difference. While no where near as plentiful as the Phantom Golds with the Bass, they were delivering better imaging and resolution and were more open. The bass was plenty good enough, and much better than the previous passive LS50’s.

On the back of the right speaker you can set up the speakers for your listening room and placement. Also, all inputs reside here. Analog, Optical, PC, Subwoofer, USB, Network and an output to the left speaker. The cable that connects the speakers comes with the set and is around 3 meters long.

I then set up a pair of suedo sands, the ISO Acoustics Aperta stands. They are aluminum and fit these speakers like they were made for them. Amazing fit and finish and look. When the speakers were placed on these, same spot, they were lifted up a tad and BOOM, now I had even better bass and focus. I had a little warmth going on but it was … magical. I then set the settings to these being on stands and close to the wall. ONG, OMG, OMG. THIS WAS IT! On the Aperta stands, with these settings I was hearing magic.

I had to get serious and get in my spot, and make sure they were set up perfectly for my “sweet spot”. Once I did this, I dimmed the lights, chilled out and sat in my chair listening to my demo playlist.

I was … well…BLOWN AWAY. These do NOT have the all out gusto and power or bass output and in your face sound of the Phantom Golds but dare I say, they sound more delicate, more focused, more complete, more cohesive, more open when compared side by side. No chest thumping shaking bass and no warm sound but it was just right. A shade or hair to the right of neutral into warm and with the detail and imaging I was hoping for, the same imaging and depth I heard from the passive versions but now they came to life with the extra bass extension and power. The way these speakers deliver music is quite special and spellbinding. Put on some acoustic guitar, piano, vocals or a mic of all and you will be shocked at the realism of the vocals and midrange. Best I have heard since my old Guarneri Evolutions and these may even be better in many ways (Guarneri can be very warm depending on amp or room and this can hinder the details and open-ness of the speaker) . The KEF’s are More accurate but also throaty and husky when needed.

These speakers ship with all cables you need and a basic plastic remote, with matching colors to your speaker. So my remote is blue and black.

You can use the remote of the touch panel on top of the right speaker to power them on, change inputs, go to bluetooth or adjust volume. 

The remote could have been better. For example, I am using two inputs. Optical and Analog. There should be buttons on the remote to pick whatever input you want but instead there is just one button to scroll through the inputs but you never know which one you are on, so it is hit or miss. The remote is also plastic, and kind of cheap. I would have loved to see a nice backlit metal remote as these seekers are pure high end in looks, build and sound but the remote was an afterthought. But back to listening…

For kicks I started to turn them up to see how loud they can go, as this is usually a test of how good a speaker really is…and as I kept going they would get louder and louder yet the volume steps are like baby steps, so I kept pushing and pushing and they became so loud my wall shelving units were shaking yet the speakers never sounded congested, they never lost focus and they never sounded harsh. They kept that same sound at every volume level I tested them at but would get louder and louder. When my shelves were shaking I decided to not go any further with the volume so I never maxed them out, but they retained clarity and focus when pushed which was pretty impressive. When loud, they can fill my room but they sound much different than the Phantom Gold’s do. The Phantoms have a warmth and just overall sense of ease and power about them, and they can blow you out of the room, but they sound much warmer and not as open as these. With the KEF’s I hear amazing things with acoustic instruments, piano and vocals. For metal and rock, the Phantoms rule the day but these are not bad at all, even with old 70’s rock. All I miss is a tad bit of mid bass thump. But the pros far outweigh that one con with these.

For my small room, these are just about PERFECT. Not too much, not too little.

As I sat in my sweet spot, I realized it was now four hours later and I was still grinning and smiling at the amazing sound coming from these. When I listened to all of my demo music not once, but twice I knew I had something very special here. No hype, no BS. No fatigue, no shrill sounds, just exactly what I had hoped for. When I had the original LS50’s I did not even want to write a review, as if I do not really love something I do not review it or write about it. So they were sold at a loss and I never spoke of them. THESE on the other hand, these are up there with some of the best I have had in my house, and I have owned systems up to $45,000 and some a little more. The funny thing is, my worst sounding system here was that crazy expensive one that neared $50,000. That showed me that the cost does not mean all out performance. Some speakers and amps are just over rated and go by name recognition, and I have learned this the hard way (by buying and selling and losing). After having these LS 50 Active Speakers in this space for a while now, I can not imagine taking them out, even for the Phantom Golds. THEY ARE THAT GOOD. They offer something that is hard to pin down, and hard to get from larger speakers as well. They are so lifelike, yet do not shout of of the speakers like the Klipsch do. They are not direct, but when you listen you feel an expansion of a soundwall  that stretches out beyond the speakers. You hear precise layering of instruments and voices and damn good imaging.

KEF has a future classic here.

But remember, they did not get this good until I set up the DSP on the back and put the stands in place. Now they are locked in, and just give me a wide soundstage, precise imaging, amazing layering of music (you hear each instrument clearly) and vocals to die for with some artists. Bass is tight, snappy and amazing, and I do not need a sub here..in fact, I would not want to muddle things up by adding one. I do not feel these are lacking bass and unless you are addicted to Hip Hop and beats headphones you would not find them lacking either, unless you had them in a huge room. What is truly awesome is the bass never ever gets boomy or muddled, nor does it ever interfere with the delicate mids and treble. It is tight, and called upon the needed. Amazing integration here and KEF really has created a speaker that truly blew me away, and for much less than all of my old setups. CRAZY!!!

Listening to Only by RY X had his voice floating in the middle of my room with a scary realism that blew my mind. I had this effect with a couple of other speakers ($25k and $16k) but never with US$2200 (excl sales tax) self powered speakers. As the guitar and piano were behind this voice, it was almost like VR audio, lol. At that point I knew, I KNEW these were staying no matter what I had to do. Now, the old lS50’s suffered with rock or metal music, and some electronic as they did not have the balls and gusto to reproduce that music properly. THESE CAN to some extent but if you like hard driving rock and metal, I’d say there are better options. These excel with voices, acoustic, electronic, jazz, and even modern pop and country. With Rock and Metal they sound great but you may miss the driving thump of larger speakers with more mid bass. I am listening to KISS ALIVE II on vinyl as I write this and while some mid bass thump is missing the soundstage and realness of the voices and instruments make me feel like I am there. The old LS50’s could not do this. So these are much more versatile than the old ones that were raved about everywhere.

I have used countless HiFi setups in my days, over the last 20 years or so and I have had opportunities to use systems ranging from $500 to $50,000 and this right here, these KEF Powered Active Wireless speakers? In my top 3 easily yet they come in at $2200 and include all you need from amps, dac and inputs. All in one, the future of HiFi. Set these up right, use a good source and cable and yes, there is a marked improvement over a generic optical) and they will reward you with some amazing organic beautiful sound. This is what 2 Channel is meant to sound like, and the fact that these come in at this price point makes me wonder what other high end manufactures will be doing for the near future.

Of course there is another con to these. With all electronics being INSIDE the speakers, if an amp goes out you are sort of screwed. If a DAC goes out, screwed. With separate components we can fix of swap what is broken easily. With these, not so much. So while we do not know about the longevity of these, they seem to be built to a very high standard, and so far, so good.

My advice if you buy these?

USE Dedicated stands and set them up correctly. If like me you are limited with this due to the cables needing to be attached, get some ISO Acoustics Aperta stands, that were actually made just for LS50’s and set them up like I did. Take your time and angle them in to your sweet spot. I have some toe in. Set them up as on stands but far from the wall if going the ISO Acoustics route and  you will have rich sound with plenty of tight, never boomy bass. Of course, room size and dimensions come into play so work with it. When set up just right these will be incredible.

Videos

KEF's LS50w is a more affordable hi-fi system in a box - John Darco