Castle

History - Since 1973 Castle has been a loudspeaker manufacturer in the truest possible sense with both design and manufacture of their world famous speakers housed entirely in one factory. Castle is rare amongst loudspeaker manufacturers in that they not only manufacture the drive units and electronic components found in their speakers but also the beautifully hand crafted real wood veneered cabinets used to enclose them. When Castle was formed the founding concept was to be a complete loudspeaker manufacturer and despite changing times and the globalisation of manufacturing Castle still retain this as the basis for the company.

                                                 The Castle Knight Series consists of five stereo pairs,
The Knight series delivers real-wood veneers, innovative bass loading and sumptuous sound quality, at affordable price points.

The Castle Knight Series consists of two standmount speakers and three floorstanders.
The Knight 1 and Knight 2 are both two-way standmount designs,
The floorstanding Knight 3, Knight 4 and Knight 5 incorporate Castle's proprietary TPT (Twin Pipe Technology) bass loading system, using the internal volume of the cabinet to extend bass response.   

Knight Series - The Castle Knight series is born of a complete understanding of acoustic principles, exceptional high-frequency clarity, depth of character and lustre - remarkable traits which reflect its outstanding performance. Featuring Castle's trademark of smooth and rich performance, a new standard in build and value in a package dedicated to high-quality stereo audio, whilst performing with speed and accuracy, characteristics that are important in enabling close acoustic matching to achieve the highest level of performance. Detail and neutrality are of utmost importance when building a loudspeaker, an evident characteristic shown throughout the design and construction of the Knight series.

High frequency driver - The Knight series was designed and manufactured using drive units and components built in-house, from the ground up - only possible because of our world-class research and development. The Knight series achieves superb high-frequency performance using a 'softdome' tweeter which produces a more controlled performance than metal equivalents and an innovative aluminium-core voice coil which matches and even exceed the bandwidth possible from metal domes without having to worry about inherent problems. Accuracy of high frequencies is core to the ability of any loudspeaker to render three dimensional soundstages whilst providing high class acoustic performance.

Cabinet design & Bass driver - In most loudspeaker designs, room modes are easily excited by forward or rear-firing reflex ports, which can cause resonance and a resulting 'boom' at particular bass frequencies. Whilst giving an impression of an impressive bass response, this boom frequency masks all others making bass indistinct and slow. Using TPT (Twin-Pipe Technology), a new generation of transmission-line, vented through the speaker base - a system that couples the bass response within the cabinet enclosure using a twin-pipe quarter wave design to provide a smooth and even bass response which augments that from the main bass driver with clarity. Using a rigid yet light mixed-fibre cone material in the bass driver makes it fast enough to track the most complex score and its unique 'TPT' (Twin-Pipe Technology) transforms the performance of all its floorstanding speaker models, using the internal volume of the cabinet to extend the bass response without using unruly reflex ports. Adorned with the highest quality genuine wood veneer, the Knight series offers more than just a taste of high-end luxury. Finish - Made from fine real-wood veneer that is sourced from sustainable timber, with the most beautiful deep-figured slices and cut from real trees.

TPT is new variation on transmission-line loading, delivering deep bass without the 'boom' that can result from traditional reflex-port loading. In many loudspeaker designs, room modes are easily excited by forward- or rear-firing reflex ports, which can cause audible resonance at certain bass frequencies. Whilst this can give the impression of a powerful bass response, the resultant 'boom' masks other low frequencies, making bass sound slow and poorly defined. Instead, the TPT system utilises the internal volume of the cabinet to extend bass response, delivering a smooth and even result that augments the main bass driver's output perfectly.

TPT couples the rear output of the bass drive unit to the air in the room via a column of air in the cabinet. This column is tuned to optimise the output of the bass unit at low frequencies in the same way that the air columns in a pipe organ transfer energy efficiently, so the listener feels, as well as hears, the low frequency output. The result is deep, tuneful, well-defined bass from speakers that are easily accommodated in a wide variety of room shapes and sizes.

Peter Comeau, Castle's Director of Acoustic Design, is responsible for voicing the Castle Knight Series speakers. Here, he further explains the TPT bass loading system:

"In essence, TPT a meld of Castle's established quarter-wave loading and reflex loading, achieving what is essentially a mass-loaded quarter wave reflex pipe. The 'Twin Pipe' refers to the internal layout where the drive unit is positioned part way down a folded, tapered column. This exits through the base of the cabinet and is mass loaded by the air trapped between this 'port' and the plinth.

"The tuning of the TPT system can be altered by adjusting this air mass for the optimum bass extension and control. Castle's existing Harlech S2 floorstanding speaker uses a similar Twin Pipe Quarter Wave system; the difference between this and the TPT system lies in the level of mass loading and damping used which, in the case of Knight Series, shifts closer to typical reflex performance, without the often associated boominess and lack of bass control, whilst still maintaining the benefits of improved bass extension."

All four speakers couple a 25mm textile dome tweeter with an innovative aluminium-core voice coil, delivering a performance that matches or even exceeds the bandwidth possible from metal dome tweeters, whilst avoiding their inherent problems.
Bass and midrange cones are fashioned from a cocktail of natural fibres that is extremely rigid and very light, able to perform as a perfect piston at sufficient speeds to track even the most complex of musical scores. The random nature of the grain contributes to an exceptionally inert diaphragm that is free from the resonances and 'ringing' of cones fashioned from lesser materials.

The component parts of all five speakers were designed from the ground up and are manufactured in-house. This enables a close synergy between the drive units, which in turn allows Castle to implement a simple second-order crossover, without the need for complex electrical correction of drive unit characteristics. This contributes a sound that is accurate, detailed and ultimately faithful to the source material, whilst also ensuring that the speakers are easy for any amplifier to drive.

Castle has long been famed for the craftsmanship evident in its wood-veneered speaker cabinets and the new Knight Series is no exception. Despite the competitive pricing of all five speakers, their cabinets sport high-quality veneers sourced from sustainable timbers; only deep-figured slices are used, cut from real trees rather than reconstituted mush. Each pair of speakers is hand-finished with mirrored, book-matched veneers, sealed and waxed in a process that takes more than five days. Only when a depth of character and lustre that befits the Castle name is reached are they released for final testing.

Discussing the Castle Knight Series, Peter Comeau comments:
"Castle is now part of the International Audio Group family of companies, yet its core values remain: British design, furniture-grade cabinets and a performance that's accurate, refined and musically absorbing. The new Knight Series is a perfect continuation of Castle's fine traditions, delivering real-wood veneers and sumptuous sound quality at affordable prices, with all the component parts manufactured and assembled in-house, and painstakingly finished by hand."