Windsor Duke

The Windsor Duke is equipped with an 8” woofer, purposely-developed together with a 28mm textile dome tweeter, to perform seamlessly in a classic bookshelf / monitor styled cabinet.

The drive units have all been engineered from the ground up, using cast alloy components, yet retaining the essential character through the use of new woven Polypropylene cones and glass-fibre voice coils.

The cabinet work is, as you would expect from a product bearing the Castle name, first class. The hand-selected, book-matched pairs of veneers are sourced from the original suppliers to ensure continuity in the Castle legacy. Our dedicated ‘hand – finished’ team is trained to deliver the highest quality ‘furniture – grade’ finishes and build. No two pairs are the same!

Made in the UK

Castle are proud to announce the Windsor Series, signalling the return to the UK for the manufacturing of Castle Loudspeakers. Castle Windsor Series comes, with the craftsmanship and quality that is self-evident and clearly marks the brand’s intention to restore and build upon the reputation of the brand for superlative quality loudspeakers.

Echoing the origins of the brand that was established in 1973; the speakers are hand built and hand finished, by our loudspeaker production experts, in England.

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A Collaborative Development:

To ensure the Windsor Series is truly something special, Castle has harnessed the talents of world- renowned speaker designer Karl-Heinz Fink and his Fink Audio team. Built over decades, Fink’s track record of developing excellent loudspeakers is exceptional, He was recently described as “today’s most influential speaker designer” when presented with the Outstanding Contribution Award at the What Hi-Fi? Awards 2022 – a fitting tribute to the success of his designs. 

Windsor Highs

The frequency unit follows the classical formula of a high-consistency exposed polyester dome, with a pressure equalised Ferrite magnet system and a stable metal front plate. No Ferrofluid is used in the tweeter in order to guarantee the highest possible dynamic range. This also keeps the resonant frequency below 800Hz, for optimum performance.

The treble unit’s voice coil has a diameter of 28mm and is equipped with a copper cap on the pole piece of the magnet. This reduces distortion and intermodulation, delivering a tangible increase in audible detail at very high frequencies.

A Royal Weave

The Polypropylene used in the cones is precision cut into thin strips, woven back into a sort of fabric and comes together again to form a solid foil. This foil gets pressed into the final shape and then cut to size.

This is a much more complex way of creating a polypropylene cone, but it has significant sonic benefits. The process creates a material with different properties of rigidity, at different directions between the voice coil and the surround. This helps to minimise resonances, which produces a flatter response curve – a desired characteristic of any drive unit designed for high-performance audio.

The resulting cones, with a diameters of 200mm, feature surrounds fashioned from low-hysteresis rubber which will not deteriorate over time.

Regal Magnetics

Improved openness of the midrange performance

The magnet system in the Castle Windsor Series includes an aluminium compensation ring. This ring helps minimise the variation of the impedance during the operation of the drive unit. As a result, the harmonic and intermodulation distortion values are reduced, for improved openness of the midrange performance.

A Voice Coil of the Upper Class

Maintaining purity of signal

The voice coils are made from glass fibre, bonded with high-temperature resin – the stiffness and rigidity of this material is extremely close to that of aluminium, but it doesn’t generate eddy currents like aluminium would. Thus, it maintains signal purity by its very design.

The mid/bass drivers’ magnet system includes an aluminium compensation ring, which helps to minimise impedance variations during operation. As a result, the harmonic and intermodulation distortion values are reduced, contributing greatly to an open and expressive midrange performance.

Built Like a Castle

Drive unit development has progressed markedly in recent times, yet the principles that govern loudspeaker cabinet design have remained constant for decades. The most important research for low- colouration cabinets was conducted by the BBC some half a century ago, and loudspeaker enclosures are still manufactured in accordance with these findings to this day.

The main cabinet structure uses dual-layer MDF panels separated by a flexible, but thin layer of specially engineered acoustic glue. This glue is purposely developed to dampen resonance in the critical midrange of the dual-layer panels. In order to achieve the optimum rigidity at lower frequencies, point-to-point bracing was used. The result is a quiet cabinet, without prominent peaks, and controlled output.

The Cabinet

However, while the principles of acoustically optimised cabinet design are well-founded, it remains a complicated process to ensure that a speaker’s enclosure is ideally matched with the mounted drive units. After many hours of analysis, development and consideration of the established principles, a new methodology was chosen for the optimisation of the Castle Windsor cabinets.

Point-to-point bracing is applied to achieve optimum rigidity at lower frequencies, joining opposing panels without spreading resonance to other parts of the cabinet. The result is a ‘quiet’ cabinet, without prominent peaks, delivering a controlled output. Simple in theory but intricate in design and engineering – a trait of the Castle brand philosophy.

Arhitectural Veneers

Castle has long been famed for the craftsmanship evident in its wood-veneered loudspeaker cabinets and the new Windsor Series is no exception. Their cabinets sport a choice of architectural-grade walnut or mahogany 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 mirror red, book-matched veneers, sealed and waxed in a process that takes several days. Only when a depth of character and lustre that befits the Castle name is reached are they released for final testing.


General DescriptionTwo-way standmount
Enclosure TypeBass reflex, rear ported
Treble driver28mm microfibre dome
Mid/bass driver200mm woven polypropylene cone
Sensitivity (2.83V @ 1m)90dB
Impedance8 ohms nominal; 4.2 ohms minimum
Speaker Gross33kg (Master carton/pair)
Speaker Net10kg (Each)

Recommended amp power30 – 150W
Frequency response (+/-3dB)52Hz – 22kHz
Bass Extension (-6dB)39Hz
Crossover frequency2.1kHz
Cabinet volume26L
Cabinet dimensions (HxWxD)470 x 280 x 310mm
Stand Gross 10.5kg (Master carton/pair)
Stand Net4.4kg (Each)