Castle brings high-end speakers back to the UK with Windsor Earl and Duke models

Classic British Hi-Fi brand Castle has brought loudspeaker manufacturing back to the UK for the new Windsor Earl and Windsor Duke (pictured), which boast premium wood-veneered cabinets and audiophile grade components.

The Windsor Earl is the smaller of the two new models, measuring 43x24x26cm, while the Windsor Duke is a more expansive 47x28x31cm.

The Windsor Series has been designed by speaker pioneer Karl-Heinz Fink and his team. Fink is responsible for the Diamond 12 Series from Castle’s sister-brand Wharfedale.

Every critical part of the two Windsor models has been developed and manufactured in-house, from the drive units to the cabinet to the crossover network.

Both the Windsor Earl and the Windsor Duke feature mid/bass cones made from a complex polypropylene material. The material is created by precision-cutting polypropylene into thin strips, weaving them into a fabric and bonding them together again to form a solid foil.

This novel material has different properties of rigidity in different directions, minimising resonances and producing a flatter response curve, which is desirable for high-performance audio. The cones have surrounds made from low-hysteresis rubber that we’re told will not deteriorate over time, and voice coils made from glass fibre bonded with high-temperature resin to maintain signal purity. The Windsor Earl cone has a diameter of 165mm while the Windsor Duke cone has a diameter of 200mm.

While loudspeaker enclosures are still manufactured in accordance with the BBC's findings from half a century ago, it is still a complicated process to ensure that a speaker's enclosure is ideally matched with the mounted drive units.

The new Castle Windsor models use a new methodology to optimise their cabinets, with the main structure using dual-layer MDF panels separated by a flexible layer of specially engineered acoustic glue. Point-to-point bracing is applied to achieve optimum rigidity at lower frequencies, resulting in a ‘quiet’ cabinet without prominent peaks, delivering a controlled output.

The speakers use a 4th order LKR (Linkwitz-Riley) crossover that integrates the purpose-designed drive units. The crossover was developed using advanced computer modelling and listening tests to achieve a flat response, an easy load for amplifiers, and a low distortion measurement, says Castle.

All critical inductors in the crossover design are of the 'air core' type, which prevents hysteresis or distortion through the network. The main inductor resistance is compensated in the mid/bass driver's magnet system, so there is no disadvantage from the slightly higher resistance of this air coil.

Cabinets are available in a choice of high-quality walnut or mahogany veneers sourced from sustainable timbers; only deep-figured slices are used, cut from real trees rather than reconstituted material. Each pair of speakers is hand-finished with mirrored, book matched veneers, sealed and waxed in a process that takes several days.

The Castle Windsor Earl and Windsor Duke loudspeakers retail for £3,850 and £4,500 per pair respectively. They can also be purchased with a pair of dedicated, open-frame stands, tailor-made for optimal positioning and performance; these stands add £400 to the price of the Earl, and £500 to the price of the Duke.