THE NEW CASTLE WINDSOR SERIES LOUDSPEAKERS COMPRISE OF THE CASTLE WINDSOR EARL AND CASTLE WINDSOR DUKE

Classic British loudspeaker brand Castle Acoustics brings manufacturing back to the UK for the new Windsor Earl and Windsor Duke.

Since its formation 50 years ago, Castle Acoustics has been known for the quality of its hand-crafted cabinets and the ability to make the key components in-house rather than buying off the shelf.

Castle Windsor Duke in Mahogany

CASTLE ACOUSTICS

Castle’s current range includes various speakers, including the latest versions of the classic Richmond and Avon models, but there hasn’t been an all-new Castle range since the Knights in 2010.

Castle Windsor Earl

CASTLE WINDSOR SERIES

Now, Castle is ready to launch two entirely new standmount speakers, the Windsor Earl and Windsor Duke, which together form the Windsor Series. Their veneered, classically proportioned cabinets evoke the golden age of HiFi.

Castle Windsor Duke front and back

In keeping with Castle tradition, 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. In addition, these are the first Castle speakers for many years to be not only designed but also made in the UK.

The Castle Windsor Earl is the smaller of the two models, measuring 43x24x26cm (HxWxD), while the Windsor Duke expands the cabinet in all directions to 47x28x31cm.

Castle Windsor Earl front and back

KARL-HEINZ FINK

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, both for his own brands, FinkTeam and Epos and for the other brands including right up to the current, Diamond 12 Series from Castle’s sister-brand Wharfedale. 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.

Castle Windsor Earl on stands

Fink has always been a keen admirer of Castle speakers, in fact, he has worked with the brand before, having designed the Castle Richmond 3i in the early 2000s. Almost 20 years later, the chance to work with Castle’s in-house team to develop two new speakers was an opportunity he seized with alacrity.

Castle Windsor Duke on stands

CASTLE WINDSOR SERIES MID/BASS DRIVER

Both Castle Windsor models feature mid/bass cones made from a polypropylene-based material. However, instead of being produced by simply forming a foil under a vacuum, the polypropylene is precision-cut into thin strips, woven back into a sort of fabric, and bonded together again to form a solid foil. This foil is pressed into the final shape and cut to size. The process creates a material with different properties of rigidity, at different directions between the voice coil and the surround.

Castle Windsor bass driver

The resulting cones, with diameters of 165mm in the Windsor Earl and 200m in the Windsor Duke, feature surrounds fashioned from low-hysteresis rubber which will not deteriorate over time. 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.

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.

CASTLE WINDSOR SERIES TREBLE UNIT

The high-frequency unit used in both Windsor models follows the classic formula of a high-consistency exposed polyester dome, with a pressure-equalised ferrite magnet system and a metal front plate. No ferrofluid is used in the tweeter; 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.

Castle Windsor treble

CASTLE WINDSOR SERIES CABINET ENGINEERING

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. 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.

Castle Windsor Duke cabinets

The main cabinet structure uses dual-layer MDF panels separated by a flexible, but thin, layer of specially engineered acoustic glue. This glue has been specially developed to dampen resonance in the critical midrange frequency region. 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 which is a cornerstone of the Castle brand philosophy.

CASTLE WINDSOR SERIES CROSSOVER NETWORK

Both Windsor models utilise a 4th order LKR (Linkwitz-Riley) crossover that allows the best integration of the purpose-designed drive units. Developed using a combination of advanced computer modelling and many hours of listening tests, the core aims were to achieve a flat response, an easy load for amplifiers and a low distortion measurement. All critical inductors in the crossover design are of the ‘air core’ type – this means there are no metal cores present in the circuit, preventing 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.

WOOD-VENEER FINISH

Castle has long been known for the craftsmanship evident in its wood-veneered loudspeaker cabinets and the new Windsor Series is no exception. Their cabinets sport 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 mush. Each pair of speakers is hand-finished with mirrored, book matched veneers, sealed and waxed in a process that takes several days.

Rear of the Castle Windsor Duke

MADE IN THE UK

Like most British audio brands, manufacturing of Castle speakers moved to East Asia some two decades ago to maintain retail prices at the level the market demanded, while design functions such as R&D and industrial design remained in the UK.

Last year, Castle’s parent company IAG unveiled a new ‘Made in the UK’ initiative to enable the manufacturing of specific products to be brought back to the UK without skyrocketing costs. IAG has expanded its facilities at its base in Huntingdon, Cambridgeshire, incorporating key manufacturing, assembly and finishing processes for specially selected products in addition to the R&D function already located there. A 9,000ft2 production facility has been added to the existing building, including a new anechoic chamber, making a total of 25,000ft2 of office, lab and manufacturing space. The Windsor Earl and Windsor Duke are the latest models to benefit from this new facility, following the entirely re-engineered new versions of classic speakers from Castle’s sister-brands Mission and Wharfedale, the Mission 770 and just-launched Wharfedale Dovedale. These are the first speakers from Castle, Mission and Wharfedale to be officially ‘Made in Britain’ for many years.

CASTLE WINDSOR EARL SPECIFICATIONS

Speaker type Two-way standmount

Enclosure type Bass reflex, rear ported

Treble driver 28mm microfibre dome

Mid/bass driver 165mm woven polypropylene cone

Sensitivity (2.8V @ 1m) 89dB

Impedance 8 ohms nominal; 4.3 ohms minimum

Recommended amp power 25-100W

Frequency response (+/-3dB) 58Hz-22kHz

Bass extension (-6dB) 45Hz

Crossover frequency 2.2kHz

Cabinet volume 15.8L

Cabinet dimensions (HxWxD) 430x240x260mm

CASTLE WINDSOR DUKE SPECIFICATIONS

Speaker type Two-way standmount

Enclosure type Bass reflex, rear ported

Treble driver 28mm microfibre dome

Mid/bass driver 200mm woven polypropylene cone

Sensitivity (2.8V @ 1m) 90dB

Impedance 8 ohms nominal; 4.2 ohms minimum

Recommended amp power 30-150W

Frequency response (+/-3dB) 52Hz-22kHz

Bass extension (-6dB)  39Hz

Crossover frequency 2.1kHz

Cabinet volume 26L

Cabinet dimensions (HxWxD) 470x280x310mm

CASTLE WINDSOR SERIES PRICE AND AVAILABILITY

The Castle Windsor Earl and Windsor Duke loudspeakers are available from April at RRPs of £3,850 and £4,500 per pair respectively, in a choice of walnut or mahogany real-wood veneers. Both models 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

HiFi Pig Says: Karl-Heinz Fink knows how to make loudspeakers, we look forward to hearing his latest creation.