Making Bowers & Wilkins 800 D4

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Making Bowers & Wilkins 800 D4

Bowers & Wilkins’ Worthing factory produces 6,500 pairs of 800 series loudspeakers every year, a figure that likely exceeds any other range of high end loudspeakers. So once they have production up and running they don’t rush into changing the model range until significant improvements have been made across the board. But this year after a longer interval than usual (six rather than five years) they have introduced the fourth generation of Nautilus derived 800 series loudspeakers or D4 as they are known. When this range went from from D2 to D3 the cabinets on the larger models were dramatically changed by reversing the wrap of laminated wood from a flat front to a curved one, this time around this approach has also been applied to the smaller members of this select group. Look a bit closer, and look inside as well and you will see many that things are different across the range.

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Getting back to the factory the first stage of production is cabinet building, here they use sustainably sourced Northern European veneers to build up the plys for each ‘box’. The smaller models have 12 layers and the largest 18 with either book matched veneers on the outside or white paper for models that get a paint finish. The cabinets are built up using dry contact glue sheets between each veneers and these are cured at 140 degrees in huge forming presses to create the bent wood shape. One of the more obvious changes for D4 is the use of an aluminium top plate between the Nautilus Head and the main body of the cabinet, this replaces machined wood and is said to offer greater rigidity. It also needs finishing and Bowers have chosen Connolly leather for this application, a material that looks nearly as good as it smells.

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The majority of cabinet finishing is done by robot sanding machines that have force sensors which detect the apertures in the box in order not to round off the edges where the drivers come through. For the paint finished models there is a large automated spray painting booth and a track that carries a line of cabinets along, here another robot dressed in appropriate garb to keep its self clean, applies four coats of black or white paint prior to another stage of finishing before giving them another four coats. Thereafter the cabinets are cured in a large oven before being polished with the final finishing stage done by hand.

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Solid Body tweeter housings, new version on left and original on right

The tweeter housing for the new series is now 30cm long, notably longer than its predecessor and twice the weight, this gives the machined aluminium greater stiffness and allows for a two point flexible coupling to the Turbine Head that supports it. The latest 800 series continues to use a diamond dome tweeter which is created by literally growing synthetic diamond onto a substrate to create a 40 micron dome. What has changed are some details of the magnet structure behind it, something that will be investigated when a pair of speakers turn up for review. 

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Bowers have made up crossover templates for each of the 800 series models, these show assemblers not only the layout of each component on the panel but also the orientation too. You may notice the huge capacitors on the new 801, one of many special elements found in the range topping model. Now that the smaller 800s have the reverse wrap cabinet introduced in the bigger models they all have aluminium backs which provide structure and heat sinking for the crossover as well as plenty of space for component layout.

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801 cabinets with internal metal bracing

The 800 D4 midrange driver retains the woven fabric Continuum cone and the bass drivers still have their ‘aerofoil’ variable profile cones with syntactic foam damping. Unlike the more affordable Bowers loudspeakers these models and their drivers are made in Worthing. They also continue to make the rather original Nautilus model at the factory albeit to order with a 20 week lead time.

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The Turbine Head remains a bulbous lump of machined aluminium but now has tuned mass damping on the internal fins to minimise vibration. Likewise the base of the 801 uses constrained layer damping with Tecsound ‘goop’ to do a similar job, all of the floor standing bases are now aluminium with mountings for substantial M12 spikes and four wheels to aid manoeuvring. The 801 also gains a silver shorting ring in place of copper on the midrange driver as well as more metal parts in the matrix bracing within the cabinet, all of the models benefit from this to an extent but the top dog gets more including bracing around its reflex port.

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Possibly the most radical change on these speakers is the change of spider on the midrange drivers. This is a device that keeps the voice coil former in the centre of the magnet and has traditionally been made of corrugated and doped fabric. Bowers have come up with a plastic replacement that is made up of six tapering legs and looks so simple you wonder why no one thought of it before. Probably a materials thing but possibly because the standard option wasn’t actually broken. They claim that the spider is 80dB quieter at 1kHz, which sounds like a lot but presumably conventional spiders don’t make that much noise in the first place. Nonetheless if there are no drawbacks with this idea if could be a winner. More importantly it’s relatively inexpensive so will be rolled out to the company’s more affordable three-way models in future. A smaller change is the introduction of a foam phase plug (replacing paper), this is light enough for the job but offers better bracing for the voice coil.

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The facility that Bowers & Wilkins have at Worthing is very impressive and undoubtedly the largest in the country, it allows the company to achieve very high standards of fit and finish at prices that are far from excessive by high end standards. Personally I can’t wait to hear what they have achieved with the new models, the last range was extremely good to begin with.

Jason Kennedy