Bowers & Wilkins
800 Series Head Assembly
Bowers & Wilkins 800
Matrix Cabinet Assembly
800 Series Head
800 Series Head Detail
800 Series Tweeter Assembly
800 Series Head Assembly
600 Series Tweeter Assembly
Bowers & Wilkins 801
Bowers & Wilkins 801 - Abbey Road
Bowers & Wilkins 800 Series Range
800 Series Head
In my role as Applied Research Engineer, I developed and translated innovative research ideas to real-world prototypes that provided proof of concept for product development.
Bowers & Wilkins has long been regarded as pioneers of the art of speaker design. The research and development lab in Steyning, West Sussex is commonly known as the ‘University of Sound’. It was the first self-contained facility in the world dedicated exclusively to analysing the reproduction of sound.
The Nautilus was the end result of an ambitious R&D project that B&W had ever undertaken. The brief was to do whatever was necessary to make the best loudspeaker anyone had ever heard. Every pre-conceived notion of what a speaker should be was challenged during a five year development programme. The technology inherent to the Nautilus naturally trickled down into the highly-regarded Nautilus 800 Series which was, in its own right, four years in the making.
800 Series Tweeter
The tube-loaded tweeter conceived and developed for the Nautilus 800 Series was a development inspired by the Nautilus technology. The sound that emerges from the rear of a drive unit, into a conventional box cabinet, reflects around the enclosure and causes distortion in the sound radiating from the front. To combat this, tapering tubes filled with absorbent wadding were used to absorb the rearward sound energy and reduced resonances to an insignificant minimum.
The tweeter motor system needed to be physically as small as possible to maintain the small frontal area essential for avoiding diffraction problems. In addition, maximum sensitivity was required to maximise the output capability. The pole piece was bored to allow the radiation from the rear of the diaphragm to travel through to the tapered tube attached to the rear of the pole piece seamlessly. It was also profiled at the tip, following the radius of the dome diaphragm, to prevent unwanted resonances occurring behind the dome.
Copper clad aluminium ribbon wire was employed for the voice coil. Aluminium has a lower density than copper which reduces the moving mass. The ribbon wire (which is rectangular in cross-section) is used to eliminate all air gaps that are a consequence of using round section wire. This ideal packing factor maximises the volume of conductor present in the magnetic gap and significantly raises the sensitivity.
800 Series Midrange
The midrange drive unit diaphragm is manufactured from Kevlar®. B&W developed a closely-guarded recipe for the resin mixture that enhances the material’s strength and flexibility to lower distortion and improve the impulse response.
The conventional roll surround was improved by means of ‘surroundless’ suspension. A foamed material ring, with resistive mechanical impedance identical to that at the edge of the cone, was placed under the cone’s edge. Bending waves travelling up the cone are almost totally absorbed by the foam ring.
The chassis of the FST™ driver is designed to minimise any impedance to the flow of air from the rear of the driver. To reduce reflection boundaries immediately behind the cone, an FEA optimised neodymium magnet assembly was designed.
800 Series Bass
The woofer cone diaphragms were developed using a low density Kapok/Kevlar cone pulp with a very high stiffness / mass ratio. The overall structure is effectively a thick laminate, with a very high resistance to the static bending stresses caused by cabinet pressure.
The voice coils were lengthened and the magnet motor systems were optimised using finite element analysis for even greater linearity and a double, mirrored spider construction was employed to ensure that axial piston motion was maintained at all levels.
The voice coil former sleeve was manufactured from incredibly stiff filament wound carbon fibre and was elongated to create a physical joint with the carbon fibre dustcap as well as being attached conventionally to the cone.
800 Series Cabinet
The tapered tube loading of the bass system used in the Nautilus could not be realised in the 800 Series due to cost implications. Increasing the panel thickness and curving the rear surface creates increased enclosure stiffness and provides an interior shape which has fewer internal acoustic resonance modes. To realise this curvature, thin wood laminations are bent around a former under heat and pressure. Adding the internal Matrix™ system that braces the structure like the ribs of a ship’s hull, creates a stiff, yet well damped, enclosure.