BOWERS & WILKINS 800 Diamond

The key word for designing the cabinets of the Diamond series was stiffness. The cabinets are not simple boxes - rather they employ a curvaceous shape that provides a sufficiently dead structure with no internal modes at manageable costs. The inertness of the cabinets is further enhanced by using 36mm thick panels and proprietary Matrix bracing. Bowers & Wilkins achieved great rigidity plus great mass that, combined with the damping properties of wood, resulted into a structure that exhibits better properties than an aluminum one. By the Matrix system the already minimum cabinet resonances have been further reduced by 45dB to the silence I described earlier.

The leading edge of the 800 Diamond series is the 26mm diamond dome tweeter confined within its tapered tube. With the diamond tweeters Bowers & Wilkins managed to virtually eliminate the break-up mode by moving it to 80kHz. The issue with the mass of the dome was ameliorated by making the dome only 40 micrometers thin, which was made possible by the vapor depositing technique.

The tweeter is encased in an exponentially tapered tube and it is attached through a hole in its pole to a tube that vents to the rear of the enclosure. This allows the sound energy, radiating from the rear of the dome, pass through the pole piece and disappear without reflecting back. A secondary use for the tube is as a heat sink – B&W claims that the tweeter is capable of withstanding unclipped high frequency peaks from an amplifier rated up to 1 kilowatt with its distortion staying under 0.4% in the critical range.

Furthermore, as the tweeter’s diaphragm moves only by a maximum of 0.5mm it was necessary to isolate it from mechanical energy arising elsewhere in the system. That is why a special elastomer was employed to hold the tweeter and tube in the housing. The whole assembly is then decoupled from the midrange unit by two gel pads to float it free and inhibit any external interference.