Bowers & Wilkins Diamond Series 804 D4 loudspeaker
The boxes sit there in our storage unit, opposite the 20 banker’s boxes that hold 33 years’ worth of product-measurement workbooks. The two large boxes are for the Bowers & Wilkins Matrix 801s my wife owned when we got married in 1987 (footnote 1). The four smaller boxes are for the B&W John Bowers Silver Signatures and their stands, which I purchased after reviewing them in June 1994. Both pairs of speakers gave superb sound quality back in the day, but now they sit there in the storage unit, their boxes giving me recriminatory looks when I visit.
Stereophile has reviewed many Bowers & Wilkins speakers since the first, the “pregnant kangaroo” DM6, in December 1977. The most recent was the 705 Signature standmount, which I wrote about in December 2020. I concluded my review of the 705 Signature, which costs $4000/pair, by writing that “this elegant loudspeaker stepped out of the way of the music in a very satisfying maner.” So, last summer, after I watched a video presentation of Bowers & Wilkins’s new Diamond Series 800 D4 series loudspeakers, I asked for review samples of the 804 D4 floorstander, which costs $12,500/pair.
The 804 D4
The D4 800-series loudspeakers are mostly similar to the D3 models (footnote 2), but they incorporate a few revised and upgraded design features. The 804 D4 differs most from its predecessor in that it features what the manufacturer calls the “reverse-wrap cabinet” that had been used for the larger floorstanding 800 series models. The elliptical-plan enclosure has a flat back faced with a vertically ribbed aluminum panel, while the front baffle is gently curved to optimize dispersion. The midrange unit and twin woofers are housed in circular aluminum pods mounted to the baffle. The enclosure has a cast aluminum top panel, covered with a padded material, and the internal Matrix bracing now uses panels made from solid plywood rather than the previous MDF, these reinforced with aluminum bracing.
The 1″ tweeter, which uses a vapor-deposited diamond diaphragm, is mounted at the front of a 12″-long tapered tube machined from a solid aluminum billet. This sits on the top of the enclosure with two compliant mounts. The tweeter’s motor has a vented pole-piece so that the back wave can be absorbed within the tube. (I couldn’t detect any output from the end of the tube.) B&W says that “the tweeter’s motor assembly has been re-engineered to allow the drive unit to ‘breathe’ more effectively with no loss of performance. The result is a notable reduction in the resonant frequency behind the tweeter dome.”
The 5″ midrange unit uses a cone formed from Bowers & Wilkins’s now-familiar silver-colored, woven Continuum material. This material is said to be very light and stiff, with very high self-damping. As with earlier generations of this driver, it dispenses with a conventional surround in favor of what B&W calls its Fixed Suspension Transducer (FST) technology. Instead of the conventional fabric “spider” that keeps the voice-coil centered within the motor, the D4 series’ midrange driver features a “composite Biomimetic Suspension” system that presents lower air resistance to the rear of the drive unit’s diaphragm. The result, according to B&W, is “unprecedented midrange transparency and realism.”
The two 6.5″ woofers use the manufacturer’s Aerofoil cones, which have a low-mass “syntactic foam” core, with a carbon-fiber skin that varies in thickness from a minimum around the central voice-coil, increasing as the radius increases then thinning again as it approaches the surround. This topology is said to maximize stiffness without adding mass. The D4 speakers add a new foam Anti-Resonance Plug, which B&W claims “gently braces the voice coil and lowers distortion as the cone moves through its operating range, ensuring even cleaner bass.”
The woofers are reflex-loaded with a flared “Flowport,” which has small dimples in its surface to reduce turbulent air noise. While the 804 D3’s port was on the front baffle, the D4’s port fires downward into the 1″-high airspace between the enclosure and the cast aluminum base; the enclosure is supported on four short legs. On the base, a constrained-layer steel damping sheet is said to control resonances. The speakers arrive with rubber-tipped feet, which can be replaced with heavy-duty carpet-piercing spikes that are included in the accessories box.
Crossover details are not available. Electrical connection is via two pairs of high-quality binding posts at the bottom of the rear plate. Supplied jumper cables allow for single-wiring.
Optimizing the positions of the 804 D4s proved to be a little more difficult than I was expecting from my experience with the 705 Signatures. With the speakers as close to the wall behind them as I could manage with the short flight of stairs to the vestibule behind the right speaker, this gave the best transition between the lower midrange and upper bass, but the lowest-frequency room mode was excited too much. I moved each speaker forward so that the mode was lower in level, but now the upper bass was too quiet.
I ended up with the 804 D4s close to where the PSB Synchrony T600s that I reviewed in the November 2021 issue worked best: each front baffle 131″ from the listening position and 81″ from the front wall. The woofers of the left 804 D4 were 36″ from the LPs that line the nearest sidewall; the right-hand speaker’s woofers were 54″ from the sidewall behind the bookshelves that line it. When I sit in my listening chair, my ears are 36″ from the floor, level with the 804 D4’s midrange unit. The speakers were toed-in to face the listening position. Once I had decided on their final positions, I replaced the rubber-tipped feet with the spikes. I didn’t use the magnetically attached grilles.
Footnote 1: You can find my measurements of this pair of Matrix 801s here.
Footnote 2: Kal Rubinson reviewed the D3-series 802 loudspeaker in June 2016.
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B&W Group Ltd.
US distributor: Bowers & Wilkins
5541 Fermi Ct.
Carlsbad, CA 92008
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