May / June 2005
Until it was spelt out by the powers I don't think I fully realized how strong Bowers & Wilkins' (B&W) domination of the high end of the loudspeaker has become. Of course there are other brands and many of other individual high-end models out there, but B&W's share of the market with its extensive 800 series is enormous, and this means that uniquely among high end producers, B&W is able to benefit from the economies of scale in a way that is the envy of other producers. Just as an indication of what this can mean in practice. I have here a pair of large, well built loudspeakers with sapphire tweeter domes, which currently cost UK sterling £32,000 a pair. Shortly after they arrived, I received the review sample of the Bowers & Wilkins 800D which has an even more exotic dome, which in every meaningful respect is more elaborately specified and built, which has a wider operating bandwidth — and which costs £13,000 a pair. Even allowing for all the other uncontrolled variables this is a massively different proposition. I don't believe there is another manufacturer with the credibility and power of the B&W name behind it that could offer a similar speaker for this kind of money, and this surely is mainly because of the number that B&W can shift.
The subject of this review is the 800D, the innocuously designated successor to the Nautilus 800 — but oh what a difference a letter makes. The original Nautilus 800 was not quite the flagship, but it quickly established itself as the de facto range header as the bigger and costlier 801 was all but unusable in normal surroundings, its bass always sounding unwieldy and slow to these ears. Both the 800 and the 801 have been directly replaced with similarly designated models with a D suffix as part of a new, expanded 800 series, but the B&W website asserts that the bigger model has a bass alignment suited to rooms with a 'more controlled acoustic'. In other words, the 800D continues to reign supreme for ordinary super rich mortals.
B&W however appears to have leapfrogged the opposition with its diamond dome. Diamond is the hardest of all elements, which allows fabrication of very thin, light and stiff structures that delay the first HF break up resonance to a very high frequency. Most alloy domes have a first HF resonance around or a little above 20kHz, and the best of breed alloy or titanium domes come in around 27kHz. The predecessor of the B&W diamond dome fell into this latter category. The CVD diamond dome from B&W by contrast has a first HF resonance around 74kHz, and the resonance is very well damped, as I have seen for myself on a test jig at B&W HQ in Steyning, UK.
The obvious question to ask at this point is — so what? Who other than the odd passing bat is going to care about a clean frequency response that extends three times further than the limit of human hearing? The answer is that the frequency response is a great strapline for a technology story, but it really isn't the most important factor. Because the first resonance is no high, it turns out to be very well damped, and there is very little phase distortion (group delay) in the treble, or even considerably above the audio band. The absence of group delay extends through the audible treble as well, where the high Q out of band resonances of lesser tweeters generates in band group delay (i.e. phase distortion).
Perhaps more important still is that the behavior of the dome has allowed B&W's engineers to redesign the dome's suspension. The older models used a flat cellular material, where the new tweeter has a synthetic rubber half roll surround. This in turn has improved the tweeters' low frequency behavior which has allowed the use of a simpler lower order high pass filter, which was a specific design aim. A single layer voice coil has a silver plated centre pole (improving sensitivity) which acts as a shorted turn, reducing the inductance of the primary winding. In the original Nautilus 800, the tweeter was housed in a molded tapered tube behind the dome which absorbs much of the acoustic output from the back of the dome. In the 800D the same basic idea is followed, but the tube is now a substantial die-casting, and it sits a little closer to the midrange unit, and slightly further forward thanks to the changed phase relationships in the revised crossover.
The rest of the speaker will look similar to the original Nautilus 800 to practiced B&W watchers, but in this cases appearances deceive. One important change is to the twin bass drivers, which steal a leaf from the Focal.JMlab design book by using a newly designed acoustically relatively opaque cone material consisting of a layers of woven carbon fibre sandwiching an 8mm thick aerospace expanded structural foam core made from a material called Rohacell. The material is different from the Focal W-cone material, but the idea is the same: to help block reflected energy from inside the enclosure making its way to the outside world. This new cone replaces a thin Kevlar/pulp cone.
The original woven surroundless Kevlar cone housed in its round Marlan enclosure has changed little, but even here there have been improvements behind the scenes, for example a new strengthened basket structure. B&W has also tinkered with the compliances of the decoupling used between the main carcass and the midrange enclosure, and between the latter and the tweeter assembly.
Otherwise all is much as before. The crossover network is housed in the base and so is not subject to significant electromagnetic coupling to the enormous magnet systems, but B&W has not taken the opportunity to remodel the rather harsh looking box shaped plinth, which has been redesigned very effectively in the 801D. The main enclosure is still built as a continuous curved ply structure with an internal Matrix reinforcement, producing a structure of enormous strength, with a down firing port using B&W's favored Flowport tapered construction with golf ball dimples to reduce wind noise.
The statistics are as awesome as ever. This is a loudspeaker that tips the scales at 275 lbs apiece (or 125kg as we prefer in the UK), and the 800D is extremely big, though not especially tall at 46.5 inches plus a little for the redesigned feet, which have soft and spiky sides. From the electrical viewpoint, sensitivity is fairly high (90dB/W/m), but although the nominal 8 Ohm impedance is benign, the 3.1 Ohm impedance over much of the most power hungry part of the band makes this a challenging speaker to drive, though most high grade amplifiers will be able to cope without problems. Still, and taking account the 800D's prodigious power handling capacity, this is a speaker that is best coupled with solid state amplification rather than the tube powered type, which may well be able to match the B&W's qualitative requirements, but which will inevitably limit its dynamic capabilities, and which is unlikely to deliver the requisite grip and authority.
Setup is not inordinately complicated, though you'll find you don't need enormous amounts of room. My own 3.5 m x 9 listening room did nothing to cramp the 800D's style. The bass was clean and extended, the mid open and airy, and the whole system snapped into focus at a listening range of 2.5 to 3 meters, which meant sitting well away from the back wall. Leave a couple of feet behind the speakers to ensure the best bass/mid balance, and a clean, open and airy balance. Orientation is easily arranged. The tweeters should be pointed at, or just behind the ears with a degree of precision that is necessary because the dispersion of the tweeter is very narrow near its upper frequency limit. The speaker can be tilted if necessary by adjusting the feet.
The original Nautilus 800 was always a formidable beast, but it was not without its detractors. The main area of criticism was the overall balance, which tended to be on the lean side of neutral. The Nautilus 800 was not going to boom in normal situations — or even abnormal ones — and bass extension was not lacking. But the sense of weight and of power was not always there. This has been put right in the new model. Indeed B&W claims that the balance of the whole range is more consistent model to model, which was an acknowledged weakness of the original Nautilus 800 series. The new 800D is devastatingly powerful, with a truly muscular, physical bass, but with no hint of excess or of overhang in my listening room, even though it is on the smaller side of ideal for any speaker this big. The B&W newcomer is also surprisingly delicate in its responses to changing musical soundscapes, and the sense of a loudspeaker that knows about timing was very strong.
Timing however is one of those qualities of a loudspeaker, or a system as a whole, that is most difficult to pin down. Although it appears to be a quality mostly associated with bass instruments, it is utterly dependent on how the mid and upper harmonics of bass notes are reproduced, and these harmonics typically extend right through the midband and deep into the treble. And this is where the 800D comes up trumps. Perhaps it is the sweetness and open quality of the treble, or its unexaggerated feel. Perhaps it is the unusually homogenous integration between the various drive units, or perhaps it is the lack of group delay, which after all is a property intimately associated with phase and therefore timing. Whatever the cause in the improvement over the previous models, which could occasionally sound a little wooden and pedestrian, was hard to ignore. Orchestral textures reproduce with more of a propulsive quality, more bounce and vitality when required, more gravitas, grip and a firmer sense of texture otherwise. Objectively the change is not big, but the musical effect is little short of profound.
You will not be too surprised to hear that the treble itself has improved, but in some ways the upper frequency region of the 800D is surprisingly understated, probably precisely because it behaves so well. Tonally it is neutral, the most neutral I have ever heard from a B&W speaker, and at least on a par with the best I have heard from Focal.JMlab's beryllium dome, or the best electrostatics for that matter. The 800D's resolving power is nothing less than sensational, but the tweeter goes about its business in a completely transparent way. There is no hint of aggression, nothing sharp or edgy, but no level of fine detail is too subtle to be reproduced with clarity. Nothing passes the diamond tweeter by, and this also includes the contribution that it makes to the reproduction of ambience and 'air'. Yet there is nothing intrusive about the way that the high frequency content of program material comes across.
The one area of the speaker that has changed least, and which arguably should be first up for consideration when he next revision falls due, is the midband, the domain of the Kevlar FST (fixed suspension) driver which continues little changed from Nautilus 800 days. To these ears it is improved, presumably thanks to the cleaner bass, the revised crossover to the tweeter, and the tweeter itself that is responsible for reproducing the harmonics of frequency fundamentals. The whole effect is cleaned up, more architectural, and carries with it greater impression of image depth. But there is still a hint of a quality that was also apparent with the Nautilus 800, namely a slight unevenness, a suggestion of coloration that changes as the pitch of the music changes. There is a hint of boxiness in the midband, and of a loss of image depth and differentiation, albeit very minor.
The reasons for these observations are open to conjecture, but one obvious possibility is that it is rooted in the way the woven Kevlar diaphragm works. Intentionally, the design behaves asymmetrically on different axis, the idea being for different regions of the outer part of the cone to work in anti-phase at high frequencies, so that the effective radiating area of the cone reduces at the frequency being looked at rises. This is how the designer has been able to use such a large drive unit: in fact it is only acoustically large at the lower part of it's passband, and it effectively shrinks at higher frequencies. But this process is probably not perfectly linear, indeed B&W acknowledges that the FST drivers is operating in its break up region for part of the time. This could be the source of some colorations, but they are mild, and perhaps only noticeable at all in the light of the extremely fine performance of the system out towards the frequency extremes.
Drivers: Two 250mm Rohacell cone bass units, one 150mm woven Kevlar cone FST midrange unit, one 25mm CVD diamond dome tweeter
Frequency Response: 25Hz to 33kHz (-6dB)
Minimum Impedance: 8 Ohms nominal (3.1 Ohms minimum)
Crossover Frequencies: 350Hz and 4kHz
Power Handling: 50 to 1000 Watt
Cabinet Finishes: Cherrywood, Rosenut or Black Ash real wood veneers. Black cloth grill
Accessories: Four spikes and soft feet included
Dimensions: 1180 x 450 x 645 (WxDxH in mm)
Weight: 125 kg each