B&W DM110 and DM220 loudspeakers

It is always an intriguing and usually a pleasurable business to investigate new loudspeakers from B&W. I say usually' because, if once in a while we have not met ear to ear on a new model, such intransigence on my part has always been met with the utmost courtesy and always overridden by our mutual respect for the end result, music. In the case of these two recent arrivals, DM110 and DM220, no divergence of opinion arises. DM110 is a two-unit reflex design, with a 200mm bass/midrange crossing over to a 26mm tweeter at 24kHz; DM220 has an additional bass unit brought in below 300Hz, and uses a sealed enclosure of considerably increased volume. Both have been conceived bearing in mind the more stringent requirements of Compact Disc reproduction and that of other digital source material; both too are admirable examples of the advances in performance which modern technology allied to skilled brains can bring to modestly priced products. And it is this facet which provides the intrigue in this instance—but lam rushing ahead.

One sunny day last March 1 had responded to John Bowers's invitation to visit his (then still incomplete) new Research and Development Laboratories at Steyning in Sussex. This enterprise, which must have cost the company a mint of money, had enabled him to put a few miles between his research team and the inevitable but distracting day-to-day queries arising at the Worthing factories, and at the same time release space there for an increase in production. Perhaps one day our space will permit a full description of this research facility, but on this occasion a brief look round settled into a long session in the new listening room, where we first sampled some very experimental items which may reach the market one day. After a break for lunch, the early prototypes of DM 110 and 220 came out and, although there have been a few changes since (I was there as a guinea pig you will comprehend), they were as impressive then as I find them now. Really and truly, so many of today's modestly-priced loudspeakers now sound so good that tomorrow's expensive ones are going to have to face up to that boastful challenge, "Follow that!"

The B&W team's approach to the triangular equation—cost, appearance, performance-.-turned out to be an interesting one, starting with an evaluation of the effectiveness of every single item involved, both parts and labour. To me, an outside observer but privileged to know the formulae adopted by several of B&W's competitors, I found their solutions refreshing. For example, I know of no one else's economy models which can boast a bass/midrange unit manufactured within the strong foundation of a complex zinc alloy diecasting. Where some others use plastic trims to impress the ignorant, but in truth to hide their skimpy pressed steel basket, B&W's hefty frame, firmly held on to a sealing gasket on the front face of the cabinet by six very substantial screws, represents added strength at that weak point which often encourages colouring vibrations to occur in lesser designs. The initial tooling investment for this item alone is high but, by dimensional planning so that the cost can be shared around a number of models, by designing for automated assembly so that the frame's essential accuracy is its own jig, by making the cosmetic trim also seal the cone surround, plus a few other tricks, the overall values change.

Lightweight paper cones are used to lift sensitivity in the type BZ200 bass/midrange units, coated in the case of the DM220. The shape is unusally fiat, with a very long paper-on-aluminium voice-coil former wound with high temperature wire. The tweeter too is a new B&W model, designated TZ26, and is an edge-driven dome formed in a soft plastics material. Crossovers are simple and orthodox but the effective rate of their slope is as much due to the mechanical design of the units as to the electrical constants. In both cases, the networks are bolted to the extension of the terminals (4mm sockets and screw) recessed in a panel at the rear. Cabinets are formed of 15mm particle board with vinyl imitation wood veneers in simulated American walnut or black ash. Front and rear are brown or grey vinyl, and the units are finished in brown with dark red trim or black with blue trim, Particle board frames covered with brown or black stretch-fabric are retained by a trio of pegs.

In any design of the type we are considering, a proportion of the overall sound emanates from the cabinet walls and its control and contribution are major factors in the overall success of the final product. Therefore the skills of the design team are at full stretch when they know that a substantial part of the overall cost rests in the box. It is interesting to see the tricks used, both to keep this cost in bounds and to harness the structural materials most effectively. In both boxes the rear cabinet wall is recessed, glued and locked in grooves machined in all four sides, a fundamentally stronger and more linear method than the normal rebate. In the DM110 reflex cabinet, foam plastics lining is used on all internal surfaces but, by gluing it in place, a 'lossy' bond is formed with the walls dissipating stored energy. The reflex port is placed immediately below the bass unit and takes the form of a 50mm diameter pipe 70mm long. The DM220 sealed enclosure is not lined, but is heavily damped by a filling of synthetic wool wadding. Of course both models benefit from the strong frames of the bass unit(s) clamped so firmly to the front panel and, by 90 rotation of their 'double D' shape, brought close to the edges in each design so that internal struts are unnecessary. Incidentally, although these low frequency units have very light cones, their roll surround and corrugated rear suspensions are correspondingly free-moving so that the open-air bass resonance at 30Hz is unusually low. There is well over 1cm of movement available and, although linearity would not be maintained over this travel, no knocking can occur. The reflex enclosure produces tightly coupled band-pass resonances of 16 and 78Hz. As I sometimes find when the two resonant frequencies of a reflex system are over two octaves apart, the single 67Hz resonance produced with the port blocked can be preferred by some listeners in some Situations. It also avoids slight colourations becoming audible from inside the box via the port, but I am sure they won't approve of this heresy in Steyning. The coated cones used in the DM220 had free air resonances a few Hz higher, suggesting a lighter voice-coil, and two of them in the considerably larger box produced a 62Hz resonance, well spread by the 'wool' damping.

A revealing experience

As I have hinted, listening to these two loudspeakers is a revealing and throughly enjoyable experience. The new tweeter has a free-ranging extended treble response, devoid of spits and false sibilance; and in each case it integrates admirably with the cone unit so that no obvious discontinuities in response or distribution mar the image. Lower down, the DM 110 exhibits a few colourations which impart a slight 'aw' character to the sound and it is warmed up by the contribution of the port emanations. By comparison, the DM220 is cooler and more impersonal, perhaps even a trifle hollow, but it has the benefit of its obviously tight bass extension. Both possess above-average sensitivity such that 25-30 watt amplifiers can produce daunting volumes of sound on demand without losing clarity and detail. Listening to BBC Radio 4 quickly identifies the variations in character of speech due to different microphones and studio reverberation. Compact Discs as varied as Roxy Music and Stravinsky come at you with vivid transient impact, while the gentler pianism of the ever thoughtful Brendel have that note-by-note identity which is one of the hallmarks of excellence in reproduced sound.

There must be a flaw somewhere, and in this case it seems to me to be in the inadequacy and ugliness of the stands provided with the DM220 and available -as an extra for the DM 110 at £2250. You might disagree but, at anywhere near these prices, few loudspeakers could stand comparison. So I say to B&W (or anyone else) "How do you follow that?" 

Manufacturer: B&W Loudspeakers Ltd., Meadow Road, Worthing BNII 2RX. Price: £109,90 and £199,90 per pair

Geoffrey Horn