From the January 1989 issue of Gramophone.

Specifications

DM550: Closed box 75-20,000 160,26 87 10-75 8 352 x 204 x 243 mm 5.5 £149.00. DM560: Reflex 65-20,000 200,26 90 10-75 8 490>' 236 .302 mm 8.5 £199.00. DM570: Reflex 55-20,000 200,26 91 10-120 8 634 236 .302 mm 10.75 £249.00. DM580: Reflex 50-20,000 2>' 200,26 91 10-150 8 886>' 236 .407 mm 18.5 £399.00. Manufacturer: B&W Loudspeakers Ltd., Meadow Road, Worthing BN II 2RX.

When John Bowers died in December 1987 he had experienced the satisfaction of seeing his multi-million pound loudspeaker company grow from a one-off garage enterprise in the short space of 21 years. But those of us who knew him were well aware that this was not his principal source of pride. He was far more delighted by the acceptance of his major achievement, the 801 loudspeaker (Gramophone January 1980 and March 1988) as the standard primary monitor in the world's foremost classical recording studios; exemplified in England by Decca and EMI.

And yet with hindsight I am inclined to another view. Significant as was his determination to produce it, and its subsequent influence on the recording industry is undeniable, another and far less spectacular decision he had made soon after the launch of the 801 was to be his real memorial. That decision was to produce a range of domestic loudspeakers in what is now called the 'affordable' category without sacrificing the B&W standards he so cherished.

To this end, eschewing the practice of his major competitors, everything (except cabinets) was to be B&W made and whatever compromises arose were to be decided on musical grounds. The first of B&W's 100 Series surfaced six years ago and rapidly set a new standard in what was then the £100 per pair mass market. Eventually there were four models in three series over the years and I well remember that on several occasions when we had intended to include one or other of them in a group review, they walked all over the opposition to such a degree that they had to be considered separately. Eventually we were able to include one of them in a recent group (May 1987) and even then, if you re-read Ivor Humphreys' report of the occasion, you will have little doubt about our feelings. So it came about that in all sorts and sizes of listening situations and in a myriad of countries all over the world, more than half-a-million examples of this enterprise are to be found.

When you have had a colossal success like the 100 Series which has brought expansion and prosperity to your company and its workforce, a replacement range has to be most carefully planned. Change is necessary as material cost increases dictate the use of alternative materials, manufacturing processes progress along unexpected lines and above all, technological advances promise 'better for less'. These considerations had been occupying John Bowers's thoughts for some time before the fates took a hand and, only a few months after his passing, I was shown a then unnamed prototype pair which, on a short listening test, seemed to be something of an advance on the current version (then DM 110-1).

Review samples of the four models in the new 500 series-550, 560, 570 and 580—coincided with their exhibition at the Chicago Summer CES Show and my first dip into the pile was obviously to the 560, second in the range and the 110 'equivalents' that I had heard before. At first impressive, they soon turned out to be flawed by a noticeable coloration in the treble which put a tin edge on voices and equally undesirable sharp disturbances on the smooth flow of strings and woodwind. Surely I would not have missed this on the prototype, even on a brief immersion? Early 'phone calls produced the information that everybody who mattered was at Chicago but eventually prompted a visit to B&W's laboratories at Steyning, there to make a direct comparison between the two pairs. This quickly showed the failing to be almost undetectable on the prototypes. Not for the first time, frequency response measurements in their anechoic chamber gave no indication of the whereabouts of the problem, the two response curves almost covered one another: wonderful things, ears! Further investigation led to the fact that a different make of capacitor had been used in the tweeter network, and this proved to be responsible by shifting the balance of signal between the bass/midrange unit and the tweeter over a narrow frequency band, whilst the overall response remained level. As a distinguished critic was wont to remark, "You can't savour wine by reading the label." So, with a handful of capacitors and an hour or two's work with the soldering iron, we could now proceed with the review.

All four models have a number of common features. Cabinets are of particle board with simulated but very tasteful veneers of walnut or black ash. Cloth-covered grille frames have bevelled edges and are fixed with pegs into receptacles inserted in the front baffle, whose front edges are also bevelled to continue the line. This front plate is moulded from a loaded structural plastics material of considerable strength which, in the case of the two smaller models, covers the whole front. In the two larger versions, the lower quarter is veneered and the grille stops short to expose it, breaking up the otherwise large blank area. Moulded stands are available and they should be filled with dry sand—they add a strange hooting sound if this is not done. Both of the two smaller versions can also be considered suitable for shelf mounting. Another common feature is B&W's excellent metal dome tweeter, flush mounted in a special 'D' shaped moulding for these models, which sports a soft plastics cover to smooth any diffraction tendencies. Matching soft plastics trim rings also cover the bass/midrange unit frame fixing screws so that a most tidy appearance is presented to those who prefer to operate with the grilles off. This is, however, a practice to be discouraged because of the extreme delicacy of thin metal domes which can be completely ruined by one touch. Fortunately it is not necessary because it is easily proved that the grilles' presence is undetectable by ear. All versions are fitted with reasonable quality 4mm socket terminals recessed at the rear and are protected from gross abuse by a 2A quick-blow fuse.

DM550

Turning first to the smallest model 550, we find a loudspeaker which is admirably scaled for the smaller room and fitted with a 160mm bass/ mid-range unit. All the units have flared paper cones, doped on the rear surface, long voice-coils and formers, cast alloy baskets and substantial ferrite magnets. An unusually large corrugated rear suspension and rolled concave surround allows for a large cone movement and a low freeair resonance, in this case 52Hz. The 550 is a closed box design with an average amount of foamed plastics filling and the in-box resonance rises to 84Hz. An interesting feature is that, on this model alone, there seems to be some sort of soft compression ring fitted between the front baffle and the cabinet frame. As in all versions, crossovers are simple; in the 550 just a pair of inductors, a single capacitor and an equalizing resistor to reduce the tweeter output; as a closed box design it has 3dB lower sensitivity than its brothers. Even so, a pair can produce adequate sound in the sort of room in which it is likely to be used, when coupled to any good 30- to 50-watt amplifier. After all the listening tests had been done, I set them up in my study (about 44m3) driven by the 10-watts-per channel of a venerable Revox A77 tape recorder and I have not run into obvious overload yet; indeed the overall result is most pleasant on some old stereo music tapes I have been checking.

I must admit to cheating on the stands I used for the main listening sessions as I had the hefty and taller Celestion ones from last month's re view; because I don't seem to be able to accomplish the necessary sand filling without getting a quantity underfoot, I evaded the issue this time. Placed where I had the Celestions, I found a strong preference for the 550s to be faced straight down the room, whereas the Celestions were much better crossed in front of the listener; proof again of how a little experimenting can pay off. My L-shaped listening room is quite large, about 70m3 plus a I 5m3 lobby and one would not normally choose so small a pair of loudspeakers, nevertheless they gave a good account of themselves; no deep bass of course but adequate for most music and of a warm smooth character in keeping with the excellent upper treble. There was a touch or 'glass' to the upper middle which robbed sopranos of their liquid tone and was always most noticed on the human voice; on general programme material it could be dismissed. Priced at £149 for the pair, plus a decent pair of stands if bookshelves are not available, and coupled to a good low-cost amplifier such as the Technics SU-600 reviewed in November, they would form the basis of a very worthwhile system for the smaller room.

DM560

Moving on to the 560 we find a change to a reflex loaded 200mm unit, the port placed in the front face below the unit and appearance matched to the tweeter above it—a nice touch, courtesy of Kenneth Grange of Pentagram Design (though I'll not forgive him for those two screws showing in the bottom bevel). The larger unit, this time with a convex surround, has a free-air resonance of 35Hz and the in-box pair of bandpass resonances then occur at 18 and 80Hz. The crossover now has an additional pole and the sensitivity of the tweeter is set higher to match the 3dB improvement brought about by the 200 mm unit and the reflex support. The bass response holds a little lower than the 550 in practice but then falls away more rapidly, sounding looser and somewhat less natural to my ear. There is still the trace of reediness in the upper middle but muted and much better covered than as received. Although its larger size and its ability to go louder than the 550 will impress some people, there seems to me to be little advantage in terms of musical quality. Nominally of 8 ohm impedance, the 560 fell to 4 ohms between 12 and 15kHz but this is not significant on programme.

DM570

At first glance the 570 might seem to be just a taller 560 but in fact there is another and quite significant difference in that the bass/mid-range driver is changed to a version with a larger 30mm voice-coil and a double-size magnet, and is able to handle considerably more power. However, its free-air resonance turned out to be a little higher at 40Hz and the bandpass resonances have been brought closer together at 20 and 70Hz. This model is, in my opinion, the most satisfying of the group; the bass end appears to go lower than it really does and is better controlled. In some rooms it might be found preferable to close off the port--quite literally put a sock in it! This comment has been known to upset certain designers although I fail to see why it should, in this case it just produces a single 'closed box' resonance at 60Hz and the more gradual roll-off below it, common to the genre. The upper-middle reediness is nowhere so marked in this bass/midrange unit although changing the Elcap reversible electrolytic capacitors for the preferred Bennie version was still worthwhile (changing to some polyesters I had on hand seemed a further improvement but they are expensive).

DM580

Lastly, we come to the 580, replacing the old 300, an excellent and much admired loudspeaker. Here a second 200min unit is added to the configuration of the 560 at low frequencies but in this floor-standing cabinet the internal volume is more than doubled. It is not only taller but much deeper; because of this it has been fitted with strong internal bracing to the side walls. The bass units used here appear identical to those in the 560 and have the same type number. However; in the one I exa mined they had higher free-air resonances of 45 and 55Hz respectively. I thought this to be a rather wide tolerance as the pair of 560 units had checked out at 34 and 36Hz. The cabinet has a reflex port in the rear face above the recessed terminals, although in this model it was filled with a very resistive foam plug causing the complete loudspeaker to measure as a closed box with a single 70Hz in-box resonance. Removing the foam bung produced bandpass resonances of 74 and I4Hz. I am not sure what to make of this interesting discovery but my comment on the 570 is possibly enhanced by it. The second bass unit is brought in at low frequencies by a single series inductor, a very gentle introduction starting above 250Hz and fully operative below 100Hz. As both units are then effectively operating in parallel, the impedance in this busy area falls close to 4 Ohms and any accompanying amplifier should be of a type which can cope with this.

This large loudspeaker could go very loud indeed and is the most sensitive of the quartet. It went somewhat lower in the bass than the others but certainly not in proportion to its increased size. In two rooms in which I tried it the 70-80Hz region seemed excessive, possibly because of floor reflection, producing a marvellous beat on pop music. It still had traces of the upper-middle problem which seems to be a characteristic of the new 200mm units although I must admit that several other listeners failed to observe or remark on it; nevertheless I am pretty sure most classical ears would do so in time.

So, are these 500 Series loudspeakers worthy successors to their widely accepted predecessors? I think that to the classical music listener the answer can only be a somewhat hesitant yes, with a strong leaning towards the 550 for economy and the 570 (perhaps with a sock in it!) as favourite. Certainly they have lower coloration than the previous range, whose embellishments were of a pleasant sort, often adjudged to enhance the final result. Of course other makers have made comparable advances and so the gap has been closing all the time. I think the pop enthusiast will be far more excited by these new models and, who knows, that huge market may well be the one that B&W has targeted. All four models are skilfully styled to have aesthetic appeal in a variety of surroundings, all are of far above average construction using quality materials, and all are made in England. 

Geoffrey Horn