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Dynaudio BM6A

Active Nearfield Monitors By Paul White
Published March 1997

Paul White puts Dynaudio's new nearfield monitors to the test and is actively impressed...

At one time, active monitors were treated with suspicion by the typical user — they seemed over‑expensive, and you didn't get to choose what power amps to use — but now we know better. In fact, it can be argued that the active approach is the only way to make speakers behave properly — passive systems are a monstrous compromise, and it's a credit to their designers that the better ones work as well as they do.

Construction & Appearance

Dynaudio's BM6A monitors, are, to my knowledge, the first active nearfield monitors the company has produced — they're certainly the first I've seen — and they are essentially based on a design that can be traced back to the PPM2 broadcast monitor. The Dynaudio BM6A incorporates a pair of specially‑designed, discrete 100W MOSFET amplifiers fed from a phase‑aligned, 4th‑order electronic crossover operating at 2.2kHz. The input stage is a balanced instrumentation amplifier fed from a standard XLR connector. Two level controls provide a 4dB adjustment range for the high‑ and low‑end frequency response (50Hz and 15kHz); these are useful in helping to compensate for proximity to reflective surfaces and, to a lesser extent, to help match the speakers to the acoustic character of the room. A switch selects between +4 and ‑10dB sensitivity, and power is fed into the unit via a switched IEC mains socket.

Measuring just 338 x 216 x 285mm, the speakers supplied for review came in a wonderful natural light wood finish with radiused cabinet edges that would complement my Victorian stripped‑pine studio furniture a treat (see picture). Sadly, the wood‑veneer finish costs extra — for the basic price, the speakers come attired in the more familiar 'studio black'.

Dynaudio is essentially a company dedicated to building driver units, with complete systems being just a small part of their business, so it it comes as no surprise that both the high‑ and low‑frequency drive units are made by them: the 26mm fabric dome tweeter is protected by three metal bars in the form of a star (or Mercedes logo if you're that way inclined), while the bass/mid driver is a 170mm unit with a synthetic cone, roll surround, and the characteristically large Dynaudio dust cap with edge slots. A dual‑colour LED set into the front panel shows when the speakers are powered up, and flips from red to green after the short power‑up delay time has expired. A second LED comes on to let you know the protection circuitry has started to earn its keep.

At first glance, the cabinet appears to be unported, but closer examination of the rear panel shows a narrow porting slot right at the top of the cabinet. The remainder of the back panel is taken up with a heat sink, so as to furnish the amplifiers with adequate cooling without the need for a fan. The result is a speaker little larger than a typical compact nearfield monitor, yet capable of a 45Hz‑22kHz response (‑3dB) and with a hefty peak SPL of 116dB per cabinet at 1 metre. The continuous SPL is quoted as 101dB. Both amplifiers are protected against DC faults and thermal overload, and there's a photo‑active limiter on the tweeter. I hadn't heard this term before, but I'm told the device is a fast‑acting true RMS limiter, which enables transient peaks to pass through the amplifier, but prevents heavy current overheating the tweeter.

Listening Test

Auditioning active speakers is easier than checking passive models, because with any passive system, there's always the nagging doubt that the amplifier you're using might not be best suited to those particular speakers. With active speakers, all you need to do is connect a good CD player to the inputs, and you're in business. I wheeled in my standard test CD collection, but in the interests of retaining some vestige of musical credibility, I'm not going to tell you what all of them are. One of them is Jennifer Warnes singing Leonard Cohen (the Famous Blue Raincoat album), which is actually a very nicely recorded album and not only provides a good test of bass extension and vocal clarity, out also shows how good Leonard Cohen's songs can sound when somebody else is singing them! The other I'm prepared to put my hand up to is Madonna singing 'Live to Tell' — the QSound tricks used on this mix provide a nice test of stereo imaging. This particular track is mixed a little on the bright side, but not enough to make it unpleasant.

The verdict, after much swapping of discs and comparisons with my ATC monitors, was that the Dynaudio BM6As are voiced just a hint bright — but only a hint. Overall, the sound stays smooth and very natural, even at fairly high levels, and the benefits of active powering show up in almost dictatorial control of the bass end, which remains both tight and deep. There's also plenty of level.

Dynaudio speakers have always been effective at presenting a detailed mid and high end, and this pair is no exception. The sound has a strong sense of intimacy, but there's little or none of that edgy raggedness around the crossover frequency that lets down so many otherwise competent monitors. Well‑recorded voices retain clarity and articulation, but without becoming scratchy or sibilant — a trait often shown up when female vocals are played through imperfect monitors.

Stereo imaging is important for nearfield monitors, because the stereo panning and effects for most mixes are set up using nearfields rather than monster monitors. In common with other Dynaudio speakers I've used, the imaging is convincing and stable, with centre‑panned sounds hanging nicely between the speakers. Stereo enhancement techniques push the sound out beyond the extremes of the speakers, and again, good imaging is essential if such effects are to retain their integrity. These speakers convey an impression of both stereo width and depth, and it's also worthy of note that the sweet spot is nice and wide — you don't hear any significant HF rolloff or any serious imaging degradation until you've moved a long way off‑axis.

Summary

Over the past couple of years, a number of active monitors have sprung up in the £1200 to £1500 price bracket, many of which are exceedingly good performers. You can make accurate mixes on any of the better models, and any preferences probably come down more to personal taste than to any significant technical supremacy. Even so, when you're spending this kind of money, it's always as well to shortlist two or three pairs, then listen to them side by side.

I've always had the greatest respect for Dynaudio studio monitors, and while I still use ATCs as my reference, there's no denying that Dynaudio manage to deliver a very close‑to‑neutral sound that is at the same time lively and inspiring to work with. I'd certainly be more than happy to do all my mixing on these little beauties, and it's unlikely that anyone would complain that they weren't loud enough.

Why Active?

Given the possible sources of audio contamination in the average studio, it's amazing that hi‑fi enthusiasts still spend days discussing the merits of different types of speaker cable, some of which costs more than the speakers it's connected to! The entire debate is rendered irrelevant in an active monitor system, because the power amplifier is located only inches away from the drive units. What's more, there are no crossover components between the amplifier and speaker to further add to the complex load of a loudspeaker, or to compromise the damping factor of the amplifier. Another benefit is that as the crossover works at line level, before the power amplifiers, the designer can use far more precisely‑controlled EQ curves and include phase compensation — and it's even possible, to some extent, to compensate for frequency response anomalies in the driver/enclosure system. Comparing active and passive versions of the same speaker invariably reveals the active version to be capable of louder output before the onset of audible distortion, as well as sounding tighter, and being better controlled.

Pros

  • Wide, stable imaging.
  • Well‑controlled, smooth and honest‑sounding.
  • Tight, reasonably well‑extended bass end.

Cons

  • No obvious cons at the price, though some

Summary

These monitors have the ideal attributes for either nearfield monitoring in a pro environment or for main monitoring in a serious project studio. They manage to sound lively and detailed without being fatiguing or harsh.