Coherent Systems - Reviews

Hi-Fi Plus - Issue 60 - September 2008

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The Belles Labs MB-200 Mono-blocs

Reviewing power amps can present a particular problem. After all, accumulating material to fill the pages of our august journal isn’t exactly helped by a feature count that could be listed on the back of a Bryant & May box. Of course, you can usually rely on the presence of some enormous ex-Soviet transmitting valve, smuggled off of Russian spy trawlers, or a transformer hand wound by a castaway, who developed his design whilst wiling away the long years on some misbegotten island, and who is now so inured to isolation that he won’t return to society. What any journalist hopes for, searches for, a few even pray for – is a story; something, anything on which to hang his piece.

The Belles MB-200s are resolutely, almost bloody-mindedly devoid of artifice or embellishment, feature or frippery. They are neat, basic, compact, and conventional. They are nicely pit together, but no more than that. They are solidly built but a world away from the sort of immoveable behemoths that cross my threshold with lumbar-threatening regularity. They offer the bare minimum of connections – and those are far from flash. They arn’t ugly; they arn’t even plain. In fact, to all appearances they’re just plain ordinary. The only characteristic they have that sets them apart is the preponderance of plain common sense that’s informed every aspect of their construction – and that’s hardly a story.

“So why,” you might well demand, “are you bothering to review them?” And I’ll thank you for asking – for that, now, that’s a story, because the thing with these amps is nothing more, nothing less than their musical performance. There’s no other reason to buy them, but believe me, it is reason enough.

Actually, I might have overstated their sheer ordinariness just a little: Class AB; differential circuit topology, eight pairs of Mosfets per channel delivery 200 watts into 8 Ohms and 400 into 4. It’s all pretty text-book stuff, even if it has been executed with an exacting eye for detail and a mind that weighs equally the paper performance of an amplifier and the more, shall we say “subjective?” aspects of the job. Indeed, textbook is as good a term as any to describe the performance specs of the MB-200. Conservatively rated (and I really do mean that), it will deliver a peak current of 64Amps and has a damping factor greater than 2000. It’s also flat from 0.2Hz to 125kHz. All from a package about the size of an Audiolab and which weights around 14kg – most of which is down to the ridiculously large torodal transformer employed. In fact, the last time I saw an amp that exceeded the chassis to transformer ratio of the MB-200, it was the Vitus integrated – and that had two channels!

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But that tidy paper performance is reflected in the mechanical detail too. The amp is neatly enough put together, but there’s also ample evidence of an enquiring approach to wider issues. So the aluminium chassis is constructed from plates of three different thicknesses to help reduce dominant resonance, while the surprisingly solid result is perched on four Stillpoints feet, to deal with both the vibrational energy generated by that huge transformer (not to mention associated power supply components and all those output devices) and also to help isolate the circuitry from external interference. The socketry is simplicity itself, with only one single-ended RCA input (despite the differential circuit) and one pair of speaker binding posts – although at least those come from Cardas. Letting the overpowering sense of Puritanism drop for just a moment, you can have the amps in a choice of black or silver finish, but that’s it as far as luxuries are concerned.

Yet, as soon as you fire the MB-200s up you realise that there’s something special going on. There’s an instantaneous and lucid clarity that revels in instrumental detail without being overstated. They’re also rather more powerful than the 200 Watt tag suggests, and I used them with a host of different speakers, ranging from the Goldmund Logos, 1 and Spendor SA1 to the Eben Ayra C1, the Usher 6371 and Gersham Sonogram. The sheer variety on show there should tell you something about these amps’ unflappable character. Indeed, the only time I heard them in any discomfort was driving the ultra critical and clinically revealing MartinLogan CLX full-range electrostatics, a combination that sounded uncharacteristically threadbare and strained through the upper registers. Neither product exhibits such tendencies in other company, making me wonder whether the Belles are more at home with more conventional loads than that presented by the big ‘stats. Certainly, none of the dynamic speakers presented the amp with any problems and those requiring a tight grip on an extended bottom (yes Gershman, you know who you are) or a little extra welly to wake them up occasionally (yes, yes Logos, that would be you) received exactly what was required – and more besides. Indeed, while they’ve been in residence the Belles have become something akin to the “go-to guys” in my current amp stable, simply because they seem to fit effortlessly into so many system situations.

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How do they stand up against the competition? Well, they might lack the sublime tonal delicacy and dynamic dexterity of the Hovland RADIA – but they deliver considerably more power and generally handle awkward loads with consummate ease. Likewise, they lack the absolute stability and top to bottom continuity and presence of the Ayre MCRs – but they deliver a quicker and more obviously transparent sound that many might well prefer. And the point about the Belles is that they stand comparison with those amps in spite of the fact that they cost considerably less, less than half in the case of the Ayres. No, the Belles MB-200s aren’t better than the RADIA or the MXRs – but they are snapping at their heels, which makes them an absolute bargain in monetary terms. Besides which, they also bring their own special quality to proceedings.

All those adjectives I’ve used up to now might just sum up a classically controlled yet ultimately, musically sterile solid-state powerhouse. But the Belles have that necessary ability of any really good amp – invisibility. They are so devoid of grain and dynamic constraint that music flows from the soundstage completely unimpeded. It’s a skill they share with the Hovland and Ayres, but in combination with their astonishing transparency and sheer clarity, they produce some quite breathtaking musical moments, a host of captivating instrumental detail. Listening to the (normally murky) opening passage of the Stewboss classic ‘Wanted A Girl’, the wash of sound behind the picked guitar and bass lines – which starts out as thunder and rain – is effortlessly revealed as a shimmering array of differing and carefully medled percussion. The count-in has an intimacy and quietly convincing breathiness that conjures singer Greg Saffarty with an almost physical presence, preparing a path for his eventual vocal entry, adding an all-important humanity to this desolate song.

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But it’s parser tracks like the Duke Ellington/Ray Brown ‘Do Nothin’ Till You Hear From Me’ (from This One’s For Blanton) that reveal the MB-200s’ inner workings. There is a slight vestige of Mosfet softness to leading edges, which robs the plucked bass notes of that last ounce of immediacy and attack. But at the same time there is an easy flow to the difficult lines, absolute pitch security and precision spacing of the notes, that makes what can be a difficult and somewhat staccato track on the wrong system sound fluid and engaging, even catchy – and I never thought I’d say that about what amounts to extended bass solo. The gently tailored leading edges have their upsides too, and the occasionally strident interjections from the Duke take on a less aggressive tone without losing any of their rhythmic urgency.

In fact, as well as getting out of the way of the music just like any good amp should, the MB-200s almost seem to give it a quick brush and tidy ip and a gentle shove to help it along. They are wonderfully even top to bottom, and if they err tonally it is ever so slightly to the lean, clean side of things, making sure that the signal is never burdened with unwarranted dollops of extra weight, slowing or slurring its progress. It’s a quality that also makes the Belles something of a fixture around here. I used them with both the Connoissuer and their own matching pre-amp with excellent results, and sources as varied as the Grand Prix Audio Monaco and Kuzma turntables, and Goldmund, Wadia and Zanden CD players. Their surefooted and confident delivery never once let me down. The particular qualities of the Monaco have rarely been as apparent, the differences between the Wadia and Zanden players rendered clear and distinct.

The MB-200s mark a seriously impressive debut for Belles, as least as far as Hi-Fi Plus is concerned. But like all good stories this one saves the best for last. At around £5K, there should be plenty of taker for the MB-200, but if that’s a little rich for your blood then there’s a line-integrated on the way, whilst moving up in price you have a choice of 500 or 80 Watt Class A mono-blocs – none of which I’ve heard. Yet! But what I have heard is the LA-01 line-stage and if you think the MB-200s are a bargain, just wait until you hear this sucka...

TECHNICAL SPECIFICATIONS
Type Solid-state mono-bloc
Output Devices Mosfets
Inputs 1pr RCA/phono
Input Impedance 1.9v
Input Sensitivity 100kOhms
Outputs 1pr Cardas binding posts
Output Power 200 Watts/8 Ohms
400 Watts/4 Ohms
Dimensions (WxHxD) 432 x 119 x 330mm
Weight 15.9kg
Finishes Blacks and Silver
Price £6250 pr.
UK Distributer:
Coherent Systems
Tel (44)(0)1684 310849
Net. www.coherent-systems.co.uk
Manufacturer:
Power Modules Inc.
Net. www.powermodules.com

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