Published On: January 11, 2009

Sudgen A21 Amp Reviewed

Published On: January 11, 2009

Sudgen A21 Amp Reviewed

Another Richard Allan design from overseas woos, Ken Kessler with its Class-A (not to be confused with Classé') operation in the esoteric Sugden A21 power amp.

Certain manufacturers have pre-empted Class-A operation as if they invented the technology, so it's easy to forget that nearly-forgotten British brands went to market with Class-A designs 30 years ago. As this isn't our classic hi-fi supplement and I'm not at present in a position to determine exactly brand was the first in the world to issue a shop-ready Class-A amplifier, it's enough to point out that the Sugden (or, more precisely, Richard Allan) nameplate graced commercially-available products nearly a decade-and-a-half before any of the current practitioners.

Additional Resources
• Read audiophile power amp reviews from the likes of Krell, Mark Levinson, Audio Research, Linn, Naim, VAC, VTL, NuForce, Pass Labs and many others here.
• Read about tubes on the Audiophile blog, AudiophileReview.com.
• Want to read audiophile stereo preamp reviews? We have dozens from brands like ARC, Krell, Classé and many more.
• In the market for audiophile loudspeakers? Here are over 100 reviews from brands like Wilson Audio, THIEL, MartinLogan, Bowers & Wilkins, PSB, Vandersten, Magnepan and many more.

This very magazine published James Sugden's seminal articles as far back as our November 1967 issue, with his 10W/ch Richard Allan A21 appearing that year for £52. By 1969, for the princely £56*, one could purchase an updated, renamed version called the Sugden A21 Series Two, one of which the current Sugden firm loaned me for the purpose of putting the latest version into context. Rated at 10W/ch and running as hot as you'd expect, the A21 Series Two provided a deliciously prescient taste of high-end audio in the 1980s and 1990s, the magazine articles giving no clues as to Class-A's eventual ascendancy.

They make amusing reading, though one referring back to them must accept that it was the tenor of the times which allowed a writer to describe the transistor as "the nigger in the woodpile". The Forces of Darkness preferred Class-B or -AB with Sugden defending Class-A operation and its total avoidance of switching distortion. As we now know, after a decade-plus of high-end pure Class-A solid-state amplifiers from the USA and elsewhere, Class-A costs more, is less efficient and generates copious amounts of heat, but sounds a helluva lot better than Class-B amplification.

As it was succinctly described by Gordon J. King in , "Class-A working is achieved by biasing the push-pull output transistors to the middle of their working characteristics, so that the collector remains virtually the same whether signal is being handled or not." What made the appearance of Class-A so novel back in the late Sixties was simply a matter of timing: King points out that the development of the A21 was possible because the germanium transistors of the day, which couldn't handle the heat, were being replaced by far more suitable silicon types. By the late-1980s, Musical Fidelity was able to offer the A2, an integrated amplifier purporting to operate in Class-A mode, for under £300.

If the anachrophilic tone of this piece is starting to grate, note that it's wholly appropriate. What I have before me is a made-in-1998 J.E.Sugden A21a integrated amplifier, a direct descendant of the A21 Series Two, still manufactured in West Yorkshire and still as unrelentingly British as you would want it to be. Better yet, I just learned that this amplifier has been around virtually unchanged for nine years. Which just might be (1) the longest we've waited between launch and review (although fellow HFN/RR contributor Eric Braithwaite reviewed it seven or eight years ago for another magazine...), and (2) it's enough to mark the A21a as probably the "oldest" integrated amplifier in continuous production. But it sure doesn't sound that way.

Unlike its large, funky, trad predecessor, the A21a measures a truly svelte 430x360x72mm (WDH) including the knobs, speaker terminals and substantial heat-sinkery. Those dimensions are what you'd allow for a conventional, cool-running, minimalist solid-state integrated, and yet the A21a lacks no functions; by design requires that horizontal heat dispersion running along its sides. And still it offers four line inputs, a proper phono stage and the basics. Across its front are a rotary source selector, buttons for tape monitoring and mono operation (yippee!!!), and a pair of rotaries for balance and volume. At the far right are a yellow LED and power-on button. My only ergonomic grumble? No centre detent for the balance setting. At the back, the A21a provides an IEC mains inlet, multi-way binding posts for a single pair of speakers, gold-plated phono sockets and an earthing post.

Inside, it's dual-mono for the amp sections, each channel residing on a vertically-mounted PCB fixed directly to the heat-sinks. The pre-amp stage has its own PCB running the depth of the cabinet, with the optional phono section consisting of a daughter-board factory-fitted at the rear of the main PCB. And smack in the middle, adding to the unit's substantial weight of 9kg, is the heart of the power supply, a massive toroidal with separate windings for each channel. Parts quality is top-rate, the A21a filled with capacitors, resistors and switches I've seen in far-costlier designs, and the finish and build-quality are confidence-inspiring.

A word of caution: an ostensibly clean and handsome design, the A21a is available in silver or black, but J.E.Sugden will finish it in other colours if your taste is of the non-existent variety. Whatever your own proclivities, try to resist the temptation to opt for what the company calls 'gold', the finish as seen on the review sample and one conceived for shops, hi-fi shows and, as Sugden's Tony Miller put it, "Christmas." Gold? I think not. Rather, it calls to mind the words 'vial' and 'specimen'.

Rated at a modest 25W/ch, the A21a acts like a 75-watter - hardly what I expected of an amplifier with the built-in power restrictions caused by opting for Class-A circuitry. Any experience with other 'baby' Class-A amps will not prepare you for the sheer driving force the A21a possess...within reason, that is. But the A21a is merely reflecting a couple of decades' worth of transistor evolution since the A21 Series Two, which it substantially outperforms as far as sheer grunt is concerned. Sugden has employed what it describes as "the latest multi-emitter bi-polar devices with low internal resistance, high gain and speed characteristics." Other changes from old to new include gain stages in cascode configuration, increasing the bandwidth and minimising phase shift. And as much as the antique collector in me wants to play Luddite and claim that the old A21 is the one to own, the A21a is faster, more detailed, smoother and much more transparent. Hell, the only arguments I can still produce in favour of the oldie are almost entirely based on the look of the faceplate.

With the two Sugdens sandwiched in turns in-between a pair of New Audio Frontiers Reference speakers and sources including the Krell KAV-300cd and a Basis 2000 turntable with Rega arm and Grado Prestige cartridge, I set about assessing old-vs-new before attempting to position the A21a in the current market. Anachrophiles will be both pleased and dismayed, the latter response being elicited by the aforementioned list of gains. But pleasure comes when you discover just how commanding the oldster remains, even surrounded by modern ancillaries and digital sources.

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Yes, the A21a's extra headroom, courtesy of another 15W/ch, is substantial, but the oldie still drives some ornery speakers like Quad ESLs and LS3/5As with ease; the New Audio Frontiers speakers are so sensitive that the elder amp's volume control never strayed past 11 o'clock. So 'loud' just ain't an issue. But what the A21 Series Two has which will keep lucky owners from ever letting go of this thirtysomething is a sort of gentility, a breeding, a type ofwhich isn't just a part of the original 1967 design; it's redolent of the era.

Which is not to say that the A21a is brash or rude or vulgar. Quite simply, it's . Which is a couple of characters too long to be a four-letter word. In this sense it means 'analytical', 'matter-of-fact' - almost cold-blooded. And that's as it should be, if we're true to the goals of accuracy, low-coloration and an absence of distortion. The A21a, nostalgia and valve prejudices and high-end leanings be damned, is absolutely faithful to its . At the risk of incurring a wave of wrath from across the pond from which I might never recover, I have to say that the A21a made me think continually of...Krell.

It possesses, on a far smaller scale, of course, the kind of virtues which make Krells THE choice for a large number of high-end customers of the solid-state persuasion. The Sugden's sound is detailed, coherent, top-to-bottom consistent and cut into the air with a precision that suggests keyhole surgery. Even with bass-heavy recordings and while driving massive towers like the References, the bass never flubbed, never exhibited a teensy trace of overhang. Treble attack was ideal for listening to flurries of fast trumpet and guitar work, especially if coming from a system which made it impossible to separate the notes. And the A21a understands three-dimension soundstages.

Of course, the Sugden lacks the slam of a 3000-plus powerhouse. It will not crack plaster, though it will produce levels to earn you a place on if you own high-sensitivity speakers. Sorry, gang, but headbanging costs loadsamoney. Conversely, the Sugden will never place you in the invidious position familiar to NAD3020 masoch- er, owners, whose amps struggled to drive a pair of cans. The Sugden is like Goldilocks' preferred porridge. Oops, there's that subliminal gold message...

Sonically, then, there's no downside unless you swear by single-ended triodes or push-pull EL34s, in which case Class-A solid state amp would prove to be an anathema. Rather, the A21a is a delightful stepping-stone toward Krell and the like, for those wa-a-ay short of the requisite dosh. At 749 in line level form, its adjusted-for-1998 pricing means that inflation has touched Sugden only a bit; the company says that working backwards, 749 is the equivalent of 72.50 circa 1967.

Then there's the mm+mc phono stage for another 70. Alas, I preferred the smoother, quieter NAD PP-1 at 39.95, but that lacks moving-coil suitability. A competent Sugden dealer, however, will certainly allow you to hear a phono-equipped A21a against an A21a with an outboard phono section of your own choice.

But don't let the question of the phono stage distract you. The Sugden A21a, now that the Musical Fidelity A1 is a memory, is the choice if you want affordable Class-A. Phrased that way, you might think I'm describing a victory by default. Not so: the Sugden has few rivals at or near its price; my personal shortlist features only the Audio Analogue Puccini SE and the Musical Fidelity X-A1.

Remember: we're talking about an amp made by salt-of-the-earth Yorkshiremen who can't be bothered with the nonsense attached to specialty audio. They'll never shout about the A21a, any more than they boasted about their own pioneering efforts in making Class-A technology available to the masses. And this is behaviour which makes the Sugden A21a the best-kept secret in British hi-fi.

Bar none.

Additional Resources
• Read audiophile power amp reviews from the likes of Krell, Mark Levinson, Audio Research, Linn, Naim, VAC, VTL, NuForce, Pass Labs and many others here.
• Read about tubes on the Audiophile blog, AudiophileReview.com.
• Want to read < a href="https://hometheaterreview.com/stereo-preamplifier-reviews/" style="text-decoration: underline; ">audiophile stereo preamp reviews? We have dozens from brands like ARC, Krell, Classé and many more.
• In the market for audiophile loudspeakers? Here are over 100 reviews from brands like Wilson Audio, THIEL, MartinLogan, Bowers & Wilkins, PSB, Vandersten, Magnepan and many more.

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