Clayton Audio M-70 Monoblocks

Clement Perry
21 September 1999


Monoblock amplifiers rated at 70 Watts per Channel
Price: $5,600 per pair
Designer: Wilson Shen
Class A bias switchable to A/B
Voltage Gain: 26dB
Input Impedance: 47k
Dimensions: 9.25 × 20 × 9
Weight 42lbs
8151 Stratford Ave.
Clayton, MO 63105 USA
Tel: 314/862-6017
Fax: 314/862-0765

"….unknown to many, is revered by well-heeled audio writers, and has a reputation as the gorilla-amp killer"

Take a wild guess: What weighs a mere 40 lbs, measures 9 ½ inches wide by 12 ½ inches tall and about 18 ½ inches long, is unknown to many, is revered by well-heeled audio writers, and has a reputation as the gorilla-amp killer? The Clayton Audio M-70 Monoblocks. That’s what!

Wilson Shen, Clayton’s chief honcho and designer (and retired IBM engineer), designed these amps obviously with serious intentions. Considering the competition and the way they sounded in my rig, I think he’s accomplished something deserving of high praise.

The Skinny

My review samples arrived in double-boxed cartons that, thank God, are easily handled. They are stylishly finished in a black anodized brushed aluminum finish (which I presume to be the only color), with "Clayton Audio" engraved on the grille. These unusual looking amplifiers come as a relief from the typically heavy backbreakers that have become a cliché in the high end, causing many a newcomer to believe "the heavier, the better" (much to the chagrin of experienced old timers). Untrue.

One of the M70s’ cooler features are the heatsinks adorning the top, resembling what’s under the hood of some hot rod sports car. The feet on the M70s’ back panel are another, which I assumed (wrongly) were for vertical setup if ever necessary. But they are intended, I’m told, for easy storage when not in use. Nice touch. (But why would I want to put away a reference-sounding product?) Can’t you just see it coming … "Honey, what are these two long black thingies in the closet next to the Hoover?"

The M70s’ face plates hold a rocker switch for powering on and off (with a full six seconds delay), accompanied by a corresponding light. Another innovative feature is an adjustable bias setting between Class A and Class A/B. Note: I did most of my listening in the high bias setting, except for comparison’s sake. (The Plinius line of amplifiers offer bias adjustment options in their products also, with equally good results).

The rear panels of the M70s are equipped with both single ended and balanced inputs. Large WBT speaker posts and gold plated RCA/XLR inputs insure high quality connection. A red LED power-on indicator light is also located on the back panel in case the audiophile, in the throes of his obsession, should ever forget while changing cables that the amp is still powered up -- this is a handy and thoughtful feature.

The Sound

"Well, I can summarize the Claytons’ performance with one word: Accurate. This is manifested in the amps’ unqualified composure and ability to control difficult passages, while never offering a hint of their own personalities. Damned impressive!"

Before I describe my setup, I want to say thank you to Terry Rossen for allowing me the extended period for auditioning. I listened to the Claytons for well over a nine month period, which I think is essential for proper evaluations. First impressions can be misleading, especially if the amplifier is good sounding from the start. Setup is essentially the same as for all previous reviews: The Von Schweikert VR6 (sadly, now discontinued), as well as the new Canadian loudspeakers from Cliffhanger Audio (review forthcoming) whose CH2 monitors accompanied by their matching W2 subwoofers at $3,000 the pair is damn good-sounding. Digital, of course, is by way of the Meitner Bidat processor and DSS transport sandwiched between the RDP-1 Digital EQ from Z-Systems. All digital components rest on No. 3 Vibrapods which clearly introduces very nice sonic improvements (thanks, Anna Logg). All cabling is the new Harmonic Tech Pro Silways, while I managed somehow to piggyback all my Bybee Quantum Interconnect filters for digital links between the Bidat, Z-System and Meitner transport. (The balanced Bybee filters are employed out of Z-1 System into the Meitner transport). The Bybees seem to excel when used farther upstream, and with interconnects, you can’t get any farther than that! The Quantum Line Conditioner offers a level of purity to the incoming signal that has, in my opinion, proved revelatory.

"The ability (under normal listening conditions) for this "little engine that could" to handle the mighty B3 Hammond without cracking under the pressure, down to what appears to be its lowest octaves, proved exhilarating."

After a solid, 90 day break-in, I attempted to understand the fuss among the cognoscenti over these cute little beasts (our very own Frank Alles reviewed them quite favorably in The Audiophile Voice). Well, I can summarize the Claytons’ performance with one word: Accurate. This is manifested in the amps’ unqualified composure and ability to control difficult passages, while never offering a hint of their own personalities. Damned impressive! Another impressive feature is the ability to sound unlike the typical transistor device: no hint of brightness in the upper treble, no shortage of timbral accuracy, integrity, or what many call "bloom." Nowhere was there any exaggeration taking place. On the contrary, the Claytons retain what silicon-designed devices excel at: tight and fastidious bass. They combine the best of solid state and tube sound in this region.

Bass control and extension, when played at normal listening levels, is superior to my former reference KR Enterprise VT-800 SE’s. This fine vacuum tube amp over-saturates the upper mid-bass, thus providing a more romantic signature. The sound, usually characterized as airy but with gobs of bloom, can be overly seductive, especially on massed strings. To be honest, I still prefer it, but would not describe it as "accurate."

To return to the amps under review, serious bass passages on the Hammond XB3 Organ in Joey DeFrancesco’s CD entitled Joey DeFrancesco Live at the 5 Spot (Columbia 53805illustrates this point quite matter-of-factly. And, Nat Adderly’sWork Song, featuring Grover Washington on tenor Sax, clearly shows the Claytons’ ability to keep Grover distinguished and well in front against a well-defined and cookin’ rhythm section. The superb simultaneous control of both frequency extremes proved very impressive, considering the amps’ modest 70 watt rating. (Here again, the VR6’s 96dB sensitivity provides a synergism.) That would have been satisfying enough, but midway into this piece comes DeFrancesco’s Hammond work and Lordy, Lordy, Mizz Clordy, did the Claytons come to party! The ability (under normal listening conditions) for this "little engine that could" to handle the mighty B3 Hammond without cracking under the pressure, down to what appears to be its lowest octaves, proved exhilarating. The recording is good, but here its "live" quality was rendered even more excellent! And, the crowd’s participation was even more involving against the impact and swing of the Hammond. You could feel the excitement in the air. The Claytons’ honesty let you in on the amazement of the occasion by stepping aside. I was very impressed by the ability of the Claytons to sound as if nothing was in the way of the music.

What I didn’t expect from these transistor amps (or any other, for that matter) is the absolute lack of grain in the upper midrange and treble. Pure of character down to their silicon hearts, and possessing as non-transistor a sound as I’ve ever heard, they are completely devoid of glare. The amps increased the level of purity in my system, allowing individual instruments and voices to be superbly defined in a more convincingly realistic space. In Reference Recording’s "Lord, Make Me an Instrument of Thy Peace" (RR-57CD), they clearly distinguished the deep organ notes behind the massed choir, unlike earlier listening experiences using strictly tube amps. These previously unrealized deep organ notes provide the foundation for the choir - and for me, chills - in this deeply moving version of a prayer by St. Francis of Assisi. The Claytons demonstrated an ability to communicate not just sonic accuracy, but what I believe to be a more emotionally "honest" aural account of this music.

Switching over to their A/B mode certainly helped turn the actual temperature down few degrees in my room. Sonically however, it stayed quite hot, and they continued to cook the music I handed them. Overall, in this mode I noted not too much difference in the M70s’ performance aside from a very slight softening of the lower bass.

The amps performed flawlessly with Harmonic Technology’s wonderful power cords, which I much preferred to the Clayton-made power cords included with the amps. I did use the Clayton cords near the end of the review period, but they just didn’t jive with my system. So -- no, thank you, I’ll pass on these.

A good lesson in synergism, perhaps.


"…played within their capabilities, presentation throughout is as natural as all get-out…"

Sonically, the Claytons are a gem, but there are other concerns. At $5,600, the price isn’t cheap when you consider the limited power rating (only 70 watts) versus the competition. You can’t play these amps at gut-crunching levels -- they’re not designed for that purpose. When I did attempt to push the Claytons, I encountered problems. Traditional transistor sound came back to haunt me with that typical hard-sounding treble riding the top, while the bottom started boomin’. (The KR’s give out too when pressed but are much more forgiving when running out of steam.) In other words, the competition’s tough. A Krell or Levinson, comparably priced, offers you more power, not to mention prestige and pride of ownership, and a stronger resale potential should you ever choose sell your equipment for future upgrade. Further, as good as the Claytons sound, I never thought of them as a better sounding design than the newest Krell or Levinson designs I’ve heard. In this strange and finicky market, sounding as good as the competition simply doesn’t cut it for a new product.

In summary, the Clayton M70s are a neutral, ultra-clean design slightly depleted of the ambient bloom one hears with the best of tubes. While you won’t get the "Howitzer" bass capability of the big solid state designs, bass definition and control belie the moderate, 70-watt power rating. (If you want to shake up the earthworms, then I’d pass if I were you.) However, played within their capabilities, presentation throughout is as natural as all get-out, and with great control. Pinpoint imagery is up there with the best I’ve auditioned. If you like to listen at modest to normal levels, there’s very little to fault here, and if I were in the hunt for a true musical transducer -- an amplifier of great merit for less than seven grand -- these would have to get a strong recommendation. They’re that good. And, they stand right up there with the big guns from Krell, Madrigal and Balanced Audio, at half the weight.

The above-mentioned caveats excepted, the Claytons will not disappoint even the most critical listener.
clement perry 

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