Equipment Review No. 3 April 2002
The Clayton Audio M-100 Mono Power Amplifier
8151 Stratford Ave. Clayton, MO., 63105
ph 314.862.6017; fax 314.862.0765
This mono amplifier is a good one, about as good as it gets, and the best power amplifier reviewed to date in these pages. Well....at least until I get to the review of the Sierra Everest mono amps which retail for around $20,000. Though, for those who are expert at reading between the lines, that last sentence does not mean that the Everest is necessarily a better power amp than the M-100s.....that conclusion is yet reserved. But reserved for only so long; I fully intend to give my comparative conclusions once the full measure of the Everest is taken. As far as the M-100 goes however, I've got it in the bag.
Tale of the tape
Each M-100 mono amp weighs in at 47 lbs., is 9" x 9.25" x 20" (HWD), and cannot be converted to stereo use. Bias is true class A, and in that mode it runs hot, but the amplifier has a low bias switch which drops the heat sink temperature a good 15 degrees Fahrenheit, it also cuts Class A output by 50% (though overall output remains the same). Class A output into 8 Ohms is 100 wpc, and 200 wpc into 4 Ohms. Circuitry is discrete. Input impedance is 47,000 Ohms. One set of speaker terminals (WBT). RCA and XLR inputs for single ended and balanced operation. Each amp has a 1,000 VA toroid transformer with 120,000 uf of capacitance. The M-100 also has 8 Motorola high current bipolar output devices per channel. The use of the high current devices result in this amp having an amazing current capability - 200 amps continuous! There are no capacitors in the signal path. A "power on" sequence keeps the amp from damaging the speakers upon turn-on. Each amp has 26 volts of gain, and AC polarity is correct from the factory.
Preamps with the M-100s should probably be solid state. The input impedance of 47 kOhm doesn't totally preclude tube preamplification, but to get all the dynamic life this amp can deliver, I'd go solid state. During my auditioning, excellent sound was attained with the Aloia, and Symfonia preamps. Both of these preamps have brutish power supplies, and for them, the 47 kOhm input impedance of the Clayton was exactly what the music doctor ordered. So, if you be using a Blowtorch, a Reflection, a McCormack, a Klyne, or anything quality coming from the solid side of silicon valley, it will work with this amp. Speaker-wise, the M-100s can dump some current into a speaker, and it will keep dumping that current down to 1 Ohm! Yes, 1 Ohm!!....part of that story being the high current Motorola bi-polar output devices - they are high speed and they can pound out the juice. We, as audiophiles, tend to throw around the phrase "high current" sometimes when it isn't really warranted; it sounds snappy though, like we know some technical stuff. However, in this case the phrase is appropriate. This amp is Krell-like in the current department, which means that it loves a low impedance loudspeaker, absolutely going into a feeding frenzy on loads that hover around 2-6 Ohms. Yet, it's not so muscular in the power supply department that 10 to 16 Ohm loads strangle it at the outputs. Stay away from high impedance loudspeakers, though, if you want this amp to do its very best. There's something special at work when this Clayton is doing its thing into a 4 Ohm load that has to be heard to be believed. I just wouldn't use this amp into a load over 8 Ohms for optimum performance. Clayton has a nice little specialty power cord for the M-100, but I liked the JPS Kaptovator the best in this application. Interconnects used during auditioning were from JPS and Mapleshade.
Sometimes the most accurate way of describing the sound of a component is to pass along an experience. Had several with this amp, but the most telling was clearly the "Clapton - Cat" night visit. The Clayton amps had been breaking in for over two months, and serious listening had just begun a night or two before. This night had been reserved for the old chestnuts in the collection; Red Norvo, Drink Small, Eric Clapton, The Allman Bros, Tchaikovsky, and Stan Rodgers were all in place. These recordings have what I need to get a true reading on a component, and while I listen to many recordings, these come out at prime time. On this occasion, I'd been listening since 7 p.m. and at around midnight I walked into the bedroom where my wife was reading one of her Nero Wolfe mysteries. Standing in the doorway all I could tell her was ... "I've never heard Clapton before". And indeed I hadn't. This time the music was different than every time before....It was his voice, and it came to me with the arrival of the M-100s.
Now, to understand the importance of such a statement, one has to know that I've been using Clapton's "Unplugged" as a reference since it came out in 1992. Its pulses and organic, natural tones have been a part of every appraisal made with the Big Rig from the day of its issuance, and if I've heard Malted Milk and Old Love once, I've heard them a thousand times - literally. Not only have I heard it in the Big Rig, I've heard it at shows and demonstrations with systems costing as much as a townhouse in Midtown. But I'd never actually heard Clapton's voice before (!) - I was a little bit dazed. Upon hearing my proclamation, all Laura said was, "Try Cat Stevens, then report back". Turns out I'd never heard Cat either. At least not until the M-100s were in the system.
From time to time, I stumble across a sound that is practically impossible to describe other than say it is "right". I think back some years to an experience that I had with the Sci-Fi Crown Joule loudspeakers, RE Designs power amp, and Metaxas preamplifier. I don't recall the specifics of the set-up, but the sound from that combination was "right", unbelievably so. I knew it the moment I heard it, but I've never been able to adequately describe it; one of those "you know it when you hear it" things. And it's when you hear a system that is "right" that the words to describe the performance disappear. They disappear because you realize that all the old adjectives and descriptive terms used so many times before simply won't work anymore...they don't fit. There was a rightness with the M-100s in the midrange and the human voice that made description very difficult - it was "right" in so many ways, but of course, not perfect. More on nits later.
The Clayton mono amplifiers have tremendous bass response, very much in the same league as the best that have been in the Big Rig. So, which companies does that include? I've had amps in from Krell, Coda, Polyfusion (the 960 was a monster), Counterpoint, RE Designs, Sunfire, Sierra, Plinius, etc. And the Clayton M-100 mono amps are as tight, deep and fundamentally correct as any, and that's true in spite of the somewhat limited power rating ascribed to the amps of only 100 wpc. Watts are not watts, and the current and control that are part of the Clayton formula make it one powerful amplifying mutha'. Not to trash the makers of other well respected brands, but there is something special about the bass from a power amplifier with a ton o' power supply and multiple super high current bi-polar output devices. In the case of the M-100s tight visceral bass does not mean restricted or light as it can in some solid state designs. I guess, in terms of bass tone the Clayton amps are a bit tubey in terms of the spectral balance (great timbre), but never loose or ill defined as tube amps generally tend to be.
Listening to Red Norvo's "Forward Look" provides the standard for percussion and tone colors. I compared the M-100s at length to the SimAudio Moon W3, and the NTA OTLs. The Naked Truth Audio mono OTLs were incredible at doing one thing, and good in other respects. What the OTLs did wonderfully was impart to the music an amazing sense of musical immediacy. Having heard many a tube in my day - including C-J, ARC and VAC - the dynamic presence that the NTA displayed in the mids was more than a matter of simply using tubes, or an OTL circuit. If it were just that, then all tube amps would possess the same stunning presence, which they do not. The Clayton mono amps were within a bat's eyelash of possessing that same dynamic spontaneity, i.e., the feeling of being at the mic and of having the leading edge dynamics leap at you from nowhere. The Claytons were a tich down in that regard from the NTA. But, while being only a tich down in that respect, the M-100s maintained its immediacy over a much wider swatch frequency wise....from the depths of the bass through the lower treble. Quite an accomplishment.
Compared to the Moon W3 from SimAudio, there were some strong similarities, especially in the major aspects of the sound, i.e., bass definition, midrange presence and treble. But the W3 couldn't drop my jaw with the human voice the way the Clayton did. As fine as the SimAudio is, even when used with the Triphasers, it ended up missing some of the intangibles, the little things that the M-100s excelled at.
In addition to that, the M-100s had a presentation that was at the same time detailed and grainless; allowing the natural textures of a recording to come through in an uncanny way. The combination of which (leading edge dynamics, spontaneity, musical immediacy, and an utter lack of an overlying grain artifact) allowed me to hear Eric and Cat in ways that I had never heard them before. In the simplest of terms, this amp let through a little more of the music through a wider window than the others by imposing less of its personality on the performance. Because of it, this is a reference quality device.
Lest you think this the perfect amplifier, I should add a few nits and picks at this point. Like other amplifiers, the M-100s have an overall coloration. Unlike other amplifiers, its coloration does not reduce the total transparency of the amp....it just shades it. Like Clayton amps I've heard in the past (S-40), there is a shading toward darkness, call it a moody flavoring. I'm not referring to warmth, or the warm audio nest sensation. There is a difference between warm and dark. Warmth is cuddly, dark is brooding. Hey, for now, that's the best I can do. And while the Clayton M-100s are not prohibitively so, there is a touch of darkness to the sound. Almost gothic like, these amps have a little bit of an aura. Bad? Not so bad that I wouldn't purchase them in a minute, for the coloration is minor, and for the most part sympathetic to the musical replay process (meaning it doesn't impede it).
I almost forgot imaging. The M-100s have some of the densest, most solid images this side of Mt. Rushmore. With even more power one might get a little more rounding out and dimensionality on the seamless stage. But in this regard, the Claytons have the lateral spread of the McCormack DNA-225, and the precise 3D layering of the Aloia. Those are some pretty impressive credentials.
Again, a great power amplifier. The M-100s are not as pretty on the inside as the SimAudio Moon W3; for that matter it's not as pretty on the outside either. But sonically, the M-100 is a superior product in pretty much every way, and without the assistance of the Tritium Triphasers being an absolute necessity (though it was a plus).
Compare this amp to an amplifier of the past? Not easy. In all honesty, when looking for a sonic comparison I keep coming up with the Monarchy SE 160 mono amps. They too are all discrete, and operate in the class A mode. The SE 160 however, has a tube front-end and MOSFET output devices, while the Clayton is all solid with bi-polar outputs. Both are just a tad dark, both are dynamic to the hilt, and each amp images like a bandit. However, the Clayton is better in the bass and projects a more powerful persona. The Clayton is more finely resolute, and slightly more revealing of super subtle textures while ever staying in control. But it's close, both are exceptionally gifted designs. Also, in comparing the Clayton to the SE 160 instead of the Aloia amp, I am acknowledging the Clayton's heightened ability to catch the flash and energy of a performance. You may recall last month when I made reference to the SE 160 as a "flashy" sounding amplifier, the M-100s have that same panache and verve...they can replicate the electricity of the moment.
- Martin DeWulf
- John Sunier
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