Tuesday, February 9, 2010

Clayton Audio S-40 power amplifier

(This was a neat Class A amplifier I used for the better part of 2008. I could live happily with this amp for the rest of my life.)

A few months ago, I found myself trying to choose between two absolutely wonderful power amplifiers to see which one would take up permanent residence in my reference system. Both were fairly expensive, both were well-respected in the audio world, and both took my system to places it had never been before.

The first amplifier was a well-known classic tube design from a highly respected company. Every recording sounded warm, natural and beautiful through this amp. It had enough power to drive most speaker systems, which suited my needs, as well as my desire to continue using tubed amplification after leaving the world of single-ended triodes. But ultimately, I felt it was just a little too soft.

The second amplifier was a stunning example of precision audio equipment, a gleaming, teeming piece of industrial architecture. It was solid-state, so I wouldn't have to worry about the cost of replacing tubes (that first amp had quite a few). It also had a lot of power, so I would never be hamstrung when it came to reviewing speakers. But ultimately, I felt it was just a little too dry.

Around this time, the Clayton Audio S-40 amplifier showed up at my door. It was less expensive than the other two amplifiers, and had less power as well. The Clayton was certainly attractive in its own dark, brooding way, but didn't quite have the wow factor of the other two. I'm not sure why I didn't take it seriously at first. In retrospect, I feel a bit foolish. But to paraphrase Goldilocks, this amplifier turned out to be just right.

Show Me the Amp!
Clayton Audio, based in Clayton, Missouri, is a very low-profile company. It doesn't even have a website. Clayton has been in business since 1994, however, and has been quietly building some of the most intriguing Class A amplifiers in the industry. Headed by Wilson Shen, a former IBM systems designer, Clayton Audio originally featured two products: the monoblock M-70 and the S-40, both of which come in the same case. (Clayton has recently added some new and more ambitious models to their line.) The physical appearance of these amplifiers is somewhat striking, with a basically square and compact countenance offset by a very deep chassis. These amps will require dedicated amp stands, since they are probably too deep to fit comfortably in most equipment racks.

The top of the S-40 is also unique. Long fins, serving as a heat sink, run all the way from front to back, covering the entire top plate. This offsets the otherwise chunky, square appearance of the amp, making it appear almost streamlined. These heat sinks are necessary, of course, because the S-40 provides 50 watts per channel of pure Class A power. But while the case and heat sinks of the S-40 were warm to the touch during normal operation, the amp did not heat my listening room to uncomfortable levels on warm summer days. In fact, I can think of a few tube amps that I've owned that ran much warmer.

In his days at IBM, Shen developed a strong working relationship with Motorola, which influenced his ideas on amplifier design. The S-40 eschews the practice of using MOSFETs in the output stage, and places Motorola bipolar power transistors in their place. These devices had never been used in an audio product until Shen did it. He also used his pull with the folks at Motorola to select only the highest quality semiconductors and parts for his designs, and kept the ball rolling by using DH Labs wiring, Sprague capacitors, C&K switches, Omron relays and so on.

The S-40 I received differs somewhat from the original design in that the power has been increased from 40 to 50 watts per side. (One wonders why Shen didn't change the model number to S-50 to reflect this!) Since the original S-40 had a reputation for sounding much more powerful than its power rating, this can only be good news for those looking for compatibility with a wide range of speakers.

Show Me the Sound!
As I said before, the S-40 bridges the gap between classic tube sound and modern solid state characteristics in an intriguing way. In many ways, it was truly the best of both worlds. (After seeing Clerks, it's hard for me to use that phrase without giggling just a little.) I used the Clayton in my reference system over the course of many months, occasionally pulling it out of the system to review this amp, or that amp. While some of these products may have surpassed the performance of the S-40 in one specific way or another (and usually at a significant increase in cost), the Clayton felt like a comfortable old friend when I returned to it. It knew my musical tastes well, and it communicated to me in a relaxed, friendly way that made me feel welcomed in my own listening room.

If that sounds a little touchie-feelie to you, well, that's the point. Every time I fired up the Clayton, I'd literally heave a big sigh of relief. The S-40 was able to provide all of the warmth of the best tube designs, and yet add enough vital detail to the presentation to stave off the feeling that I was missing something in the mix. At the same time, the S-40 never sounded harsh or bright, even when the recording came up a bit short in the lush, romantic department.

For instance, my Sundazed LP pressing of Wilco's Yankee Hotel Foxtrot is notable for revealing every last detail in this busy mix, but it can sound dry and unemotional with certain solid state amplifiers. At the same time, many of those little details can be lost through tubed amplification, especially SETs. The Clayton was able to walk that tightrope and once again give me the best of both worlds (snicker). The pain, heartache and chronic migraines came through in Jeff Tweedy's crackling, expressive voice like never before. While this is one of my very favorite recordings of the last decade, my appreciation for it grew even more with the S-40 in the playback chain.

Show Me the Love!
I'm tempted to pull out that old review cliché and call the S-40 the Honda Accord of amplifiers. You know, it doesn't come in first place in any single department, but it performs so well across the board. But I think the Clayton is actually the Acura NSX of amplifiers. While it may not be as breathtakingly fast as a Ferrari or a Lambo, it's user-friendly and offers regular audiophiles the chance to experience the very best for slightly less money.

I have heard one or two amplifiers in my system that I would ultimately prefer to the Clayton. Those amplifiers, as I said before, cost a lot more money. Like a Ferrari or a Lambo, they consistently provided big thrills and prompted me to exclaim “Wow!” more than once. But the Clayton is that special car in your garage, the one you've owned for years, the one you buff with a diaper, the one you actually have a long term relationship with.

I could switch to analogies about women here, but I think you get the point. I like the S-40. I like having it around. I hope it stays.


  1. Nicely done. My Claytons started out as M70s, and were the first pair that Wilson upgraded when he brought the M100s to market. You describe the Clayton Audio relationship very well; these are the amps you keep. I've loved them with very fluid preamps (Audible Illusions) and I love them even more with clean and detailed preamps (Placette Audio). They were fantastic at 70 watts and they're just as good, just bigger, at 100 watts. The S40/S50 is the exact same sound; I've always wondered if the M70/M100 weren't just S40/S50s bridged.

    I really don't care if most folks have never heard of this company, or if the guys in the stereo shops sneer at it because it isn't SET or it isn't 10000 watts or "big name". Without actually living with Clayton gear day after day they just don't know what it's about.

    Maybe we should invoke the late great Charlton Heston and that "from my cold dead hands" line of his he used with the NRA.

  2. As an owner of M200s... you hit it right on the head. Great review.

  3. As an owner of M200s your review is spot on. A great product.

  4. Thanks guys for the comments. I really dug that amp.