Shine On You Crazy Diamond
Surely there had been some mistake. I was expecting an amplifier, after all. This box just delivered, measuring some 14 inches wide, 12 1/2 inches tall and 24 inches long, certainly must contain a mini monitor rather than an amplifier. Aside for the UPS shipping label on top of this unassuming plain brown carton, it was tagged with only one other label. This second 11 by 4 inch white label read simply, "Clayton Audio," in blue script with the description, "Power Amplifier," in blue block lettering immediately beneath it. How unique! So, this was the way it was to begin.
Opening the box revealed that it was indeed as labeled; the box contained an amplifier. Once out of its carton, the amplifier appeared rather graceful looking. The thick black face plate and gold appointed back made this rather oddly shaped amplifier seem quite intriguing. The heat sink was terribly unorthodox, as it ran the entire length of the top of the amplifiers slender body. In all, the amplifier offers a simple, almost Spartan, elegance.
The front of the unit is simply appointed, with only an illuminated rocker switch and a status indicator lamp mounted directly above that. These are both centered on and recessed into a panel on the 3/8" thick face plate. The only other appointment on the front of the device is the "Clayton Audio" designation directly above the recess.
The rear of the unit is dominated by the large WBT five way speaker binding posts located nearly dead center. Just above them are the WBT gold plated RCA inputs. There are no provisions for XLRs and, quite honestly, who cares? The only valid considerations for balanced inputs are 1) very long cabling runs between a pre-amp and amplifier or, 2) when connecting components which utilize fully balanced circuit design so as to maintain that balance throughout the chain of equipment. As the Clayton S-40 is not of the balanced design, that pretty much negates the need for balanced inputs saving you a few bucks on additional hardware which is not needed.
The most useful feature on the back panel, to a reviewer in particular, is a power LED. It is located directly above the single ended inputs, making it nearly impossible to damage a loudspeaker (when inserting a signal cable) by forgetting to power down the amp. Nice touch! In the lower left corner are a series of panel mounted fuse holders, for convenient fuse changing, as well as an external grounding point. The unit rests on four feet of aircraft quality aluminum that, after extensive testing, were found to be as effective or more effective, sonically, than any other type of feet I tried under the amp. What struck me as unusual about the back panel is the application of a second set of four feet, identical to the four on the bottom, one in each respective corner. These are provided to protect the cabling on the back panel form being smashed up against something (a wall, the back of a cabinet, etc.) when positioning the amp.
Powering up is a treat. It is fully 6 seconds after toggling the power switch to the on position before the first of two relays closes. It is another 3 seconds before the second closes and the status lights acknowledge that the unit is ready for action. My only real complaint comes from something which was already changed to meet the concerns of other consumers. While the WBTs are unarguably more sturdy and attractive, they are very difficult to tighten thoroughly. As they do not have a hexagonal end, which would allow for the use of a "Post Man" or similar type wrench, they must be hand tightened. This can be difficult, especially for someone who changes wire often or who wants to get a really good bite on todays larger varieties of loudspeaker cable. Oh well, if that is all I have to complain about, it is little enough.
Welcome To The Machine
My Clayton saga begins with a communication from SoundStage! editor Doug Schneider. It seemed harmless enough. Would I consider reviewing for SoundStage! as well as authoring my column, Synergizing? My answer was a resounding yes. I had actually missed reviewing since I had closed the door on my rag, the audio analyst, and started writing for David Robinson and the extraordinary team at Positive Feedback Magazine. It would be a pleasure.
I hardly had time to delete the response for my email folder when the message came in that Terry Rossen, of TRI, the manufacturers representatives for Clayton Audio, would like to "turn me on" to the Clayton sound. The first thing I asked for was a little background on the company.
Clayton Audio is located in, of all places, Clayton, a picturesque suburb of St. Louis. The company was founded in 1994 by Wilson Shen. Wilson had been at IBM for 14 years as a system designer and previous to that, had spent time at RCA. The company spokesman, Dr. John Nye, is a professor of Economics at Washington University in St. Louis, and a classical music enthusiast, whose listening evaluations helped shaped the Clayton's final sound.
The results of this collaboration have yielded two designs, one being the single chassis stereo unit, the S-40, which retails for $2950. The second design, a mono block pair designated M-70 that Marc Mickelson reviewed in the August 1996 SoundStage! issue (Doug Blackburn performed a followup review in March 1997), is also built on the exact same chassis as the S-40. Both the stereo and the mono models are somewhat unconventional in todays world of solid state amplification. They both utilize the latest generation Motorola bipolar power transistors, configured as emitter followers (current driven), rather than MOSFETs in a voltage driven output stage. They also employ very low negative feed back designs, another oddity for current solid state design. Hmmmmmm. This was getting interesting.
When the two men decided to join forces, it was a given that they wanted to produce only reference quality amplification for those who valued the palpability and elegance of natural, live sound. They settled on these new Motorola semiconductors, which would be their first ever application in an audio device. These new and unique bipolar output transistors are multiply paralleled in an effort to afford smooth sound, long-term reliability, and extreme stability. To that end, they chose to employ only pure class A designs.
At this point, a brief explanation of amplifier types, and their operational modes, is in order. There are two basic types of power amplifiers today, the Push-Pull and the Single Ended designs. These terms apply to the methods of operation used with the power output devices in order to achieve the final signal amplification. With the Single Ended variety, one transistor (or a group of transistors working together) is used to reproduce the entire output waveform. In the Push-Pull method, two separate transistors (or groups of transistors working together) are used to reconstruct the signal. One of each of the devices (or group of devices) is then responsible for only one half of the resultant output waveform. Because the Clayton is of the Push-Pull variety, as are the majority of todays audio amplifiers, I will limit the rest of the discussion to the methods, or classes, of operation for that particular design.
Picture a sine wave. Got it? Good. Now, envision a horizontal line running directly through that sine wave at exactly the vertical mid-point, now referred to as our null point. We now have the top one half of the waveform, or the crests, residing above the horizontal line. The bottom one half of the waveform, the troughs, reside below our imaginary null point, the horizontal line. In the Push-Pull design, one of the two transistors (or groups of transistors) is responsible for reproducing that top half of the waveform and the other, its complement, is responsible for reproducing the lower half of the waveform. In other words, one complement recreates the crests and the other the troughs. Which complement is on and which is off at any given time is determined by where the drive signal is, in relationship to that null point. Above the null point (our imaginary line running horizontally through the full sine wave), and the Push complement is in its duty cycle. Below our null point, and the Pull compliment is in its duty cycle. Now we can look at how the power for each half of the waveform is managed, which will describe its method, or class, of operation.
Class B amplifiers are typified by having one of the complements, responsible for only one half of the full output, turn on only during its duty cycle. It then turns completely off when it is done reproducing its half of the output and rests while the other complement runs through its duty cycle. When that second complement is finished, and the drive signal swings back past the null point into the first complements half of the waveform, it then switches back on again. In other words, each complement is only on when the audio drive signal requires it to be. It then switches completely off as soon as it is done with its half of the signal.
In class A amplifiers, both halves of the complement are on all the time. This means neither half of the Push-Pull complement ever shuts off nor throttles back from full current draw, even during the half of the cycle that it is at rest. This is achieved by the application of a forward bias current applied to both complements so that, even with no drive signal, each complement remains fully on. Because they have the same amount of current running through them at all times, under duty and at rest, they draw as much power at idle as they do at full volume!
Class A/B is simply a combination of the two previous methods. Each complement draws current during the entire cycle, just drawing slightly less during its rest half of the cycle. This prevents it from ever switching completely off, thereby providing a much faster turn on response than a class B device when called upon to deliver its half of the output.
If you were to take a close look at the resultant output signal from each class of operation, you could see why no one uses pure class B amplifiers for audio applications. There is a marked distortion, right in the middle (vertically) of the reproduced audio signal, as the complement called upon for duty takes a fraction of a second to "switch" on. The brief period of time required for turn on causes a gross distortion in the waveform. The result is very amusical. Class A/B is a much better method, as each transistor is always slightly on. This prevents "hard" on and off switching, smoothing out the "notch" distortion from class B operation quite considerably. Most of todays audio amplifiers operate in Class A/B. Finally, with class A operation, the devices are completely on all the time yielding the lowest switching distortion available from a Push-Pull design.
As you would expect given Wilsons background, the power supplies are built to a standard that would embarrass many much higher priced designs and are said to have temperature tolerances superior to many of those "super amps." The S-40 uses two 69,000 uF computer grade capacitors for the shared supply and each channel has its own additional pair of 4,700 uF capacitors. This means the S-40s total capacity is a whopping 156,800 uF (2 x 69k plus 4 x 4.7k) in conjunction with a 1 KVA transformer. This little guy is said to develop 100 amps of current! Can you say spot welding?
The S-40 seems quite conservatively rated and, based both on the power supply configuration and its performance, appears to have enormous current reserves. This is essential in order to drive the sometimes wildly varying speaker loads presented by some of todays loudspeakers with aplomb. The S-40 is said to double its output into 4 ohms and continues to develop usable power down to 1 ohm! This amplifier was designed to handle difficult loads in a manner that has all the traditional strengths of solid state design; deft bass control, abundant power, high current delivery and wide frequency response. At the same time, Wilson wanted to produce a refined, grainless sound with good depth and imaging that recalls - without seeking to imitate - the best attributes of tube equipment.
Wilson feels that parts selection is critical. During his stint with IBM, Wilson worked closely with the Motorola engineers. This relationship paid off, not only for IBM, bit it also helped Clayton later when Wilson turned his efforts to the audiophile market. His relationship with Motorola led to samples and technical support during the design period of both the Clayton prototypes. As Wilson puts it, "I selected all the good stuff from the marketplace." Carefully selected audiophile-grade parts are used throughout, including wiring from D.H. Labs, FETs from Siliconnix, rectifier bridges from IOR, switches from C&K, signal input/output connectors from WBT, relays from Omron and capacitors from Sprague (picked only after going through various samples from Mallory, Siemans, Philips and Nichicon).
The custom-made heat sink for the Clayton amplifiers presented itself as the biggest challenge for Wilson. No one was interested in manufacturing the 9" x 18" x 2" fin heat sink in the small quantities he required for start up. The heat sink design is an integral part of the amplifier. It not only serves to conduct heat away from the discreet devices, but it doubles as the top of the chassis and is required to house the PC board as well. Once again, Wilsons long term relationship with "Big Blue" paid off. A project manager of IBMs IPO (International Purchase Organization) found a major heat sink manufacturer who was willing to take on the project.
The Clayton Audio project started with the M-70 mono blocks. The S-40 uses the same chassis for a lower power output stereo rig, attempting to keep the same sonic qualities of the big sibling. Wilson says he borrowed this concept from his favorite line of automobiles, BMW. As Wilson states, they have always utilized the same chassis with differing motors, such as the 540i and the 528i.
Before I go into my description of the S-40s performance, I want to take a minute to thank my extended listening group. By allowing me to substitute the unit into a wide array of systems, I have had an opportunity to bring to light this amps performance with a broad variety of associated equipment. I sincerely appreciate the kindness of Hal (whose system appears under our synergistic systems as firstname.lastname@example.org), the Gallo-meister, Dr. D and the Piano Man.
Wish You Were Here
Right out of the box, the S-40 sounded a bit constricted, flat and harsh. That is to be expected, I guess. Not necessarily those particular traits, but I firmly believe that no component, active or passive, is at its best until it has been run in for a minimum of 100 hours. Some devices take even longer to come into there own. So, no critical listening was done to the unit for the first week out of the box.
After all the burn in with both Compact Disc's and FM, I fired up my ol' Nitty Gritty and dropped needle to groove. The first thing apparent with this amp was a fairly forward presentation, as if I had moved several rows closer to the performance. Yet not in the way some lesser models provide an "in your face" immediacy that is, in my opinion, annoying and incorrect. It's presence is remarkable. It provides an enchanting intimacy with chamber pieces and a startlingly "live" sense to most rock, blues and jazz.
Judging by its near effortless dynamics and stunning transient capability at reasonable volumes, I have no doubt it delivers more than it claims in the power department. I had played Rock N Roll at volumes much louder than normal while cooking during the run in period and the unit never stumbled. As a joke, I emailed Terry Rossen that he must have accidentally sent me the "experimental 100 watt per channel" prototype. Chris Layton's drum snap near the beginning of the title cut from Stevie Ray Vaughn's Couldn't Stand The Weather is sharply rendered in its attack: crisp and finely defined. The visceral assault on your senses throughout "L'Daddy" from James Newton Howard's James Newton Howard & Friends is breathtaking. This amp never foundered with complex dynamic material unless it was asked to play way past its capability. If you intend to ask it to develop 110 dB peaks, you may as well forget it. At realistic listening levels of say 80 to 95 dB, performance in this category is superb. This units dynamic performance belies its modest power rating.
Also immediately discernible is this amplifiers uncanny ability to ride extremely tight rein over the sound stage once it throws it into place. Listening to the comical "Church" from Lyle Lovett's Joshua Judges Ruth, in which Lyle valiantly tries to talk the prolix preacher out of the pulpit so the hungry congregation can go eat, demonstrated the unit's ability to accurately portray the layering of the instruments. In this cut, the voices of the choir in the background and the location of the two soloists and Lyle more to the foreground is steadfastly recreated. Absolutely first rate! With the right speakers, they completely get out of their own way and leave only the musical event. Ive never heard this done any better, at any price.
This particular attribute simply stood out time and time again. With the 1977 Crosby, Stills & Nash release CSN, the cut "Fair Game" is sprinkled with a myriad of percussion "noise makers" of all types, maracas, shakers, stuff like that (you'd never guess I'm not a musician). They all take on a definite "place" throughout the soundstage and then never budge from the location they initially occupy. With the 1982 Crosby, Stills & Nash release Daylight Again, the S-40 offered the most articulate and deepest sense of layering Ive ever experienced from this disc. It has an uncanny ability to present a realistic sense of the liveness of the room as vocals and instruments decay.
The opening of Roger Waters Amused To Death offers the sound of barking dogs off to the extreme stage right, almost directly off my shoulder and seeming to be some 60 or 70 feet away. This was presented so realistically that Katana, my resident audiophile feline, jumped from his seat next to me and ran to the front door (also to my immediate right) and voiced his strong disapproval for the whole thing.
In the opening to Rush's "Witch Hunt" from Moving Pictures, lots, and I do mean LOTS, of little things are going on within the stage. Nothing is misplaced, nothing wanders and nothing is slighted. One of the particulars I use on this track is this indiscriminate "percussion sound" that occurs at 2:04 and again at 2:12 into the song. It has always fascinated me, as I have never been sure what makes the sound or exactly from where it emanates. It was succinctly recreated centered and about three feet off the floor. The opening tom roll was breathtaking, revealing not only left to right positioning, but front to back queues as well. In this respect, the Clayton is second to none in my experience.
With complex passages (like the opening from Prokofiev's "Sythian Suite") or delicacies like massed strings, it is very competent at unraveling the dense and often overwhelming layers of material. It has no trouble both placing those layers in vise-like precision throughout the soundstage and never offered the slightest hint of congestion or indistinctness. Occasionally, under dynamic taxation, the upper registers offered just a hint of hardness. For the most part, they were presented with a delicacy and ease bordering on effortlessness. This is a common stumbling block for many lesser amplifiers.
"She's Already Made Up Her Mind," again from Joshua Judges Ruth, shows the depth, speed and tautness the amplifier is able to exhibit at the lowest frequencies. Moving to both my shaded dog and London ffrr of Saint-Saéns Symphony No. 3, the organ symphony, showed yet again this amp is no slouch in the bass control department. Good solid bass, tight and fast, but just a bit short in terms of both absolute control and the ability to reach to the very bottom. With a few amplifiers, the room virtually pressurizes on the lowest of the organ notes, some reaching well below 20 Hz. The S-40 offers just the slightest loss of weight here by comparison. This slight inadequacy was also evident when auditioned with friend Gallo-Meister's (so dubbed for his incredible home brewing abilities) VMPS Super Tower III's. It just doesn't excavate the absolute depths.
Moving to Ricki Lee Jones's self titled debut Ricki Lee Jones and Tori Amos's Little Earthquakes was a real treat. Ricki's wily charm comes through in abundance on tracks like "Easy Money." The piano nearly comes to life on tracks like "On Saturday Afternoons in 1963." It does such a superb job with piano's and voices, two of the hardest things to get "right," that I didnt want the music to end. With Tori, only occasionally, when playing fairly loudly, was there the slightest trace of hardness evident in the higher registers of her voice (in "Happy Phantom" and "Mother") and on some piano excursions. This may have been attributable to my Threshold FET nine/e rather than the diminutive Clayton. However, as I did notice this tendency when auditioning the S-40 in other systems, I have to come back to it as the culprit. Higher frequencies typically were presented very crisply and with fine detail, yet without that etched, edgy quality so many other solid state entrants can impart.
The male voice is presented wonderfully as well. The three distinct voices of David Crosby, Stephen Stills and Graham Nash are reproduced with chilling body and power. Listen to cuts like "Daylight Again" and "Find The Cost Of Freedom" from the 1991 Atlantic four disc compilation Crosby, Stills & Nash (way recommended, by the way). The robust, charismatic voice of Stevie Ray Vaughn, which is all too often overlooked in favor of his obvious guitar mastery, is astonishingly emotive in cuts like "Tin Pan Alley" and "The Things (That) I Used To Do" from Couldn't Stand The Weather.
This amp does an exceedingly good job at communicating the "space" of and the "air" around the instruments of a recording, as well as presenting the space in which the recording was made. It is able to wring the utmost detail from low level passages and to resolve the utter quietness found in some recordings that can give them that stark sense of reality. Introducing this amp into my reference system provided the last word in this area.
This was the single biggest achievement for me. As a long time owner/lover of full range electrostatic panels, I've grown accustom to their ability to delve down to the level of the highest associated noise floor and resolve low level detail and micro dynamics. I have to admit to possessing a strong bias here. The best amplifiers I've experienced can both "reach" down into and "play" that manifest blackness. This amp redefines that limit in my experience.
Rhythmic coordination is excellent. Although there was occasionally a slight loss of dynamic focus at the lowest registers, it is certainly not a serious transgression. Musical timing is preserved with exquisite coherency. So much so that I often caught myself forgetting that I was "reviewing" and finding myself just completely drawn into the music. Which is one of the reasons this review took nearly three months to complete. I can think of much worse distractions!
Suffice it to say that David Sanborn's sax lilts sweet and clear. Miles trumpet packs that signature brassy bite. Neal Young's guitar is blazing and ragged. James Cotton's harp literally growls and barks on cue. Ivan Moravec and Glenn Gould at the piano almost congeal before you. Jascha Heifetz' Stradivarius cries and pleads with elation. Janos Starker's cello swells with body and bloom. Sweetmans sax is so vital that you almost smell cigarette smoke around you. This amplifier is very neutral and extremely musical.
Have A Cigar
I put this little devil thorough its paces. I fed it signal from a wide range of pre-amps including my Threshold FET nine/e, a Nakamichi CA5, a Quicksilver Audio Line Stage, a Reference Line Audio Pre-eminence One A (passive), an Electrocompaniet Pre-ampliwire 1, and an Audio Alchemy DLC. It is safe to say that the S-40 DOES NOT CARE FOR the lower output impedance of passive pre-amps. The absolute worst performance came with the coupling to the Reference Line passive. I urge you to look elsewhere for an amplifier if you plan to use any passive pre amplifier. Both the Threshold and the Nakamichi showed off just a tad of hardness (in my opinion their only significant weakness) under dynamic taxation, but were truly excellent matches otherwise. The Quicksilver and Electrocompaniet exhibited a loss in the upper registers with the S-40, but faired well in overall smoothness and presentation. The DLC was a competent match, and with the right loudspeaker, sparked a very lively conversation with this amp.
Both my Linn LP12/Magnepan Unitrac 1 and Dr. Ds Oracle Delphi/Graham 1.5t utilized a Monster Cable Sigma Genesis 2000 moving coil cartridge to provide the vinyl playback duties. Both tables fared extremely well. The warmth and richness of the medium realizes its full potential under the gentle and persuasive coaxing of this superb little upstart.
Ones and zeros were provided by a Luxman D105u, an Audio Alchemy DDC v1.2, a stock Audio Alchemy DDC v3.0, the Channel Island Audio modded Audio Alchemy DDC v3.0 with the MPS power supply (both v3.0 versions of the AA DACs were fed from the Audio Alchemy DDS Pro and DTI PRO 32), an Adcom GDA 600, an Optimus CD-3400 and a Pioneer Elite CD45. The digital front ends really had their respective strengths and weaknesses laid bare in association with the Clayton. The little Optimus CD-3400 showed itself to be only a barely competent device. The Adcom, Luxman and Pioneer all showed their respective flaws, but also basked in their strengths with the S-40. The three different AA DACs under comparison showed the capability of each successive tier of improvement. My v1.2 sounded the best it ever has, reaching levels of warmth and presentation I previously though impossible. It also revealed a less than perfect bass control and a little of its color throughout the bandwidth, along with a slight tendency toward "whitish" treble. The CIA modded and MPS powered v3.0 showed that it can hold its own with the big digital rigs. Wow! This amp really allowed me to differentiate the often times seemingly subtle differences in any of the sources to which it was attached. This amp will reveal ANY flaw in any component to which it is connected, up or down stream!
Interconnects mated with the Clayton came from Nordost, StraightWire, LAT, D.H. Labs, Esoteric and my home brews (dubbed Silver Signal Tape). Winners here were the Nordost, StraightWire and my home brews. The D.H. Labs were very synergistic as well, proving to be the strongest price to performance competitor. The LAT and Esoteric just didnt seem to channel the same magic as the others.
Amp to speaker connections were provided by Nordost, StraightWire, MIT, LAT, D.H. Labs and, again, my home brews (see Talkin Shop Archives - Cables). The Nordost and the D.H. Labs T-14 bi-wires clearly are the price to performance winners here. Give this little guy some serious contenders (like the MITs and my home brews), and it really shows its stuff.
The S-40 was paired with some very different speakers: modified Acoustat 2+2 Medallion; Celestion 100; the refrigerator sized, 13-driver-per-cabinet, VMPS Super Tower III; Von Schweikert Research VR-4; severely modified KEF CS5; Audio Concepts Sapphire II ti; Gallo Nucleus Solo.
Whoda thunk? This little 40 watt marvel drove my giant capacitors, er, electrostatics, to an SPL of 95 dB. No strain, no glare. Just beautiful, liquid music. The astounding presentation of the Gallos was at its absolute finest. Their blinding speed and unflappable soundstage and image were pure magic when hitched to the Clayton. The imposing VMPSs sparkled, but didnt quite come to life. The VR-4s suffered from the pairing with the passive pre amp. I couldnt really tell how they liked the Clayton. Considering the rest of my findings, I suspect that, sans the passive pre-amp, there might be magic in the making. The Clayton/Quicksilver/Adcom/Audio Concepts combo was less than overwhelming. Midrange was warm and detailed, but the highs lost their detail and the bass suffered, even with the passive Audio Concepts subs in the chain. Since the KEFs could only be tested with the Electrocompaniet, I cannot be sure if the high frequency roll off was attributable to the pre-amp, the speakers or the sixty foot dedicated run of single ended cable between the pre-amp and the amp.
Shine On You Crazy Diamond
Lets see now. Exquisite build quality and ergonomics. Impeccable staging and imaging. Breathtaking dynamics. Accuracy of timbre and octave to octave balance. Perfectly coherent timing and pace. Effortless yet detailed high frequency extension. Solid, if not unrestricted, low frequency performance. Stunningly delightful resolution. Totally musical. This amp does it ALL. It not only accurately recreates the signal it is given, it delves into and reveals the message of the music. After all, isnt that the real trick?
Geez, I wonder if I can stuff my old amp into the Clayton box when it is time to send it back? Lets see, what if I put it in the box end first? No, too tall. What about trying the back first? Nope. Too tall again. Maybe if I just stuffed it into the box and taped it all up I could blame it on a clumsy freight driver. No, they would open the box to inspect the damage and Id be found out. Damn! I guess there is only one option. For the first time since 1989, Ive decided to bite the bullet and purchase the device under test. It is that good! What more can I tell you about it?
|Clayton Audio S-40 Stereo Amplifier
Price: $2950 USD
Clayton Audio Responds:
Wow. Another great write-up in SoundStage! We have very little to add to Greg's thorough discussion! But we would like to make one minor comment. Some passive line stages have a different output impedance, sometimes closer impedance matching is necessary to achieve the best performance from our amps.