September 2001Wyetech Labs Onyx Mono Amplifiers
by John Potis
My enthusiasm grew as I unboxed these two beautiful and seemingly well-made amplifiers. The steel chassis is completely welded to reduce vibration-induced signal aberrations. The chassis certainly seemed solid enough, and the highly polished brass handles allow for easy handling, not to mention that they add a very stylish touch. Wyetech uses a very high quality of paint with a baked-on primer coat. A black-enameled cast-aluminum box covers the power transformer, and topping off the output transformer is an engraved brass plate with the model designation and serial number. I commend Wyetech on a very good-looking pair of amps: the more time I spent with them, the more I appreciated their different yet tasteful aesthetics. Of course, beauty is only skin deep -- even for amplifiers.
As for inside, Wyetech Labs maintains that all stages are operated in "pure class A1 single-ended. " As with the Topaz amp, exceptionally large-value Solen polypropylene coupling capacitors are used in conjunction with custom-built Hammond output transformers for extended low-frequency response. All four output triodes are individually self-biased with only the plates tied together in quasi-parallel configuration, which Wyetech claims is nearly equivalent to having a single high-powered triode. The 11.5-pound output transformer provides 13 watts of power per amp and is said to offer absolute stability into low-impedance loads. The Onyx utilizes two high-current switches to toggle the output windings for selection of 2-, 4-, 8-, or 12-ohm loads. Wyetech also claims that due to the low distortion ultra-linear amplification stages employed, negative feedback is neither required nor used. The standard tube set supplied includes a single 5814A and a pair of NOS Phillips 6080WC output tubes. Available at a slight premium is a pair of GE 6AS7GAs, also NOS.
Inside the Onyx is a toggle switch enabling 115V or 230V 50-60Hz operation. Separate DC power supplies provide total isolation between the input and output stages. These consist of a triple pi filter for the 300V output rail and a double pi filter for the 450V input and driver rail. RC filter networks are said to be very large electrolytic capacitors and wire-wound ceramic resistors, which are said to provide an unparalleled ripple reduction that is too low to be seen on Wyetechs oscilloscope.
Let's get started!
At the flip of the on/off toggle switch, the Onyx goes through an auto-sequencing ritual, which is said to extend tube life through the proper powering on of each amp's circuitry. The filament voltage is applied for 45 seconds before the DC voltage power is applied. The amplifier signals that it's ready for operation through the illumination of a green LED.
Allowing for a brief warm-up period for the amps, I sat down and tuned into what was going on. The Onyx monoblocks were every bit as potent as I suspected they would be when used in conjunction with the Silverline Sonata IIs, which I had previously used with excellent success with amps as low in power as 7.5Wpc. The Onyx monos sounded smooth and refined, if a little laid-back.
At the end of this initial listening session, which featured classical music, I put on some raucous rock, and all of the sudden things were not quite so pleasing. While somewhat polite-sounding, the symphonic music had not hinted at a somewhat dark and overly reticent upper midrange that sucked much of the life from the energetic rock experience. Fearing a mismatch with the system as set up in my main listening room, I removed the Wyetechs to the family room where I was finishing up with a pair of ACI Jaguar 2000s. The more "cool" family-room acoustics and the Jaguars made for a much better match with the Onyx monos, and for the next few weeks the two made some really excellent music.
Now the Wyetechs were powering a pair of 87dB-sensitive ACI Jaguar 2000s, which were high-passed at 85Hz for use with a subwoofer. Obviously nobody in his right mind would consider mating 13W amplifiers with 87dB efficient speakers, but I think its important to note that once filtered of bass frequencies, the Onyx amps did an absolutely superb job driving the Jaguar 2000s. The implications should be obvious to those using smaller speakers with a powered sub who are in the market for a quality amplifier. Once a lower-powered amp is relieved of the burden of producing bass, most people would be shocked to learn how little power is required.
But I didnt have the amps for my own enjoyment; I had them so I could report on their sound. But there were too many variables at play, and getting to the bottom of the Onyx amps sound was impossible. So for better or worse, back into my listening room the amps went. And to my great surprise, I found that these were not the same amps I had removed from the room weeks earlier. It was now obvious that what I was dealing with was an issue of break-in.
The previously witnessed upper-midrange reticence was completely gone, and the tonal balance was fully linear and much more neutral. As a matter of fact, the Onyx monoblocks were just a touch more lively in the upper midrange and lower treble than my reference Herron M150s. In this regard, the Wyetech amps reminded me of the excellent Blue Circle BC8s that I had through here a very short time ago. Like the BC8s, the Onyx monoblocks had taken on a very slight forwardness that avoided making it into brightness. No matter what I put on, the sound was vivid and crisp without ever being fatiguing -- well, unless the recording was that way. The brass from the Fine Young Cannibals self-titled CD [IRS IRSD-5683] sounded somewhat brash and splashy, as were the high-hat strikes on both "Johnny Come Home" and "Suspicious Minds," and this harshness is exactly what's on the CD.
That I was bothered by it meant that the amplifier had indeed opened up and I was not suffering from a case of listener break-in. More good news was that other less-than-audiophile-quality recordings didnt exhibit this characteristic, and the amps were not so revealing as to make the majority of my CD collection unlistenable. Even the lively recording of Smash Mouths Astro Lounge [Innerscope INTD-90316] was completely enjoyable. While the CD seems to have been intentionally mixed on the brash side, it did not sound excessively so, and I was free to enjoy the bouncy rhythms, reverb-induced sense of expansive space, very focused vocals, and clean and visceral bass lines found on "Stoned."
Speaking of bass lines, the Wyetechs do bass in a way that will shock a lot of listeners who think that low power means weak and tubes mean mushy. The Onyx exhibited neither trait. Of course, it couldnt match a high-powered solid-state amp such as the Blue Circle BC8 with its 220 watts, but the Onyx were no wimps. I listened to a lot of rock with the Wyetech amps, and they never failed to satisfy. "The Dead Heart" from Midnight Oils Diesel & Dust [Columbia CK 40967] is laced with strong bass lines throughout that were particularly impressive and completely satisfying. Smooth, solid and palpable down low, the Wyetech amps never gave the idea that, on paper, I shouldnt have been hearing what I was hearing. If you have any doubts, I suggest a round with the Wyetechs and Depeche Modes "Behind The Wheel" from Music For The Masses [Sire 9 25614-2] and its synthesized, pounding bass line. It was reproduced as cleanly, solidly and crisply as Ive ever heard it, even if it was missing the last measure of "oomph" that a powerful solid-state amp can give it.
Of course, SET enthusiasts are less concerned with such loutish behavior from their amplifiers. The midrange is their focus. These days one of the first CDs I reach for often is James Taylors Hourglass [Columbia CK67912]. I cue up "Enough To Be On Your Way" and zero in on the vocals, which should image very firmly at the center of the stage and be rock-solid. They were with the Wyetechs. Then I listen for the unfettered clarity of those vocals. The better the presentation, the cleaner and more transparent the vocals should be -- and they should occupy a space completely free of the accompanying instruments. The Onyx monos didnt disappoint, and in my experience, this aspect of their performance has only been exceeded by one other amp: the 7.5Wpc Audiopax Model 3. Both amps convey a sense of complete intimacy -- that feeling that the last veil has been removed and you just cant get any closer to the music.
I moved on to December [Windham Hill WD-1025], a CD by George Winston containing nothing but piano solos. It just doesnt get much better than this. On "Peace," the Onyx monos threw up one huge and expansive soundstage. Microdynamics were superb, as the Wyetech amps rendered Winstons startling and incisive intonations at the ivories with rare aplomb. Each key-strike was delivered almost as an isolated event yet miraculously united into a tapestry of mood-stirring music as smooth as butter. Transparency and detail were such that I could sense the ever-varying intensity of each keystroke, which only served to better convey Winstons mood. No part of the pianos tonal range was emphasized over the other and the sense of recorded venue was so strong that there was no question about it, I had been transported to the original venue rather than bringing the piano into my home. I closed my eyes and I was all but there.
When it comes to classical music I gravitate to large-scale works. But I can only imagine that smaller chamber works would be a real forte of the Wyetechs. Not that they cant handle the big stuff. Macrodynamically speaking, for the most part the amps were very capable, and the only time they clipped was when I was playing "Liberty Fanfare" from Winds Of War And Peace [Wilson Audio WCD-8823]. This piece contains a healthy dose of one of the largest bass drums you will ever find recorded, but I was still able to play the track with musical peaks of 92dB in my 150-square-foot listening room without clipping.
And when I substituted in my Herron M150s and replayed the passage, the 150W amplifiers were not able to reproduce the drum portion all that much louder before the onset of clipping, and when the solid state-amps clipped, they did so in a much more hostile way than did the Onyx amps. Bass drum aside, the Wyetechs rendered this disc in a much more enjoyable manner than Id become accustomed. You see, the CD is performed by the National Symphonic Winds, and, in general, wind-symphonies are a tad one-dimensional in terms of their sound. Without the more highly accentuated contrasts of woodwinds, brass and strings common to other forms of music, I find the music on the disc a little flat and lacking excitement. That said, the utter clarity of the Wyetechs had the effect of maximizing the sonic contrasts within the piece, which had the effect of retrieving an oft-lost layer of texture, which in turn made the listening experience more interesting and enjoyable. Its been a while since I listened to the disc, and after experiencing it over the Wyetechs, Ill be using it more often, albeit with greater expectations.
Ive already mentioned the similarities to the solid-state Blue Circle BC8 that I reviewed recently. While I wouldnt dream of trying to drive the difficult speakers that I threw at the 220-watt BC8s, over the Silverline Sonata IIs, the two amps shared much in common sonically. Both amps shared that just ever-so-slightly forward upper-midrange tonality that always imparted just a sprinkling of added life to the music. Generally speaking, the Wyetech amps had the same effortless character about them that fellow SoundStage! writer David Dowdell so correctly ascribed to the Blue Circle amps in his sidebar to my review. No matter what I threw at the Onyx amplifiers, they almost always sounded robust and in total control. Microdynamics seemed on par with my own Herron Audio M150s monos, which sell for about 50% more and are champions in this regard. Midrange focus and detail are first-rate, as is treble purity. The Wyetech Onyx amplifiers do not exhibit any euphonic colorations classically attributed to tubes and at the same time possess some of the more positive attributes of the best solid-state amplifiers that Ive heard.
So after reading the preceding paragraph, you may well note the similarities between the Wyetechs and these solid-state amplifiers and wonder why consider the Onyx when it sounds so much like solid state? Good question! First, consider that the Blue Circle amps cost much more than the Wyetech Onyx amps. At about $7000, the Blue Circle amps make the $4500 price tag of the Wyetech amps look almost budget conscious. And secondly, keep in mind that the Blue Circle BC8s as well as my Herron M150s are two of the very best-sounding amplifiers Ive used in my system. So compared to other amplifiers in their price class, the Wyetech amps are genuinely excellent performers, and nobody will ever ascribe to them nasties such as hardness, brittleness or stridency that are potentially problems with lesser solid-state electronics. They do have that liquid intimacy that is at the heart of the SET experience.
I enjoyed just looking at the Wyetech Onyx mono amplifiers, and if you also consider aesthetics important, these amps will need to make no apologies. Fortunately, the good looks are only the beginning of the fun, as the amps sound as good as they look. With an appropriately chosen speaker (the list of players seems to be expanding all the time!), the Onyx monoblocks offer a roster of sonic characteristics that borrow from the best that solid-state and tube amplifiers have to offer -- solidity and control in the bass, midrange purity, clarity and intimacy, grain-free treble smoothness.
All this adds up to the kind of magic that Doug Schneider experienced with the more expensive Topaz amplifier -- and another recommendation for Wyetech.
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