YBA 1 Alpha HC power amplifier Page 2
The YBA 1 has been in production for several years, with the usual minor changes made in successive production runs. The review unit was from the latest production, incorporating all the changes that, in Yves-Bernard André's view, effected a significant sonic improvement. I had listened to the review sample informally for some time when I received a call from Ian McArthur, YBA's local rep, saying that, upon reflection, Yves-Bernard thought that one of the production changes was ultimately detrimental to the sound. It had to do with the silicone damping compound used on the transistors and associated heatsinks. Previously, they had used a black compound that looked messy, and they had changed it to a more transparent formulation.
The problem was that the new compound turned out to have a tendency to dry out in time, and Yves-Bernard had detected a subtle sonic degradation in some units, one that he felt was due to this drying-out process. Production was changed back to the ugly but sonically superior black stuff, and YBA retrieved the review sample of the YBA 1, replacing the damping compound. I had a good listen to the amplifier before it was taken away and after it was returned, and I can't say I heard any difference. (Of course, the delay between "A" and "B" in this A/B comparison was several weeks, and, in any case, I may not have had the sample long enough for there to have been significant drying out. Or maybe M. André's ears are of a more golden hue than mine.)
YBA pays a lot of attention to vibration control, and cautions about the importance of the surface on which the amplifier is placed. I had some concerns about how well my setup would optimize this parameter, concerns that turned out to be justified. Normally, I place amplifiers on the listening room's heavily-carpeted floor, using sharply pointed cones (Michael Green's AudioPoints are the best I've found) to penetrate the carpet to the hardwood underneath. The YBA 1 has three integral supports designed to "ground" vibration; however, these are not pointed, so they would not penetrate the carpet.
My first attempt to optimize the YBA 1's placement was to put it on a 1½"-thick wooden butcher's block, which was itself placed on the carpet. I had found this arrangement to work well with some other amplifiers, and the YBA 1 gave no indication that it was unhappy. However, just to be sure, I placed four AudioPoints under the amp. Lo and behold, there was an appreciable gain in detail and transparency. All subsequent auditioning was done with this setup. I suspect that the YBA 1's own feet provide optimal support when the amplifier is placed in a more typical equipment rack, but, as always, some experimentation with alternative supports, such as AudioPoints, would be worthwhile.
The all-amplifiers-sound-the-same folks obviously feel otherwise, but I think some amplifiers have a distinctive sound that's almost immediately apparent in the context of a familiar audio system. It may be a type of coloration, eg, hardness or softness in the upper octaves; or it may be a particularly effective way of dealing with some aspect of sound reproduction, eg, dynamics or bass. Other amplifiers have a more subtle sonic character, and it may take a lot of listening to identify it (footnote 1). The YBA 1 falls into the latter category—which might explain why I had the unit for a longer period than any other amplifier I've reviewed. (Anyway, that's my story, and I'm sticking to it!)
The YBA 1 HC is certainly one smooth amplifier, to the extent that it may initially give the impression of sounding somewhat bland. There's no spurious excitement or exaggeration of dynamics, and no part of the frequency spectrum is thrust forward or emphasized. There's none of the hyper-real focus and detail that some people think of as transparency. However, as you keep listening, you realize that the detail is there, it's just not being shoved in your face.
The two guitars on Track 2 of the familiar Chesky Jazz Sampler Test CD (JD-37) sounded very natural, and there was a good sense of the ambience of the recording environment. The South American percussion sounds on Track 3 came through in a relaxed, everything-in-its-place manner, and the voice had a pleasant roundness and warmth. The YBA 1, playing through the Dunlavy SC-IVs, preserved the slightly forward perspective of the recent Stereophile chamber music recording (Festival, STPH007-2), with the sounds of the live audience apparent but not annoyingly so. The strings in Appalachian Spring had a "rosiny" quality that was much like the real thing. Low-level dynamics were particularly impressive, allowing the communication of the music's subtle ebb-and-flow.
What the YBA 1 emphatically does not have is the typical solid-state sound. In fact, one speaker designer, who sets up his speakers differently depending on whether they're being driven by solid-state or tube electronics (less toe-in with solid-state amps), told me that he treats YBA as if it were a tube amp. If being tubelike means to be free of the characteristic upper midrange/low treble grain of most solid-state amplifiers, then the YBA-1 is indeed tubelike (footnote 2). To my ears, first-rate tube amps, like the Balanced Audio Technology VK-60, have midrange liquidity and a three-dimensionality of images within the soundfield that no solid-state amplifier I've heard fully matches, although the YBA 1 Alpha HC comes very close.
Footnote 1: The fact that it may take prolonged listening to identify a component's sonic character doesn't mean that it's unimportant. With audio equipment as with people, first impressions are often not the most reliable way of judging character.
Footnote 2: Manufacturers of solid-state electronics often claim that their products sound tubelike, but how often do manufacturers of tube electronics claim that their products sound like solid-state? Is there a lesson here?