Convergent Audio Technology SL1 Renaissance preamplifier Page 4

If I had to use just three words to name the attributes that made the Renaissance special, they would be transparency, resolution, and dynamics.

By transparency I mean the ability of a component to let me "see" into the music, so that it is obscured as little as possible by the technology involved in reproducing it. Not having JA's experience in engineering recordings, I can't say to what extent the reproduction matches what was heard in the recording session, but I can tell when it sounds more like live music and less like a reproduction. (Strangely enough, this is the case even when some of the instruments in a recording are of the electronic sort.) It's a matter of the component doing a better job of getting out of the way of the music—and that's what I heard with the SL1 Renaissance. The Ultimate was very good in this respect, but the Renaissance was better still.

For critical comparisons, I normally use a relatively few recordings that I'm very familiar with. Almost invariably, the first of these is the Chesky Records Jazz Sampler & Audiophile Test Compact Disc, Vol.1 (JD37). Track 3 features a wide range of percussion instruments as well as singing. This time, having matched levels to the extent possible, I first listened though the Ultimate, which sounded as it had before: very good indeed. When I switched to the Renaissance, the instruments seemed to be more clearly defined in space, and the ambience of the recording studio itself was more "present." I then switched back to the Ultimate and increased its volume by one notch, to make sure that I was not merely responding to the small difference in volume. The sound was a little louder, but my initial conclusion was confirmed: The Ultimate, while sounding very good on its own, did not communicate as much of the recording as did the Renaissance. I repeated this comparison several times, with a number of recordings, and my conclusion remained the same: The Renaissance was more transparent to the source, which made listening to music more involving.

By resolution I mean a component's ability to reproduce sonic details. Although transparency and resolution are often interrelated, they're not the same thing. The sound may be transparent to the source signal, adding little in the way of colorations or artifacts, but it may not be able to resolve the smallest differences in that signal. Conversely, a component may resolve a lot of detail, but add distortions and artifacts that keep it from providing a truly transparent "window" on the sound.

I'd always considered the performance of the Ultimate to be very much in the high-resolution category, and listening to the Renaissance did not change that assessment. Unlike some "classic" tube components, which give you a smooth, musically pleasing sound but gloss over some of the details, the Ultimate gave me the best of both worlds: a highly musical presentation that was also detailed—and, at the same time, did not give the impression of being (to borrow a word from digital photo processing) oversharpened. Where the Renaissance did its special magic was to go even further down this road: more detailed than the Ultimate, but without a hint of sounding clinical, or of the details representing an artificial enhancement of resolution.

I could hear this effect most clearly in the reproduction of the human voice. Listening to Sylvia McNair's Sure Thing: The Jerome Kern Songbook (CD, Philips 442 129-2), I felt I was hearing more of the tonal richness of McNair's voice, and the piano and double bass had more of the harmonic complexities that characterize those instruments. This increase in resolution was also evident in how, with the Renaissance, my system reproduced glitches in recordings. On Sure Thing, I had previously identified what I thought was an editing error at 1:32 of "All the Things You Are" (track 10), in which two takes overlap, sounding as if another singer has joined McNair for that note. This was crystal clear through the Renaissance, but more than that, for the first time I noticed with this recording other similar if less obvious instances of McNair's voice changing character in ways that seemed to represent artifacts of the recording process. The Renaissance was also outstanding in the way it let me focus in on differences in the performance of other components in the system, such as the differences between Ayre's CX-7e and CX-7eMP CD players. (How did they differ? Watch this space . . .)

Dynamics refers to how well an audio system or component reproduces the changes in volume of the source signal. The starting point is dynamic range (the ratio between the loudest and quietest passages); more recently, the related term dynamics has been applied to refer to how well a component reproduces the ebb and flow of music.

This is another of the Renaissance's great strengths. Assuming the rest of the system is up to it, the Renaissance is capable of great dynamic range. This also happens to be one of the Avantgarde Uno Nano's long suits: the speaker can play very loud without sounding strained. The Renaissance proved an ideal partner to the Uno Nano, adding no audible distortion of its own, regardless of the volume level. A more subtle effect was in the way voices emerged from the background of silence. A magic moment of this sort is in Ariel Ramirez's Misa Criolla, as conducted by José Luis Ocejo (CD, Philips 420 955-2), when tenor José Carreras is first heard. The chorus is humming, and then you hear a solo voice of great beauty. With the Renaissance in the system, Carreras's entrance had greater "suddenness," and the interplay between the soloist and the chorus behind him was, well . . . magical.

Listening to LPs
Although I appreciate a good LP as much as the next person—well, maybe not if that person happens to be Michael Fremer—most of my listening is to CDs. (So far, I haven't found music downloads or hard-drive-based music servers tempting enough to indulge in.) My experience with the performance of the SL1 Ultimate's phono section had been that it did its job well, and the noise level—a potentially problematic area with moving-coil cartridges—while noticeable between tracks, was masked by the music. My AudioQuest AQ7000nsx cartridge is claimed to output 0.3mV, which puts it squarely in the low-output class, so it's a good example of the type of cartridge that can use the extra gain from the SL1 Renaissance's MC transformer.

What I hadn't realized was that the Ultimate's noise, even when ostensibly masked by music, was discouraging me from listening to my LPs. The difference with the Renaissance was that the electronically generated noise of its phono stage was simply inaudible. With the input switch in the Phono position and the volume turned up to a normal level but with no record playing, I could flip the Mute switch on and off and was hard put to hear any difference in the amount of noise (very low in both cases). Performing the same test with the Ultimate, there was broadband noise—not loud, but clearly audible from the listening position—with Mute turned off, and a marked reduction in noise with Mute turned on. That extra 11dB of gain from the MC stage made a real difference.

I also noticed that when I played the same LPs through the Ultimate, the listening experience was simply not as relaxing. It seems that the noise level, while mostly subliminal during music, always threatened to become audible during rests in the music, and even during low-level passages. With the Renaissance I was able to enjoy the music more, not worrying about or trying to ignore any residual noise.

And I found myself listening to more and more LPs. I dug out the audiophile LPs that had been my demonstration discs back when LP was king: The Weavers' At Carnegie Hall (Vanguard); Depth of Image (Opus 3); Arne Domnerus's Jazz at the Pawnshop (Proprius PROP 7778-79); Lincoln Mayorga and His Distinguished Colleagues Vol.III (Sheffield Lab). And they all sounded terrific! My AudioQuest AQ7000nsx cartridge is getting a bit long in the tooth, but exhibits no audible signs of wear or age. Of course, there was still surface noise, but it was less intrusive than with the Ultimate—and this was definitely not because of any top-end rolloff: the highs were fully present, with a natural, unexaggerated quality. Serious jazz fans might consider Jazz at the Pawnshop to be nothing special as far as the playing goes, but I still find it a most enjoyable recording, with a wonderful sense of ambience. The sounds of clinking glasses, people talking, and applause were all there through the Ultimate as well as through the Renaissance, but somehow the Renaissance was able to more clearly differentiate the spatial cues that created a sense of three-dimensionality.

It's quite an accomplishment, if you think about it. Is there any other audio product introduced nearly 25 years ago that, while keeping the same basic design, has continued to be developed, its designer's aim always being to provide the best possible sound rather than adding new features? I can't think of any. And while Convergent Audio Technology exhibits at the annual Consumer Electronics Show, it's been a long time since I've seen magazine ads for any CAT products. Ken Stevens seems to be following the "better mousetrap" theory of marketing—and, by all accounts, it has worked for him.

The latest SL1, the Renaissance, is a most worthy representative of this tradition. To use terms that have become hackneyed, its presentation is accurate as well as musical, allowing the system to reproduce music in a way that's faithful to the source and preserves musical values, with outstanding transparency, resolution, and dynamics. The SL1 Ultimate was an excellent preamp; in every musically relevant parameter, the SL1 Renaissance is comfortably ahead of it.

Is this the end of Ken Stevens' long development of the SL1? Has every aspect of the design and its execution been tweaked to the point at which no further improvement is possible? For now, the answer has to be "Yes." As for the future—well, knowing Ken Stevens, I wouldn't bet on it.

Convergent Audio Technology
85 High Technology
Rush, NY 14523
(585) 359-2700