VTL Reference D/A processor Page 3

The treble was exquisitely smooth and free of edge. Cymbals had more of the delicate quality of brass being struck, with their harmonic structure intact, rather than sounding superimposed on a layer of whitish grundge. The treble grain that often obscures musical detail in CD playback was noticeably absent, allowing the listener to hear the wealth of nuance at the lowest level of presentation. Similarly, sibilance was not spitty and annoying, as it often tends to be from CD. Instruments' high-frequency harmonic characters seemed natural, utterly free from stridency or edge. The brittle quality often heard from CD that imparts a metallic hardness to treble reproduction was utterly absent in the VTL. In fact, the VTL achieved the most natural timbral rendering of any digital processor I've heard.

Compared with most other processors—including the Stax DAC-X1t—the VTL's treble was more laid-back and polite. The Stax tended to be a little more analytical, presenting treble detail with greater contrast. For example, the harpsichord in the "Suite in F" from Handel's Water Music (Harmonia Mundi HMU 907010) assumed a more forward position in the soundstage, increasing its musical contribution to the work when reproduced by the Stax. Conversely, the harpsichord was more subtle and less etched through the VTL. Although the VTL's presentation was soft, sweet, and mellow, it was never overly romantic or syrupy. Instead, I heard an abundance of detail, coupled with resolution of fine textures, that belied its relaxed presentation. I've found that other smooth-sounding digital processors—the Melior Digital Center reviewed last month, for example—tend to obscure musical nuances and low-level information.

Interestingly, my impressions of the VTL D/A's rendering of detail was remarkably similar to my feelings about the VTL 225W Deluxe monoblocks I reviewed last January (Vol.13 No.1), and which subsequently became my reference amplifiers. I wrote: "Instead of having detail thrust at the listener, I had to 'lean into' the music to hear it. The latter was a more rewarding experience: I felt drawn into, and intimate with, the performance instead of listening from a distance." This is exactly how I felt about the VTL D/A: the presentation of detail didn't keep me at arm's length from the music.

On most recordings I preferred the VTL's presentation of treble textures and rendering of detail to that of the Stax. On a few less-than-bright recordings, or those lacking detail, I felt the VTL had less air and life than the Stax. Overall, however, I think the VTL is closer to live music in this regard. Both processors, though, are far better at resolving musical nuances than any other units I've heard.

It is just this fine and delicate nuance that makes music so much more interesting, compelling, and immediate. I believe that this is a major reason that digital often sounds less involving than analog. Listening to digital reproduction in isolation may give the impression that nothing is overtly wrong, but it fails to achieve an intimacy with the listener. However, if an analog reproduction of the same music is heard in comparison, the digital's loss of low-level information is striking (footnote 4).

However, the VTL D/A (and the Stax) have made a quantum leap forward in bridging this gap. Both these processors achieve an unprecedented level of performance in resolving minute detail. I am surprised by the fact that as D/A converters make huge leaps in performance—giving the listener a more powerful microscope, if you will—they reveal more and more musical detail in existing CDs, despite the fact that nearly all CDs have been encoded with low-resolution A/D converters.

The VTL's midrange performance was similarly impressive, with smooth, velvety textures. There was also a nice sense of bloom around instruments not even approached by any processor except the Stax. My impressions of the VTL's smooth treble textures and presentation of detail apply equally to the midrange. Lead instruments and voice tended to be slightly recessed in the soundstage, and with soft textures. Scott Kreitzer's tenor sax, on his Kick'n Off album (Cexton CR11264), was laid-back, effortless, and had a texture that can only be described as luscious. It had a warm roundness, yet with a rich breathy quality, that pulled the listener into the performance. I attribute this impression to the VTL's complete lack of glare and hardness through the midrange and treble. Again, the Stax tended to present a more vivid, forward, and immediate rendering, with a slightly etched character.

I found the VTL's soundstaging abilities to be extraordinary, rivaled only by the Stax's. The feeling of instrumental images existing in three-dimensional space, each surrounded by a cushion of air, was remarkable. The VTL's presentation was the antithesis of flat, cardboard sterility. Some instrumental outlines were clearly heard behind others, conveying a convincing illusion of depth. Although image outlines were not bloated or frequency-dependent, they did tend to be slightly blurred and indistinct around the edges in comparison with the Stax. This created the effect of homogenizing images with each other, making an individual instrument harder to isolate in the presentation. This was especially evident on acoustic duets. For example, Julianne Baird's voice was slightly melded with the lute on The English Lute Song (Dorian DOR-90109). There was not the sense of each instrument existing independently in space heard through the Stax. Similarly, there was less differentiation between Baird's voice and the natural reverberation of the hall. Through the Stax, the hall reflections could clearly be heard behind and around her voice.

It was also more difficult to isolate an individual instrument and hear it on its own through the VTL. The vibes, for example, in Jazz at the Pawnshop (Proprius PRCD-7778) tended to be slightly obscured and indistinct when comping. Through the Stax, the vibes' sharply defined outlines tended to allow them to exist independently of the other instruments without congestion. This contributed to the Stax's slightly better sense of soundstage depth. In addition, I felt the Stax had a slightly wider soundstage than the VTL. Although both processors achieve unparalleled soundstage transparency, the nod goes to the Stax for its better resolution of image outlines. However, I felt that the VTL resolved low-level cues better than any processor I've heard.

I must stress that in these descriptions of the VTL's presentation and performance in relation to the Stax, one should keep in mind that the differences between these two extraordinary processors are more subtle than the differences between them and all other processors I've auditioned. They are both, in my opinion, significantly better than other Class A contenders.

Moving to low-frequency reproduction, I found the VTL's bass to be rounder and warmer than that of many other processors, including the Stax. Pitch definition was less precise through the VTL, lacking the trampoline-like tautness heard from the Stax. The lowermost component of bass drum was lacking a little meat and dynamic impact through the VTL.

Although I feel that the Stax errs in the direction of being overly lean and dry in the bass (noted in my original review), the VTL is a little on the warm side of reality. However, one could argue that the Stax is overly analytical in the bass, while the VTL has bloom and musicality. Some listeners may find the VTL's low-frequency presentation more satisfying, despite the less articulate rendering.

The VTL Digital to Analogue Converter sets new standards for digital playback quality in some areas. The presentation aspects in which the VTL excels—and clearly beats the competition—are also the most important musically. These include exquisitely smooth and liquid midrange and treble textures, complete freedom from hash and grain, and resolution of the smallest musical detail and nuance. These qualities combined synergistically to create an involving intimacy with the music not equalled by any other digital processor. Although the Stax DAC-X1t came very close in these areas, I felt the VTL offered a more satisfying musical experience.

However, the VTL fell short of the Stax's performance in other regards. The VTL didn't have the razor-sharp edge to image outlines, instead tending to homogenize individual instruments with the entire presentation. Low-frequency reproduction was on the warm side, rather than articulate and well-defined. Pitch definition was superior through the Stax, as was LF extension and dynamic impact. Overall, the VTL can be characterized as warm, round, silky-smooth, and liquid. This is contrasted with the Stax's slightly etched treble character and bass dryness, which contribute to a lean and more detailed presentation. Note, however, that I believe both these processors provide a qualitatively different experience from digital playback, unmatched by units employing conventional IC DACs, regardless of their design.

I must reiterate what I consider to be a serious liability of the VTL D/A: the lack of a muting circuit. The horrendous burst of noise that occurs under a variety of conditions (those that cause the processor to lose lock with an incoming signal) is most disconcerting. Although one learns to work around this problem, it is never far from one's mind when considering changing digital cables, switching inputs, etc. In addition, I am concerned about the quite large de-emphasis error of 1.5dB at 16kHz.

Despite the presentation tradeoffs with the Stax, the bottom line is that the VTL D/A Converter provided the most musical and enjoyable digital playback I've heard. On that basis, it earns a hearty recommendation, provided the reader is aware of the caveats in the previous paragraph. However, since my review sample was serial number 003, it is not unreasonable to expect design refinements in future production.

Imagine the reaction in 1982 of the CD's promoters (and the general public) if you told them that in 1990, the benchmark of performance for digital playback would be set by digital processors realized with vacuum tubes.

Footnote 4: Sheffield Lab recorded some of their later projects digitally for the CD release simultaneously with the direct-to-disc LP lacquer cutting. I have both the CD and direct-to-disc LP (in mint condition) of James Newton Howard and Friends (CD24). The comparison is striking. The difference is made all the more apparent by the fact that the LP signal was never stored on analog tape. Similarly, all Reference Recordings projects are recorded simultaneously on digital and analog tape, with the digital master providing the source for the CD release, the analog master creating the LP.
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Vacuum Tube Logic of America
4774 Murrietta, Suites 9 & 10
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(909) 627-5944
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