Balanced Audio Technology VK-5 preamplifier & VK-60/75 power amplifiers Page 4

The last part of the Transformer Saga came to pass just as the review process concluded. Steve Bednarski called to say that, as a result of the problems that some other users and I were having with the VK-60's transformers, the mechanical design of the transformers had been modified to make its performance more consistently reliable and noise-free. They wanted to send me a new pair of VK-60s containing the new transformers. (The redesign involved the power as well as the output transformers.) "Why not?" I said, especially given that Steve and Victor were going to come by to help me pack up the old amps and install the new ones. (At nearly 90 lbs, these amplifiers are no fun to move around.)

The new transformers have the same basic electrical specifications, but the changes in construction are fairly substantial. The new ones use a thicker wire in the windings, they're heavily epoxy-potted, additional magnetic shielding has been used, and they sport attractive metal caps instead of the original plastic ones. The appearance has been enhanced considerably, and so, I believe, has the performance. First of all, the new transformers are now dead quiet mechanically. More important, the latest production amplifiers sounded significantly better; the extreme highs have greater purity (footnote 3).

The sound of a really good audio system is difficult to describe. Oh, we can use terms like imaging, tonal balance, and bass extension, but ultimately it comes down to a feeling, a general sense that what you're listening to is much like live music. The best audio systems are those that allow you to forget—at least momentarily—that you're listening to electromechanical devices, and make you believe that this could be the real thing. Systems and components that make it relatively easy to suspend disbelief are the audiophile's Holy Grail. The BAT VK-5 and the VK-60 fall into this rare category of components.

As might be expected, the VK-5 and the VK-60 were at their best when used as a matched pair in balanced mode with a balanced source. (Like the VK-5 and the VK-60, the Sonic Frontiers SFD-2 Mk.II digital processor is a fully balanced design.) With the preamp and power amp thoroughly burned-in and warmed up (footnote 4). well-recorded CDs sounded open, smooth, transparent, detailed, and dynamic. Listening to the HDCD-encoded Big Band Basie CD (Reference Recordings RR-63CD), I was simply knocked out by the clarity and power of the sound—especially the massed trumpets, which are notoriously difficult to reproduce. Played at a realistic level (ie, loud), these had tremendous punch, with the kind of screaming quality that trumpets evince in real life, without harshness or edginess but also without sounding tamed or softened. Of course, the recording itself and the rest of the system (especially the Dunlavy SC-IVs) had a lot to do with producing the effect, but the VK-5 and the VK-60 more than held their own in the partnership.

The VK-5/VK-60 combination's strongest suit was probably harmonic accuracy—or, as Sam Tellig calls it, "truth of timbre." Musical instruments and voices sounded more like themselves and less like electronic reproductions. I think this, more than any other attribute, is what attracts people to tube equipment. With many tube amplifiers, especially the low-powered single-ended triode variety, this impression of timbral verisimilitude comes at a cost of high measured harmonic distortion; arguably, we're dealing with harmonic enhancement rather than accuracy. As I write this, I haven't seen any of the measurements on the VK-5 or the VK-60, but to my ears the traditional tube virtues seem to have been obtained without the equipment acting like a harmonic enhancer.

Voices, male and female, had what was at times a startling degree of realism. This was true even with some recordings that are far from the state of the art. Listening late at night to a CD of a 1980 live concert by Luciano Pavarotti and Mirella Freni (London 421 862-2), I found it easy to imagine that I was momentarily transported to Modena, listening to two of the greatest singers of our time at the tops of their forms (footnote 5). Sylvia McNair's voice on Sure Thing: The Jerome Kern Songbook (Philips 442 129-2) had a presence that was quite spooky. Part of this effect is a function of the equipment's ability to preserve the spatial cues, but I think the major reason is the preservation of the harmonics that define a voice as human and distinctive. No, we're not talking about reproduced sound that's indistinguishable from the original—we still have a good distance to go in that direction—but the VK-5 and the VK-60 added so little in the way of an "electronic" character that it was easier to maintain the illusion that this was real.

In listening to the VK-5 and the VK-60, I was mindful of Martin Colloms' suggestion that balanced components tend to be less involving, with losses in dynamic contrast and rhythm. Colloms is a highly respected reviewer who combines technical expertise with an audiophile orientation. I can't comment on the specific pieces of equipment he refers to in criticizing balanced designs—I simply haven't listened to that equipment under familiar conditions. What I can say is that nothing I heard during my VK-5 and VK-60 auditioning made me question the validity of the balanced approach as implemented by BAT. Given the right source material, I had no trouble following every detail of dynamic expression; the music was anything but laid-back or boring.

One of the CDs I brought home from Hi-Fi '95, the Los Angeles Stereophile show, was the Reel One sampler from PopeMusic. At the show, a lot of people were playing PopeMusic's Lori Lieberman CD, which I thought sounded like an extremely good recording of something I didn't particularly want to hear. It's excerpted on the sampler, and listening at home confirmed my initial impressions. (I feel the same way about Sara K., Rebecca Pidgeon, and Jennifer Warnes. So sue me.) However, the sampler also included excerpts from Unlikely Silhouettes (PopeMusic PM 1002-2), which features new recordings of the Shchedrin/Bizet Carmen and Shostakovich's Bolt.

Footnote 3: Customers who own VK-60s that have the old power transformer should contact BAT for a free update.

Footnote 4: The VK-5 seemed to need very little burn-in, perhaps because it was listened to at some length before I received it. The latest pair of VK-60s had only a minimal amount of burn-in time on them, and they did seem to "relax" after having been on and used for three or four days, with further minor improvements over a couple of weeks. Once burned-in, the VK-5 and the VK-60 sounded pretty good right after being turned on (the VK-60's autobias circuit must be very effective). The sound continued to improve for about an hour.

Footnote 5: Interestingly, a similar concert recorded in Modena 13 years later (London 443 260-2) finds Pavarotti in nearly as good voice, but the sound is harsh and artificial. This is progress?