VAC Avatar integrated amplifier
By Chip Stern   •   April, 2000 In Hinduism, an avatar is an incarnation of spirit—a god who descends to earth in bodily form. For Kevin Hayes of the Valve Amplification Company (VAC), the Avatar was meant to be nothing less than his defining statement of the state of the audio designer's art. Drawing on the high-tech refinements and scrupulous attention to individual components that distinguish his flagship high-end amps and preamps, Hayes has filtered it all down into one attractively priced integrated amplifier.

Can I get an amen? That's a tall order, especially in light of the High End's traditional fascination with pushing the technological envelope ever upward, regardless of real-world verities. Because, as I first suggested in my September report from HI-FI '99 in Chicago, "for High End to truly grow, it must reach out and become more inclusionary...and start preaching outside the congregation." The degree to which the Avatar has succeeded illuminates the great strides two-channel might yet make if it takes the time to sell new converts on the pleasures of true high-resolution audio—audio that keeps drawing you into a deeper involvement with the music—while bringing that uncompromising level of reproduction within easy reach.

"I think what really sets us apart," Hayes asserts, enunciating VAC's sonic goals, "is the amount of time and passion we spend in the process we refer to as 'voicing' the amplifier. I mean, it's only a matter of days to get a circuit like that working on the test bench and measuring well, but that doesn't tell you what it's going to sound like to your ear. You have the fundamental problem that things you can measure and get your hands around and tweak on the bench don't correlate to what the ear and the brain are doing in the perception of music. So the voicing process goes on for months: parts, routing, grounding configurations, subtly altering parts value up and down, change of dielectric in the range of caps, change in the way they're wrapped—all sorts of things come into play. So keeping things simple and keeping things low in feedback are important. Like our line stage has zero feedback, while the power amplifier have 6dB of loop negative feedback around it. And it all changes the sound in varying degrees."

The Avatar
The VAC amplifier's sturdy build makes it the bête noire of integrated amps—it's significantly larger and heavier than the tubed integrated amps we've evaluated over the past year. Its removable cage fits over a pair of side rails that double as handles. The chassis is so heavily braced that there's little chance the structure will ever flex. A sub-enclosure behind the 3/8" machined-aluminum faceplate houses the discrete preamp section, while a removable decorative panel on the faceplate reveals a set of four rotary bias controls—a very nice touch. The front panel's custom-machined knobs run from left to right across the top of the faceplate: source selector (Phono/CD/1-2-3), volume, Home Theater mode switch, Operate/Mute, and, in the middle, directly above the bias controls and hovering like Buddha's third eye, an illuminated, Marantz-style VU meter. On the bottom left and bottom right are Tape/Source and Power switches. In Home Theater mode, the preamp is disengaged, allowing control of the power amp by an external processor as the two-channel, liquid-cherry tube centerpiece of a 5.1-channel surround system.

Inside, all signal paths are kept as short, straight, and direct as possible in relation to the front and back panels, with power tubes and output transformers to the rear, and a centrally located switch in front of the power transformer to choose between ultralinear and triode operation. To the left are four 12AX7 tubes (two for the line stage, two for the moving-magnet/high-output moving-coil phono stage), and on the right are three 12AU7 driver tubes.

While the Avatar employs a pair of EL34 power tubes per channel, the manner in which Hayes has voiced them might be an ear-opener to some audiophiles. "I've had audiophiles tell me very knowingly that the EL34 is more romantic and the KT88 is more potent," Hayes recalls. "Well, no—you actually don't know that. All things being equal, certain tubes do have certain sonic characteristics, but people think they have a definite idea about the way power tubes sound from some broad observations they've made. Yet the same exact power tubes in a Conrad-Johnson circuit, in a Mesa circuit, or a VAC circuit will sound totally different."

Evaluation
Generally, when I first get an integrated amp or a set of speakers, I'll let it burn in for extended periods of time with music, which might involve playing a CD in Infinite Repeat mode while I sleep over successive evenings. I don't have any special burn-in discs; besides, I'd much rather hear how a piece of gear will morph and mellow and settle in musically, just the way you might experience those changes after you'd brought it home...perhaps experiencing some pangs of buyer's remorse. ("Gee, it doesn't sound like it did in the demo room...")

My 12' by 20' listening room is flanked, through an archway, by another room of roughly the same size—the traditional living-room/dining-room configuration so common in Manhattan apartments built ca 1910-30. Decorated in an admixture of Art Wrecko and Early Boys' Dorm, it's crammed with boxes, cabinets, computer gear, guitars, basses, drums, cymbals, and a bed in the northeast corner. The speakers are on a plane roughly diagonal to the bed, opposite the south wall of the adjoining listening room.

That first night, I set the most recent CD release of Miles Davis' Kind of Blue (Columbia/Legacy CK 64935) on Repeat and retired for the evening. For this definitive 1997 edition the engineers used a three-track tube Presto tape machine, like the one used on the original sessions and—for the first time, a hitherto-unused alternate master tape, recorded at the correct speed. (The pitch on the first three tracks was sharp through 35 years of LP and CD issues.) This is a beautiful old recording, lyrical and swinging, without too many radical dynamic shifts to blow me out of bed. I set the Avatar on a moderate volume level and turned in.

The bass and drum resolution were strong and detailed, the sense of depth and dimensionality exceptionally airy and realistic, even from off-axis across the room. And when Coltrane's solo came sliding up out of the rhythm on "So What," I realized I needed to back off on the volume—a little too full for sleeping. When Bill Evans's darkly tolling chords roused me on "Blue In Green," the presentation was still a tad vivid for sleeping; I got up to adjust the volume again. By the time Jimmy Cobb's sensual, sweeping snare-drum brushwork launched the famous vamp to "All Blues," I realized that I had to practically turn the volume potentiometer of the Avatar to full Off to keep things down to where the dynamics weren't so fully resolved from top to bottom that I'd pop out from under my sheets like an English muffin.

That gave me something to reflect on. In my experience, the real test of the mettle of any amp, tube or solid-state, is not at the Vlad The Impaler volume levels I usually favor, but way, way down in the realm of background music. If an amp needs to be cranked for you to feel an acoustic bass moving air, or for you to experience the drum kit both as a series of discrete sounds and as an organic blend, or for the horns and piano to emerge from the rhythm as if they had discrete images on the soundstage...then it's unlikely that you're in the presence of a true high-resolution musical instrument.

The VAC Avatar sounded like just that: a musical instrument, a real thoroughbred capable of reproducing complex dynamics and transient information without strain or coloration, and of eliciting heretofore unknown details with accuracy and grace. Taken as I was from the start with the aesthetic dimension of the Avatar—black and inscrutable, monolithic and alive—I immediately experienced a deep level of involvement with this amp, as I reveled in its refinement and control on selection after selection. Like Col. Sanders with fried chicken, the Avatar does music right.

But thoroughbreds can be a little high-strung: I experienced instances of mild tube distress during the audition process. Early on, one of the EL34 power tubes gave up the ghost, which I discovered when the VU meter failed to light up—I popped the fuse and discovered it was fried. A fresh set of power tubes, and all was well. Then, some months in, I began experiencing intermittent, peripheral noise, which soon worked itself out: there was a slight rasp, like a singer clearing his throat, then nothing. Oh happy day. But now and then, after I'd powered down for the night (always switching from Operate to Mute before turning off the power), I'd be greeted in the morning by a blown fuse.

Finally, after a hiatus of listening to other gear, I returned to the Avatar for a conclusive stretch of listening and evaluation. The noise was back—this time as a steady brush stroke. Suspecting that it might be related to the preamp tubes, with the volume turned all the way down I tapped the tubes gently with a drumstick. Sure enough, one of the driver tubes in the 12AU7 array was exceptionally microphonic. I replaced it, and all was well...with the sound. But all the way down to deadline, something was frying the first of the Avatar's two protection fuses after I'd power down for the night. A faulty power tube slowly going down and getting overbiased? I never did figure it out.

These speed bumps in the audition process didn't detract from my esteem for this integrated amp: The sound of the Avatar compared favorably to some of the finest tube and solid-state separates selling for twice its price. The speed, pacing, and dynamic control exerted by the Avatar's power section were perfectly balanced by the supple manner in which its line stage fleshed out and delineated realistic, discretely focused images.