Nagra VPA monoblock power amplifier Page 3

Imaging was enhanced by another quality, one more difficult to describe. I've called it "inner light" before, some quality of openness and warmth in the upper midrange and treble that's especially evident with female vocals. I've heard it with 300Bs and good 6550s—like the Svetlanas. I've heard this inner light warmer and brighter with some other amplifiers—certain OTL amplifiers—and, on one memorable occasion, as a smoldering, almost hidden inner illumination. The big 845s had it too, but very slightly. It's just a suggestion, nothing too gross or pyrotechnic—just enough to put the blush in a singer's cheek and a pout on her lips as she manifests herself between the speakers.

This relatively subtle quality was coupled with a broad illumination of the soundstage and the performers upon it. Again, nothing obvious or overdone—just transparent, open, and revealing, with a hint of warmth to match the flicker of that inner light, so to speak. And the resolution of that openness in the upper midrange and above was possible because of the speed, clarity, and coherence of the presentation. The VPAs always sounded as if they had a fast rise-time; leading-edge transients were snappy and startling but never exaggerated. And the energetic pace, timing, and energy pulled the rest of the acoustic envelope smartly along behind it: bloom, harmonic interplay, and decay were beautifully rendered. The speed of decay was almost too good, imparting a slightly dry characteristic in comparison to the Wet School of tube-amp design.

I'd never say that the VPAs sounded "sweet" on top, but they sure weren't sour. Clean, extended, detailed, revealing, and dynamic, maybe, but not sweet. Euphony isn't Nagra's At the same time, at the very top, the amps (and, I'm assuming it's safe to say, the 845s) stepped back slightly. To me it was a bit cool up there, a light balm for those hot recordings where the engineer slumped unconscious over the mixing board!

In the midrange, the VPA was a delight. Totally Nagra, the amplifier never troweled on thickly, but the beauty, nuance, and texture on tap will surely drive lucky owners mad with desire.

Let's now turn our attentions to the bass range. What exactly can 50W do on the JMlab Utopias? Good question. Well, the French speakers are about 94.5dB sensitive, so that's pretty good. But the big-port reflex woofer, I've always thought, liked power and grip. Then, too, the impedance in the midbass drops down to three point something or other; once again, grunt is good. I haven't really changed my mind about it, but I'll tell you: Within their power envelope, the VPAs did a spectacular job of controlling the Utopias and going way down with élan, power, and definition.

Is this the hem or the haw, you might wonder. Neither, I assure you. While the VPAs didn't have the horsepower to set up the really huge and overwhelming acoustic of some of the solid-state powermeisters we've auditioned, they did a credible job of sounding like 100Wpc amps—until I exceeded the posted speed limit. With the Utopias, the trick was to crank up the volume until the tubes started to bottom out, as it were, then back off a dB or so. Within these limits, the VPAs always sounded large and in charge, no excuses, if perhaps just a touch smaller in overall scale and impact than the solid-state kilowatt boys, or the giant, luscious VTL Wotans with their 48 (!) 6550s (footnote 2).

But run with the output tubes just below "saturation," the VPAs sounded first-rate all the way, and the dynamics were never less than terrific. Could I have stood it a touch louder? Sure, but not much. Did the power prove a limiting factor in the review? No, absolutely not. In fact, Nagra had "approved" the match with the Utopias during an earlier visit, when then importer Steve Lee turned up with two suitcases that, what a surprise, contained a pair of VPAs.

It was interesting to note the relationship between relative loudness and the amps' power output, as indicated on the Load Match Meter (also calibrated in watts). When they say it's the first watt that counts, they're not kidding. What surprised me was how much volume and apparent power the VPAs put out between just one and five or seven watts. In fact, orchestral works, trip hop, and Ellington sounded really loud and impactful when tickling 25 or 30W. Above that, things began to get a little loose and out of control. But it was interesting to hear how, for example, the plucked bass on Patricia Barber's Modern Cool (Premonition PREM-741-2) sounded so powerful and present, so pitch-differentiated and acoustic, while never using much more than seven or eight watts. Just goes to show: like the man said, everything's relative.

Modern Cool was just the disc to prove that indeed, E=MC2. "She's a Lady" is a good place to start if you're looking for fabulous vocals and a powerfully rendered bass. Argh, that voice...she's terrific. Via the Nagras, I was freaking yet again over this great recording. The airiness, transparency, hugely palpable imaging, sharp dynamics, and midrange development were all treats. The bass was beautifully rendered: rich, fast, acoustic, and complete. The VPAs barely lifted their power indicators past five or seven watts, even while dishing out terrific control, power, and pitch definition in the deepest nether regions.

Looking for big bass transients, I cued up Loop Guru's Loop Bites Dog (World Domination WDM 10066-2). Once again, I was impressed. Watching the indicators flicker from a mere 6 to 12W or so, I found myself listening as loud as I'd ever care to, with full power and control from top to bottom. I'd guess the 845s don't really have all that much headroom in this circuit. They put out like champs until clipping, which they do relatively "softly," as is tubes' wont. Overdriving the VPAs resulted in bloat and distortion in the bass, and a certain confusion and lack of precision higher in the frequency spectrum. But that was about it.

Footnote 2: And 48 biasing operations! Oufff, my back...
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Audiophile Systems, Ltd.
8709 Castle Park Drive
Indianapolis, IN 46256
(317) 849-5880
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