VAC PA80/80 power amplifier
especially when I'm lonely.
I love the nuances of emotion.
It's nothing new, nothing new,
The sound of glowing glass... (with apologies to Nick Lowe)
I do, I really do love the sound of a tube amplifier. I also love the glow, the physical warmth, even the smell of heated glass. Years ago, when I had my first system that could be dubbed "high-end," my wife and I would occasionally turn off all the room lights and spend romantic evenings in front of our Marantz 8B—much as other couples would cuddle by the fireplace.
But I'm not kinky about it—my real reason for loving tubed gear is that I love to wallow in that sense of emotional immediacy that hot glass seems singularly capable of presenting. So it's not surprising, really, that at the 1994 Summer Consumer Electronics Show I was drawn into a warm cave of a room where VAC's amplifiers shone out of the darkness like diamonds in a dungheap. "Toobz," I moaned, shambling into the room. "Pret-ty! Wes like."
Recognizing a bad-sound burnout when he saw one, Kevin Hayes sat me down in the sweet spot and plied me with glorious music until I was reasonably coherent. The sound from his Renaissance 140 monoblocks was intimate, yet surprisingly dynamic. Of all the exhibits I heard in Chicago, only the VAC room kept bringing me back—and I wasn't alone. Sometimes I couldn't even get in the door for the crowds. On my final restorative trip, Hayes mentioned a project he was working on. "We're almost ready to bring an affordable amp to market—one that shares a lot with what you're hearing now. Would you be interested in listening to it?"
Oh my, yes indeedy. And so, in the final months of '94, the PA80/80 showed up on my doorstep.
The architecture of feeling
The VAC PA80/80 is a single chassis wide-band low-feedback stereo amplifier rated at 80Wpc. The input circuitry of the 80/80 is based upon the venerable D.T.N. Williamson design and features a direct-coupled input amplifier and phase splitter, which results in low phase shift and precise balance of the phase splitter at all frequencies. The input/splitter and driver tubes are 12AU7 triodes operated in class-A with no cut-off or grid current. The output stage, derived from VAC's respected PA90C, features partial-triode ("ultralinear") push/pull operation, although VAC can convert the amplifiers to full triode operation at additional cost. The output tubes supplied are Golden Dragon KT88s, which operate in "rich" class-AB, being biased to an idle current of 70mA per tube with a B+ voltage of approximately 535VDC. KT90s or 6550As may also be used, but adjustments need be made to the bias point if you choose these.
The parts quality and build are superb. The transformers are impressive 14 lb, 22-section, ultra-wideband output jobbies, and polypropylene and polystyrene capacitors are used throughout. High-current rectifiers, low-ESR power supply, highest quality wiring—all the usual audiophile suspects are here.
The PA80/80 is, to my eyes at least, a beautiful amplifier—broad-shouldered and robust looking. It presents its tubes for inspection in front of its three potted transformers. Four KT88 output tubes stand in a single rank directly in front of transformers, while two pairs of 12AU7s stand in staggered array to their front. Six 450V-rated capacitors in a row mark the center of the top-plate, dividing the eight tubes into right- and left-channel groupings. The low-line front panel sports a power switch on the right and the VAC logo (in gold-plate) on the left. The center of the face is occupied by four LEDs over four tube-biasing attenuators. Since the LEDs change color from green to red through a range of orangey tints, one can accept the factory-specified bias point or match the quartet to a personally chosen bias—a nice touch.
The amplifier accepts a standard IEC modular power cable, so the tweakish may experiment with AC cords. A slow-blow 4A fuse is attached to the mains by way of a clever compartment that requires that the AC cable be removed in order to obtain access. I like this arrangement—it's logical and easy to use. The speaker connections hint at the amplifier's robust nature: there are hot taps for 2 ohm, 4 ohm, and 8 ohm operation (plus ground, of course), and the negative feedback level stays constant regardless of your choice of tap. The rugged, milled-metal posts themselves accept heavy-duty spades as well as bananas—although, because of the multiple taps, they're not intended for dual bananas. The amplifier is austere in its black and black matte finish, although dramatic contrasts are achieved through the gold accents on the front panel and on top of the transformer cases. It is also one heavy sumbitch.