Tube Power Amp Reviews

Today is Monday, February 5, and it's so buttercupping cold outside that the custodian couldn't get our school's oil burner started. Consequently, my daughter is home for the day, playing on the rug in front of the fireplace. (Santa brought a wooden castle and a fine selection of medieval figurines, some of which are headed for the dungeon as we speak.) I'm at my desk in the music room, on the upwind side of the house—and the wind is murder. The west wall is cold. The north wall is cold. The floorboards are cold. But the air inside is warm as toast: I'm driving my Quad ESL speakers with a Joule Electra VZN-80 amplifier ($12,000) that isn't at all bashful about squandering a goodly amount of energy as heat. I can't think of a more delightful quality for an amp to have, at least on a day like this.

When I unpacked the Rogue Audio Atlas, I didn't know how much it cost. After examining its chassis of high-grade steel, its silver-anodized aluminum faceplate, its sleek and slightly rounded edges, and, above all, its two chunk-o'brick transformers—for such a little thing (a foot-and-a-half square by half-a-foot high), it's heavy—I guessed around five grand. Then I called Rogue Audio and learned that it retails for $1395.

Everybody loves a bargain. No—make that: Most people love a bargain. Some just want the best, and they don't care about the cost. Some even distrust and reject out of hand any product that's not expensive enough. If you're one of these people, you might as well stop reading this review right now—the PrimaLuna ProLogue Three and ProLogue Seven are not for you. $1395 for a tube preamp? $2695 for a pair of 70Wpc tube monoblocks equipped with four KT88 tubes each? Must be based on old designs in the public domain using cheap parts carelessly assembled...

In this hobby, nothing's for nothing. To get that gorgeous midrange, with its harmonic depth and inner detail, tube-amp enthusiasts are willing to give up some things in the bass. Tube folks put up with heat and occasional maintenance—routine or otherwise. To get the ideal middle, fans of single-ended triodes are even willing to shave off considerable dynamic range and settle for ultra-efficient speakers that often have limited response at the frequency extremes. Those who say nothing is lost by preferring tubes are in denial.

Just who does Bruce Rozenblit think he is? And why is he saying those things about the late Julius Futterman? Rozenblit, relying heavily for guidance on his Electrical Engineering degree, has crafted an OTL (output-transformerless) amplifier that flies in the face of contemporary design dogma. To hear Bruce tell it, he's tamed the breed—this is how OTLs should have been done to start with, Futterman notwithstanding.

Although I retain a firm hold on the established audio world, and recognize and value all that it has achieved, I feel inexorably driven to make some space in my life for single-ended amplifiers—more especially, those that eschew negative feedback (footnote 1). A classic if costly example of the art is the Cary CAD-805C, which, to my ears, has earned the right to teach audiophiles what negative feedback really sounds like, and what damage it can do to the musical message when poorly handled. This shouldn't be taken as an out-of-hand dismissal of those many great pieces of electronics and amplification that use negative feedback—it is simply an acknowledgment, or even an assertion that negative feedback generates a sound of its own.

It's been 10 years since Balanced Audio Technology (BAT) introduced their first products: the VK-5 line-stage preamplifier and the VK-60 power amplifier. (I reviewed both in the December 1995 Stereophile, Vol.18 No.12.) The success of these and other BAT products has allowed designer Victor Khomenko (the "VK" of the model designations) and partner Steve Bednarski to quit their day jobs at Hewlett-Packard; they were joined by Geoff Poor as a partner to handle the sales end of the enterprise. BAT's current lineup includes several preamps, phono stages, a CD player, and tube as well as solid-state amplifiers. The top of BAT's preamp range is the VK-51SE, which costs $9000; their top tube power amp is the VK-150SE monoblock ($17,000/pair); if you want their best phono stage, the VK-P10 will set you back $8000.