Solid State Power Amp Reviews

"Why no review of the Ayre V-3?" queried Stephen Slaughter in July's "Letters" column, echoing several urgent posts to my e-mail address. Word of mouth on this remarkable 100Wpc amplifier was reaching fever pitch. Show reports over the last several years had sounded a consistent note—rooms that demoed with V-3s kept getting mentioned in "Best of Show" overviews. Naturally, this also meant that the pendulum had started its backward swing. "It's not really as good as people are saying," one WCES attendee confided in me. "That's why they won't give it to critics."

Several issues back, I mentioned a major "new wave" of power amplifiers coming along: the Adcom 555, the New York Audio Labs transistor-tube hybrids, and the latest Krells, for example. They demonstrate that major audible improvements are still possible in something as well-explored as the power amplifier. Not only that, some of these products demonstrate that superior performance can be combined with relatively low price.

This is something we don't see too often: an entirely new approach to power amplifier design. As Quad points out in its literature for the 405, class-A operation of transistors provides the lowest distortion, but drastically limits the amount of power an output transistor can deliver without overheating. (Most transistor amps use class-AB output operation, in which each of a pair of power transistors handles part of each signal cycle and shuts down during the other part. Imperfect synchronism between the two halves causes the familiar "crossover distortion," which accounts for most solid-state sound. In class-A operation, each output transistor draws current though the entirety of each signal cycle, eliminating the crossover transition but doubling the amount of time current is drawn, and thus tending to cause the transistor to heat up more.)