Solid State Power Amp Reviews

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.)

I must admit that even before I connected up this amplifier I was put off by the accompanying literature. B&K makes some persuasive points about the validity (or rather the lack thereof) of some traditional amplifier tests, but the literature was so loaded with flagrant grammaticides, syntactical ineptitudes, and outright errors that I could not help but wonder if the same lack of concern had gone into the product itself (eg, the term "infrasonic" is used throughout to mean "ultrasonic"). Good copy editors aren't that hard to find; B&K should have found one.

For many audiophiles, choosing a power amplifier is a vexing problem. Just how much must one spend to get true high-end sound and a solid build quality? How much power is really needed? And what amplifiers are suitable for driving low-impedance loudspeakers?

"My car is supercharged, not turbocharged, so you see there's no throttle lag," explained Yves-Bernard André as he reversed at what seemed like 80mph up a narrow cobbled Paris street. "D'accord," I mumbled, afraid to loosen the white-knuckled grip I had on the passenger grab handles. Yves-Bernard's car may have been pointing the right way down the one-way street, but it was not actually traveling in that direction. Okay, so it was 2am and the good residents of the Dix-septième Arrondissement were busy stacking Zs (en français, "emplier les ronflements"). But I still didn't think we would've been able to explain the logic of the situation to the gendarmes (les flics, en français).