Solid State Power Amp Reviews

My writing desk looks out over a large garden with chickens, bees, and feral cats. My chair sits only six feet from loudspeakers, playing softly on my left. Between the speakers sits whatever painting I am working on. That painting hangs no more than 10 feet from the oscilloscope and drill press in my kitchen. Best of all, my desk is only six feet from squadrons of ravenous sparrows attacking the suet cage on the fence outside my window.

Back in 1999, while reviewing the Wazoo integrated amplifier from Bow Technologies, I learned that its designer and company founder, Bo Christensen, had previously founded another audio company. That's how I discovered Primare. Over the years, various products from Primare have appeared at audio shows but never grabbed my attention. In a recent EISA press presentation, however, Primare showcased an eight-channel amplifier that did, given my interest in multichannel audio. I was glad to be able to attend.

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.

I have a way of grating on people's nerves. Ask Marina, my wife. She calls it my "mean streak."

Talk about a Scarlet Letter. The term class-D amplification, which describes PS Audio's new M1200 monoblocks, exists only because another amplifier innovation had already parked in the "C" space. Soon after appearing in high-performance audio gear, class-D became synonymous with "digital amplification" in part because, like early CDs, many listeners found the sound glary, hard, and unpleasant. Besides, class-D is related to "pulse width modulation" and requires a low-pass filter to block high-frequency pulses—that sure sounds digital. But they're not (see Bruno Putzeys sidebar).

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.)

When Editor Jim Austin asked me to review the new Rogue Audio DragoN monoblock amplifier, my first thought was, "Isn't that Herb's beat?"

The DragoN monoblock is the latest amplifier from Rogue Audio's Mark O'Brien. The DragoN is a hybrid of tubes and class-D, using Hypex's class-D NCore module in the output stage. Hence the big N in the name of the product.