PS Audio Stellar M1200

MONOBLOCK POWER AMPLIFIER

- MICHAEL FREMER

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 sidebar, p.85).

To this day, many audio enthusiasts remain unconvinced by class-D technology. Why?

According to Bruno Putzeys, one of the format’s leading innovators, “a high-performance class-D amplifier contradicts every single item of audiophile superstition. Designing one is the ultimate test to see if you’ve got your head screwed on right.”1 Maybe that’s why. Judging by this powerful amplifier’s sonic performance, Stellar M1200 designer Darren Myers definitely has his head “screwed on right”!

Putzeys also said, in the same interview with Sound & Vision’s Bob Ankosko, that “there are a few distortion mechanisms conspicuously missing in class-D, mostly those related to the input stage of a class-A(B) solid state amplifier and nonlinear capacitances” that are also “missing in valve [tube] amplifiers.” This newfangled technology, then, has much in common with old-school tubes.