Solid State Power Amp Reviews

The name Muse Electronics is probably unfamiliar to most audiophiles, requiring some background on the company. Muse is the hi-fi offshoot of a company called Sound Code Systems, a manufacturer of professional sound-reinforcement speaker cabinets and power amplifiers. Founded in 1980, SCS enjoyed some success with its line of MOSFET professional power amplifiers. In 1988, SCS's Michael Goddard and Kevin Halverson, both audiophiles and tube aficionados, redesigned their amplifier for the high-end hi-fi market.

The results are the Model One Hundred (a 100Wpc stereo power amplifier) and the Model One Hundred Fifty ($1900/pair), the 125W monoblock reviewed here. According to Michael Goddard, the primary design goal was to achieve a tube sound with the reliability and ruggedness of transistors. MartinLogan CLS speakers were used extensively during the design/listen/design cycle. As a result of their listening auditions and redesign, many of the changes have now been incorporated into their professional products.

On the face of it, the power amplifier has the simplest conceptual task of any audio component. Fed an audio signal at its input, all it has to do to satisfy the demands for current made by the loudspeaker is to modulate a high-voltage voltage supply with that signal. Yet power amplifiers vary enormously in their ability to perform that task without editorializing. As a result, when I find an amplifier that appears to step out of the way of the music in the manner I desire, I make the commitment, I buy it, and I stick with it.

It was a dark and stormy night. A biting, cold wind cut through Sam's skimpy jacket; ice crystals clung tenaciously to his bushy moustache. As he approached his front door, visions of a toasty-warm, Krell-heated listening room softened the chill. He could feel the glow already; his Krell amp had been on all day, awaiting his return.

James Bongiorno, the engineer behind the Sumo Andromeda, has enjoyed a long and colorful career as an audio amplifier designer. He has cast himself at times as an enfant terrible, exploding at audio critics and running scandalous advertisements (footnote 1). His best-known amplifier is the Ampzilla, produced by Great American Sound, but he also designed the Dyna 400. Currently Jim is living on a boat and serving as part-time consultant to the Sumo Company.

A decade ago, many predicted that amplifiers with switching or class-D output stages would come to dominate high-end audio. In a post–Peak Oil world in which the price of energy would always continue to rise, a class-D amplifier's very high efficiency in converting AC from the wall outlet into speaker-driving power would be a killer benefit. Although a conventional push-pull class-B amplifier has a theoretical efficiency of 78.5%, which would seem usefully high, this efficiency is obtained only at the onset of clipping; the need for the output devices to carry a standing bias current reduces that efficiency considerably, typically to around 50%. Class-A amplifiers are even less efficient, with a maximum of 25%; ie, three times as much power is dissipated by the amplifier as waste heat as is used to drive the loudspeaker (see "Sam's Space" in this issue).

Hang around long enough, and your reward is often to be taken for granted or ignored. Canadian electronics manufacturer Bryston Ltd. has been around since the mid-1970s, and while—if coverage by Stereophile is any indication—the company has hardly been ignored, it's often taken for granted.