Solid State Power Amp Reviews

When Philip O'Hanlon of On a Higher Note, Luxman's US distributor, delivered the B-1000F monoblocks, it took three of us to wrestle their shipping crates into my house and then into the listening room. Once they were unpacked, it still took two of us to maneuver each of them into position—at 141 lbs and 16.9" wide by 11.6" high by 23.3" deep, the B-1000F is far from easy to shift. Fortunately, O'Hanlon had also brought along a pair of Stillpoint stands specifically made for the Luxmans; the B-1000Fs certainly wouldn't have fit into my equipment racks. (The Stillpoints are lovely things. I recommend 'em if you go for the B-1000Fs.)

When O'Hanlon told me the price of the stands—$2500/pair—I asked what the amps cost.

"Fifty-five," he said.

"You mean the stands are 45% of the price of the amps?"

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).

In Greek mythology, Atlas was the Titan who supported the heavens—although he's more commonly shown supporting Earth itself. (Funny thing, that: the globe he was always shown supporting actually did once represent the cosmos, but at some point became the Earth.) According to Hygenus, Atlas was the son of Aether, the personification of the sky and heaven, and Gaia, the personification of the Earth. Atlas was brother to Prometheus (foresight), Epithemius (hindsight), and Menoetius (a warrior whose insolence got him smitten by a lightning bolt from Zeus, resulting in a name synonymous with "ruined strength").

Musical Fidelity's founder, Antony Michaelson, arrived at my house to help me set up the two chassis of his sleek, limited-edition, $30,000 Titan power amplifier. (The task requires at least two people.) A week later, a representative of Musical Fidelity's US importer, KEF America, dropped by to listen and to deliver three of Musical Fidelity's new V-series products: a phono preamp, a DAC, and a headphone amp. All three fit comfortably into a small paper bag; the price of the three was $700.

Over the course of his 30-plus years in high-end audio, Nelson Pass's designs have never been far from the leading edge. In his first Threshold amplifiers he pioneered the use of dynamically adjusting bias and cascode circuitry; then, in the later Stasis models, he switched gears to the simpler approach of pure class-A. All were innovative designs, and among the very best-sounding amps of their time, but were just warmups for what was to come. In 1991, Pass Labs introduced the Aleph 0, a class-A amplifier that was a startling departure from conventional solid-state designs and combined design elements generally thought mutually exclusive: transistors, single-ended operation, and the ability to output 75Wpc into an 8-ohm load. Not surprisingly, the Aleph 0 sounded like nothing else, and became the basis for the widely acclaimed series of Pass Labs amplifiers that evolved over the next decade.

High-tech, compact, and lightweight, Chord's entry-level SPM 650 power amplifier ($4995) promises robust power output, low distortion and noise, flat and ultra-wideband frequency response, and bulletproof reliability—all in what seems an impossibly small package measuring 16.4" wide by 3.4" high by 13.8" deep and weighing only 22 lbs.

I've been enthusiastically tracking the development of Bel Canto's class-D amplifiers, from their original TriPath-based models to their more recent designs based on Bang & Olufsen's ICEpower modules. With each step, Bel Canto has improved their amps' sound quality and reliability.