Solid State Power Amp Reviews

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John Atkinson Posted: Nov 29, 2011 Published: Sep 01, 1991 1 comments
To judge from the $6400 Mimesis 8, Goldmund walks its own way when it comes to power amplifier design. High-end solid-state amplifiers from US companies like Krell, Mark Levinson, Threshold, and the Jeff Rowland Design Group marry massive power supplies to large numbers of output devices (these often heavily biased to run in class-A), built on chassis of such nonmagnetic materials as aluminum. By contrast, the Mimesis 8 has a magnetic (steel) chassis, and uses a relatively modest power supply, that for each channel based on two main 4700µF reservoir capacitors. The 8 offers just two pairs per channel of complementary output MOSFETs (Hitachi K134/J49). These carry a modest bias current of around 80mA total.
Kalman Rubinson Posted: Nov 23, 2011 4 comments
As I write this, in early August, the global economy is in flux and the stock market gyrates, seeming in stark contrast with the gleaming, luxurious audio components that surround me. Perhaps there is some prescience in my rising interest in reasonably priced, high-performance products, as exemplified by the Oppo Digital BDP-95 universal Blu-ray player, which I reviewed in this column in September. Surely there must be other products that provide truly excellent sound at prices strikingly lower than expected.
John Atkinson Posted: Sep 02, 2011 10 comments
"That's just silly on so many counts, Antony."

I was talking last winter to Musical Fidelity's Antony Michaelson, who had been enthusing about his forthcoming stereo amplifier, the AMS100. It would be physically enormous—almost a yard deep—and commensurately heavy at 220 lbs. Despite its bulk, its maximum rated output would be just 100Wpc into 8 ohms. It would also be expensive, at $19,999. And to cock a snoot at environmentalists and their concerns, the AMS100's output stage would be biased into class-A up to its rated 8 ohm power, meaning that, even when not playing music, it will draw around 10 amps from a typical US wall supply of 120V. This also means that it will run very hot, making the amplifier impracticable for summer use in homes without central air-conditioning. Like mine.

Martin Colloms Posted: Aug 24, 2011 Published: Dec 01, 1990 0 comments
Cycles can be seen in the fortunes of companies. Likewise cycles can be seen in the performance of companies' products. A particular range will appear to have got it just right, whatever "it" is. The designer may have hit a winning streak and thus steal a lead over the competition. C-J set a new state-of-the-art preamp standard in the late '80s with their Premier Seven, and some of that expertise and experience are beginning to pay off in the shape of new high-performance preamplifiers at realistic prices. Moreover, the pressure was on to develop better power amplifiers to match. Two important products have emerged from all this in C-J's moderately priced FET range, namely the PF-1 preamplifier and the matching MF-200 power amp. By audiophile standards, these are moderately priced at $1295 and $1995, respectively.
Larry Greenhill Posted: Aug 19, 2011 1 comments
"Larry, you have too many amplifiers!" exclaimed John Atkinson during a recent visit. This surprised me—I didn't think it was possible to have too many amps. While I'm not going to open an amp museum, I do have a starter collection of Mark Levinson amplifiers from different eras. This either makes me exactly the right or the wrong person to size up Mark Levinson's new No.532H.
Michael Fremer Posted: Aug 12, 2011 1 comments
That is not a typo. The company is named Soulution—as in soul commitment to designing and manufacturing the finest audio gear it knows how, as in souldiering on in the face of skeptics who can't imagine why a power amplifier that puts out 130Wpc into 8 ohms or 260 into 4 ohms should cost $45,000, or weigh as much as a small pickup truck.
Robert Harley Posted: May 03, 2011 Published: Jan 01, 1990 0 comments
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.

Erick Lichte Posted: Apr 12, 2011 7 comments
Audio reviewers are kinda slutty. Not sexually, of course, but in the way we promiscuously go through equipment. Like the most popular girl in school, or Tiger Woods, we have our choice of any hot thing we want, whenever we want it. Heck, reviewers don't even have to pick up equipment at bars or clubs: the stuff is delivered right to our homes. We use the gear for a few months, then send it packing once the next hottie comes over to play in our room.
John Atkinson Posted: Mar 09, 2011 6 comments
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.
Wes Phillips Posted: Feb 18, 2011 5 comments
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?"

Thomas J. Norton Posted: Oct 01, 2010 Published: Jan 01, 1994 0 comments
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.
Art Dudley Posted: Sep 13, 2010 0 comments
One of my favorite parental duties is dispensing advice that's calculated to make me sound wiser than I am. Among those pearls: Every so often you should change your point of view—your philosophies—just to see if your opinions can stand the strain. In doing so, you may discover a few things that are better than you expected them to be!
Larry Greenhill Posted: Sep 02, 2010 Published: Oct 02, 1984 0 comments
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.
Kalman Rubinson Posted: Jul 06, 2010 Published: Mar 06, 2009 1 comments
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.
John Atkinson Posted: Mar 15, 2010 0 comments
A decade ago, many predicted that amplifiers with switching or class-D1 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).

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