Solid State Power Amp Reviews

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J. Gordon Holt  |  Mar 03, 2010  |  First Published: Jan 03, 1987  |  0 comments
Some time ago in these pages, Anthony H. Cordesman observed rather ungraciously that the whole line of Hafler electronics "could do with reworking." This was interpreted by many readers—including the good people at the David Hafler Company—as meaning that AHC felt the entire Hafler line to be mediocre. In fact, he does not. (He had given a Hafler product a positive review a few issues previously.) Tony's comment, however, did express a sentiment that most of us at Stereophile have shared for some time: a feeling that Hafler products had slipped from the position of sonic preeminence which they enjoyed during the 1960s and '70s to one of mere excellence in a field where only preeminence is acclaimed.
Dick Olsher  |  Oct 03, 2008  |  First Published: Aug 03, 1986  |  0 comments
Yet another amp from Colorado! This is the third amp to come my way from that state (the others being the Spectrascan and the Rowland Research), and at this point, after living with it for a couple of months, I'm quite comfortable in declaring the Boulder 500 to be one helluvan amp.
Dick Olsher  |  Apr 10, 2014  |  First Published: Feb 01, 1986  |  0 comments
Very few products exude opulence as do the Rowland amplifiers: the massive chassis, the gold finish, those sculpted handles on the front plate. For some strange reason the amp reminds me of Brutus Beefcake, the golden boy of professional wrestling, upon whom I stumbled one night while flipping through the myriad channels of our cable TV. The visual impact is the same: beefy. And then there's the price: also beefy.
J. Gordon Holt  |  Oct 08, 2006  |  First Published: Jan 08, 1986  |  0 comments
Eleven years ago, Threshold Corporation entered the high-end audio market with the first amplifier ever to use sliding bias (footnote 1) in its output stages. Some 10 years later, Threshold spawned another innovation: their so-called Stasis circuitry, which yielded the S-series amplifiers. The SA-1 and its lower-powered sister SA-2 are the latest from Threshold, and are the first Threshold amps to abandon sliding bias for straight class-A operation. Both use the Stasis circuit.
Anthony H. Cordesman, J. Gordon Holt  |  Dec 29, 1995  |  First Published: Dec 29, 1985  |  0 comments
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.
Anthony H. Cordesman, John Atkinson  |  Sep 09, 2007  |  First Published: Sep 09, 1985  |  0 comments
Some readers may feel that it is pushing poetic license beyond reasonable limits to call the Krell KSA-50 a "new-wave" amplifier. It has, after all, been around for several years. The Krell KSA-50 is new-wave enough, however, to be an incredibly stiff class-A design, rather than a pseudo–class-A circuit, and its 50 watts per channel are supported by enough of a power supply to drive an arc welder. You get about 70 watts of RMS power with 8 ohms, 150 watts with 4 ohms, and sufficient watts into 2 ohms to threaten my load resistors. There is almost enough power to drive a pair of Apogee Scintillas at their ohm setting—though I'd prefer at least the Krell KSA-100.
Steven W. Watkinson, J. Gordon Holt, Sam Tellig  |  Aug 10, 2009  |  First Published: Apr 10, 1985  |  0 comments
When I first heard the Eagle 2 at the 1985 Winter CES I knew this amplifier was a winner. I was eager for a chance to get my hands on it, but I also knew that J. Gordon Holt was champing at the bit to do the same. So it came as both a surprise and a delight when ye Gracious Editor gave me first crack at the Eagle 2. I wasn't disappointed; the little Eagle more than lived up to expectations. It's not the best power amplifier I've ever heard, but it's damn good. It is, in fact, better than its big brother, the Eagle 7A, in significant ways; in view of the 2's reasonable price, that's saying a lot.
Anthony H. Cordesman, Various  |  Apr 05, 1995  |  First Published: Apr 06, 1985  |  1 comments
I am reluctant to call any given transistor power amplifier a "best buy" or "breakthrough." From my talks with designers and other audiophiles, it is clear that the state of the art in power amplifiers is about to change. From where I stand, the Adcom GFA-555 is the first sample of this new wave. It is so clearly superior to past amplifiers in the low- to mid-priced range—not to mention most amplifiers two to three times its pric—that I can unhesitatingly recommend it for even the most demanding high end system.
Larry Greenhill, Thomas J. Norton  |  Sep 02, 2010  |  First 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.
J. Gordon Holt, Various  |  Apr 29, 1995  |  First Published: Aug 29, 1984  |  0 comments
I must admit that even before I connected up this amplifier I was put off by the accompanying literature. B&K makes some persuasive points about the validity (or rather the lack thereof) of some traditional amplifier tests, but the literature was so loaded with flagrant grammaticides, syntactical ineptitudes, and outright errors that I could not help but wonder if the same lack of concern had gone into the product itself (eg, the term "infrasonic" is used throughout to mean "ultrasonic"). Good copy editors aren't that hard to find; B&K should have found one.
J. Gordon Holt  |  Sep 15, 2015  |  First Published: Dec 01, 1979  |  0 comments
Imagine if you can a power amplifier with the bass richness, midrange liquidity, and high-end accuracy of the best tube amplifiers, and the inner detail, transient attack, and bass solidity and range of the best solid-state amplifiers. If you can imagine that, you can visualize what this amplifier sounds like.
J. Gordon Holt  |  May 14, 2015  |  First Published: Mar 01, 1977  |  0 comments
We cannot recall when any new products have generated as much of a stir among perfectionists as the new solid-state equipment from Audio Research. Preceded by rumors of "a new kind of amplifying device—a cross between a tube and a transistor"—the announcement of ARC's new power amp and SP-4 preamplifier elicited very mixed reactions from loyal ARC customers, some of whom gleefully anticipated a virtual revolution in audio electronics, others of whom felt betrayed by the company which, having originally convinced them that "Tubes Are Better," suddenly seemed to be doing an about-face and espousing the views of the Enemy—the "Soiled-State"—forces.
J. Gordon Holt, Sam Tellig  |  Aug 01, 1995  |  First Published: Aug 01, 1976  |  0 comments
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.)
J. Gordon Holt  |  Apr 12, 2017  |  First Published: Jun 01, 1970  |  11 comments
If we had been asked some time ago to describe our "dream amplifier," chances are we would have described the Crown DC-300. Designed originally as an industrial device, it was made available as an audio amplifier rather as an afterthought. But if that roundabout approach is necessary to produce an audio amplifier like this, so be it.
J. Gordon Holt  |  Aug 02, 2016  |  First Published: Jul 01, 1968  |  0 comments
It takes a lot of courage for a new company to launch an amplifier like this at time when most manufacturers are courting the mass market with budget-priced receivers, and Marantz is pretty firmly established as the Rolls Royce of audio electronics.

The SAE Mark II has, nominally, the same performance specs as the Dynaco Stereo 120, yet it costs twice as much as a factory-wired Stereo 120, and about 2½ times as much as a Stereo 120 kit. Is the SAE really worth the difference? And how does it compare with some other $400 amplifiers? Well, it all depends.

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