Solid State Power Amp Reviews

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John Atkinson Posted: May 23, 1995 Published: May 23, 1988 0 comments
I must admit, right from the outset, that I find reviewing electronic components harder than reviewing loudspeakers; the faults are less immediately obvious. No preamplifier, for example, suffers from the frequency-response problems endemic to even good loudspeakers. And power amplifiers? If you were to believe the older generation of engineers—which includes some quite young people!—then we reached a plateau of perfection in amplifier design some time after the Scopes Monkey Trial but well before embarking on the rich and exciting lifestyles afforded us by Reaganomics. (In the UK, it is generally felt by these people that the date coincided with the introduction of Quad's first current-dumping amplifier, the 405, in 1976.)
Sam Tellig Posted: Aug 31, 2009 Published: Dec 31, 1987 0 comments
Sometimes products are too cheap for their own good, and people don't take them seriously: the Superphon Revelation Basic Dual Mono preamp, Rega RB300 arm, AR ES-1 turntable, Shure V15-V MR cartridge, and the B&K ST-140 power amp. They can't be any good because they cost so little, right?
J. Gordon Holt Posted: Aug 17, 2012 Published: Jun 01, 1987 1 comments
"Grand Integra" is the name Onkyo has given to its line of perfectionist-oriented audio products, and the M-508 is the cheaper of Onkyo's two Grand Integra power amplifiers. (The flagship model is the $4200 M-510, reviewed by Larry Greenhill in Vol.8 No.8, featuring "high current capability," and rated at 300W continuous per channel.)
J. Gordon Holt Posted: Mar 03, 2010 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 Posted: Oct 03, 2008 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 Posted: Apr 10, 2014 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 Posted: Oct 08, 2006 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 Posted: Dec 29, 1995 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 Posted: Sep 09, 2007 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 Posted: Aug 10, 2009 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 Posted: Apr 05, 1995 Published: Apr 06, 1985 0 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 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.
J. Gordon Holt Posted: Apr 29, 1995 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 Posted: Aug 01, 1995 Published: Aug 01, 1979 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.)

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