Solid State Power Amp Reviews

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Kalman Rubinson  |  Sep 04, 2014  |  9 comments
Power amplifiers are unglamorous but essential. In theory, they have only one task. But, according to audio sage Yogi Berra, "in theory, theory and practice are the same. In practice, they are not." Amplifiers must take a voltage input signal and provide an output of somewhat higher voltage but of substantially higher current, the product of which is power. The task is complex in that this output must be applied to electrical interfaces whose characteristics vary widely from speaker to speaker—across the audioband and, for some, even at different power levels. There are no control mechanisms or feedback signals to help. The power amp must just stand and deliver.
Kalman Rubinson  |  Mar 02, 2017  |  11 comments
The power-amp saga continues. For months, I've been plowing through the market, searching for something to drive my three front speakers. (I use a two-channel amp for the surrounds.) It can be a three-channel amp or three monoblocks—it just has to sound great with my speakers, and be light enough that I can lift it by myself when I need to rearrange my system. I'd finally settled on Classé's Sigma Monos for their transparency, and because I can manage their weight, one at a time. At the CEDIA Expo in September 2016, I saw two more candidates worthy of consideration. Review samples of both arrived here almost simultaneously.
Michael Fremer  |  Sep 16, 2007  |  0 comments
How much amplifier power do you need? Most audiophiles figure a maximum of a few hundred watts per channel—beyond that, you're wasting your money or showing off. Others think that anything more than a few watts will mess up an amplifier's musical coherence or "purity," so they stop there and find uncommonly sensitive speakers, usually compression horns with cone woofers.
John Atkinson  |  Dec 15, 2008  |  1 comments
Musical Fidelity's "Supercharger" concept is simple, which is perhaps why no one had thought of it before: If you love the sound of your low-powered amplifier but your speakers are insensitive, or you just need more loudness, you insert the high-power Supercharger amplifier between your low-powered amp and speakers. The Supercharger loads the small amplifier with an easy-to-drive 50 ohms, and, in theory, has so little sonic signature itself that it passes on the sonic signature of the small amp unchanged, but louder.
John Atkinson  |  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.

Michael Fremer  |  Dec 18, 2005  |  0 comments
Not every audiophile needs an amplifier powerful enough to tax a small town's power grid while simultaneously draining his or her bank account. So, having quickly sold out of its ultra-limited-edition, extravagantly powered and priced combo of kWp preamplifier ($14,995) and kW power amp ($27,995) that I reviewed in January 2004, Musical Fidelity (footnote 1) set about capitalizing on the enthusiastic reviews earned by those giants with less expensive, less powerful, "real-world" replacements.
Michael Fremer  |  Dec 27, 1999  |  0 comments
Nothing like scarcity to create demand, right? Well, there's been a scarcity of Nuvistors out there for decades, and hardly any demand. Do you know about the Nuvistor, aka the 6CW4? It was a tiny triode tube smaller than your average phono cartridge. Enclosing its vacuum in metal rather than glass, the Nuvistor was designed as a long-lived, highly linear device with low heat, low microphony, and low noise---all of which it needed to have any hope of competing in the brave new solid-state world emerging when RCA introduced it in the 1960s.
Michael Fremer  |  Jun 23, 2009  |  0 comments
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.
Michael Fremer  |  Feb 01, 2004  |  First Published: Jan 01, 2004  |  0 comments
Thoughts of power, domination, and audio road-rage enter one's mind when contemplating Musical Fidelity's SUV-like, limited-edition, 20th-anniversary offerings (footnote 1). (Only 75 sets of kWPs and kWs will be made.) The gleaming, brushed-aluminum, two-box, oversized, overweight Tri-Vista kWP preamp is fortress-like—the "kWP" looks as if chiseled into the faceplate by grimy, sweaty hands. Each of its boxes weighs almost 56 lbs. The unit's milled-aluminum remote control, the size of a Volkswagen Microbus and looking like something Fred Flintstone might wield, must weigh over 5 lbs. The kWP outputs more juice than many power amps: 55V, with 20 amps of peak-peak instantaneous current!
Robert J. Reina  |  May 02, 2004  |  First Published: Aug 01, 1999  |  0 comments
The story of New Acoustic Dimensions, aka NAD, begins in the late 1970s. The company was founded as a dealer distribution collective to design and market reasonably priced serious high-end gear to cost-constrained audiophiles. By eliminating needless features and focusing manufacturing in low-cost production facilities, NAD has successfully delivered audiophile-quality gear for 20 years at prices little more expensive than mass-market department-store schlock.
John Atkinson  |  Mar 15, 2010  |  1 comments
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).
Kal Rubinson  |  Mar 03, 2016  |  3 comments
In the January 2015 edition of "Music in the Round," I reviewed NAD's latest Masters Series preamplifier-processor and multichannel power amplifier, respectively the M17 ($5499) and M27 ($3999). I was taken with both, but the M27 made a special impression. In many ways, it personified what a modern power amp should be: quiet, transparent, cool running, and compact. Its neat package of seven 180W channels inspired me to consider that stereo or mono versions of such a thing could supplant the ungainly monster amps I was using in my main system. So I asked NAD to send me not just one but two samples of their new two-channel power amplifier, the Masters Series M22 ($2999): Although this is a review of a stereo amplifier, I did want to have my front three speakers identically voiced.
Robert Harley  |  Jun 09, 2016  |  First Published: Feb 01, 1991  |  1 comments
Back in 1970, one Julian Vereker decided to record some musician friends in his house in Salisbury, England. Using standard, off-the-shelf electronics and tape machines, he was startled at how dissimilar the recording was to the sound of live instruments. As a result, he started designing his own recording electronics, including a recording console, of which he sold several to local broadcast facilities.
J. Gordon Holt  |  Aug 17, 2012  |  First 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.)
Michael Fremer  |  Feb 16, 2003  |  0 comments
Thirty years ago, the upstart audio company NAD revolutionized the manufacturing of consumer-electronics components by "internationalizing" the process. Instead of physically making products, NAD hired a project team in one location to design a product that was then built at a sub-contracted factory located elsewhere. The arrangement allowed NAD to go into business with relatively little capital outlay and low overhead. Other companies have since copied this ingenious business model, and, as transportation and communication have improved, doing so has become easier and more efficient. It has brought prices down and quality up—mostly in the low and middle segments of the high-end audio and video markets.

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