For many audiophiles, choosing a power amplifier is a vexing problem. Just how much must one spend to get true high-end sound and a solid build quality? How much power is really needed? And what amplifiers are suitable for driving low-impedance loudspeakers?
To high-end audiophiles, the Boulder 500 amplifier and its less expensive derivative, the 500AE (Audiophile Edition), would not seem to be "high-end" designs. They are designed around op-amps (felt by many to be generally poor-sounding), they have scads of negative feedback (which is perhaps why op-amps sound bad), and they have only a moderately hefty power supply. Why, then, is Stereophile publishing a review of an op-amp–based power amplifier? Read on...
"A high-quality amplifier must be capable of passing rigid laboratory measurements, meet all listening requirements, and be simple and straightforward in design in the interest of minimizing performance degradation..."—Cdr. Charles W. Harrison Jr., Audio, January 1956 (footnote 1)
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.
"I've know I've seen this amp before," I thought to myself when I lifted the $1200 Muse Model One Hundred out of the box, and I wasn't thinking of Robert Harley's review of the identical-looking Muse Model One Hundred Fifty reviewed in January 1990, either. No, I'd seen this amp before, somewhere else, in some other magazine, but with a different manufacturer's name.
What's in a name? Quite a bit, when you stop and think about it. Would you rather have prostate surgery by Dr. Steadyhand or Dr. Whoops? Names imply a lot, even if we don't consciously make the connection; that's why your Polo shirt was made by Ralph Lauren instead of Ralph Lipshitz.
The $1200 Counterpoint SA-100 amplifier came up to bat fourth in my listening sessions, behind (in order of appearance) the Adcom GFA-555 II (not reviewed here, but sent along by JA for comparison purposes), the VTL Tiny Triode monoblocks, and the Muse Model One Hundred. Thus, my progression went from bipolar solid-state to tube to MOSFET, with a wide spread of sonic characteristics between them: stygian bass from the Adcom; uncanny spatial presentation and vocal reproduction from the VTLs; and an overall superior sound from the Muse. I was therefore eager to see where the tube/MOSFET hybrid Counterpoint would fall in this group of very different-sounding amplifiers.
I still have fond memories of my first Krell amplifier, a KSA-50. Back in those days (date purposely omitted), my principal source of audio equipment reviews, aside from Stereophile and The Absolute Sound, was Hi-Fi News & Record Review, which I read voraciously from cover to cover every month. One fateful day while sitting by our community swimming pool, I happened upon an enlightening review of the KSA-50 written by none other than our own John Atkinson, editor of HFN/RRat the time. His words describing "the steamroller-like inevitability of the bass with this amplifier" haunted me for weeks, until I got up the nerve to audition, and ultimately purchase, my first Krell product.
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.
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.
This review should have appeared more than a few months ago. When I reviewed Linn's Troika cartridge back in the Fall of 1987, in Vol.10 No.6, Audiophile Systems also supplied me with a sample of the Linn LK1 preamplifier and the LK2 power amplifier, which I had intended to review in the due course of things. As it transpired, however, I was less than impressed with the LK2, finding, as did Alvin Gold back in Vol.9 No.2, that while it had a somewhat laid-back balance, it also suffered a pervasive "gray" coloration, which dried out recorded ambience and obscured fine detail.
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.)
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?