Power Amplifier Reviews

The concept of "investing" in a rapidly depreciating commodity strikes me as patently stupid. Just look at EBay and Audiomart. They are chockablock full of yesterday's stratospherically priced audio components now available for ten cents on the dollar. I believe the best values in audio or video components come from companies that refine bleeding-edge, hyper-expensive technology into attractively priced products.

PS audio began in 1975 as two guys' effort to create affordable high-fidelity audio equipment. Paul McGowan and Stan Warren (the P&S) parted ways after a couple of years with Paul continuing PS and Stan going on to Superphon. After a good run Paul sold PS to another audio firm who ran it into bankruptcy. Shortly thereafter Paul had the opportunity to buy back the rights to the name PS Audio for $1, and PS Audio was reborn.

The company has a history of creating audio components that epitomize the concept of refinement coupled with prices that don't require a second mortgage. That doesn't mean that PS audio products are inexpensive or can be found at your local K-Mart, but its secret of success is simple—make products with performance that equals the market leaders at half the price.

PS Audio recently introduced several multichannel amplifiers for home theater use, available in several standard five- or seven-channel versions at either 100, 250, or 500 watts per channel (into 8 ohms). The GCA-MC250 series, rated at 250 watts per channel into 8 ohms (500Wpc into 4 ohms, is available in standard five- and seven-channel versions for $5595 and $7495 respectively. (The photos accompanying this review show the seven-channel version.)

But you may also special order any of PS Audio's GCA amps in other configurations. For my own purposes a three-channel amp works better than a single amp with five or more channels. I like putting power amplifiers close to speakers, and with a five or seven-channel amplifier you are forced to use several long runs of speaker cable for the rear and side speakers. I hate that, so I use three-channel amps combined with two-channel amps in both my home theater systems. The GCA-MC250 can be custom ordered in a three-channel configuration ($4695), so that's the version I requested for review.

Gain Cells and PWM Circuits
The best sounding power amplifiers I've heard, regardless of core technology, embrace the concept that simple is better. The PS Audio GCA MC-250 typifies this philosophy. It consists of just two stages. The first uses a proprietary analog voltage control circuit called a Gain Cell, while the second stage uses a class D PWM (pulse width modulation) amplifier circuit to supply current. Each channel of the GCA MC amplifier has its own Gain Cell coupled to a PWM stage. The Gain Cells and PWMs also have their own isolated and independent power supplies.

I could spend a lot of space detailing finer points of both the Gain Cell and PWM amplifier circuits, but PS Audio has already done that on its own website. Visit http://www.psaudio.com/products/gcamc_overview.asp for an excellent technical description of both technologies as well as links to FAQs and white papers. The most important aspects of these new circuits is their ability to minimize wasted heat (the PWM is claimed to be 85% efficient), deliver a high damping factor, and operate in a highly linear manner throughout their entire frequency range.

The Thin Blue Line
Power amplifiers are not the most visually exciting birds in the audio aviary, but the PS Audio GCA MC-250 does have a bit more style than most. Although basically a big silver box, it looks a bit like an inverted tuxedo with a black insert surrounded by silver frame. Instead of a standard, boring on/off switch, the GCA MC-250 uses a blue PS audio logo on the front panel as its switch – a soft touch and it lights up, signifying it's ready for action. When "on" the GCA MC-250 also displays a thin blue line of light along the base of its black front panel insert. Fortunately, for home theater you can turn the display off via a small three-position switch on the rear panel, but I can't help but wonder why it's there to begin with. Home Theater, like a couple of other activities dear to my heart, is best done in the dark.

On the back of the GCA MC-250 sit both single-ended RCA and balanced XLR inputs for each channel, along with a small two-way switch to designate which input you intend to use. Located below the inputs you'll find a single pair of gold-plated, five-way speaker connectors. If you are the kind of person who likes premium or ultra tweaky AC cables, the GCA MC-250 comes equipped with a standard IEC AC connector suitable for anything you wish to tether to it.

During my review the GCA MC-250 performed flawlessly, with no physical or electronic turn-on or turn-off sounds to negatively effect domestic tranquility. The amplifier also displayed very low electronic noise when idling. Only the very faintest hiss when my ear was within a few inches of the tweeter gave any indication that the amplifier was on. Because of its internal circuit's efficiency the MC-250 runs very cool—so cool that it can be placed in a stack or cabinet with far less ventilation than a conventional solid-state amplifier. During most of its review tenure I had at least one other piece of gear on top of it with no heat problems whatsoever.

The Sound of One Hand Clapping
When I first started in high-end audio writing an amplifier review was easy because all amplifiers sounded different, very different. Turning out several pages of overheated sonic purple prose required little more than a couple days of listening and transcribing field notes into entertaining reading. But during the last thirty years something alarming happened. Amplifiers all got better. While they still don't sound alike (thereby totally eliminating jobs for prose-chuckers like me), the vast majority have become so neutral that the gross and easily discernable differences between amplifier A and amplifier B have vanished. Unless you have a lot of experience listening for miniscule differences you might conclude that once past a particular price point any amplifier will do just fine, and depending on your level of listening sophistication, you could well be right. But for those of a prior age who would have whiled away their evenings debating the number of angels cavorting on the head of a pin, high-end amplifiers still have enough individuality to keep life interesting.

The PS Audio GCA MC-250 amplifier doesn't give away much. Even when run full-range into a difficult impedance load speaker such as the Genesis 6.1 system, the PS Audio has more than enough power and fortitude to deliver stress-free results. When put into a more standard 8 ohm home theater speaker system where the MC-250 need not produce much below 50 Hz, the GCA MC-250 will certainly have more than enough juice for even the most over-the-top soundtrack. Whether the GCA MC-250 actually puts out the stated 500 watts into 4 ohms or only 476.1 watts won't really matter in any real world application.

But just because an amplifier has gobs of power capacity doesn't automatically mean it will produce great dynamics. Creating exemplary dynamic contrast hinges on the amplifier's low-level input circuit's signal-to-noise capabilities, not its output section's brawn. The PS Audio proprietary Gain Cel displays a level of dynamic finesse that rivals any amplifier I've heard. What I like best about the MC-250 is its dynamic honesty. With dynamically open sources, such as my own live orchestral recordings, the MC-250 can preserve the ultra low level rustling of the conductor's waistcoat sleeve against his music stand, as well as the crushing weight of the entire orchestra's triple fortissimo. On lousy recordings, such as any channel of XM Radio from DirecTV, the results sound as flat and unappealing as week-old soda.

Harmonically the PS Audio GCA MC-250 attempts to be as neutral as a judge in a divorce proceeding, and fortunately, achieves better results. If asked under pain of needles shoved beneath my fingernails to decide on which side of the infinitesimally thin line between warm and cool, additive or subtractive, the MC-250 belongs, I'd say the cool subtractive side. Yet only in comparison to the Pass X-3 is its bias toward cool really noticeable. The Pass has a bit more lower midrange body compared to the MC-250. Whether this added harmonic flavoring is additive on the part of the Pass or subtractive on the part of the PS Audio doesn't really matter. What does matter is that they are harmonically different, and depending on your speakers and personal tastes you may prefer one or the other. Listening will be required to make an educated choice.

Sometimes amplifiers that try to be absolutely neutral can sound a bit thin and brittle on high frequencies because they lack the warmth in their midrange to give the top end a bit of sugar. The MC-250 avoids this sonic pitfall. Cymbals, flutes, and even sibilant sopranos have enough air to sound natural without becoming harsh or overbearing. While in comparison to the Pass X-3 the MC-250 sounds a trifle drier on top, it still sounds completely in balance to the rest of its harmonic spectrum. Which is more correct? I consider it a matter of taste rather than absolute rightness or wrongness. Depending on the source material and the recording either could be considered right. Nastier or rude recordings are more palatable through the Pass, while sweeter-sounding selections shine on the PS Audio amplifier.

Two-channel audiophiles usually devote a lot of attention to a component's ability to retain three-dimensional spatial cues. You really can't blame them, poor dears, as they only have two channels to work with. One of the nicest aspects of multichannel music listening is that five or more channels supply more spatial information to keep our ears occupied. Still, dimensional flattening is not a good thing. Even when forced to reproduce only two channels the MCA-250 does as good a job of retaining spatial cues as any non-tube amplifier I've reviewed. In this regard it is the equal of the Pass X-3. On minimally miked, phase-correct recordings the MCA-250 delivers a dimensionally correct soundstage with only the slightest amount of truncation at the very back of the sound space.

Lateral imaging and image specificity are usually lumped in with spatial acuity, but I have heard some amplifiers, usually older tube designs, that get the three-dimensional thing right but can't get the image focus down. The MC-250 has no issues with either. On panoramically challenging dialogs, such as the "stripper angel" scene in Can't Hardly Wait, the MC-250 holds the focus of the hero's voice from the extreme left hand side of the stage, well past the physical boundaries of the loudspeakers themselves.

Any list of an amplifier's sonic attributes would be incomplete without some attention to its ability to deliver low level and inner detail. Once more the MC-250 passes with highest honors. Listening to the sound on this year's March Madness basketball orgy I could not help but appreciate the MC-250's ability to let me hear into the action, including the liberal use of words that I don't think are encouraged in English class. Fortunately for the network, the FCC's dirty word committee isn't listening through MC-250 amplifiers or it could cost CBS a bundle!

Amp Man Speaks
Several years back I wrote about a dream I had. I was a couple of hundred feet tall, striding through the downtown streets of Manhattan, carrying a humongous amplifier on each shoulder, bellowing, "I AM AMP MAN!" Since then I stopped eating persimmon pizza before bedtime and the dreams have gone away. But on occasion, I still fantasize pushing yet another power amplifier up a steep hill only to have it roll back down (packed in its shipping box of course), so I can muscle another one up in its stead. Don't get me wrong: I really do like power amplifiers. It's just that setting them up gets more and more tedious as I get older. Trust me, even the most enthusiastic audiophile eventually gets to the point he goes, "Enough! I'm not moving another power amplifier as long as I live!" I reached that place a couple of years ago, about the time I had that dream.

But sometimes unpacking one more amplifier is worth the effort. The PS Audio GCA MC-250 clearly ranks among a select circle of amplifiers that not only deliver superb sound, but also promise years of trouble-free operation. If your goal is to buy an amplifier, set it up once, and then just have it work for ten years without fear that its sonics or technology will be eclipsed, the PS Audio GCA MC-250 would be a canny choice.

Highs and Lows

Highs
Stellar sound
Efficient
Low heat generation

Lows
Not inexpensive
Deserves top flight speakers