PS Audio HCA-2 power amplifier Page 4

"In terms of real estate, that's right. When we first started working on this amplifier, the original prototypes used a very small power-supply transformer. It must have been a quarter the size of that moose you see in there now. The amplifier is so efficient that you really don't need this big transformer. At the very end of the listening period, we started playing around with very big transformers. We could measure no difference compared to smaller transformers, but we could sure hear it."

Just like the early PS Audio preamps.

"What do you think a larger transformer is doing [that a smaller one wouldn't?]?"

"I can't measure it, so this is purely speculative, but I think it's lowering the output impedance that's going to the circuit. When you demand current from a device—in other words, an output transistor—there is a tendency for the device to sag a bit. You can't really measure it, but every time I've taken a power supply and lowered its output impedance, the sound has improved dramatically. The only thing I can attribute this to is low DC resistance.

"Our Ultimate Outlet, which we market as a separate power-conditioning device, is incorporated into the HCA-2. It's a balun—a balanced magnetic device that has about 20 turns of very heavy magnet wire in series with the AC voltage. I put one of these things on the input of the HCA-2 prototype, and that was it—the big breakthrough. I'm not sure why this is true, but the HCA-2 is power-supply-sensitive—very sensitive to what kind of power cord you hook up to it."

Great Sound
In my main system, I hooked up the HCA-2 to my McIntosh C2200 tubed preamp via a balanced run of Kimber Silver Streak speaker cable. CD sources were the Musical Fidelity Nu-Vista 3D player and the McIntosh MCD205 changer. For analog, I turned to my new reference, the Ortofon Kontrapunkt B cartridge mounted in my SME 309 tonearm on my AR ES-1 turntable. I used the AcousTech PH-1 Premium Phono Stage. Speakers were the Quad ESL-989s.

Gad, I got great sound!

Want to spend a fistful of money for amplification? Want to help some high-end hotshot buy his next luxury car? I phoned Paul to ask what kind of car he drives. A 1996 Jeep Grand Cherokee with 147,000 miles.

Now, about the HCA-2's sound: There was none. The amp seemed both natural and neutral. Tubelike? Okay. I heard no harshness or edginess. The sound was uncommonly smooth.

It was also fast.

Big amplifiers sometimes sound as if they're held back by their own weight. In the immortal words of the late Howard Mandel, of Altis Audio, there is "tons of bass, tons of bass, bass all over the place."

The HCA-2 did not sound bass-deficient—far from it. But it also didn't sound bass-heavy. The amp just let go of the notes. This quality of bass, coupled with the extraordinary smoothness through the midrange and treble, made for a bracing, crisply articulated sound.

But would I get the same result in a different system?

Hey, it's easy to move the HCA-2. Piece of cake. I took it into our living room and wired it to the Sonus Faber Cremona speakers, using a Purest Sound Systems P500 "passive preamp." Unbalanced connectors. CD source was a Musical Fidelity A3.2 CD player.

For a relatively small floorstanding speaker, the Cremona is capable of surprising bass extension. The HCA-2 got a good grip on things. At the same time, the midrange and treble were smooth and grain-free. Was I lusting for tubes? Not really.

In some of his promotional literature, Paul McGowan refers to the HCA-2's "tubelike warmth." I don't think these are the words I would use to describe the sound. "Tubelike warmth" suggests, to me, some kind of euphonic coloration, some tubelike tinkering with the sound. The HCA-2 was remarkably free of the rich, overripe, sometimes woolly sound associated with tube amplification. There was plenty of bass, but it was extended and tight, not "all over the place." The treble was superbly extended, so much as my ears can hear—not rolled-off, the way tube amplifiers can sometimes sound.

The HCA-2 was "tubelike" in that it managed to avoid sterility. It did not sound neutral to the point of being overly lean and harmonically thin. The sound wasn't lean like Jack Sprat, or fat like Sprat's wife. It was nicely balanced in between.

I can hardly wait for the matching PS Audio 8.0 preamp. Paul's preamps have always been rather special. Meanwhile, I recommend the HCA-2 very highly. If there is any downside to digital switching, I couldn't hear it in the HCA-2. The advantages look fairly significant: relatively low cost, compact size, almost no heat generated, and, apparently, consistent performance into any speaker load. Nor did I hear any significant increase in noise using the amplifier's unbalanced inputs.

The PS Audio HCA-2 is not another "me, too" amplifier, but a revolutionary product. If you're in the market for a power amplifier at any price, I urge you to give it a listen, even if you're a big fan of tubes. Even if you're thinking of spending much more money.

It will be interesting to compare PS Audio's bigger stereo power amplifier, the Classic 250 Reference Standard, which was just going into production as I finished this column. That's a more conventional amplifier: big, big power supply, large heatsinks, same feedback-free class-A input stage. I bet the Classic 250 will sound different—more authoritative, perhaps, more weighty—but I doubt it will sound more musical than the HCA-2.—Sam Tellig

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