Tube Power Amp Reviews

Well, not really. Less than a week into use, one of the Golden Dragon KT88 output tubes failed—I think the tube lost its vacuum. I noticed when the output from the right channel amp seemed lower than the output from the left. It was.

Kevin Hayes replaced the matched pair of KT88s—no problem. But Kevin did suggest that the Quicksilver amp might have been at fault. No other Golden Dragon KT88s had failed in the field, he said, unless traceable to improper operating conditions.

Not so cool, Kevin—I think this pair did fail in the field: more specifically, in my listening room. Yes, I set the bias correctly and monitored it closely, too. The second pair of KT88s worked fine in the amp, as did the original pair of non-Dragon KT88s supplied by Quicksilver. I have no reason at all to suspect the Quicksilver amp. Still, Kevin did make good on his guarantee.

The amps themselves are beautiful—an astonishing buy at the price. ($2300/pair), I find the chrome chassis aesthetically pleasing, and the KT88s, too, are lovely to look at. Incidentally, the chassis is slightly larger than the chassis of the "standard" Quicksilver KT88 amp, which is finished in black. And the speaker-connecting strip is much improved—easier to connect audiophile cables, not so cramped. Once again, Quicksilver has a winner. In fact, I'll go out on a limb and say these are probably the best values in a tube amp that I have ever encountered.

Are these the best tube amps? Probably not. With all the other changes in equipment, it's hard for me to give an absolute answer, but I think that both the VAC amps and the Defy 7 have even more in the way of transparency—delicacy, detail, etc. And good as the Quicksilver is in the bass, the Defy 7's bass is, I think, even tighter: better defined. But these other amps cost more. I can live happily with the Quickies and intend to do so. My overall impression is that they're greatly improved over the already excellent "standard" Quicksilver KT88 model, which is still in production. My advice: spring for the difference.

Meanwhile, Wayne Schuurman of Audio Advisor sent me a prototype of one of the new $895 VTL Renaissance tube amps. I was prepared to like it—except for just one fault. There was no sound coming from the right channel. The left channel sounded just fine, though. This was the prototype. I heard later that one capacitor was hooked up incorrectly.

Finally, I want to say another word about the Golden Dragon tubes. I've also tried their 12AX7As—substituting them for the GE tubes on the Quickies—with what I think is an improvement in overall smoothness and detail. I'm hearing very, very good things about the Golden Dragon 12AX7As used in preamps! It's reassuring to know that someone is doing something about assuring a supply of reliable, good-sounding tubes—even if they do come from Red China. And the prices for the Golden Dragon tubes are very reasonable—no one is being ripped off.

I gather that the Golden Dragon tubes were developed at the Shuguang tube factory in China, with help from British tube mavens now associated with PM Components. The tubes are boxed beautifully, too—I'm reminded of the menu cover at my favorite Chinese restaurant. (I think Kevin Hayes should include a fortune cookie with each shipment. Let's see, open up that cookie. What does your fortune say? "Your Shuguang Golden Dragon KT88s will give you many years of excellent sound, but watch the bias.")

With tubes like the Golden Dragons—and amps like the VACs, the Defy 7, and the new Quickies—it may be time for you to think seriously about tube gear, too. Of the tube amps I've had lately, none of the Quickies gave me trouble—I don't blame the amps for the Golden Dragon KT88 that went out. The VACs functioned flawlessly. And the Jadis—well, Count Veekh-tor has admitted his culpability there. I seem to have bad tube karma when it comes to VTL.

I gotta tell you this. Hyperfy had a pair of Manley 350s. No, they didn't explode or anything. But when he turned them on, he'd sometimes trip all the circuit breakers in the house. At night, the whole house would go dark. Flashlight in hand, Hyperfy would tear into the basement. It was wonderful.

Now...what's this?
A solid-state amplifier from strife-torn Yugoslavia? (My daughter is heavily into the study of Serbo-Croatian. Czech, too.) From sort of behind the (rusty) Iron Curtain? Let's see how it compares with its capitalist counterparts...

Flash!
After I finished this column, I had a problem with the other Quicksilver amp in which I had installed Golden Dragon KT88 tubes. I turned the amps on first thing in the morning (they'd worked fine the night before). I heard a sputtering noise and reduced output in the left channel. I checked the bias—sure enough, the left-channel Quicksilver was now biased at 50mA instead of 100. Drat! I changed to the original KT88 pair that came with the Quickies and the amp was still biased at 50mA.

At the moment, I'm trying to sort things out. Did the tubes fail, taking out the amp? Or did the amp fail, taking out the tubes? I'm not sure it'll ever be resolved.

The failure of the second amp (tubes?) gave me a chance to listen at greater length to the Krell KSA-150, which was sitting silently between my Quicksilvers. Initial reaction to the Krell—and this is coming off a string of very fine tube amplifiers, mind you—is very favorable. One thing is certain: the bass alignment of the Krell is phenomenal—very powerful and very tight. And there's a complete absence of solid-state nasties. The KSA-150 has to be one of the smoothest, sweetest amps around, and it doesn't require possibly volatile Chinese fire bottles to make it work.

So where does that leave you? Probably the same place it leaves me: confused. I mean, it would be easy if the Krell sounded shrill or steely—but it doesn't. And just as Adcom and B&K have succeeded in getting themselves very close in sound quality to where the Krells of this world used to be, ampwise, now Krell has succeeded in getting itself up there another notch or two compared with the Krell KSA-80, for instance, which the KSA-150 replaces. (I don't mean to dwell on Krell. However, I don't have Jeff Rowland Design Group, Threshold, Mark Levinson, or Spectral amps in my listening room at the moment.)

Yes, there are "tube" qualities which no solid-state amp seems to touch—although the Krell is coming very, very close, while it has sonic virtues of its own, particularly in the bass. But it's not just sonics you have to weigh: it's the "pissing dog" phenomenon. It's one thing to talk about tube-amp aggravation in the abstract, another to be actually faced with it—and, as you can see from this article, I've had my full share. The VTL 225s—EL34 Chernobyl. The VTL Renaissance 70/70—DOB (dead out of the box) in one channel! The Jadis Defy 7—with defiant capacitor. Now the problem with the KT88s and the Quickies. Tubes are sweet, but don't be surprised if I wind up keeping the Krell.