Tube Power Amp Reviews

Based in the Czech Republic, KR Enterprise is headed by an occasionally gruff Dr. Riccardo Kron and his American-born wife, Eunice, who operate the company out of a partially abandoned factory that was once part of the state-owned Tesla High Vacuum Technology facility in Prague. The Swiss-funded company is unique in that it manufactures both amplifiers and the tubes that power them. KR's tubes have found favor with other amplifier makers as well—especially the 300BXS, electrically identical to a standard">http://www.stereophile.com/features/229">standard 300B but rated at 25W in class-A.

The last Lamm product I had my hands on was a pair of M1.1 monoblocks (see Vol.18 No.4, Vol.22 No.7). I liked those hybrid tube/solid-state amps quite a lot.

Even as the gulf narrows between the sounds of the best solid-state and the best tubed amplifiers, most listeners remain staunch members of one or the other camp. Similarly, when it comes to video displays, the plasma and liquid-crystal technologies each has its partisans, though that conflict's intensity is relatively mild, perhaps because video performance, unlike audio, is based on a mastering standard that establishes color temperature, gray-scale tracking, color points, and the like (I'm deeply in the plasma camp). But in audio, the "standard" is whatever monitoring loudspeaker and sonic balance the mastering engineer prefers, which makes somewhat questionable the pursuit of "sonic accuracy." Still, in a power amplifier, a relative lack of coloration is preferable to amps that Stereophile editor John Atkinson has characterized as "tone controls"—usually, if not exclusively, of the tubed variety.

The challenge is biblical in character, if not in scope: A half year after railing, in these pages, against our industry's overabundance of products that cost more than $20,000, fate has given me such a thing to review.

I have always been fascinated by audio power amplifiers. I even tried building about a hundred of them. My best friend in high school, Bill Brier, taught me the basics of soldering, wire management, and reading schematics. He loaned me his Dynaco Stereo 70, and gave me a hot-running, 20W, class-A transistor amp that he'd built on his mother's kitchen table. Bill took me to concerts, and taught me about classical and jazz music. He had perfect pitch, tuned pianos for money, played every instrument in the orchestra, and had memorized the complete keyboard works of J.S. Bach before he turned 16. And this stuff was all on the side—mainly, we built drag race cars together.

There's something special about big tube amplifiers. No other audio component has such a primal appeal or can so quickly reduce grown (?) audiophiles to Homer Simpsons sighing, "Mmmmm...toooobs." EveAnna Manley, president of Manley Laboratories, understands the effect of high-powered tubes on the audiophile brain and shares the obsession. A Harley rider, mountain climber, and devoted music lover, she is one of the industry's most individualistic characters. You just have to appreciate a gal who ends each CES by blaring Rage Against the Machine at top volume.

My reviews always begin in bizarre ways. Take David">http://www.stereophile.com/david_manley_tubes_logic_amp_audiophile_soun… Manley...please! (Just kidding.) On the last day of Winter CES 1995, I found myself towing a tuckered-out JA to a few final rooms. (This was just after the January '95 David Manley/Dick Olsher tube-rolling brouhaha, footnote 1, regarding who should do what to whom, and with which particular tube.) So as we passed Manley's room, John Atkinson thought to stick his head in (the noose) and say hello.