Tube Power Amp Reviews

Ah, Brazil...land of coffee, the samba, Pelé, Rio-by-the-sea-o, and tube amplifiers. All right, so perhaps the amplifier connection isn't quite as well-established. But one Brazilian amplifier designer, Eduardo de Lima, has published articles in Glass Audio magazine that are viewed by many as groundbreaking, and his evolving products have been seen at various specialist tube equipment shows. De Lima—president, founder, product designer, and principal owner of Audiopax Sistemas Eletroacusticos—is an electrical engineer who started out designing equipment for a telecommunications company, but since 1995 he's devoted his talents to designing a wide range of audio products, including speakers as well as preamps and power amps.

Single-ended triode amplifiers (SETs) have a considerable following, but even their most devoted fans admit that its maximum power output is not among an SET's strengths. You'd be lucky to get an SET that puts out 7Wpc, and some (like those using the 45 tube) are closer to 2Wpc. Highly sensitive speakers (eg, horns) will tend to offset the power limitation, and SETs usually sound more powerful than their measurements indicate, but the laws of physics still apply: 2W is 2W, regardless of the kind of amplifier that produces it, and an amplifier's manner of clipping and recovery from overload take us only part of the way toward achieving greater volume.

Single-ended triode (SET) amplifiers are typically paired with horn loudspeakers, for good reason: most SETs produce very low power, so to get acceptable loudness you need a highly sensitive speaker, which means horns. Similarly, horn owners are often advised that the best amplifier for their speakers is a SET. Certainly, the horn-SET combination can be magical, but, in my experience, SETs are not the only type of amplifier that can sound good with horns.

Not since Sonus Faber's Amati Homage loudspeakers took up residence in my listening room has a piece of audio gear elicited so many "Oohs," "Aahs," and "Wows" from friends as Hovland Company's dramatic-looking, EL34-driven Sapphire power amplifier—especially when it was switched on and glowing orange and blue. It drew unsolicited attention and admiration even when turned off. Not that, on or off, its unusual looks didn't also have their share of detractors. As with Hovland's chrome-façaded, blue-backlit HP-100 preamplifier, some found the Sapphire too shiny, too gaudy, and generally just too much. Me, I'm thumbs-up on the Sapphire's looks—I found myself staring at it incessantly. But anything that draws such intensity of response, whether love or hate, must be doing something right. B&O shouldn't have a monopoly on striking-looking audio gear.

It's always good to tear into a good steak with Tor Sivertsen, Conrad-Johnson's main marketing man.

"Larry—if I'd told you 10 years ago that McIntosh would be heavily into tubes in the 21st century, what would you have said?"