Tube Power Amp Reviews

Not only does the venerable vacuum tube refuse to lie down and die, as everyone predicted when audio went solid-state; it continues to deliver better performance than anyone had imagined it could. Only a few years ago, we could characterize "the tube sound" as being sweet but soft at the high end, rich but loose in the midbass, deficient in deep bass, and bright and forward, usually with excellent reproduction of depth. Since then, we've seen the introduction of what might almost be called a new generation of tube amplifiers, which rival solid-state units in those areas where tubes used to have weaknesses, but have given up little of the tube's sonic strengths.

When I reviewed VTL's MB-750 monoblock amplifier in the December 1997 Stereophile (Vol.20 No.12), it was a transitional time for the company. Luke Manley had recently taken it over, and he and his wife and partner, Bea Lam, were aggressively retooling. They introduced new business systems, including rigorous inventory and quality control; rebuilt VTL's dealer network around top-rank dealers; and systematically upgraded the products themselves to improve their consistency, reliability, manufacturability, and performance. VTL's goal, Luke explained to me at the time, was to build amplifiers that competed with the very best, and to "make the tubes invisible to the customer."

"More power!!!"

Manley is not a new company; it's the last name of the president and chief designer of VTL, David Manley, whose Model 300 has been my reference standard power amp for the past two years. In fact, Manley is not even a new brand name; it's the name of VTL's "deluxe" line of electronics, built (ostensibly) to industrial standards of ruggedness and reliability.

It's customary to think of "the tube sound" as being warm, rich, weak through the deep bass, fat through the midbass, forward through the midrange, bright through the middle highs, and soft at the extreme top, with superb rendition of depth and spaciousness. The "solid-state sound," by contrast, is generally thought to be cool, detailed, and pristine, with powerful deep bass, controlled midbass, rather reticent (laid-back) midrange and mid-highs, and a somewhat crisp high end, with variable (roulette-style) reproduction of depth and spatiality.

We have to talk. Are you sitting comfortably? Is the reading light okay? Have a little something to drink at hand? (Audio is thirsty business.) The audio world is abuzz over the reintroduction of the single-ended triode amplifier. This is the first of three reviews of such amplifiers I'll be bringing you, along with two speaker systems with which to play them.

Brian Tucker, the US Quad importer, introduced me to the Woodside MA50 tube amplifiers and their manufacturer, John Widgery, during the 1992 Summer CES. Tucker's combination of Woodside MA50 tube amplifiers and Quad ESL-63 USA Monitors sounded unusually neutral, dynamic, and detailed. This was good news; back in 1987, Dick Olsher (Vol.10 No.6, pp.104–5) was unable to recommend an earlier Woodside-manufactured amplifier, the Radford STA 25 Renaissance. Brian mentioned that the MA50's design is a much-improved version of that earlier Radford model. Time for another review.