Tube Power Amp Reviews

Lee de Forest filed for a US patent on his "Audion"—the first triode—on October 25, 1906, but never could explain why it worked (footnote 1). It was up to Armstrong and Langmuir, in their pioneering work, to place the hard-vacuum triode on firm scientific ground. When the US entered World War I in April 1917, the Army had to rely on French tubes. Six months later, Western Electric was mass-producing the VT-1 receiving tube and the VT-2 transmitting tube. However, it was only in the decade following World War I, as designers became conversant with the triode amplifier, that many of the crucial elements of tube amplification were nailed down. Technical issues such as coupling two gain stages and selection of optimal coupling impedance were already resolved by the mid-1920s. The triode ruled supreme until the tetrode came along in 1926, followed in 1929 by the pentode from Philips's research laboratories in Holland.

Owning a powerful tube amplifier is like owning a classic automobile. Great pleasure may be had, but ownership involves a little more care and maintenance than usual.

Jadis, an audiophile company specializing in all-tube amplifiers and operating out of a small French town, has enjoyed a good reputation for some years, even if some of its models have suffered from the reliability problems that occasionally afflict the largest tube amps. Another problem area is that of power consumption and heat output. In common with class-A amplifiers and high-bias A/B types, including solid-state models, larger tube amps give off substantial heat. The Defy-7's 240W idling consumption may or may not be welcome, according to your location and the season.

It was back in the mid-'70s that David Berning made a name for himself in the Baltimore-Washington area as an avant-garde designer—someone with a truckload of fresh ideas about tubes. At the time, though Audio Research was starting to crank out pretty decent amplifiers, tube design was pretty much reduced to a rehash of the Williamson circuit and the Dynaco mod of the month.

I dig tube amps. When all's said and done, good tube amps seem to sound more like real life than most solid-state gear; even after listening to and enjoying the hell out of musical solid-state designs like the Audio Research D-240 II and the Muse Model One Hundred, once I hook up the big VTL Deluxe 225s again it's just like going home. I could go on about timbral accuracy and clearer midrange textures, but the bottom line is, music just plain sounds better when you shoot it through good tubes, and once most people experience that magic, they're hooked.

When I reviewed VTL's 25W Tiny Triodes in April 1991, I found them to be incredibly fun little suckers to play with, but got frustrated with their inability to drive my Spica Angeluses to reasonable levels with most of my recordings. I loved what I was hearing, but there wasn't nearly enough of it! As it turns out, John Atkinson was listening; not just to my plea, but also to the new VTL Compact 160 monoblocks in preparation for a full review. However, while all this was going on, David Manley decided that the power-supply voltages in the 160 weren't beefy enough to exploit his new KT90 output tubes; back the amps went for a transformerectomy.

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.

The VTL 225W DeLuxe monoblocks are very similar to the 300W monoblocks that received such an enthusiastic reception from J. Gordon Holt a year or so ago (in Vol.11 No.10) and, ultimately, most of the audiophile community. Technically, they differ only in output tubes and transformer: the 225W uses EL34s, the 300W uses 6550s. The 225Ws, at $4200/pair, cost $700 less than their more powerful brothers. The question may be raised: Why have two models so close in price and performance? According to David Manley, the 225Ws were built on special order for audiophiles who preferred the sound of EL34s to the 300Ws' 6550s. Demand was so great for the EL34 version that he decided to add it to the line. They look almost identical, the only difference being the smaller output transformer on the 225W and an additional filter capacitor on the 300W's top chassis.