Tube Preamp Reviews

Musical Fidelity's Tri-Vista kWP, introduced in 2003, was an impressive, high-tech, "statement" audiophile preamplifier. Its outboard power supply weighed almost 56 lbs—more than most power amplifiers—and its hybrid circuitry included miniature military-grade vacuum tubes. As I said in my review of it in the January 2004 Stereophile, the kWP's chassis and innards were overbuilt, the measured performance impressive, and any sonic signature imposed on the signal was subtle and, essentially, inconsequential.

"Are You a Sharpener or a Leveler?" was the title of my "As We See It" in the February 2009 issue. The terms sharpening and leveling come from work in the field of perception by the early Gestalt psychologists, sharpening referring to the exaggeration of perceived differences, leveling to the minimization of those differences.

We audio writers have our niches. Mikey loves analog, Artie likes to play with horn speakers and assorted oddball British kit, and I really enjoy reviewing affordable speakers. There's something exciting about hearing the fruits of the labors of a creative designer who's applied his talents to meet a stringent price point and created a speaker that can entice into our hobby the financially challenged music lover.

If I had to pick one amplifier designer as having had the greatest continuing influence on the high-end market, as much as I admire John Curl, Audio Research's Bill Johnson, and Krell's Dan D'Agostino, the name of David Hafler inexorably springs to mind. Not because he challenged the very frontiers of hi-fi sound, but because he combined a fertile, creative mind (footnote 1) with a need to bring good sound to as wide an audience as possible, both by making his products relatively inexpensive and by making them available as kits. (The Major Armstrong Foundation apparently agrees with me—they presented David with their "Man of High Fidelity" award at the summer 1988 CES.) It remains to be seen if the Hafler company will continue in this tradition, now that David has sold it to Rockford-Fosgate. But there is no doubt that many audiophiles were first made aware of the possibilities of high-end sound by Hafler products in the late '70s, and by Dynaco in the '60s.

Whenever an audio high-ender thinks about tubes, he usually thinks about Audio Research. This is only natural, because Audio Research Corporation was almost single-handedly responsible for saving tubes from oblivion in the early '70s when everyone else switched to solid-state. But ARC was soon joined in its heroic endeavor by an upstart company called Conrad-Johnson, which entered the fray in 1977 with its PV-1 preamp, priced at an affordable (even then) $500.

If any single link in the audio chain should be free of sonic personality, it's the preamplifier. Though a preamplifier's basic job description is "source selector with volume control," from hi-fi's earliest days preamps have been the designated dashboard: the more dials, switches, and lights, the better. All that control came at the cost of quiet, transparency, and tonal neutrality. Still, the quixotic quest for the mythical "straight wire with gain" continued to lead to minimalist designs, including impractical unbuffered "passive" preamps, in which cable length, thus capacitance, affected frequency response.