Tube Preamp Reviews

When I began my journey into audiophilia, I was in awe of the Audio Research Corporation's flagship SP preamplifiers. As I sat there in the early 1980s with my modest Apt Holman preamp, all of my friends had ARC SP6Bs. By today's standards, the SP6B was colored, did not portray a realistic soundstage, and lacked sufficient gain to amplify the low-output moving-coil cartridges of the day. But it had an intimacy in the midrange that was intoxicating. (Still considered a classic design by many, the SP6B's price on the used market has remained virtually unchanged for 30 years.) Then, still in the early '80s, ARC raised the bar with the SP-10 ($3700). It had 15 tubes and an outboard power supply, and set a new standard for delicacy, drama, and authority. (John Atkinson still has the SP10 he bought in 1984.)

Following the introduction of their very expensive, tube/FET hybrid SP11 preamplifier, there were rumors that Audio Research was working on a hybrid tube/transistor preamplifier targeted to cost less than $2000. The rumors were confirmed when ARC showed a black-and-white photo of the SP9 at the 1987 Winter CES. Obviously, like all magazines, we were impatient to receive a review sample, but the first review of the SP9 actually appeared in the summer '87 issue of Peter Moncrieff's IAR Hotline. Peter's review was almost intemperately enthusiastic, comparing the SP9 positively with early samples of the SP11 and suggesting that its sound quality was considerably better than would be expected from its $1695 asking price. Naturally, we were anticipating good things when our review sample arrived in Santa Fe in late July.

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.

In red letters on the first page of Chinese audio manufacturer Audio-GD's website are these words: Wisdom in mind, enthusiasm at heart.

I like this goodwill greeting because it sets a mindful tone. I presume that sentiment was issued by one Mr. He Qinghua, because farther down the page, it states, "All Audio-GD's products are designed and developed under the leadership of Mr. He Qinghua." When I began my auditions, I took this salutation as an advisement, making it my plan to study Audio-GD's Vacuum HE1 XLR line-level preamp with as much wisdom as I could muster and the enthusiasm of high expectations.

A quarter-century ago, when we were just getting into wine, my wife and I took a trip to Napa Valley. At one premium vineyard, we took a taste from the $20 bottle, then, for the hell of it, a taste from the $50 bottle. The first taste was nice; the second was alarming—an explosion of flavors, a gateway to sensory delights that we hadn't known could be had from a barrel of crushed grapes. We wobbled away, concerned that high-end wine might be a dangerous hobby.

It's been 10 years since Balanced Audio Technology (BAT) introduced their first products: the VK-5 line-stage preamplifier and the VK-60 power amplifier. (I reviewed">http://www.stereophile.com/tubepoweramps/766">reviewed both in the December 1995 Stereophile, Vol.18 No.12.) The success of these and other BAT products has allowed designer Victor">http://www.stereophile.com/interviews/767">Victor Khomenko (the "VK" of the model designations) and partner Steve Bednarski to quit their day jobs at Hewlett-Packard; they were joined by Geoff Poor as a partner to handle the sales end of the enterprise. BAT's current lineup includes several preamps, phono stages, a CD player, and tube as well as solid-state amplifiers. The top of BAT's preamp range is the VK-51SEhttp://www.stereophile.com/tubepreamps/1103bat">VK-51SE;, which costs $9000; their top tube power amp is the VK-150SE">http://www.stereophile.com/tubepoweramps/536">VK-150SE monoblock ($17,000/pair); if you want their best phono stage, the VK-P10http://www.stereophile.com/phonopreamps/871">VK-P10; will set you back $8000.

How important is the use of balanced circuit typology in the design of preamplifiers and power amplifiers? Ask the top audio designers (I didn't, but just play along, okay?) and you'll get a wide variety of opinions. Some reject the balanced approach outright, arguing that it represents a needless duplication of circuit components, and that better results can be achieved if the same attention and resources are devoted to perfecting a single-ended circuit. In his provocatively titled article "Balance:">http://www.stereophile.com//features/335/">Balance: Benefit or Bluff?" (Stereophile, November 1994, p.77), Martin Colloms questioned the advantages of balanced designs, suggesting that while the results may be better in certain respects (eg, noise level), the reproduced sound may suffer in other, perhaps more important ways (eg, rhythm and dynamics).