Tube Preamp Reviews

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.

Some readers who read my praise for Audio-GD's R7HE MK2 digital-to-analog converter, in Gramophone Dreams #66, may have dismissed that DAC as a cheap, made-in-China product without questioning their own viewpoint-without considering the R7HE DAC's potential greatness.

I grew up in the '60s and '70s watching high school friends dismiss Japanese motorcycles, mocking their "primitive" two-strokeness, dissing their nation of origin, calling them "cheap Japanese junk" and posing for photos on their four-stroke Harleys, Triumphs, and BMWs. I remember how I trained my ears to identify the sound of each brand's engine. Harley-Davidson owners were constantly bragging about their bike's "deep-throated long-stroke sound." Triumph and BMW owners were equally proud of their rides' unique motor sound.

At the time, it seemed that every country's motorcycles had their own national sound. I thought that none of those national motorcycle sounds was more singular and aggressively wild than the jackhammering two-stroke power delivery characteristic of Japan. (Before I liked single-ended triodes, I liked two-stroke engines.) I figured that Japanese bikes, especially dirt bikes like my neighbor's '73 Honda CR125M Elsinore scrambler, sounded different because they possessed newer, more sophisticated, more forward-thinking engineering, while Euro-American brands were embracing change reluctantly, if at all.

Almost 50 years later, I figure it's those same four-stroker dudes, who are old now, complaining about the ridiculously high "collector prices" people are paying for '70s-era dirt bikes, while simultaneously dismissing the virtues of some of today's sophisticated, forward-thinking audio products, which happen to be made in China. From my perch in Bed-Stuy, where pubescent gangs of helmetless youth ride unlicensed, unregistered Japanese dirt bikes (and only unlicensed, unregistered Japanese dirt bikes), it seems to me that those geezer friends are exhibiting the same closed-minded, xenophobic attitudes and expecting a different result.

What I believe, but neglected to say in Gramophone Dreams #66, is that today, if a product is designed, engineered, and manufactured in China by a Chinese company, its quality will likely be comparable to that of products made in the UK, or America, or Germany, or wherever. I've reviewed outstanding products by Line Magnetic, HoloAudio, and Denafrips under the banner of that belief (footnote 1).

It's true that there can be communication, service, and customer-support risks to purchasing gear manufactured in Asia, especially when it lacks distribution through local, traditional channels. Such risks typically are addressed, sufficiently or no, by the manufacturer and importer. Anyway, they are partially offset by the opportunity for much higher value than you would expect from a product made in a country with higher labor costs.

Products sold through Underwood HiFi (including products from Audio-GD) present an acute value proposition-and return policies that are rare in this industry. On the one hand, relative to quality, the price seems particularly low. On the other hand, like other products bought from Underwood HiFi, this one comes without the zero-risk return policy that's common from online retailers. If a product works-is not defective-and you choose to return it anyway, you pay a 15% restocking fee. What's more, you'll find information online saying that Audio-GD offers a 10-year warranty, and it's true. But that warranty is from China and is not serviced locally, and shipping to China and back for a 50lb amplifier is expensive. Consequently, Underwood provides a two-year warranty. Needed repairs are made at Underwood's Georgia shop; the customer pays shipping one way, Underwood the other way. That same shop, of course, provides out-of-warranty service if it's needed.

I decided to review the Audio-GD Vacuum HE1 XLR line-level preamplifier ($3999) in the hope that it would turn out to be an especially strong value proposition-a reference-level component at a relatively working-class price. So, is it? Let's find out.

Description
Audio-GD's Vacuum HE1 XLR tube preamplifier is big (17" wide, 18" deep, 5" high), heavy (48.5lb), and so easy to operate that it doesn't even come with a user manual. For the most part, it doesn't need one-but see the caveat in the Setup section below.

What it does come with is a heavy, aluminum, five-button remote control you can use to select among three balanced (XLR) and two single-ended (RCA) inputs; adjust the volume; and mute the music. The HE1's front panel is dominated by a brushed-silver Volume knob set against a standard-looking black aluminum faceplate and flanked by three silver buttons, one for power and two for selecting the input.

The Vacuum HE1 XLR is fully balanced and line-level only-no phono. It sports no fewer than 10 vacuum tubes. The preamp may be Chinese, but the tubes are Russian, said to be "aviation-grade": six 6H2N-EB twin triodes and four 6U4N-EB half-wave rectifiers; you can be confident that the HE1's power supply is tube rectified. No brand is specified.

Those four twin triodes together are said to produce a maximum of 11dB of gain. One of the most unusual features is a built-in regenerative power supply, also seen in the R7HE DAC I reviewed. Regarding its 100-step current-mode volume control, the Audio-GD website says, confusingly, that "the signal only passes through a resistor and then is fed to the next stage, bypassing the volume control."

Setup
Yes, Audio-GD's Vacuum HE1 is simple enough to be self-explanatory. But with no owner's manual or setup guide, I didn't notice until almost too late that, deep inside the chassis, those preinstalled tubes are secured and cushioned against hostilities by Styrofoam inserts that must be removed before the amp is powered up. I spotted the foam's whiteness through the top-panel vents at the last moment, as I was plugging in the power cord. A minute later, I found two included Allen wrenches, needed to remove two sizes of cap screws that secure the amp's thick, well-fitted top panel.

Inside, the Vacuum HE1 XLR looks super-sturdy and intelligently organized. A major portion of chassis yardage and weight are devoted to power: three transformers and AC-regeneration circuitry. Beyond that, it was tubes everywhere, plus scores of what appeared to be made-in-France Solen capacitors.

Listening
Whenever I exchange one audio component for another, the first thing I notice is what I suddenly hear that I didn't hear before or, just as often, what recorded info went missing after the swap. The things that always change are the quality and quantity of reverb reproduction, the amount of corporality, and the illusion of transparency. And generally speaking, these changes are easy to spot.

When I replaced the Lab 12 Pre 1 tubed preamp ($2290) with the Vacuum HE1 XLR in my tubed daily-driver system (footnote 2), the change in sound character was more subtle than I expected, felt more than heard, nothing I could point a finger at. The Lab 12 Pre 1 presents recordings in the light of a cloudless spring day; the HE1 offered a different kind of clarity, beautiful to observe but difficult to describe. It wasn't darker, grainier, fuzzier, or blurred, but it was different in its luster and plasticity.

The Vacuum HE1 XLR highlighted the rhythmic charms and tone magic of my most-played Qobuz album: Debussy's Corner: Works for Flute, Viola & Harp, performed by the Trio Medicis (16/44.1 FLAC, Cypres/Qobuz). This ain't no tight-pants high-distortion rock'n'roll; this is low-key, charm-you-to-tears instrumental music with a spotlight on watery beauty. The Audio-GD let this beauty through unmolested.

However, via the Lab 12, the music jumped higher and felt more vigorous. In comparison, the HE1 sounded low-key. On the other hand, the Lab 12's tone was slightly bleached, its bass regions slightly thinned compared to the Vacuum HE1, which played slightly richer and thicker. Similarly, the GD pre produced more obvious three-dimensionality than the Lab 12 pre. I credited the Audio-GD's power supply for those effects.

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Footnote 1: The quality of manufacturing in China varies widely, from crude and primitive to the cleanest and most sophisticated. I've been told by more than one manufacturer that they have things manufactured in China because no one else can do it. But some people have other reasons not related to quality-politics, economics, human rights-for not doing business with China (or with Russia, where the tubes used in this preamp are made, but that's another story). Such decisions are best made by well-informed consumers rather than hi-fi magazine editors.—Jim Austin

Footnote 2: This system features Elekit's TU-8900 amplifier driving the Falcon Gold Badge speakers.