Sporting fully balanced circuitry, ten vacuum tubes, and an amazingly modest price relative to its performance, any serious audiophile in search of a preamplifier really NEEDS to hear the Audio-gd Vacuum HE1 XLR preamplifier. The design wastes no money on popular but unnecessary processor features like multi-channel preamps, internal DACs, bass management, or AV bypass circuitry. This is a component designed for the stellar end of two-channel performance, plain and simple.
If you’re an imaging fan, and who isn’t, the Audio-gd Vacuum HE1 XLR (The “VHE,” henceforth) preamplifier is a “must-hear” component. It dishes traditional vacuum tube imaging without the traditional vacuum tube vices of soft treble or high distortion. You might not normally consider a preamplifier to be the key component of a good soundstage, but you’d be wrong – at least in this case. Unlike most contemporary vacuum tube preamplifiers (most of which strive to sound as “solid-state” as possible), this VHE preamplifier embraces and makes the most of its thermionic heritage. The result is imaging magic.
Audio-gd Vacuum HE1 XLR Tube Preamplifier
- Fully balanced circuitry
- Spectacular sound staging
- Neutral frequency response
- Exceptional parts quality
- Bargain price for the performance
- Clicks on volume changes
The Audio-gd Vacuum HE1 XLR preamplifier arrived at my door with the highest expectations ever for a review item. Having previously reviewed the company’s solid-state HE-1 Preamplifier, and finding it to be world-class, I was looking forward to finding out what the company could do with a tube product. To say that the VHE had big shoes to fill would be a colossal understatement. I encourage you to check out that article for a little background. Almost all my comments on the original HE1 preamplifier also apply to the new VHE.
Owner and designer, He Qinghua has designed and sold Audio-gd products with the motto “Wisdom in mind, Enthusiasm at heart” for many years. His designs have previously won First Prize in the U.S. National Semiconductor Audio Design Contest.
With strong research and development capability in audio technology, Audio-gd offers a complete line of equipment including DACs, preamplifiers, and power amplifiers.
The company follows the following design rules:
- All products are hand-crafted by experienced technicians.
- All products undergo 100 hours of burn-in, including listening testing.
- All parts are carefully selected and paired for sound quality.
The Audio-gd company has grown steadily and is becoming very well-known in both local and foreign markets.
Audio-gd Vacuum HE1 XLR Tube Preamplifier Features:
- Fully balanced circuitry throughout
- Built-in regenerative power supply
- 10 tube complement
- “Applied Vacuum Rectifier” without silicon elements on signal and tube power circuitry
- All power capacitors sourced from Solen
- Remote control for volume and source switching
Vacuum tube compliment:
Russian-made 6x 6H2N-EB and 4x 6U4N-EB
NOTE: Tubes are matched at the factory and burned in for 100 hours prior to shipment.
Tube filament voltage:
User recommended burn-in time:
100 hours (additional)
Recommended warm-up time from cold before use:
Recommended power-on duration:
<8 hours per day
Signal to Noise Ratio:
>96dB (2VRMS output, unweighted)
<300 ohms (unbalanced RCA)
20-20,000Hz +0/-2dB (see graph at end of specification section)
Total Harmonic Distortion:
<0.02% (see graph at end of specification section)
1VRMS output / 280mV input
22Kg / 48.5 pounds
(W x L x H – with feet) 430 x 450 x 125mm / 16.9 x 17.7 x 4.9 inches
Power Cord, Remote Control, Spare circuit board & emitter for Remote Control, 4mm Allen Wrench, Stretch gloves for handling tubes, Graphic of tube locations, Copy of warranty
$2,830 (excluding shipping costs)
10-year repair guarantee
If the damage is user-caused (any time frame): Free repair but customer pays all shipping.
All the following apply to non-user-caused damages (factory defects):
For the first 15 days from purchase: Automatic replacement if defects are found – All shipping costs are paid by the manufacturer
Between 15 days and first year from purchase: Repair cost by manufacturer – Shipping cost is refundable up to original shipping amount
Between one and ten years from purchase: Repair cost by manufacturer – All shipping is at customer expense
Preamplifier review 2020, vacuum tube, tube preamp, balanced circuitry, XLR, Audio-gd, vacuum he1 xlr
The Audio-gd Vacuum HE1 XLR preamplifier arrived double-boxed and with internal foam protection around the vacuum tubes. So before use, the consumer must remove the top of the case, using the supplied Allen wrenches. Then remove all the Styrofoam.
The controls of the Audio-gd Vacuum HE1 XLR preamplifier are straightforward. You have on/off, an input selector, and the volume knob. The remote control is similarly streamlined. It’s finished in silver aluminum and is substantive and well-marked. Unfortunately, it isn’t backlit making it hard to find in a darkened room. You’ll need a smaller Phillips screwdriver to remove the back and install the two AAA batteries.
Many previous Audio-gd products included their signature Audio-gd Current Signal System (ACSS) technology, but this has been eliminated from the VHE. The second (rightmost) XLR output jacks that have been substituted are welcome, although that second XLR output set is NOT fully balanced. Perhaps the cost of additional output buffer amps was prohibitive at the price point of this preamplifier? The leftmost pair of XLR output jacks are fully balanced.
Despite a 100-hour factory break-in period, Audio-gd encourages the owner to perform another 100 hours of home break-in time before critical listening. The owner’s manual also recommends no more than 8 hours per day of run time for the preamp. This means that a new owner will spend 12.5 days of preamplifier burn-in (at 8 hours per day) before the unit will sound its best. I was highly skeptical of this, but I did notice that the sound kept getting more spacious for all 12.5 days of the burn-in period. All listening notes are made after the additional 100-hour home-burn-in period.
Even once burned in, Audio-gd recommends a 20-minute warmup period before each listening session for the unit to become thermally stable. Being less than patient by nature, I often disregarded this but did find that the unit sounded better after being thoroughly warmed up.
The Audio-gd Vacuum HE1 XLR preamplifier is large and heavy. It will take a robust equipment stand to hold it, and a generous amount of ventilation height above the top plate, thank you very much. The preamplifier (as you might expect with ten vacuum tubes inside) does run hot. After warmup, I measured 101oF using my thermal gun on the top plate. This is warm, but not hot enough to pose burn hazards to pets and children.
There is no requirement that the user bias the tubes. All adjustments for bias and channel-to-channel gain are done automatically by the internal circuitry. This should also allow for future tube changes to be done with a minimum of economic and technical angst on the part of the owner. The Russian-made 6H2N-EB and 6U4N-EB tubes were apparently selected for not only good audio performance but also for long service life.
Speaking of the tubes, I was surprised to see that Audio-gd chose to use alternating current for the tube heater filaments. It’s an old axiom of tube design that the use of direct current normally makes for lower background noise. But whatever Audio-gd has done, it is successful – the preamplifier is completely quiet, even with the ear against the treble horn of my Klipsch speakers. This is likely a consequence of the inherent noise-canceling properties of balanced design.
The Audio-gd Vacuum HE1 XLR preamplifier uses fully balanced circuitry from input to the primary (leftmost) XLR output jacks. Balanced circuit design uses two independent amplifiers per channel, one handling the positive swing of the waveform and the other the negative. Most preamplifiers on the market with XLR in and out jacks lack fully balanced circuitry.
Some find balanced circuitry advantageous; others consider it superfluous. If you’re in the latter category, Audio-gd also offers the Vacuum HE1 SE (single-ended or unbalanced) vacuum tube preamplifier for $2,390 USD. I can’t comment on that product, not having had the opportunity to hear it, but would expect it to sound substantially similar to my review sample.
Inside the case, Audio-gd uses premium EVERYTHING. Film capacitors are used generously, as are metal-film, close-tolerance resistors. Wiring is dressed effectively, and shielding is used to avoid noise. Even the power-supply capacitors are top quality. I honestly can’t see how Audio-gd is able to offer this level of build quality for the price. I know of no other manufacturer that offers even remotely equivalent build quality for less than two or three times the price of this preamplifier.
My only criticism of the Audio-gd Vacuum HE1 XLR preamplifier’s setup process is the self-adhesive plastic feet. The user is expected to attach these adhesive plastic pads to the aluminum feet of the preamplifier. The stick-on feet, however, tend to pull loose under the weight of the preamp, leaving the aluminum underneath to scratch your equipment rack. I’d have much rather had some screw-in feet with Teflon pads that would be far more robust. But as Mick Jagger once sang, “you can’t always get what you want…”
The first thing that I noticed about the Audio-gd HE1 XLR preamplifier was its tendency to make a slight popping noise through the speakers when the volume is changed by the remote. The pops are not loud, and wouldn’t damage anything, but they’re definitely noticeable. This is not an occasional behavior; it seems to happen almost every time the volume is changed. There is no issue when it’s adjusted from the front panel knob. Once I realized this behavior was normal, it ceased to bother me, but I mention it because it might bother some folks.
The second thing that I noticed was the sluggishness of the preamp to respond to volume changes from the remote control. If your music is recorded at different levels (most is), you may find that the volume is much too soft or much too loud when changing tracks or albums. This is normal and has nothing to do with the preamp. But when the volume is suddenly found to be way too high or too low, you may spend some time pressing the volume buttons on the remote control before the preamp decides to respond. Often, I had to press the volume buttons multiple times before the preamp began responding. I found this irritating.
To be sure the volume-response delay wasn’t my fault, I pulled the batteries from the remote control and tested them with my Volt-Ohm meter. Both AAA batteries tested 1.58 Volts (like-new condition). I then pulled the VHE forward in the equipment rack to ensure that the shelving above or below wasn’t obscuring the necessary line-of-sight connection between the remote control and the preamplifier. No difference.
I did eventually notice that the orientation of the remote had an effect on the reception at the preamplifier. When the remote was held parallel to the floor, the response was more consistent. But if it was oriented at right angles to the floor when the buttons were pushed, the preamp volume response was far more unpredictable.
But even with the remote in its most effective orientation, the preamplifier was still reluctant to respond. It never actually refused to change volume, but I often had to either push the remote’s buttons repeatedly or wave the remote about before the volume changes were implemented.
The current preamp’s remote control has a feature that allows the user to hold down the up or down volume button causing a four-click simultaneous volume change at one time. But my review unit lacked this feature. Audio-gd’s European distributor, Magna HiFi of the Netherlands, informs me that they are aware of the remote control issues and have already implemented a fix as of May 2020. Since my review sample was shipped prior to that revision, I can’t comment on the efficacy of their fix. Other than the two issues noted above, the preamplifier functioned as expected.
Like the Audio-gd HE1 solid-state preamplifier that I reviewed, the Vacuum HE1 XLR didn’t significantly change the voicing of the material it was fed. It was remarkably transparent to the source, although the solid-state Audio-gd HE1 preamplifier is slightly better in this regard.
Associated Equipment used for this review:
External Western-Digital Blue 4TB HDD attached via USB to
HP desktop or Apple MacBook Pro running Roon 7 software connected by Ethernet to
AURALiC Aries Streamer in Roon-Destination mode connected via ABS/EBU cable to
AURALiC Vega DAC feeding balanced analog output to
Audio-gd HE1 solid-state or Vacuum HE1 XLR preamplifiers both via XLR outputs to
Emotiva PA1 Class-D mono-block power amplifiers or
Heathkit 12-watt mono-block power amplifiers (unbalanced preamp outputs only) or
Ashly FTX-2001 pro amplifier to
Emotiva T2 tower speakers or
Klipsch RP600m bookshelf speakers or
Magnepan LRS speakers and
Emotiva Airmotiv S-15 subwoofers (R&L pair) with DSP equalization
I deliberately threw in the Heathkit 12-watt mono-block power amplifiers because I wanted to see how very-high-input-impedance amplifiers (300K ohms) would affect the tonality of the Audio-gd Vacuum HE1 XLR preamplifier. The result: other than the even greater soundstage imparted by the little Heathkit tube amplifiers, there was no noticeable difference in the frequency response of the preamplifier.
The original solid-state Audio-gd HE1 preamplifier was and is a sound stage superhero, but the Vacuum HE1 XLR exceeded even the performance of its solid-state predecessor. The sound stage from the Vacuum HE1 XLR is remarkable. Even with cone-in-box speakers, I got holographic imaging. With the Magnepan LRS speakers, it went to even another level! If you’re an imaging fan, as I am, the VHE (or perhaps its single-ended counterpart, the Vacuum HE1 SE) are “must-hear” products.
Some of the material I used to audition the Audio-gd Vacuum HE1 XLR preamplifier included:
Roy Orbison “Mystery Girl Expanded CD”
The title track “She’s a Mystery to Me” is one of those ethereal-sounding songs that just becomes an earworm; you’ll be humming it all day. The VHE floated a wide and deep soundstage (however artificial it may have been on the recording) that just pulled me in with different instruments appearing at different horizontal locations and different depths in the soundstage. The locations were so precise, that with your eyes closed, you could point to the exact virtual location of each instrument in the recording.
And despite all this width and depth, Mr. Orbison’s voice sounded realistically centered without bloat or artificial exaggeration. How the preamp does this, I don’t know, but the effect is lost without the preamplifier in the signal path.
Sixpence None the Richer “Sixpence None the Richer”
The money track from this CD, “Kiss Me,” is another that you’ll find yourself singing under your breath for an extended period after hearing it. Strummed guitars are sweet-sounding and presently real, and when the lead female vocal begins singing, the fact that she sounds so in-the-room and lifelike is startling. Again, this is a sound staging marvel with both broad and deep imaging.
I offer the following two measurements provided by Audio-gd. The first depicts the frequency response of the preamplifier. Critics will note that the treble response begins its roll-off at approximately 5KHz but is down only 2dB at 20kHz. Despite this treble reticence compared to many solid-state preamplifiers, the treble did not sound in any way soft or rolled off. In fact, I considered the Audio-gd Vacuum HE1 XLR’s treble to be one of its strengths.
The second measurement by Audio-gd depicts the total harmonic distortion of the Audio-gd Vacuum HE1 XLR preamplifier. Again, despite the somewhat higher distortion than would be expected for a premium solid-state preamplifier, the sweep seems better than many I’ve seen for vacuum tube products. And it must again be mentioned that none of the measured distortion was audible at any time during use.
The AUDIO-GD VACUUM HE1 XLR PREAMPLIFIER is the best preamplifier I’ve ever heard. Considering its bargain price, I recommend it very strongly.
- Transparent-to-source frequency response
- Amazing soundstage
- Exceptionally high-quality construction (built like a tank!)
- World-class sound quality for a bargain price
- Fully balanced circuitry throughout
- Suppression of pops while changing volume via remote control
- More robust feet that are less likely to scratch rack surfaces
- Slightly tighter bass response
This preamplifier has more of a tube character than other recent examples of tube design that I’ve heard (those being, specifically, the McIntosh C220 preamplifier and the Audio Research VT80-SE Integrated Amplifier). Some potential buyers will LOVE this, and others will consider the VHE to be far too romantic for their tastes.
But don’t think that the Audio-gd Vacuum HE1 XLR preamplifier is that much like your dad’s Dynaco or HK Citation gear – you will not suffer with muddy bass, an overly warm frequency response, or the rolled-off high frequencies of those vintage products. Instead, you get a very open and airy sound (“transparent” in audio-journalist speak) that allows you to enjoy even poor recordings with an unprecedented soundstage and razor-sharp imaging.
As a final reality check to find out what the Audio-gd Vacuum HE1 XLR preamplifier really sounded like, I played my usual trick. After becoming accustomed to the sound of the VHE, I yanked it out of the system and listened using my AURALiC Vega DAC as both a DAC and a preamp, hooked directly to the power amplifiers. And? The Audio-gd Vacuum HE1 XLR definitely thickens the bass. If you’re a stickler for clean and crisp in the nether regions, the VHE may not suit you. The VHE also imparts a greater harmonic richness to midrange voices and instruments when compared to the source music track. Do these flaws disqualify the VHE as a world-class preamplifier? I’d vote No.
In fact, I consider the Audio-gd Vacuum HE1 XLR preamplifier possibly the best that I’ve heard. Period. The factors that prompt me to that conclusion include its sound staging capabilities, transparency to source, open and airy treble presentation, a not too wooly bass response, and the way that I’m constantly being surprised by how good even well-known recordings sound through this thing.
To get a preamplifier with even remotely equivalent sound, in my experience, one would have to spend multiple thousands of dollars more. So, based on the performance to cost ratio of the Audio-gd Vacuum HE1 XLR preamplifier, it is not only superb on a cost-no-object basis but also groundbreaking for its price.
If I didn’t already own the most-excellent sounding, solid-state Audio-gd HE1 preamplifier, I’d definitely be buying this review sample. And in fact, I’m going to be really, really sorry to see this preamplifier go home again!