Product Review

Balanced Audio Technology VK-31SE Stereo Tube Preamplifier

Part I - Introduction, Features, Listening

January, 2004

Jason Victor Serinus



Tube Compliment: Four 6H30

THD: 0.005% at 2 Volts RMS

MFR: 2 Hz - 300 kz - 3 dB

Noise: - 105 dB

Input Impedance: 100 kOhms

Output Impedance: 400 Ohms
XLR and RCA Inputs and Outputs
Size: 5 3/4" H x 19" W x 15 1/2" D

Weight: 35 Pounds

MSRP: $4995, Remote is $500 Extra,
     Phono Stage is $500 Extra


Balanced Audio Technology



When I recently told a salesperson that I was considering auditioning the VK-31SE, he said to me:

“One thing about BAT is while many high end companies greatly inflate their prices, selling equipment for way beyond what it's worth, BAT's prices really reflect the quality of components and research the company puts into them. They could charge a lot more for their products. They really are incredible value for the money.”

I first encountered Balanced Audio Technology equipment in the mid 1990s, when a local Bay Area dealer began to carry BAT products. I was mightily impressed with what I heard. My positive feelings only increased when I heard BAT gear in that dealer's room at a San Francisco Home Entertainment Show. Since then, I have met numerous highly discriminating audiophiles, from dealers and musicians to website editors (our illustrious John Johnson amongst them) who have sung BAT's praises.

Some months back, when I was unable to use my reference Bruce Moore Companion III preamp because it was undergoing upgrades for months on end, I contacted BAT's Geoff Poor to obtain one of their new preamps for review. I of course had an ulterior motive: short-term sonic salvation.

Geoff suggested I try the new VK-31SE. While this model shares the fully balanced topology of its bigger and far more costly brother, the VK-51SE, its coaxial inputs and outputs render it compatible with an amp such as my Bruce Moore that lacks balanced inputs.

I was quite eager to hear a preamp built around the 6H30 SuperTube. I first heard this tube in designer Alex Peychev's preamp/DAC, a unit not yet commercially available. Ever the comparison shopper, I wished to hear what a different designer would do with the tube.

At the same time, I was well aware of what my audio engineer friend Bob Olhsson recently said to me when I asked him about the possible superiority of SACD to DVD-A and of DSD recording technology to PCM. Bob suggested (in rough paraphrase) is that assuming a platform or technology has something good going for it, what matters most is how well it is implemented. It doesn't matter how “super” the format (or the tube) if the implementation is not up to snuff. It's how well you record and master your music, as well as the quality of playback equipment you choose, that ultimately determine which format sounds best.

In BAT's case, I expected the implementation to be super.

Technology and Features

BAT claims that the VK-31SE's power supply incorporates a Super-Pak that doubles the power supply energy storage from the level of its predecessor, the VK-30SE. The VK-31SE's power supply provides over 260 joules of energy storage, an amount sufficient to drive many power amplifiers. BAT claims that this results in noticeably improved bass response, both in ultimate heft and tautness.

BAT has also newly introduced paper-in-oil capacitors as power supply bypass capacitors; these allegedly contribute to smoother and more extended high frequency performance. Anyone who owns a VK-30SE can have it fully upgraded to VK-31SE status.

The VK-31SE is turned on via a Standby/On/Off button. During the 50-second power-on sequence, during which no sound is transmitted through the preamp, volume can be pre-adjusted. Normal or inverted phase, mono/stereo, choice of input, and the mute feature can also be selected during the power-on sequence. When the preamp is turned off and then back on, one must wait another 50 seconds before it is again ready to play.

Volume, input selection, and other features are displayed via a Vacuum Fluorescent Display that can show up to twelve alphanumeric characters. Display brightness is adjustable. There are five inputs available, each of which can be renamed and programmed according to the user's needs. For example, if input 2 says “tuner” but you instead wish to connect one of two DVD players, you can reprogram the display to say “DVD 1” or “DVD 2.”

A function button controls balance, relative volume, phase, mono/stereo, relative volume setting (an adjustment that allows volume to decrease or increase automatically when moving between sources with very different output levels, e.g. tuner and CD player), display, and input name assignment.

The volume knob, which also serves as a balance control, continually rotates without making any noise. Volume ranges from 000 to 140; I found myself most comfortable, depending upon the source, anywhere between 74 and 90. The volume display can either show decibel readings with respect to unity gain or decibel readings with respect to maximum gain. Note that this does not mean dB loudness coming from your speakers. It is a number in reference to electrical gain.

The rear sports five (5) inputs: three pair of RCA (coaxial), and two pair of XLR balanced. It has one fixed (tape output) and two pair main outputs (one RCA, the other XLR).

The BAT comes with an easy to handle, full-function remote control ($500 option). This enables one to adjust volume, mute, fade up and down, and choose the input source, phase, function, display, and on/off.

First Impressions

I am sure some Secrets readers have received high-end products exactly when they were promised. My experience over the last few years, however, suggests that if something is promised in three months, it is more likely to arrive within six to twelve. While the BAT did arrive at chez Serinus much sooner than most other products I request for review, it was after the return of the upgraded Bruce Moore preamp. I therefore only took a quick listen to the BAT, instead turning the bulk of my attention to evaluating upgrades to my own preamp. I needed to become familiar with my new reference before going any farther.

I did, however, register some initial impressions of the BAT VK-31SE. I could not help but be impressed by the sheer weight and solidity of the unit, the colorful and superbly organized layout of internal components, and the most unusual, unquestionably imposing cosmetics. Next to the BAT, my other components appeared very Plain Jane (which is not necessarily a bad thing, especially if you don't like Jack's looks). That the BAT offered the promise of excellent sound, decor-defining design, a full-function remote control, and the possibility of minute adjustments of volume seemed like a dream.

My first brief audition, however, suggested that dreams may not accurately reflect reality on this gross material plane. On the plus side, I clearly heard far more lower midrange and bass than through the Companion III. The midrange was spectacularly full and neutral in timbre. What I didn't hear, however, were the open highs that I can now hear through my upgraded Bruce Moore Companion III. When it came to top extension and transparency, I sensed that something was absent from the BAT presentation.

System Upgrades

As weeks passed, and I continued experimenting with a host of preamps and other components, I became aware that my reference system was not operating at the level it should. I thus engaged in a series of system upgrades. Only after successfully completing those upgrades and getting accustomed to the changes did I return to the VK-31SE.

Permit me to detail those upgrades:

1. The replacement of my old Audio Alchemy DDS-Pro transport with a heavily modified Sony 707ES from the workshop of Alexander Peychev When listening to music via its AES/EBU output, the Peychev-modified Sony transparency far more resolution, brilliance, transparency, and detail. (The Audio Alchemy, at least in XLR-out mode, sounds noticeably thinner and fuzzier). The ultra-Sony's lower noise floor, grain-free highs and tighter bass are an especial boon, enabling me to hear deeper into the heart of the music.

2. The replacement of the short power umbilical cord between Perpetual Technologies P-1A and Monolithic Power Supply with a Revelation Audio silver power cable. Especially notable is the increase in bass response.

3. The latest and hopefully final modification to my Talon Khorus X speakers. This includes the addition of Bybee Filters to tweeters and woofers, a switch to Shunyata internal wiring, a change of crossover capacitors and values – the new crossover is entirely different from the Khorus X's first generation crossover -- and speaker repositioning. The latter was accomplished with the invaluable assistance of Bob Bergner of, who used a soundcard and program developed by Rives Audio (manufacturers of the Parc) to measure the Khorus X's frequency response and interaction with my relatively untreated listening room.

The Khorus X's response is now remarkably flat throughout the spectrum, with few bumps and dips. The sound is far more extended on both ends of the spectrum, with much greater transparency, smoothness, and detail. This upgrade has definitely enabled me to more clearly what is going on with a particular piece of equipment. It has also granted me untold amounts of pleasure.

It was only after these upgrades were completed that I returned to the VK-31SE. What I heard was quite different than before.


My first listen was to the opening tracks of the new René Jacobs recording of Handel's Rinaldo (Harmonia Mundi), a recording that's critics voted one of the best of 2003. While the period instrument orchestra's sound was very full, it seemed lacking in the sheer range of color I experience at live performances of Philharmonia Baroque Orchestra, American Bach Soloists, and visiting authentic music ensembles such as Musica Antiqua Köln. When the recorder first entered, for example, its distinctive tone did not sufficiently stand out from the other instruments. The sound was very warm, perhaps warmer than in real life (a common trait of tube electronics), but the lack of differentiation between color and timbre of instruments was troubling.

As a second example, when the drum was struck strongly on track 7, its impact was certainly striking, far more so than through the Companion III. But while the initial strike on a drum skin usually sounds notably different than the reverberant sound that immediately follows, here they seemed to blend into one sound of similar color. This was not the case with the Companion III, which with the right tubes does a marvelous job of conveying timbre of instruments. I also felt that the OM1-Quantum, which in all fairness costs over $1500 more than the VK-31SE, was better at clearly conveying the nuance of fast coloratura vocal runs.

I next turned to Stephen Halpern's superbly engineered Crystal Bowl Healing (Inner Peace Music). The first track includes a recording Halpern made years ago in Egypt of the sound of his fist striking the side of the sarcophagus in the King's Chamber of the Great Pyramid. The sound was very deep and airy, with more slam than through the Companion III. But the color of the sound reminded me of the same color that I heard from the drum on the Handel disc, that is, not true-to-life. The sound of striking both the sarcophagus and the crystal bowls seemed more true on the other preamps.

When Halpern would move his mallet around the edges of the crystal bowls to produce their unique ringing sounds and overtones, their resonance seemed very full and life-like through the BAT. Nonetheless, the zzzz of the mallet was not sufficiently differentiated in timbre from the ringing tone it drew from the bowls. I heard far more color using either the Bruce Moore Companion III or the Reflection Audio OM-1 Quantum. However, I also noted that the liquidity of both tube products was more seductive than the somewhat drier sound of the otherwise superb solid-state OM1-Quantum.

The most revealing recording I auditioned was one my neighbor Charles brought over. Always a lover of esoterica - nirvana for Charles is the sound of a rarely heard theorbo - Charles brought over a John Cage recording of Ryoanji (Hat Art). This 1995 disc is an early example of 24-bit recording and is quite revealing.

Cage's composition, inspired by viewing the famed Ryoanji Zen meditation rock garden in Kyoto that consists of 13 rocks surrounded by raked sand, is minimalist to the core. It begins with periodic strikes on a drum, creating sounds that resound in space. Percussion is irregular, separated by long periods of silence. Almost magically, an oboe enters. The difference in timbre and emotional impact -- literally the spiritual nature of the two instruments -- is profound.

I found the sound of these instruments more neutral and truer to real life through the OM1-Quantum. The bottom resonance of the tone was far more striking, with a remarkable contrast between the sounds. Charles thought the bass of the VK-31SE not in keeping with its treble, as though the bass swamped the highs. As I understand his comments, this means that to his ears, the bass stood out because the treble was less than ideally extended.

I also tried the VK-31SE with Monarchy 100 solid-state monoblocks here for review. These I thought a better match, the tube preamp lending a welcome liquidity to the proceedings. I also felt the highs sounded better. This of course suggests that the performance of the VK-31SE depends greatly on system synergy.

This leads me to my final point. I have two friends, both fellow members of the Bay Area Audiophile Society (BAAS) who own upgraded McCormack DNA-1 amps. Some years back, these amps were widely praised as lower cost alternatives to Krell amplification. Their bass slam is excellent, even more so when upgraded. But I find they still sound distinctly solid state, compensating for a lack of midrange warmth with overly accentuated highs that lack the undertones that make them ring true. Far worse sounding was an older Bryston amp, owned by another BAAS member that rendered everything monochromatically edgy and brittle in timbre. Bryston used to be known for treble that was too snappy for some tastes, but seem to have calmed that down in their newer models. All these men subsequently discovered that they could make their amps far more listenable by the use of after market power cords, especially those that tend to darken the treble and fill out the midrange. One McCormack owner uses a Shunyata Black Mamba, the other a host of Shunyata Pythons.

This leads me to an important point. My hunch is that at least 90% of people who might audition a product such as the VK-31SE would match it with electronics, speakers and cabling incapable of transmitting the full range of sound with neutrality. Their components might excel at playback of electronically processed pop recordings, for example, but fare less well with well-recorded classical music. (I think here of all those speaker reviews I've read over the years that say “great for rock, less suitable for chamber music”). For such individuals, the BAT's excellent bass reproduction and solid midrange would prove a distinct asset. In fact, what I perceive as an apparent lack of treble extension might prove just the ticket to luscious sound.

Click Here to to Part II - On the Bench and Conclusions.


© Copyright 2004 Secrets of Home Theater & High Fidelity

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