Brilliant Corners #12: Balanced Audio Technology VK-80i integrated amplifier, Ortofon Cadenza Bronze phono cartridge

In 1976, a Soviet fighter pilot named Viktor Belenko made an emergency landing in Hokkaido, Japan. He was flying a MiG-25 supersonic interceptor jet and, upon touching down, requested political asylum. This proved to be a stroke of brilliant luck for the Americans. The MiG-25 remains one of the fastest and highest-flying aircraft ever produced, and Belenko's defection allowed them to have a tantalizing look at the technology inside.

After the US Air Force took the plane apart piece by piece, the Japanese returned it to the Soviets in 30 containers, charging them $40,000 for crating services. Later, the Soviets sent the Japanese a $10 million bill for missing parts. Both invoices are still outstanding. In the meantime, Belenko became a US citizen through an act of Congress and, after changing his surname to Schmidt and marrying a music teacher from North Dakota, settled in the Midwest and co-wrote a book about his ordeal. He died at age 76 in Rosebud, Illinois, this past September.

Among the top-secret loot found inside the Soviet jet was a large, heavy triode vacuum tube used as a regulator in the power supply of the MiG's radio. It was known as the 6C33C. (The enormous electromagnetic pulse caused by a nuclear explosion would fry a transistor. Tubes were used in military equipment with such an eventuality in mind.) As it happens, the 6C33C also offers unusual and promising abilities in less dire applications: remarkably high transconductance and current-handling ability combined with very low impedance. This triode can create some serious watts without requiring a heroically large or complex output transformer. In the 1970s and '80s, the Soviet military complex produced the tube in vast numbers, so new-old-stock examples are still widely available. Perhaps not surprisingly, the audio manufacturers best known for working with this device—Balanced Audio Technology (BAT) and Lamm Industries—are American companies founded by Soviet immigrants.

BAT VK-80i integrated amplifier
My introduction to this fascinating triode, with which I share a birthplace and approximate date of issue, was the BAT VK-80i integrated amplifier ($12,000; footnote 1). Visually, the amplifier does bring to mind the MiG and, more broadly, the Cold War aesthetic: With its fierce incised metalwork, large footprint, and LCD display on the front panel, the VK-80i looks decidedly martial. If you told me that the VK-80i's function was to measure the outflow of heavy water from the control rods of a nuclear reactor, I might believe you. Then again, I majored in poetry at a liberal-arts college, so deceiving me about technology doesn't require mastermind-level cunning.

The fully balanced, push-pull VK-80i produces a nontrivial 55 triode watts per channel from two pairs of output tubes operating in class-AB while relying on a very restrained 3dB of global negative feedback. Four 6SN7 tubes perform input duties. BAT co-founder and chief engineer Victor Khomenko (those are his initials in BAT's product names) told me that the amp can push out significantly more wattage than that. Conveniently, the BAT uses an autobias scheme that compensates for fluctuating line voltage and aging tubes. It also does away with internal fuses, relying instead on a protection circuit that monitors each output tube's behavior, muting the affected channel in case of malfunction.

On a recent morning, I spoke to Khomenko via Zoom. We quickly switched into our mother tongue, which I think was fun for both of us. I left the Soviet Union when I was 9 and wholly ignorant of consumer electronics, and during our confab I learned the Russian terms for things like "amplification stage" and "idling current." Thanks, Victor!

Khomenko grew up in Leningrad (present-day St. Petersburg), where he built his first reel-to-reel tape recorder at age 10 and went on to work in consumer electronics. (He's still obsessed with reel-to-reels—he sent me a photo of his listening room (above), which appears to house a forest of these machines along with a pair of Avantgarde Acoustic Trio horn speakers.) In 1979, Khomenko immigrated to the US and found himself, somewhat unexpectedly, in Wilmington, Delaware. He had $400 to his name. (My family and I arrived the following year in the somewhat more spacious environs of New York City.) He soon joined Hewlett Packard, working in gas chromatography, and had a hand in the design of the steroid testing equipment that led to Canadian sprinter Ben Johnson's disqualification at the 1988 Olympics. But his love of music—mostly classical, followed by jazz—and audio kept needling at his soul until, in 1993, he formed Balanced Audio Technology with HP colleague Steve Bednarski.

While working on the design of the first BAT power amp, the VK-60, Khomenko considered the usual beam tetrodes like the KT88 and the 6550, but decided they weren't sufficiently linear. He also ruled out large radio transmitter triodes like the 845 and 211 because of the lethal voltages and massive transformers they required. The 6C33C solved both of these problems but introduced one of its own: The tube has an unusually wide range of sample-to-sample variation and a high failure rate. According to Khomenko, during the selection process he discards a great many 6C33C-Bs. He strongly suggests that customers source replacement output tubes directly from BAT.

Khomenko is an empiricist at heart and relies heavily on computer modeling to design his gear, but he told me that the VK-80i measures no better than "pretty well." To finalize the design of their products, he and Bednarski use their ears. In a 1995 interview in this magazine, Khomenko said this to contributor Robert Deutsch: "Although measurement is very important for designers, the usual measurements in typical reviews are not as meaningful for the average consumer. I think magazines like Stereophile should be reducing the number of measurements, not increasing them. For the average person, it's very difficult, even impossible, to predict sound quality on the basis of measurements."

My time with the VK-80i began with a bit of waiting. Initially, the left channel muted after a few minutes of play, and Bednarski quickly diagnosed a faulty output tube. After I replaced the left pair of 6C33C-Bs, the amp operated with nary a hiccup.

I connected my sources to one of the BAT's three single-ended inputs using Auditorium 23 interconnects, and the BAT to AC using AudioQuest's Thunder power cable and Niagara 3000 power conditioner. I took advantage of the VK-80i's high impedance (6–8 ohm) speaker outputs and 18' runs of AudioQuest ThunderBird ZERO speaker cables to connect it to the Klipsch La Scala loudspeakers.

Let's listen: I've recently discovered Pretaluz, a 1998 record by Angolan singer Waldemar Bastos (Luaka Bop 6 80899 0029-1-2). Produced by downtown New York guitarist-singer Arto Lindsay, it features Bastos's languid tenor, which takes on a remarkable range of tone color, and a small band of Angolan and Portuguese musicians. Stylistically, the music mines a kaleidoscope of influences: Afro-pop, samba, fado, morna, as well as traditional Angolan music-and-dance forms such as semba, rebita, and kizomba. The recording, which Luaka Bop issued on vinyl for the first time in 2023, sounds vivid and rich.

Listening to the LP's opening track, "Sfrimento," I was struck by the vigor, scale, and dimensionality the BAT brought to this record. Bastos's voice issued from within a cavernous soundstage, about 10' above the La Scalas, and when the background voices came in, they were positioned well behind it. The music sounded effortless, well sorted, and perfectly controlled: Even when the arrangement got busy, I was able to easily discern and follow every element. And the sometimes startling dynamics of Bastos's singing were conveyed with beauty and bracing force and without a hint of strain, breakup, or distortion.

The VK-80i shares this majestic presentation with the Line Magnetic LM-845IA, another large-triode powerhouse, but sounds less obviously "tubey." In fact, at no point during my time with the BAT could I hear any emphases, omissions, or other deviations from a flat frequency response: It's quite possibly the most neutral-sounding tube amp I've heard. But unlike some amps that create a sense of neutrality and control at the expense of vitality and color, the VK-80i allowed the recording to sound alive, saturated, and liquid.

I'd be remiss not to mention the BAT's knack for transparency, aided by its very low noisefloor. Listening to Rachel Podger play the Suite No.3 in C Major, BVW 1009 from J.S. Bach Cello Suites on violin (24/192 FLAC, Channel Classics/Qobuz), I was treated to an explicit, exciting depiction of her faster-than-usual tempi and dancelike approach to pieces that, in less capable hands, can be stolid and even plodding. But the BAT also revealed how the odd decision to record Podger in a hugely reverberant recital hall obscured some of the filigree of her playing and made her sound frustratingly distant.

Further kudos to BAT for the VK-80i's stellar volume control, a 90-step resistive ladder that changes loudness in 1dB increments; the volume and active input are displayed on the front panel. Also terrific is the hefty, all-metal remote, which, in addition to the usual functions, can dim or turn off that bright blue readout. Though I haven't tested it, I'm confident it can also tenderize a veal cutlet or, with enough arm speed, disable an intruder.


Footnote 1: Balanced Audio Technology, 1300 First State Blvd. Suite A, Wilmington, DE 19804. Email: steve@balancedaudio.net. Tel: (302) 999-8855. Web: https://balancedaudio.net/.

ARTICLE CONTENTS

COMMENTS
georgehifi's picture

Very close to listening to good pure Class-A solid state amp.

Cheers George

Bacheaudio's picture

Very nice article Alex , Molodza

Ortofan's picture

... for $13K, a McIntosh C22 Mk V preamplifier plus a McIntosh MC275 Mk VI power amplifier?

https://www.theabsolutesound.com/articles/mcintosh-mc275-vi-power-amplifier-and-c22-preamplifier/

Expofan's picture

This BAT integrated amp for $12K

Ortofan's picture

... requires a tube replacement before it will function properly.

JohnnyThunder2.0's picture

the aesthetics of Mcintosh components (many don't and they are massive.) Also more cords more interconnects more upgraded power cables etc. It's not a good comparison. Pick another integrated.

Laphr's picture

I've noticed since I joined not long ago that Ortofan habitually diverts away from the reviewed component. Is this a service the magazine offers that I'm unaware of? Or do editors find this second-guessing as odd as I do?

Good to see the low impedance 6C33C in such a great-looking amp, and from a reputable brand. From the writer's report it sounds like BAT got a nicely linear behavior from a tube not often seen in commercial products.

JohnnyThunder2.0's picture

a semi annoying form of second guessing the magazine. I think he feels he is doing people a service by be being a contrarian as he NEVER has anything positive to say about the product that is being reviewed. It wears thin after a while.

Glotz's picture

What is even more troubling is he doesn't offer the WHY he is consistently offering alternatives. The suggestions always seem half-baked, without reference to reviewed products as a proper comparison- with experienced notes or comments.

Not insulting, just a very real observation.

Ortofan's picture

... Klipsch La Scala, the Luxman LX-380.

https://luxmanamerica.com/product/lx-380/

https://www.soundstagehifi.com/index.php/equipment-reviews/1402-luxman-lx-380-integrated-amplifier

PeterG's picture

I have not heard the BAT, but I own the McIntosh combo. This review did not give me FOMO (thank goodness! haha), but it would have been nice to do this obvious comparison. My read is that the BAT is more neutral, though comes up second to McIntosh in terms of fun, presence, and ravishingness. A reasonable trade-off either way

DaveinSM's picture

Fascinating historical backstory, and another example of the writing in Stereophile being a cut above most everything save the New Yorker.

Ortofan's picture

... an explanation by Victor Khomenko as to how and why a 6C33C output tube can "create some serious watts without requiring a heroically large or complex output transformer."

JohnnyThunder2.0's picture

of others without the simple grace of applying a compliment to a suggestion? Are your take aways always sins of omissions and negative ?

Expofan's picture

I was thinking something similar, Johnny. Not sure what's going on there.

DaveinSM's picture

Actually, there is a good editorial reason why the author didn’t further go into the technical details of that vacuum tube (which I’m sure can be found with a google search).

I thought the length of the historical lead-in was perfect, tying in an interesting and true story without digressing too far from the main point, which was the product review.

Only someone pedantic would demand all the details about the tube, not realizing that adding all that would actually detract from the overall quality of the piece itself in terms of interest and readability. And cohesiveness.

Ortofan's picture

... a google search found, as to why the author didn’t go further into the technical details of that vacuum tube is that the author majored in poetry at a liberal-arts college.

DaveinSM's picture

Dude, you really are a jerk.

A quick google search on “khomenko” and “6c33c” pulls up links to so much more information out there, it could make a separate article. This has nothing to do with the author’s credentials and everything to do with your own malingering laziness.

This is a well written, entertaining article.

Laphr's picture

It may be time to ask Ortofan that eternal question, what is it you actually do around here?

Most audio tube people are already well aware of the 6c33c's unique properties as a pass element. It's not always a first choice where plate curves go, but its a very robust, attractive triode and expertly set up it obviously works well, as the review and decades of prior 6c33c art show.

To automatically divert the article over into a conventional beam tetrode feedback amp also evokes a kind of malingering laziness.

Jim Austin's picture

... partly to point out that the author of this piece is also the author of two books reviewed well in the New York Times. One of them is a memoir, so if you want to know more about the author, buy it and read it.

One thing you'll see immediately is that in contrast to many online critics, Alex puts his work out there under his own byline, staking his reputation on every word. I've been an editor for 20+ years, and Alex is on the short list of the finest writers I've worked with. (He also has a much deeper knowledge of hi-fi and its history than you do, very likely, though it's impossible to be sure when you hide behind a monicker.

Ortofan, I'm not going to ban you from participation in these threads, but I will tell you that, with some exceptions, you are in my opinion a mostly malign influence. I welcome you to take your commentary elsewhere.

Jim Austin, Editor
Stereophile

beave's picture

moniker, not monicker

beave's picture

When you say he (Alex) has a "much deeper knowledge of hi-fi..." are you saying he has a deeper *technical* knowledge? Or just what kind of knowledge do you mean?

Glotz's picture

Stereophile has been a audio journal juggernaut for decades.

Their scientific method is sound.

hiendmmoe's picture

I believe BAT charges $250 per output tube for this Amplifier and all others. $1000. To replace tubes on average every 2 years will scare most away from owning tube equipment that requires expensive maintenance!

JohnnyThunder2.0's picture

but anyone purchasing a tube amplifier for the past 30+ years knows this already. And it is not every two years - if you listen 24-7 maybe. You may disagree but not everyone in this hobby feels that way. Will it scare away "most"? No. If you want a tube amp you will "roll" with it.

georgehifi's picture

hiendmmoe: "To replace tubes on average every 2 years will scare most away from owning tube equipment that requires expensive maintenance!"

Correct if you listen every day like I did with them for a couple of hours, add 1/2hr more for warm up, these 6C33C's tubes run very very hot and eat themselves up. (originally they were a Russian designed tube, used for their early MIG fighter jets) They kinda look Russian with the spikes on top.

Cheers George

hiendmmoe's picture

These tubes are no longer made. Tell me why they cost over 4 times as much as they did 5 years ago?
To say most will not care about the cost is foolish. BAT charges $250 per tube today. $500 per tube in 5 years isn’t unrealistic thinking!

Yeti 42's picture

If it’s body and quiet background you want the SPU Royal, N or G, would make an interesting comparison to the Cadenza Bronze, if a suitable arm is available to cope with the weight and compliance of 8. Play some solo piano with it and you’ll know.

EmmaHund's picture

I can't help but wonder who all these reviews of astronomically priced gadgets are for?? How many amplifiers will be sold? I'm pretty sure there won't be more than 100 sold, probably less.

Is the review for the lucky 100 who can afford the amp? Same thing with eg 'Bowers & Wilkins 801 D4 Signature' ($50,000). How many speakers will be sold? There are countless other examples.

If it's Stereophile's policy to almost exclusively test stuff in the astronomical price range, then of course I can't be against it. You do what you want.
However, it would be immensely more interesting if you tested gadgets that ordinary mortals can afford - much more often than is the case now.

Thanks.

moniker's picture

Designing your amps around Russian tubes is clearly not such a clever idea.

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