David Manley: Tubes, Logic, & Audiophile Sound

As founder of California-based Vacuum Tube Logic of America, David Manley is at the forefront of the current renaissance in vacuum-tube audio equipment. In addition to manufacturing some highly regarded audiophile components, VTL has introduced a line of tubed professional equipment that is finding its way into recording studios. David has a lifetime of experience in tube electronics, recording studio design, disc cutting, music recording, and most recently, analog/digital and digital/analog converter design.

David is highly opinionated, outspoken, and controversial. He expresses his strongly held beliefs with a passion and conviction that the printed word does not adequately convey. Moreover, he has a unique perspective on music reproduction and audio electronics, garnered in over 30 years of audio work in South Africa, England, and now America.

During a visit to the VTL factory, David's lab, and his newly built recording studio, I had an opportunity to discuss with him his views on a wide array of topics. I began by asking him what made him come to America and start a tube audio electronics business:

David Manley: First of all, you've got to know that I love America. I've been coming here for 25 years and always hoping, praying that I'd end up settling here. I would have taken a much lesser excuse, including sweeping a studio floor [laughs]. California is the best place in the world to manufacture this kind of electronics...

I planned to put amplifiers like these into production all the time I was in the recording business. A lot of the circuits I use I've refined over those years in recording, either as monitor amplifiers or mike preamps or whatever. We started the business in England even though I named the brand for America: over there the term "vacuum tube" is related to mercury barometers and things, while in America they think "valves" are related to oil lines and faucets.

I tried to launch VTL here in 1981, tried to get a small production line going off prototypes I'd brought with me on a visit. But I had a disappointing would-be distributor then who let me down rather badly, and I almost gave up the project. England is a good place to start such a business, and the whole thing was geared to export anyway—with America as one of the prime markets. As soon as the sales in America started to exceed the supply from England, I brought the manufacturing here. Boy, am I pleased I did.

Robert Harley: Many of your designs appear to be based on old textbook circuits. Has progress been made in amplifier design or are today's components just better?

Manley: It's not that they're old designs. In tubes, everything that you can think of, somebody's tried in some way or another. You can connect a tube many, many ways: you can use the anode for the cathode and the cathode for the anode, and you can ground the grid—the grid will use the cathode as an input, etc. So there's hardly any variation on circuitry that hasn't been tried in the amount of time—60, 70, 80 years—that the tube's been around.

So, as such, any design will have been preceded, but maybe not in a sonic way. Somebody may have used such and such a thing in a transmitting way, or in a radar way, or in a medical application. The designs I do are based, sure, on sound, known technology. But each design is unique insofar as how you lay it out and the kind of components you use and little novel ideas and twists you give to what might be regarded as a dogeared textbook configuration. Little things you do make it radically different and better.

Harley: How important are measurements and specifications in designing audio equipment?

Manley: Very important. I always say that I use measurements and specifications to confirm what my ears tell me. And I've heard a lot of things that measure well and sound not well, but I've never heard anything that measured absolutely disgustingly sound good. There is some relation. Obviously there has to be. It's just that I place the listening test above the measured specifications. But sure, they're important, and I use them. I believe in them. But I don't believe in syndromes like "anything you can hear I can measure," because that just isn't true. I always ask those people when they last measured a Stradivarius or Guarnerius violin. Or how do you measure the difference between a Steinway and a Bösendorfer or a Bechstein? All three excellent pianos.

I love that other issue about measurement vs listening—when people promote the blind panel test, which of course I have no faith in, or even interest in, other than to laugh at. If you were choosing a piano for a concert hall, would you get two or three name pianists that you knew and respected, or would you put it up to a blind committee to help you pick a concert-hall instrument?

You needn't bother to answer that. Your smile tells me everything.

I don't believe you can design good playback equipment until you know what goes into a recording. I think recording and playback are inextricably interlinked. You can't just build playback equipment by relying on the commercially available records without knowing A) what goes into them, and B) how they can be improved, because they're flawed themselves. I think it's also part of the whole circle. What we're doing now is to try to make good recording equipment available. It should make better records, which means they'll be made available to the audiophile community. I think all those things are irrevocably locked in a circle—a continuous chain.

The recording aspect of our business is mandatorily beneficial to our mainstream business of playback equipment for audiophiles. You can only make a really good recording knowledgeably when you've absolutely competently covered the art of playback. It's similar to when you're lining up a tape machine: you don't know how good the record amplifier is, or is not, until you've referenced the playback system to be optimum. Then you can adjust the record amplifier to that standard (footnote 1). The two things strongly intercouple. I feel that VTL has a distinct edge by being in both sides of the field.

And it's starting to grow. There's definitely a strong feeling around town. I don't get into every studio in the world, but I get into a lot, especially Hollywood studios. There's a strong tendency—a desire—to get back to better recordings. The rooms with good acoustics and good consoles are getting more and more business as the accent goes off plug-in material—MIDI (Musical Instrument Digital Interface) and electronic instruments plugged right into the console. And there's definitely an extremely heartening swing toward wanting better sound. That's a reality. I'm not just imagining it. We've done much, much more business in that arena in just this year, which is our first year of supplying professional equipment. Which, by the way, I intended to be in from the day I started VTL. I couldn't wait until we had special development funds to make recording equipment available.

Harley: What's in the signal path of most recording chains?

Manley: Garbage and toilet paper and chewing gum and fish-and-chips and squibs and toffees and things. I'm much in admiration of the work you've done trying to put a healthier relationship between the recording community and the audiophile community. But you and I both know very well that a lot of stuff in the recording chain would give an audiophile heart failure if he either saw its entrails or heard it. There are certain mixing consoles—you know their names, the most illustrious and expensive—I guarantee an audiophile would run screaming from his room if he had to spend an evening listening to his music all the way through one of those mixing console channels (footnote 2).

When multi-track recording stuff came in, size and compactness and price were very considerable factors in choosing equipment. Because while you might have had a 16-microphone console with four or five playback channels or whatever, you're suddenly confronted with having to have 60 inputs, each to cost little money and be very small. Guys now put in equipment with huge facilities—tweaks, knobs, and devices to outdistance the competing studios. And it seems the choice mixing console, the one that costs from a third to a half a million dollars, is one loaded with the most number of features and toys—on every channel. You could never use 60 channels of parametric [equalization] combined with 60 channels of compression and limiting and so on.

The whole thing is feature-ridden and compact, and looks classy and costs a lot of money and attracts customers. But the sound is not worthy of merit. Some of it is—I think "execrable" is a good word—disgustingly bad stuff. You find this in illustrious tape machines: beautiful transports and so on, but electronics that are diabolically terrible. They measure okay and they identify the tune passing through them, but not much better than that.

A good example of the convenience-over-sound attitude is the story of how 48V phantom microphone power came into being, which I think is another obscenity in recording (footnote 3). And it's all done at the altar of economy and convenience and size and dollars.

As I understand the story, a major microphone manufacturer commissioned a marketing operation to find out why the sales of capacitor microphones were either tailing downward or not growing the way they'd like. And the one answer that came ringing through strongly at the end was that the users, who were the studio operators, highly disliked the separate power-supply box. They didn't want that damn little box lying around near the studio input plugs on the other foot of the boom base or wherever. So they said, okay, fine, we've got a system to eradicate that box in solid-state. We'll run the energizing voltage for the amplifier circuit in the mike head along the audio cables. Which is bad enough when you think about it, relying on just common-mode rejection to cut the noise.

But the price of that is they have to couple it out through high-capacity electrolytic capacitors. They couldn't use a big polycarbonate or polypropylene because they'd be bigger than the damn microphone. So they're using 10$c portable-radio–quality electrolytic caps to carry the whole audio signal of a couple-thousand-dollar microphone. Through a 10-cent cap. Bingo. Death. Death to what the capsule is doing.

Harley: Why has there been so little concern by recording engineers about sonic quality?

Manley: I don't think they willfully pollute the signal path. "Can we dig up a piece of horrible stuff here to try and degrade the signal?" But I think it's for a combination of speed and convenience features, client-attracting doodads, and what have you. You're right in the sense that they aren't as worried about it as they should be. An audiophile would take the unnecessary crud out of the path. Sound-degrading crud. The answer is for more people to become audiophiles.

Harley: Why is there such diversity between audiophile values and the audio engineering establishment's values?

Manley: I think it's pretty sad that the recording community—or at least the AES-steered part of it—regards the audiophile community—the true listening enthusiasts—as tasteless lepers or troublemaking, nit-picking bums who don't know anything and just buy expensive equipment unhampered by taste or knowledge. That's a gap that needs to be healed.

It's wrong. Because that's how the start of good recorded music was sold into the public: "Look at how hi-fi we are able to give you now, to take the orchestra home and make it really good." And then they do an about-face and say "Good enough is good enough."

Harley: There is apparently a belief that amplifier design has reached a pinnacle and no further work can make amplifiers any better: they're all the same already.

Manley: No, they're saying that if the equipment you can buy at Radio Shack isn't good enough for you, you're an obstreperous, overcritical swine. That's what they're saying. They say all those amplifier designs are the same, and all amplifiers sound the same, and you're just too rich. You're spending too much money, and nitpicking. And that's not how it should be.

Harley: Why do you think there is so little emphasis on listening and striving for greater sound quality?

Manley: Without being defamatory to anybody—and I'm pretty good at that—I really think because these guys are so progress-driven—with the word "progress" in quotes. If it looks like it's new and might give a whole lot of people new jobs or expand a certain area of manufacturing ability, that constitutes progress.

They hate tube people; they say that tubes are retrograde, even mentioning tubes sets electronics back by decades. As far as the AES is concerned, when tubes started to be replaced by transistors, they'd've liked to have taken a hammer and smashed every tube and every piece of quality equipment that existed because they regarded it as museum stuff—and irritatingly good. If they even acknowledge that it's good.

The most overused advertising copy word is "new." Apparently you could sell anything if you put "new" in neon letters just before it. To my way of thinking it's a retrograde word—something new may not have been tried out properly yet. But apparently it's a very wanted word among the buying community of all kinds of commodities. The AES are what they are because they are the forefront of "new" development. They're obviously of the persuasion that anything new beats anything old.



Footnote 1: The record and playback electronics of analog tape machines must be aligned before each session. An alignment tape recorded with varying frequencies at a precise and reference fluxivity is used as a playback reference. After the playback circuit is correct, the machine's record electronics are aligned to the playback electronics.—Robert Harley

Footnote 2: It's not unusual for a signal to pass through at least 50—and as many as 100—op-amps in a pop or rock recording.—Robert Harley

Footnote 3: Condenser (capacitor) microphones require a DC polarizing voltage on the capacitor plates as well as a supply for the built-in pre-preamp. In phantom powering, the 48V DC supply originates at the console and is carried on both the same "hot" and "cold" conductors as the tiny (about –35dBm or 15mV) balanced AC audio signal.—Robert Harley

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