The Place where Tone Begins--Interview with Mesa Engineering’s Randall Smith

Home | Audio Magazine | Stereo Review magazine | Good Sound | Troubleshooting



Part bohemian, part capitalist, and all boyish enthusiasm, Randall Smith is a renegade audio designer who revolutionized rock and blues with his legendary tube guitar amplifier, the Mesa Boogie. All tube and all tone, he’s a biker Edison, and perhaps the second most important figure in the history of guitar amplification. Not to slight Jim Marshall or Hartley Peavey, but when it comes to amps, Randall Smith plays Miles Davis to Leo Fender’s Louis Armstrong. And now he’s made a bid to enter the high-end cosmos with his first dedicated audio design — the Mesa Baron reviewed elsewhere.


above: The Mesa Baron (no longer in production)

“One of my main goals was to bring the mondo quality performance and power of a hand-built, dual-mono, all- tube amplifier within reach of more people. And while the Baron is our flagship, no-compromise power amp, I didn’t think the market needed another piece coming in at over $10,000 —yet that’s where many units offering comparable power and features are priced.”

Despite such assertions, Randall Smith is careful not to pick a fight or make pejorative judgments about the reigning masters of high-end tube design. In fact, he goes out of his way to acknowledge the inspiration he’s garnered from hearing the crème de la crème at audiophile shows.

Randall’s just bringing his own set of paints to show and tell, and trying to depict a singular sound signature. As the holder of around a dozen patents related to tube design, he isn’t exactly a new kid on the block, and sees the transition to High End as a natural, logical progression.

“I don’t think it’s such a leap for us because it all has to do with music and it all has to do with tube amplifiers. At some point manufacturing is manufacturing. And what we’ve done for 25 years is hand-build tube amps I’ve designed that use all the parts, tools, and methods we have at our disposal, so there’s no big difference there. I think it would be harder to go the other way—from High End to musical instruments. To make guitar amplifiers you’d have to add so much bizarre preamp circuitry, then get it and a speaker to function reliably in a small integrated package under the most abusive conditions imaginable.

“I’m the empirical designer,” he explains by way of trying to define his muse. “I’m step-by-step, try-everything. I’ve got my pre conceived notions and expectations, but I’m not limited by them—or I try not to be. And I’m not reluctant to admit that something didn’t work. Well, this should have worked out this way, but it didn’t. So what’s the lesson there?’ I allow myself to be led by intuition. I go into design trances. There are so many variables a designer is juggling simultaneously that you can’t think of it as a linear process. You’ve got to have a global concept of what the product is from the outside to the inside: from the circuit, to the circuit layout, to all the components and how everything is mounted and how it’ll be assembled.

“I keep trying to refine that vision, getting clearer and clearer, focusing in on the vaguest areas. Like, ‘I’m not so sure about that—well, I better get sure about that!’ I do a lot of thinking while I’m swimming and just hanging around— it’s never turned off. Luckily, my wife Susanne understands and extends me support whenever she finds me looking slightly glazed.”

Randall Smith’s branches extend ever outward into the worlds of music and high-end audio because his roots in both music and applied technology run deep. Born in Berkeley, California in 1946, Randall was lucky to come of age under the tutelage of adult figures who refused to accept anything less than his best effort. Randall’s mother and sister played piano, and his dad was first-chair clarinet with the Oakland Symphony. A big-band arranger and legit sax player who could sight-read anything but couldn’t improvise a lick, Randy’s dad employed gentle, methodical discipline to temper his son’s native intuitions, without snuffing out the boy’s creative flame.

“My first musical awakening came as a kid in the cradle,” Randall recalls. “The old man would take out his tenor and play, and when he did, something magical happened. My memories go all the way back to the smell of the sax and the saxophone case. I’ve still got it, and I still play his horn; it still has that same smell — somewhere between cane and mildew. The old man started me out on clarinet. Once I saw all the shiny buttons and keys, I just wanted to wail, but he told me, ‘You’re going to learn the open note, B, and when you can play that to my satisfaction, then I’ll teach you B-flat.’ So he had me playing one note for two weeks —his attitude was, If you can’t play one note, how are you going to play a lot of them? He forced me to learn the dynamics of a note, and it was all about long tones —which is still the exercise for horn players. You start pianissimo, with a clear attack, and build up to as forte as you possibly can without vibrato; then put some vibrato on it, and trail it back down to pianissimo. You relax and you breathe and you listen.

“He was all into the Zen of getting your throat open, having a little smile at the corners of your lips — the pro techniques for producing a centered tone. He taught me that it wasn’t about playing a lot of notes; it was about making music and hearing all the elements of a single musical tone and being able to identify and control them: the attack, decay, pitch, vibrato, overtones. If you smile—this is especially true for saxophone and woodwind players—it gives the sound a kind of a lift. The pitch doesn’t change, but the emotion does. I remember hearing one of the great singers—it might have been Sarah Vaughan—and she said, ‘Yeah, I like to play with saxophone players who smile.’ And I went, ‘Right on!’ because that’s what my dad always told me. ‘You’ve got to smile when you play, starting from those muscles just underneath your ears. And of course, you bend your knees, rotate your hips forward, and point your butt toward the center of the earth — because that’s the place where tone begins.’ Is that great or what?”

In 1954 Randall heard the Dave Brubeck Quartet with Paul Desmond on a home-built system with 6L6 tubes and a Karlson enclosure. “Makin’ Time” was a minor blues that stirred a profound spiritual connection in Randall, and before he knew it, the boy was gone. He took up alto sax frustrating his more staid teachers with his instincts for improvisation. “Yeah, I was the opposite of my dad in that respect. I played much more by ear. My reading was kind of weak, but usually if I heard something once I could play it. I always had a good sense of rhythm, and later I took up drums and played in a rock band during my Berkeley days. Can’t really play guitar, though,” he chuckles. “Just barely enough to check out an amp.”

An ambitious youngster, Randall’s single-minded pursuit of a Boy Scout merit badge during a summer competition transformed him from Tom Sawyer to Tom Edison. “A friend suggested I go for a woodcarving badge, because that would be easiest. So I made three carvings and took them over to the Merit Badge Counselor’s place at the end of a country road.

“I couldn’t even figure out where the damn entrance was, and I’m banging away at his garage door, when out stepped this big, tall cat, a dead ringer for Dirty Harry. So right off, I was nervous. His name was Stan Stilson. I introduced myself and handed him my three wood carvings. He kind of glanced at them, then looked at me, and we stepped inside and walked across the shop floor.

“Then he turned to me and said, This is a band saw. I’m going to show you how it works.’ He took my three wood carvings and ran ‘em through; turned ‘em around and ran ‘em through the other way. Then he looked me straight in the eye and tossed them in the trash barrel. “That’s what I think of your work, and therefore, that’s what I think of you. Every time you make something, you’re leaving behind a relic of who you were and what your values were at the time you made that. You’re leaving behind artifacts. So if you don’t care any more than that, you’re only cheating yourself.’

“He was right. Here I’d gotten used to goofing off in school —still getting good grades —and this guy just busted me. And that’s something real important that’s missing in education today. You’ve got to bust somebody’s ego down to about the thickness of an oil stain on the driveway before they’re willing to stop being defensive and actually open up and receive information. I’ll tell you, the master- student relationship ain’t what it used to be. Stan Stilson actually did me a favor by making me feel like a worthless piece of crap, because he instilled in me a real devotion to quality.

“Stan built control systems for industry, and introduced me to the whole world of electronics. His crowning creation during the time I was hanging around there was the heating and air-conditioning control console for the Nautilus — the first atomic-powered submarine. He fabricated electronic circuitry like a great visual artist, but with this added dimension of functionality. To me, Stan was like Merlin the Magician, and his work represented the crossroads of art and science.

“It turned out that his son was four years older than me and had just started building some ham radio gear. Because his dad had been so tough on me, I practically lived there for a month while I carved about a dozen different things, sharpened all his tools, cleaned u the shop, and got to know his family really well. Once I finally earned that merit badge, I started building amateur radio equipment alongside his son.

‘As he learned to trust me, his son and I got the run of his shop. It was scratch-building stuff right from the get-go: forming up the sheet metal and punching all the holes to mount tube sockets and transformers. I made a succession of different tube transmitters, which actually aren’t that far removed from power amplifiers. There’s really a lot of similarities, except that an audio amplifier hooks up to a speaker and a radio amplifier hooks up to an antenna. But the vacuum-tube principles are the same, the construction techniques are the same, the power supplies are similar, and the basic concept of conducting the resources of the power supply to another medium are exactly the same — even if the medium isn’t.

“Then cars and girls took over. I got a British sports car, a very character-building devotion for a kid to have, because you have to keep fixing it constantly. I know that Kevin Hayes [ VAC] had a British roadster, too. Mine was a bug-eyed Sprite, and it introduced me to the pleasures of racing around in British sports cars. I just got back from a vintage race up in Seattle, which was the most fun I’ve had in the longest time. Anyway, we’re getting off into racing, but all things are connected—it’s all about vintage engines, vintage racing, vacuum-tube audio, and classic jazz. Not only do they share archaic origins, but there’s some sort of soulful interconnect between them. They stand the test of time and represent true devotion to one’s art.

“My other great mentor lived just up the street in a house designed for him by his friend, Frank Lloyd Wright. Maynard P. Buehler made his fortune inventing firearm hardware, had the most amazing machine shop, and liked to rebuild his own Rolls Royce engines. Maynard had a big handlebar moustache and smoked one of those Meerschaum pipes like Sherlock Holmes. I’d show up lugging some parts under my arm, and we’d pop the flywheel up on this big old lathe, grind off half a dozen pounds, and make it into real racing stuff”

So, armed with a practical grounding in the arts and technology, our young beatnik ended up at Berkeley throughout the cultural revolution that started with Mario Savio and the Free Speech Movement, got kind of burnt out on the whole existential coffee-shop scene, and spent his college week ends hopping freights and playing in the rock’n’roll band Martha’s Laundry. “That’s where my latent electronics talents resurfaced. One night the keyboard player’s amplifier blew up —a Sunn 200S, which was really just a thinly disguised Dynaco with a lousy preamp. We were totally penniless, so I told him I’d fix it.

“He showed up the next day looking real nervous, and I reassured him that I knew enough not to louse it up. Anyway, it was a real easy fix — the usual blown tube and smoked resistors —but he was a real LA guy, amazed at the idea that any one could fix such a thing. Next day he told me we were going to open up a music store together. ‘What do we know about a music store?’ I asked him. ‘Leave the store front to me, and you just repair stuff. Everybody around here is playing in bands, and nobody can fix anything.” Within a year, Randall and Prune Music were servicing amps for the Grateful Dead, Jefferson Airplane, Santana, and all the Bay Area bands.

Then the guys in Country Joe & the Fish decided to play a joke on their guitarist, Barry Melton. “ ‘Can you take his Fender Princeton and jack it up to some ridiculous level where he’ll melt and go deaf when he turns it on?’ And I said, ‘Yeah, that sounds like fun, and I’ll try to keep it so that it looks absolutely stock.’ So I stripped every part off the chassis and redid it with 6L6s so that it put out like 60 watts through a single JBL 12. Truly the wolf in sheep’s clothing. I ended up doing about 200 of them, the majority of which used four 6L6s, and put out almost 100 watts at clip. Audiophiles may not realize it, but it’s typical for a guitar amp to run all night long at up to twice the power of clip—that would be 50% distortion, which is rocking pretty hard—only to get knocked over by a roadie. Which is why I developed the hammer test. Every amp we make gets walloped with a ball peen hammer—except the Baron, which draws a hard-rubber version. It’s a great diagnostic technique and confidence builder. If the amp can’t take it, it’s not ready for the real world.”

So you kept hot-rodding amps until Fender began wondering where all these transformers were going?

“That’s right. I had this order pending at Fender and it wasn’t shipping. Finally I phoned them up and they said, ‘Oh, yeah, you. Well, we’re not shipping you transformers any more because you’ve bought so many you’ve disrupted our whole production flow. Besides, we found out that you’re tearing apart our amplifiers and completely rebuilding them, and we don’t want that. We just want you to fix them.’

“So I phoned up the company that was manufacturing all these transformers for Fender, I told them what I wanted, and the guy said ‘Fine.’ I heard this old mechanical adding machine going in the background, then he came back and told me, ‘I need a check for $123,618 and we’ll get right to work on your order.’ Well, what are you telling me?’ I asked, and he replied, We custom-make transformers, and you’ve got to order a thousand of each configuration; that’s our minimum, and that’s what it costs. Since you have no credit, we need the money in advance.’ I told him thanks for his help and hung up.

“I sat there trembling for a while as I saw my fledgling amplifier-manufacturing career going bye-bye, like in the comic books where dollar bills with wings on them are flying away. Then I decided to call upon all of my most formidable literary resources and write this guy a letter. I didn’t hear anything for about a month. Finally I got a call back from Bob Iverson, their VP of Sales, a great Midwestern gentlemen and a real slow talker. Well, I got your letter; and I read it, and it laid around on my desk, and I read it three or four times, and I didn’t know what to think about it, so I took it home and I showed it to my wife, because women often have a good sense about these things, and she said, ‘Show it to your boss— I think he might want to gamble on this guy.’ So I took it to him and it sat around on his desk, and he couldn’t decide whether to pass it on or not. He didn’t feel okay about making a decision, so he took it home to his wife and she said the same thing, ‘Seems like you might be able to trust this guy — go ahead.’ So he took it to his boss, who owned the company, and the same thing happened again! This guy said, ‘Man, I don’t know, this is kind of a big risk,’ so he took it home to his wife and she said, ‘Hey, this guy’s got character—you ought to do it.’ The trouble is, we don’t know how to get around the minimum without charging you an incredible price.’

“And at this point I told him, ‘Look, I’ve been thinking about this thing, too, and I’ve got an idea. What I want is similar to some Fender designs you make. Couldn’t you just add mine on to the end of their order and save some setup time?’ And that’s how we got started, and now we’re among their top customers and we’ve been working together for 25 years. We began customizing transformers right from the start, because there were some Fender things they wouldn’t give me, and there was some Fender stuff that I didn’t want. Anyway, that was then, and now one of the greatest things about this company is that they’ll still make any number of prototypes until we’re satisfied. I usually call up, hat in hand, and apologize. Well, if I was a real engineer, maybe I’d know how to spec this better. Here’s basically what I want and here’s the possible variations I want to compare.’ What was great is that their old chief designer told me, Well, sonny, don’t feel embarrassed, because a good output transformer is only half science and half black magic—but the black magic half is more important. We’re never really sure, either.’”

Can you compare Simul-Class to TandemState Imaging?

“A lot of the thinking that led to Tandem State Imaging in the Baron proceeds from Simul-Class—which was one of those happy accidents. I had some prototype amp hooked up to the ‘scope, just fooling around and burning it in, when something in the bias supply failed just as I happened by. It had a sinewave going, and as the bias voltage went from what it was supposed to be—which was rather high—it gradually came all the way down to zero. So I watched the amplifier as it basically passed through all the classes of operation. It was like getting hit by a lightning bolt. To the marrow of my bones I had a deeper understanding of all the classes and their consequences, because at that second I saw them all in a continuum as the amplifier burned itself up. Then I got to thinking about the virtues and drawbacks of each class, and it hit me: Rather than a traditional class-AB amplifier that changes classes as it gets louder, how about combining two separate classes of the amplifier simultaneously such that one always remains class-A triode regardless of the volume level, while the other—a pentode class-AB pair—can be optionally switched onto work in parallel and thus contribute the bulk of the power. So this is the SIMULtaneous operation of two different amplifiers, each working in a different CLASS, both running together in parallel.

“Through experimentation, we finally developed an out put transformer that combined these two circuits. The results were stunning for guitar, and we’ve built tens of thou sands of them. When I tried it in the Baron, at first blush it was very seductive, but ultimately it wasn’t successful. It wasn’t neutral enough, and had way too much personality— it was too much of a sound creator rather than just an amplifier, which is great for a guitar amp, but not for High End. It didn’t disappear. Simul-Class has always worked best with two pairs of output tubes, and as you know, the Baron uses three pair per channel.

“But that experiment did spark the concept of individual and incremental switchability between triode and pentode operation for the Baron’s three pairs of power tubes; and that, combined with switchable negative feedback, is what makes up Tandem State Imaging.”

How does the Baron employ negative feedback?

“It’s global. That is, there’s a single feedback path and it encompasses the entire circuit. The four-position rotary switch allows you to select zero negative feedback or three incremental additions.

“The Baron can be configured to produce very impressive distortion and response specs, mainly by increasing the feed back levels way beyond what we currently offer. The trouble is, no one used those positions when they were available. In fact, based on responses we get from users, the highest feedback setting—which is still a relatively moderate amount—is very rarely used, and the most commonly used position is zero. I think that says a lot about the correlation between specs and sonics.

“You see, negative feedback is a corrective technique where a portion of the signal is taken from the output and fed back to the input, but out of phase with the original signal—it works by cancellation.

“Theoretically, what it does is equivalent to reducing the gain of the amplifier from, say, 100% to 50%. The total distortion is also reduced by half. Then, if you redouble the amp’s gain, you return to 100% gain, but the distortion remains halved. That’s because the amp only amplifies signals present at the input terminal, and since the distortion was generated internally and isn’t present at the input terminal, it doesn’t increase. Thus, an amp that employs 6dB feedback will have half the distortion of the same amp with zero feedback.

“Now this can be a real seductive scenario, because negative feedback—like a cheap perfume —can be used to hide a multitude of sins. The real trouble occurs when you have a flawed amplifier design that relies on negative feedback to cure its problems. The trouble must literally appear at the output before it can be fed back to correct the problem. If we listened to pure sinewaves, it would work as advertised. But because music is constantly changing, the feedback always lags minutely behind, and the transient musical content suffers.

“You lose .so many of the expressive nuances that make each musician special as well as information that reveals the venue acoustics and provides that sense of reality that’s the goal of High End. Although, having said all that, I must con fess that my sense of musical reality stems more from being there as a participant — on or at least near the stage — whereas many amp designers seem to prefer the more distant perspective of being an observer rather than a player. Anyway, in discrete increments, negative feedback can be added to help tune the overall response of the system and exert a musical influence over speaker behavior for varying types of music. But first, as is the case with the Baron, an amp has to work well without it.”

What’s the effect of negative feedback on speaker performance?

“With more feedback, damping increases and the speaker motion is reduced. But as the feedback is reduced, the varying load that the speaker presents has a greater effect on the amplifier’s frequency response. In other words, when you’ve got a lot of negative feedback in there, the amplifier will have a nice flat frequency response, but as you turn it down and down and down, you get peaks and valleys that represent the changing speaker impedance at different frequencies.

“You’re presenting a differing load to the amplifier, and usually a speaker impedance curve has a couple of big peaks and a valley—then it just trails off after that. So it’s anything but flat. Curiously enough, there’s a near-universal preference for little or no feedback. This is another example of how spec performance and sonic performance seem to be in opposition.

Why didn’t you employ the venerable 300B tube?

“Because there are others already doing it quite nicely. That’s their area of expertise. Mine is with the 6L6 and its sib ling, the 5881. These are wonderful tubes, and I’ve spent decades working with them: developing transformers, sockets, circuits, and so on. What helped us to hold down the price point on the Baron is the number of parts that share a common usage in both MI and High End. That’s why the Baron is dual-mono: We developed our largest power transformer to support a six-tube output circuit. It was far more practical to employ two of those for stereo than to start from scratch and attempt to come up with a single transformer that could handle both channels. And having two separate power sup plies is clearly a better alternative. So it’s a win-win situation.”

The Baron’s owners’ manual delineates the behavior and properties of diode, triode, and pentode tubes in terms of surly crowds of drunken Irishmen acting as a metaphor for electrons, and cocktail waitresses functioning as fetching force fields. What inspired that bit of whimsy?

“Frustration. In trying to give a straight explanation, I had to keep backing up and laying more technical groundwork. Finally I just had this image of the windings in the grid as the louvers on a bar door—controlling access, all the while revealing tantalizing hints as to what lies beyond. The more I thought about it, the better it worked out. We’ve gotten lots of positive comments on the manual, especially that section. So we’ll be putting it out on the Internet, making the whole manual available by itself for $5. And it’s worth pointing out that I’ve a good deal of Irish in my background, so no one can bust me for picking on some downtrodden minority. In fact, my Lotus 7 has a plaque proudly proclaiming its color as Irish Racing Green, not British Racing Green, thank you very much. So perhaps a wee dram of the single-malt late at night helped inspire the allusions to an Irish pub. And I assure you it was a very vintage whisky, because Susanne brought it back for me from London. You see, I’m a very lucky guy, and I love what I do, and I’ve probably enjoyed more than my share of the luck of the Irish.”

[based on a 01-1997 Stereophile article]

More ...






Prev. | Next

Top of Page   All Related Articles    Home

Updated: Wednesday, 2015-09-16 5:26 PST