- 869 -
Enhanced Triode Mode
Integrated SE Amplifier
Interviews with Tim de Paravicini
By Steve Harris, Stereophile, November 2007
How many hi-fi professionals can say that they've designed at least one of every part of a complete recording system, from microphones to tape recorders to vinyl-disc-cutting electronics? Probably only Tim de Paravicini (footnote 1). Best known to audiophiles for his extraordinarily durable EAR valve amplifiers, Tim is also an electronics guru to the professional recording world. His global reputation today is based on more than four decades of making things better, building equipment that stands the test of time.
In the 1970s, Tim spent four years as chief amplifier designer for the prestigious Lux company in Japan, coming up with such models as the classic high-end C1000 preamplifier and M6000 power amp. In Japan, too, he met his wife, Oliva, who taught him Japanese while he taught her English. Returning to the UK, he set up his own company, EAR (the initials originally stood for Esoteric Audio Research).
In the 1980s, Tim designed and built his first complete system of record-cutting electronics, for Island Records; as a consultant, he designed the hugely successful A1 integrated amplifier for Musical Fidelity. By the 1990s he was rebuilding Studer and Ampex analog tape recorders for ultimate-quality studio mastering. At hi-fi shows one year he used master tapes from Pink Floyd to demonstrate his astonishing "direct drive" Quad electrostatic loudspeaker, in which the high voltages for the electrostatic panel came directly from the tubes of his special amplifiers.
In the present decade he's added a turntable, CD, and loudspeakers to EAR's Yoshino line of domestic products, while continuing to take on major projects for professional clients; for example, a disc-cutting system for Mobile Fidelity Sound Lab. He's also acted as a design consultant to Quad for the new QC24P tube phono stage and the II/80 tube power amp.
But it all began at the dawn of the 1960s, when, like most teenagers in England, Tim heard rock'n'roll for the first time. He also learned to play the drums.
"I was a boy in Nigeria, but then I was brought to England to be educated. Did the usual thing, school, college, and then I went off to South Africa. But even when I was at school I was involved with bands in one form or another. It's a kind of addiction, rock'n'roll. I first saw it when I was about 12 or 13, and that was the holy grail. I was brought up with classical music, my mother loved to play classical music, but I was at the age where I didn't want that.
"Of course, the other notable at my school in Stevenage was Ken Hensley of Uriah Heep. I think, even at the age of 13 or so, I was able to see that this guy had the push, the determination, he wasn't going to rest. You've got to have that spark or fire by the time you're 15 or 16, some sort of drive to keep you going. I suppose that was my guiding light.
"The other thing was poverty. Necessity is the mother of invention. If you haven't got the money, you can't just go and buy the nice toys, you have to make them, and that puts you in good stead to learn how to do these things the hard way.
"In South Africa at that time [the late 1960s] there was no television, so hi-fi was very much broader-based, and (white) people who had disposable income were buying even the B&O class of hi-fi. So at that time there were more McIntosh amplifiers there per head of population than there were pretty well anywhere else. It was luxury having no television, in a sense!
"I worked for myself, and for a couple of hi-fi stores and a couple of studios in Jo'burg, and I did repair work and consultancy for one of the stores that imported McIntosh and Luxman and other high-end brands. It was there that I met the guys from Lux, who were on a sales trip, and they offered the invitation to go to Japan.
"I'd been in South Africa for seven years, I'd done this, that, and the other in hi-fi, been involved in rock groups, with PA systems and so on. So, not just domestic hi-fi; I'd been involved in audio from the microphone to the loudspeaker. I just wish more people who listen to hi-fi understood what goes on at the front end of it all before they pontificate about the quality of recordings, and realize that a lot of them are compromised badly.
"Anyway, in Japan... the Japanese have always aspired to quality. At Lux I luckily had the ability to do what I more or less wanted to do; occasionally, they would ask me to develop or design a particular product, but it was usually a consensus. And one or two of the products have become classics in their own right. For example, there was the MB3045 amplifier, a 70W transistor amp. Then there was the C1000, and the M4000 and M6000 amplifiers. Even Robertson-Aikman [the late Alastair Robertson-Aikman of SME] had them at one time.
"I was quite pleased it all happened, really. I was never happy with mediocrity, and I don't think that I could have ever persuaded a British company to go to that measure. If I look at Peter Walker with Quad, he started off being at the top end of the market in the 1950s; the Quad II and 22 were among the best half-dozen amplifiers in the world; but as time went on, through the transistor generation, the 303 and then on to the 405, they slipped down the ladder. They lost that aspirational position at the top. The Quad Electrostatic was the only speaker that was at the top of the ladder, and it still is at the top! But as far as electronics were concerned, they missed it. The problem with British companies was, of course, the lack of investment at that time, although Quad were better than most, which kept them ahead. But the Harold Leaks of the world didn't invest in new products. But the time I was in Japan, the mid-1970s, was a time when Japan was prospering very well, and was prepared to take risks and gamble on things. If a company could see that they would make a minimum ultimate run of 10,000 units, it was worth going for.
"Fortunately, we had a couple of very good industrial designers. We could discuss it and come up with what we wanted, and they would interpret it and come up with a clay model. Lux built everything in clay as a dummy model before actually committing to putting a complete product together in the proper sense. And it's that detail, subtlety, that quality. I'd love to try and emulate that with my own products, but with the best will in the world, I don't have the capital to do the swish tooling. But I still try to keep an air of quality with my products.
"One example is that Stereo Sound award on the wall behind you, for the EAR 859. Curiously enough, I sold more 859s in Japan in that year (1995-96) than all other valve amplifier competitors together! I think that was a wonderful statistic. The modern equivalent of that is the EAR 834p phono box, which has sold very well all over the world.
"One of the measures of what I've tried to get is how much changes hands on the secondhand market. What is the brand loyalty? That, to me, is important, even in the pro audio market, where some competitors have come along and copied the ideas I've put out, cheapened them. They'd sell a stack of them, but then you'd very quickly see the secondhand pages full of them! "
I commented to Tim that, although hi-fi can be a bullshit business, you can't bullshit pro audio customers.
"No. It's a tool to them, it's not a frivolity. And they're not going to suffer fools gladly. Home hi-fi, well, you can go back even 50 years and there's a lot of product that was cheesy, and came and went.
"In South Africa I'd been in and out of doing pro audio, in the form of PAs and peripheral studio equipment. In Japan, I hardly touched any pro equipment. The nearest I got to that was forming the tape club at Lux. We had 40 people who had open-reel tape recorders, and a mixing console and a splitter box. We would go and rent a hall and hire musicians and record some music, so that everybody went home with their own master tape. And everybody clubbed in and put in... well, in today's terms, 50-100 GBP at a time, a relatively small amount, but when you amassed it together with 40 people, you had enough money to pay the musicians.
"Because the Japanese aspire to have the best quality. When I came back to England, I couldn't convince people about master tapes: 'Oh, if it ain't a Linn turntable, it ain't good enough' sort of thing. I was confronted with people accepting a record as if it was better than my master tapes! And it's not, I'm afraid.
"But, as I say, when I came back to England I had to face the competition. I chose not to try and fight them head-on, but to carve my products the way I felt they should be.
"I was a consultant to Michaelson & Austin at the very beginning, and I worked for a company called Tangent, which made loudspeakers. I was responsible for trying to develop an amplifier and active speakers under a high-end badge for Tangent, which was called Moonlight, an embarrassing name! I got back into professional audio equipment here in about 1983, when I met some people from studios who wanted some stuff, and I designed a disc-cutting system for Island Records.
"I know that I can make vinyl sound better than it ever does, because I know what all the limitations are in the cutting electronics. It wasn't just the amplification, it was the approach to the concept of dealing with the feedback on the cutter heads and everything else. Neumann and Ortofon and the others had all followed the same avenues, and I just said, well, I'm going to look at this with a fresh sheet of paper and see what I can do to tackle the problems.
"That system cut quite a few Number Ones. If you cut vinyl properly, it will sound virtually indistinguishable from the master tape. That's the ultimate aim of what I'm trying to do: to preserve the sound as closely as possible all the way through. And Mobile Fidelity have got the current version of the concept at their place in California.
"I've been lucky to do tasks for people like the Pink Floyd. It's equipment that has to stand the test of time. Does it sound any good, or does it destroy the sound? Does it hold the integrity of what they're after? And so on. My compressors, for example, make controlling the level easier, without it sounding as if you have crushed the life out of the music. And of course in the studio you have to modify the events, because you are trying artistically to produce an end result. If you're recording classical music, it's a slightly different ball game than pop music; but pop music is meant to be an electronic artistic event, and there aren't any rules! And it's mentally more stimulating.
"But with home hi-fi, the fire's never gone out. I still want to do something better than anybody else. That was the whole motivation from the beginning. That's the competitive nature of it. And the business side, the money side of it, was secondary to producing something of quality."
When CD arrived in the 1980s, Tim de Paravicini was among the first to explain the shortcomings of the new format's sound quality by pointing out that existing analog media were superior when analyzed in terms of sampling rate. He argued then that a digital medium would need a much higher sample rate than 44.1kHz (and a higher bit rate than 16) to match the resolution of analog tape or vinyl. I asked him to explain this again.
"Well, the quick nutshell of it all is this. An analog microphone we all understand, and a valve or transistor amplifier is linear in its working range. On a vinyl record, when you are cutting an acetate, there is no modulation or chopping it up; you are down to the molecular level of the acetate to store that information. It's a totally random but very minute-resolution storage system.
"When it comes to digital, it's how to operate it, how many bits we devote to it, and the sampling frequency, as to how we store that information. The original digital system of CD, with 16 bits and 44.1kHz sampling, was what the mathematicians deemed to be the minimum acceptable to human hearing for so-called hi-fi. They never looked at all the artifacts and all the problems. And they never did enough analysis of the human hearing mechanism to realize that we don't stop hearing at 20kHz; people can discern and detect sound up to 45kHz. We have, as I say to people, an equivalent risetime of 11 microseconds in the hearing mechanism. And the ability to resolve detail in those digital systems wasn't quite good enough.
"In analog, you can change the thing and keep on aspiring to perfection without a compatibility issue. With digital, once you change any parameter, you've got a compatibility issue. Now, you can record on ProTools at 24-bit/192kHz, but it's not compatible with CD. I did my own summation, and this is from 20 years ago, that if we did 384kHz at 24-bit, we'll have a system that will resolve on a par with the best analog. That's the holy grail. And the problem, for the computer people, is having the balls to go that whole hog.
"At the moment, they are going the opposite way. Digital radio came along with a promise of perfect sound forever on the radio, and the BBC made all sorts of spurious claims using what I'd call not-true comparisons; for example, showing that they could drive a car around and digital would sound better under certain circumstances.
"FM, when it was designed in the late 1940s, had a dynamic range of 80dB potentially, and FM has the linearity of an analog system, because the equivalent sampling frequency is around 108MHz, which is huge, and gives an extraordinary resolution. And then they come along with a digital system that is only 13 or 14 bits, and 32kHz sampling.
"And now, with digital radio, even Radio 3 [the BBC's classical-music and arts radio station] has been cut down to 160 kilobits per second. They've now abused us, putting on more and more channels of poorer quality on digital radio. What is the purpose? It's not high quality! They don't care any more about quality, that's the saddest part. Whereas, with stereo and FM, the original aspiration was towards quality. With the BBC, back in the 1950s and 1960s, there was a relaxed quality in listening to Radio 3, for example, or Radio 4. But as time has gone on it's been mutilated. And now Radio 3 is processed until it's not very palatable.
"People will eventually believe McDonald's tastes good, if you force them. But there are people who like good food, and go out of their way to look for good food. The same with good music. And music is human emotion, it is every bit as important to us as food, because music conveys everything from laughter to crying to smiling to tears of joy.
"We've got to get people to realize, hold your horses, before it all disappears. In the pop field now, young bands are realizing that if they put the vinyl out, they know that the kids can't copy it. And the kids can now say to their peer group, 'I've got the Rotten Tomatoes record (or whatever the name of the band is), you haven't got it yet.' There's pride of ownership. But if you've got an iPod with 1000 tunes on it, you haven't got anything tangible to show what you own. It's a bit bucket, basically. And that's why, I think, vinyl has survived and has been growing. Because you've got a package, the record and the sleeve, that has some meaning."
Tim thinks that people will be playing vinyl records for the next 30 years or so. So perhaps it should have been no surprise when he decided to launch his own turntable, the EAR MasterDisk.
"The turntable is so complicated to discuss, it would probably take a couple of hours to describe it; it's not something that could be grasped in a few minutes. But the principle, what I was after, was a turntable that didn't sound like a turntable. I wanted you to hear the record, warts and all, but I didn't want you to hear extraneous problems that were going on in the room. That's why I developed the magnetic drive-coupling system, so I could divorce all the outboard world from the platter and tonearm. That was the secret of the thing, to make sure that the platter and tonearm are one entity that is isolated from the room and from all the boundaries, from noise and so on."
More recently, Tim finally decided to launch a CD player as well.
"I could have put out a CD player a long time ago, but I didn't. I held back, looking at it carefully, because I don't want to put out a product that has my name on it and have it coming back to haunt me. There's nothing to stop me doing new technology, I'll use transistors. If somebody wanted me to do class-D switching amplifiers, and I thought they were good, I would do them. If I thought they were good.
"Lots of people have made so-called valve CD players with a couple of token tubes. Most of them don't actually address the problem correctly, because a lot of them, if they're going to offer balanced outputs, actually go back into op-amps to do the balanced output configuration. So they've got this token tube doing not very much.
"I looked at CD players and I decided to use the Wolfson chipset, because I considered that to be the most analog-sounding (for want of a better word) D/A converter in the business. What I had to do, instead of using any further op-amp technology, was to get the output of [the DAC] and amplify it in the valve domain, and use an output transformer with a line stage similar to what I use in my professional audio equipment, to have the ability to drive both professional audio lines and consumer domestic audio. And if people want a minimalist setup, with an analog volume control on the CD player (and an output up to 5V instead of the usual 2V), it can drive any power amplifier.
"That's it! That's the logic of it. It doesn't have to be mega-expensive to make a statement. I want to sell a realistic number of them. It allows me [to compete], in the next year, when we can see what is the commercial reality of multichannel sound, whether Blu-ray or HD DVD win that race.
"A lot of audiophiles would like 2.1 [channels] rather than 5.1, 6.1, or 7.1. In other words, they've got their home theater, but they can't be bothered with the side speakers and all that, because they know it's all gimmicks. And if you reprocess the multichannels back to two channels and have a subwoofer driven from the 0.1 channel, you can get all your explosions and things to happen with your pictures. So I think 2.1 is a very good logical conclusion to it all. Instead of 5.1 upwards, go backwards!"
With the launch of his own Primary Drive loudspeaker, Tim de Paravicini can now offer a complete hi-fi system.
"I wanted a speaker that had some of the qualities of the Quad electrostatic, a dipole package that was not too big and awkward and had a degree of appeal to the domestic side of the family. I don't claim it to be the best-sounding speaker, though I consider it better than most packages on the market. But it had to be affordable and usable in the home, in a realistic situation.
"Basically, it's a dynamic speaker system, with a tweeter and a midrange and a bass unit. The bass unit and the midrange drive a membrane. The bass unit makes a membrane of effectively 12" by 18" (305mm by 457mm) surface area bend and vibrate to put bass into the room. So it has dipole properties. I don't make the drive-units myself and I subcontract the cabinets, but it's still my basic principles."
Tim has often been regarded as an eccentric genius, an audio maverick, always outspoken, sometimes outrageous. At one hi-fi show at least, when asked by another exhibitor to turn the volume down, he turned it up. He's been known to throw visitors out of his demonstration room when they've asked particularly stupid questions.
If Tim has mellowed in recent years, it might be because he's now getting more of the rewards and recognition his work deserves. Although his aristocratic ancestry can be traced back to 15th-century Italy, for him the important thing is what you do and how well you do it.
"Think about a thing carefully, and try and do it correctly," he says. "Don't think 'How can I save, cheapen it, cut corners, to bodge something to sell.' If you think with a salesman's hat on, you will never make a good product."
By John Atkinson, Stereophile, September 1990
Meeting Englishman Tim de Paravicini for the first time, you start to wonder if your mind has slipped a gear, whether premature brain fade has cut in. The conversation seems not only to be racing by unexpectedly quickly, but also subjects you hadn't even realized were subjects are being examined in knowledgeable depth. It was at the end of the 1970s that I bumped into Tim at a trade show in the UK; having wanted to ask his opinion of tube-amp design, knowing that the gangling, wispy-bearded, Nigeria-born, one-time resident of South Africa and Japan, ex-Lux engineer (footnote 1) had cast a magic wand over the Michaelson & Austin product line, I found myself instead being treated to an exposition of color phosphor problems in TV monitors. For Tim is a true polymath, his mind seemingly capable of running at high speed along several sets of tracks simultaneously.
But it is in the areas of tube-amp design and transformer winding that he has netted a worldwide reputation. Dick Olsher and Jerry Novetsky interviewed Tim on these subjects for Stereophile back in 1984 (footnote 2) his Esoteric Audio Research (EAR) amplifiers are sought after, particularly in Japan, for their solid-state-esque bass performance; we bought a pair of his natural-sounding tube microphones and an EAR tube mike preamp for use on Stereophile's recording projects; and his HEAD step-up transformer is still remembered by many audiophiles as one of the most musical. These days Tim has been turning his attention to professional audio, in particular the restoration of classic tube tape recorders and analog disc cutting. It was Tim, in fact, who cut the lacquers for Stereophile's at John Dent's Exchange Studio in London, and he has done excellent work for both Water Lily Acoustics and Chesky Records in the US, and Island Records in the UK. I had lunch with Tim at the 1990 Consumer Electronics Show and started by asking how he'd gotten involved in the high-end industry's sharp end:
TdP: It goes back 20 years, when I was involved with rock and roll bands. Having worked on all aspects of the studio industry, when I ran into John Dent, who was then the cutting engineer for Island, five years ago or so, we got talking and I said, having thought about it over the years, I didn't like the sonic signatures that were being cut onto records. Knowing what master tapes sounded like, I didn't like what the finished products sounded like. John Dent gave me the opportunity to prove that I could design electronics for a cutting system that got rid of the sonic signatures of the cutter head, that I could make a transcription system that had the minimum audio degradation between master tape and playback.
The biggest impact on the sound is the way the motional feedback on the cutter head works. A typical cutter head is a mechanical system with mechanical colorations, the end result being that there is a mechanical "clunkiness," for want of a better description, that I could hear on records. And because it is a mechanical system, the ability to capture detail on the record is also somewhat missing.
Once he'd got agreement from Island (footnote 3), John Dent gave me the funding to go ahead with the project. I spent some three months designing a system that would deal with these problems. The first cutting head I used was a Western Electric, but since, whether they're large or small, they're all basically similar, they all have a pair of drive coils coupled to an amplifier to move the chisel and a pair of feedback coils; the exercise is roughly the same in all cases. Each one, however, has a different sonic signature because of the size and the way it's built.
JA: And, of course, they're not intrinsically flat in frequency response.
TdP: No, traditionally, stereo cutter heads are designed with a resonance at 1kHz which is used to take care of part of the RIAA net curve; ie, the fact that the cutter head rolls off at 6dB/octave below 1kHz takes care of the 318-microsecond time constant of the RIAA curve. (Ortofon take a slightly different approach to the RIAA correction; the Ortofon cutter head designs are around 2kHz.) So you only need a bit of bass correction for the 50-cycle turnover point. But on the opposite side of 1kHz, you then have to boost massively to put in the RIAA pre-emphasis. Now the cutterhead falls off by some 30 or 40dB by 20kHz, so you've got to actually boost the drive to the cutter head by about 50dB at 20k...
The very old electrical mono cutter heads, such as the Grampian, for 78rpm cutting in the electrical domain rather than the acoustic, were designed in a different way. The original approach was to design a cutter head which had an electrical resonance of somewhere between 10 and 20kHz... 78s were therefore cut with what was effectively a flat, constant-velocity characteristic. So driving these old primitive mono cutter heads with an ordinary 10W tube amp, with no correction whatsoever, gave them an approximately ideal characteristic for replay...While they had high-frequency coloration, they actually did a very good job in the midband. But when Neumann came in with motional feedback, they had to design the head a different way...the resonance was brought right downband and then you had what would be called the second-order resonances, which were typically around 10kHz.
JA: The combination would give you this "clunky" sound...
TdP: Yes. What I would call a "quacky" sound. What I specifically did different was how I read the motional feedback signal, how I read the sonic signature of the head, and how I negated it. All my research was done by the simplistic method of bonding a cartridge to a cutter head rather than actually cutting records, in order to cut down time and to avoid wasting lacquers. And immediately I could recognize all the colorations because I was able to treat this as a real-time, line-in/line-out system. The end result was a system that degraded as minimally as possible: ie, the level of comparison, cartridge, and the replay phono equalization, the degradation is about equivalent to that of putting audio through one 741 op-amp chip. That's my point of reference.
JA: But that sounds terrible! One antique op-amp chip?
TdP: But no other retrieval system can even approach that... no other recording system of any description can come even close to that minimum standard. I'm just trying to put it into context; that to get that far is no mean achievement for a complete system, including a needle, a lump of rock, roughing around in a groove.
JA: Were the cutter heads modified mechanically? Or is it all done electronically?
TdP: They were all electronically fixed. If you do it right, you can make it work. Because the whole point had to be that it had to work with a stock system. It's no good having a system that is not compatible because day-to-day commercial running of the studio means you have to have serviceability and reliability. I have done the same thing with both Neumann and Ortofon heads, and the end product, the record, nobody knows which records were cut with the old Western Electric or which were cut with an Ortofon, or the Neumann. Nobody knows. And I'm not going to tell them which ones are which.
JA: When the studio tried your system out, what was the reaction of the artists?
TdP: Some of John's better clients immediately heard this quality. People like Jim Capaldi's manager, they were aware of it. For one Jim Capaldi record, they were that impressed that, rather than sending copy masters around the world, John had to originate the lacquers for the world production of the record. They wanted all the records pressed to have the same quality. With others, there was a degree of, "It doesn't sound like a lump of vinyl." Their expectations were screwed up, because they'd produce a master tape in the studio, and because they know that they're not going to get the same thing on vinyl, they tend to be artistically pumped up, making something up for the end sound.
JA: My own experience when I was involved in making records was that when the final two-track master was mixed, it never sounded like the way we wanted the record to sound. Only when that same tape was transferred to disc, did it sound right.
TdP: That is a problem with some people. But Dire Straits and one or two other bands do try to produce what I call very pure, very clean sounds.
JA: And then you cut the groove with as clean a signal path as you can.
TdP: Yes, I want to retain the master tape in toto. I want the person out there to experience the same thing that I'm experiencing.
We talked for a while about the problems in obtaining a consistent supply of lacquers, the acetate-covered aluminum blanks on which the cutting engineer enscribes the grooves, and about how lacquers from different companies produce different sounds when the LP is finally pressed from the resultant metalwork. And the metalwork itself presents significant problems. Tim now uses a company in Leicester, England, who've recently installed a new plant:
TdP: Getting good metalwork is a problem. Unfortunately one of the best metal-plating plants in America, Allied, decided to close. EMI in England lost their quality many, many years ago. You see, the problem is with all these processes, because it's a black art it's really the skill of the people involved. Now, the skilled guys at EMI were already pensioned off and buried; the new guys who replaced them hadn't acquired those subtle skills...so those skills have died. There are very, very few places in the world where these traditional black-art skills are maintained.
JA: But surely the basis of economic development in the modern world is that men with skills be replaced by machines that can be operated by relatively unskilled labor? A record company can't stay financially viable if it has to depend on a small number of skilled people in order for its products to be produced. That's one of the reasons why machine-produced CD has been so attractive to these companies; it's a real mass-production medium that doesn't need arcane and archaic skills for it to be produced at an acceptable and consistent level of quality once the capital outlay on the plant has been made.
TdP: That is the whole point. And the point is that there are intangible qualities. If you take a parallel, Rolls-Royce use craftsmen for their cars; no amount of computers and robots can build a car with that indefinable property that a Rolls-Royce, or a Jaguar, or a Mercedes has. The Japanese, for example, are trying to build fine motorcars that will do everything correctly, but they just don't have that indefinable property that is an art form. You can't become a Rolls-Royce overnight. You can't make a machine do a Picasso. So it depends what you want. Are you after something that is a good art form; you want to do nice music?; or are we going to have it computerized? Instead of buying records, you could just buy a program that plays your MIDI [synthesizer] at home, and you would have electronically recreated music in your home. But it would be sterile; it would be the same as having a speech recognition system that then tells the other end to regenerate a facsimile of your speech, instead of transmitting your voice down the telephone. We are trying to dehumanize this real-time life experience...
JA: And then you're no longer involved with quality.
TdP: Exactly. And this comes down to a commercial decision rather than an artistic decision. The same way that television or FM radio [operates] on a level that satisfies the bulk of people rather than all the people. I personally prefer to have the best. You can either buy cheap pianos or you can buy Steinways. You can either buy a Toyota or an Aston-Martin.
JA: To return to records...
TdP: There was a recent letter from Bob Ludwig in The Absolute Sound. [Issue 61, p.24, about the fact that the one-step process of which TdP is an advocate and which was used for the remastered version of Stereophile's Poem LP is less accurate than the traditional three-step, due to the fact that the freshly cut lacquer has to be sprayed with silver before it can be electroplated to make a stamper, and that that silver layer remains in position on the stamper]. Well, the silvering left on the nickel stamper is literally only of the order of a molecule thick. And that is worn off in the first four stampings or so. Because it is only a molecule thick, it doesn't actually have any tangible degradation because it will still be pulled off, when they plate the interstage, second, and third plate to the final stamper. And the second problem is because of thermal cycling, the fact that the nickel plate, when they grow the second and third generations in the tank, changes temperature. You have a bimetallic action going on. And so you do get problems with the three-step that the one-step doesn't have. Another problem is that no metal deposits absolutely uniformly. So you get grain boundaries that produce a higher noise on the third generation that the first generation doesn't have.
JA: So you feel the one-step process, even with the silver temporarily left on the stamper, is still the more true representation of what was cut into the lacquer.
TdP: It's very good, yes, because this new company [in England], their nickel plating is so good that they're actually doing laser hologram credit-card stampers by exactly the same process. That is molecular-level information. The same as the record.
JA: I think that a lot of people don't realize that the information on an LP can be an order of magnitude smaller than the pits on a CD.
TdP: Exactly. The information on an LP extends down to half a molecule of vinyl. It's a good system provided one takes care. That's the bottom line. I mean, why are people still buying turntables? LP is supposed to be dead.
JA: I understand from talking to some manufacturers at this show that American audiophiles, at least, are not buying as many turntables as they used to.
TdP: They're not buying as many, no. But there are still people buying them. There are still manufacturers of turntables in America.
We continued our conversation with a discussion of Tim's modification of the industry-standard Sony PCM-1630 for CD mastering. While he leaves the digital section alone, he basically rebuilds the analog circuits so that they minimally degrade the sound. (Martin Colloms's Stereophile review of the '1630 in Vol.10 No.5 mentioned that the analog sections of the processor are based on relatively ordinary NE5534 op-amp circuitry.) I asked Tim what CDs had been transferred to digital with his modified 1630.
TdP: Well, all the CDs put out by Charlie Records, See For Miles, and Affinity Records in England, quite a number by Dire Straits, Cat Stevens, Bob Marley, the Wailers, and Lincoln Kwaze Johnson; Island's catalog... And we did Kavi Alexander's CD [Arturo Delmoni performing Bach, Kreisler, and Ysaye, Water Lily Acoustics WLA-WS-07CD].
JA: What do you see as the major problems in digital replay and recording?
TdP: We are stuck with a system that has already been formatted by Sony and by Philips 10 years ago. We are well down that road and it's going to be awfully hard to change it. I think perhaps in five years' time, a second, up-market system, like HDTV in television, will happen in digital...That has got to happen. But at the moment I don't think the vested interests wish to have another completely new format.
JA: I could be cynical and say we already have a low-resolution, mass-market medium, which is CD, and an up-market, high-resolution medium, which is the LP.
TdP: That is exactly what I am trying to say. And the LP is still not a finished art. I'm still doing development. Other people are still doing development on cartridges and all the rest of the chain. Because the LP's an analog system, it's not bound by the same limitations of, for example, saying we will have 525 lines, take it or leave it. The parallel is that analog film, Kodak film rolling through a shutter, is actually holding its own. And in England a lot of the newsreel companies are going back to their Arriflexes, because there's a lot of creativity that they can do in film, in celluloid, that they can't do in video.
JA: And if you think that the analog medium, film, offers ten times the line resolution of good video...
TdP: And film is going through continuous improvements. They can improve the definition and the contrast and everything in film without upsetting the compatibility. They can still put it on the same projector. That is the whole crux of it. I think vinyl still can be a viable medium, but it's a matter of how it's [distributed]. The difference is that film and video in the studio industry are used by professionals, so they haven't got to worry about the distribution. Whereas with vinyl and CD, we have to deal with trying to distribute it, to disseminate it, as against keeping it in-house. I mean the same argument can be applied to magazines. Why aren't Hi-Fi News or The Las Vegas Times sold as microfiches? Why don't they get down and print magazines this small and sell people magnifying glasses?
JA: The answer is that the centuries-old format of the magazine is more portable, more easily accessible.
TdP: That's my argument. We should keep with things that are acceptable in human terms. I mean, vinyl is not practical for jogging but there is a time and a place for enjoying music. I don't go jogging when I'm in a concert hall; I may go jitterbugging, but I don't go jogging!
JA: Tell me how you set your priorities when you designed EAR's The Mic.
TdP: Was it transparent? Did it capture the whole sound picture? A lot of the traditional microphones, for example, don't have enough bass response. When we're listening to live music in a theater, there is a dimension of the theater that with our eyes closed we could recognize where we were sitting, in the Royal Albert Hall, or the Queen Elizabeth Hall, or Barbican, or wherever. If you're familiar with the buildings, it doesn't take five seconds to realize which one you're in. Most of this is the low-frequency signature, the fundamental reflections of the building, the time decay of the building, and the low-frequency pattern; they all have to be phase coherent for us to recognize it.
JA: The English writer Rex Baldock years ago said that it was in the infrasonic region that the hall signature imposed itself on the music.
TdP: Precisely. And human beings use vibration of the body, as well as what we hear directly through the ears, to build the sonic picture. The tradition that we only hear down to 20Hz is rubbish. We actually perceive sound all the way down to 3Hz. Below which the body cannot experience vibration of any description; the body has designed itself so that we don't hear our own legs when we're walking, or running. The traditional concept should be rewritten to say "Experience of sound extends to 3Hz." But the traditional mike manufacturers tend to consider themselves doing well if they get a bottom E on a bass guitar. Commonly 42Hz. And they say that's fine.
The problem is that those microphones lose some of the information that should be there. So trying to understand the microphone's job is a compound picture. Do we hear? Do we feel what it's supposed to be doing? Even if some consumers haven't got reflexes to experience it all. That's irrelevant. As long as we can produce and inscribe into the finished product all that we can, then it allows those who are in a more privileged position to at least share the experience more validly.
JA: Does that mean that when you cut records, you don't roll off the extreme lows?
TdP: We cut records all the way down to sub-5Hz. So it's a matter of whether the guy's turntable has the correct arm and the correct resonances, and the damping on the arm, whether it retrieves the bottom end accurately or not; that is not for me to judge. As long as it's been inscribed on the record, I know that it can be recovered with the right equipment.
JA: Did you choose to use quite a large Milab capsule to capture that low-frequency information?
TdP: No, the capsule is moderate size. The reason for using the rectangular capsule is that it's more akin to a ribbon microphone, to a line source. Stereophony, bounded by walls, requires two pure line sources to reproduce the stereo picture. If the microphones are effectively line sources (in fact, my next-generation microphone will be even more of a line source), it's going to use a capsule some 2" tall and 5/8" wide; all the HF coloration is reduced in the horizontal plane and that gives us better localization in the horizontal plane. And the same way the head has temporal response; in other words, we hear certain frequencies above the head and in front of the head; I want the microphone to do that so that we can convey more of the dimensions of the sound that we are trying to record. So that we can position the orchestra in three dimensions. Left to right, as well as up and down and back to front.
JA: That's a real area of contention. Most theoreticians say that stereo imaging is only two-dimensional: side to side and front to back.
TdP: Well, we seem to manage to hear very effectively in the real world where a sound has come from pretty well all points of the compass. In other words, if somebody comes up to you from behind, you know he's there.
JA: But there is some ambiguity in height perception. It is hard to distinguish whether you are hearing a soundsource directly under your feet or above your head.
TdP: Oh, there are areas of ambiguity, yes. So humans have the ability to turn their heads and try to zero in. But there is [a small enough degree of] ambiguity to at least make our choice error-minimal. We tend to turn our heads in the right direction in the first place.
JA: And that adds rate-of-change information which resolves the ambiguity.
TdP: Yes. But the more we can get that property into the recording, the more we will then have a recording where the head is stationary. In other words, it will have no more and no less realism than what we would experience if our head if we were sitting still in the recording environment. We would go to a holographic experience where we could say, "Let us dial ourselves into the original experience."
JA: To return to the mike, a lot of your design philosophy seems to be very traditional. The use of tubes, and particularly the use of transformer coupling.
TdP: Yes, because I have to be practical and use the mike in a conventional environment where there are long cables and where cables have to be of practical dimensions. It is no good me using cables that are 2" in diameter. And I use a transformer to be able to give me an output that will transmit down a 100 ohm cable correctly... A transformer can achieve consistently high common-mode rejection, it has the ability to withstand high superimposed noise signals... Active balanced circuits have weaknesses which transformers don't have if designed correctly. The problem is traditionally what I call "wound" transformers that have been compromised too severely.
JA: It's another black art.
TdP: It's a black art. Yes. Likewise, tubes have dynamic properties that transistors don't easily have. And tubes are very rugged; they may have microphony, they may have other disadvantages, but at the end of the day they are extremely robust beasts. And they're not significantly any less efficient than transistor circuits. After all, power is power. You can't squash the watt, as I put it.
JA: A 100W tube amp is around the same physical bulk as a good 100W transistor amp.
TdP: Because heat is heat. I should also say that because tubes are made on a mechanical process, they're actually remarkably consistent.
JA: If you can get the skilled operators to make them. I understand that the Chinese company that's using the old M-O Valve company tooling had a lot of consistency problems in their tubes because of the lack of experience of their operators.
TdP: Experience, yes. But I'm talking about an all-things-being-equal condition.
JA: You do design with transistors for some of your third-party projects, Musical Fidelity, for example.
TdP: Yes, yes. I have no particular personal preference for any medium. Whether it's transistor or tube, each can do its job well. But through EAR I choose to purvey tubes, the same way that Rolls-Royce still purveys large cars and doesn't make small cars. But what I did for other people is less stringent.
JA: You also appear to be a traditionalist in amplifier design in that you reject the use of a lot of voltage regulation. Both your mike preamp and your G88 preamp that you introduced at this show (footnote 4) use traditional power non-regulated voltage supplies.
TdP: Because a good building doesn't require props to keep it up. I take the same approach: if you design the circuitry properly, it doesn't need prosthetic aids.
JA: But can't you see the temptation for designers when a 20-cent, 3-pin chip buys them 50dB of hum rejection?
TdP: Yes, but if I can already achieve that, why do I have to bother? It's as simple as that. And putting a regulated supply on is not going to give me any benefits that I don't have already. It's going to give me disadvantages, because it's going to make the product more susceptible to fragile power sources. Whereas when I have an unregulated system, the product is relatively immune from mains disturbances.
JA: I noticed yesterday you turning your preamp off while it was playing an LP without there being the usual speaker-destroying bangs...
TdP: I can have mains crap-outs for up to a couple of seconds without there being any tangible problem. The mains can crap out or brown out, and the preamp won't have a problem. Whereas with a lot of regulated circuitry, there is going to be a cutoff point before the parachute fails.
JA: And then it fails catastrophically.
TdP: Yes. I prefer to build equipment that, if all else fails, will still limp. So if you're in a recording session and there's a glitch in the mains, at least the recording will still go through okay. I don't want to be downed because of that one problem. The same way a lot of people are going back to cars with simple, mechanical engine management systems rather than the modern mega-electronic management systems because there are less things to go wrong. As a result, they're more likely to be able to limp home [when things go wrong]. And if an electronic management system fails while you're [passing], for example, you're a dead duck.
It is better to have a system that is less prone, long-term, to problems, but it has to be designed correctly to cope with the short-term problems. Regulation is only a device used by conventional circuits because they conventionally are too sensitive to their power supplies. I try to design the beast to be relatively immune to the supply. Now one of my tube-amp competitors puts regulators willy-nilly everywhere. But some of those regulators are actually noisier than the prime regulator they have at the beginning of the supply. So they have achieved nothing. It is just a sales argument: "We have 10,000 regulators in this product; it must be better." "More" is not necessarily "better." That is my argument. That's the whole point.
JA: I understand your G88 preamp also doesn't use any capacitors in the RIAA EQ.
TdP: I'm using inductors to generate the RIAA network, passively. There is no feedback. The reason is that all capacitors have different sonic signatures, which has been written about ad nauseam by many people over the last 10 years. An inductor is wound with copper wire and is easy to wind at consistent linearity that allows me to get away from the problems of voltage distortion that capacitors have. It allows me to produce a low-impedance network to keep the noise floor of the preamp down. It allows me to generate a good accuracy beyond the two ends of the audio band. And it also allows me to provide a preamp with a good overload margin at high frequencies so the clicks and spikes of the records do not overload and do not intermodulate.
Provided it's done correctly and shielded correctly, you don't have any hum problems. The inductors are used in a balanced configuration, but I'm not going to go into all the intimacies of how it's achieved. That's still proprietary. But I am formally stating that I am the first to do it.
JA: Do you use a transformer for the moving-coil input?
TdP: Yes, I still use a transformer. I'm using what is in fact the HEAD sans packaging in the preamp. [A transformer] is still the most efficient way of converting one high-grade signal to another level. I'm also using balanced topology all the way through the preamp so the phono amplifier ends up with a balanced output transformer.
JA: Do you have favorite tubes for each application? There appear to be two factions in the US. They appear to go for either the 6DJ8 or the 12AX7 and their derivatives.
TdP: I don't have any particular favorite tubes. I use both. It's horses for courses. But the 6DJ8 never should have been used as an audio tube. It was originally designed by Mullard as a television front-end tube. It was designed as an RF amplifier and an RF oscillator to operate at 200MHz. It's a frame-grid tube, consequently it was never designed to have low mechanical noise, it should never have been used for audio. Because of the fact that it was used in televisions to operate on the 90V supply, it is a high-current triode by comparison to the 12AX7. But it's only fit to do service in certain parts of the audio circuitry. It should not be used carte blanche all the way through. I use it in my preamp, but only in the high-level balanced sections since it does a good job of driving the transformer.
JA: One tube you never see is the EF86 pentode (footnote 5). I only ever recall seeing it in the front end of the Radford ST25 power amp.
TdP: The EF86 is a very good tube for preamps. It's an incredibly linear tube. It has the gain, it has low microphony, it doesn't need DC filaments to make it work quietly, because it was designed to operate with a center-tap 6V filament. In those days , DC filaments were prohibitively expensive, because of the cost of low-voltage, high-current rectifiers. It was designed for low-level microphone or photomultiplier amplifiers, projector sound and so on. So it had to have all these requirements designed in, it had to have a mechanical construction that minimized microphony. Quite the opposite of the 6DJ8, which was designed to do a certain job of work a different way.
I would use [the EF86] but for the fact that it is only produced in one country now. All the original Mullard stock is effectively finished, so from a production point of view it is not a viable tube to use. The problem was that people weren't using the EF86 in the '60s because they'd gone to transistors. Mullard didn't really see the need to keep it in production because it was only service-replacement volume, which was minuscule since tubes tend to have a life of the order of 100,000 hours. Power tubes have lifespans in the thousand hours or low thousands, whereas some of the small-signal tubes can have lives quite easily in the hundreds of thousands of hours; people don't realize that tubes can very nearly equate with transistors as far as longevity is concerned. I would love to use it. But the reality is that if you're going to produce more than one piece of equipment, forget it. It was a beautiful tube but unfortunately the uncertainty of buying it precludes it in modern-day manufacture.
JA: When you designed the Luxman 3045 in the '70s, you used an exotic NEC pentode wired as a triode. A 1990 tube designer, however, is pretty much forced into using the commonly available tubes.
TdP: You can always produce a one-off product with whatever you wish. You can produce a one-off using Western Electric 300Bs but you can't produce it in volume. Unless you use something that you know you can buy in five or ten years' time, it is really foolhardy to try to tread that path.
JA: This being the beginning of the '90s, will we still be playing LPs at the beginning of the next century?
TdP: I hope so.
JA: Do you think there will still be plenty of tube-amp manufacturers around?
TdP: Yes. We haven't seen the end of tubes yet. I mean, they were developing quite miniature tubes in the late 1960s for hearing aids, and the British Aircraft Corporation in England used micro-miniature tubes in their early missiles. It's just that when transistor technology came along, tubes got pushed to one side. In fact, a re-analysis of the tube is happening in computers. They're developing chips with cold-cathode tubes.
JA: Each chip carries many little microtubes, each about 20μm [half a thou'] across...
TdP: ...which operate on very low voltages. It can only get better. If we had devoted as much attention to tubes in the last 15 years as has been devoted to semiconductors, I think tubes would have been in a much more interesting state today.
Now married to a Japanese wife, Oliva, Tim is one of the few Western engineers to have been employed in a creative role by a Japanese company. The classic Lux 3045 tube power amplifier is a TdP design, as were the monstrous M6000 and M4000 power amplifiers, two of the first Japanese transistor muscle amps.
In the "Almost All-Tube Issue," Vol.7 No.3, May 1984.
About three years ago, John Dent decided to take the gamble and go it alone. He and his partner, Island's second cutting engineer, hocked their houses, rented a premise in Camden, and called their cutting studio The Exchange.
the revolution continues...
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− Established 1973 −
"love what you listen with"
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