Meridian's Bob Stuart Page 2

Holt: The audio and digital sections have their own supply?

Stuart: In the MCD there are separate regulated supplies for the servo, the digital, and the audio sections, but they share a common transformer and grounding system. In the Pro, the supplies for the servo and the D/A and audio section are completely separate. And we isolate the audio section from the RF section, which reduces the level of spurious ultrasonic material by at least 18dB.

Holt: You mean, much of that ultrasonic garbage was the result of electrical interference from the digital circuitry into the analog circuits?

Stuart: That digital clock is hammering away at 4MHz, and it is difficult to keep it out of the audio circuits. Also, the audio circuits in the Pro are DC-coupled, and servo loops are used to hold all the proper operating voltages and prevent any DC offset from ap™ pearing at the outputs. There are no coupling caps in the outputs, and that gets rid of one of the most important sources of degradation in many CD players.

Holt: Yes. Output caps have been identified as a major liability in CD players, but I think this is just because the high capacitance values needed make it almost mandatory to use electrolytics or tantalums, which are the worst around for audio use.

Stuart: When the MCD came out, it got very good reviews in the UK, Japan, and in many quarters in the US. In the UK, Decca, EMI, Nimbus, and BBC use the machine, and it's also being used by BIS and another Scandinavian record company. Lots ofpeople making CDs are using the MCD to listen to them, and we got involved in a number of listening tests with Nimbus, and particularly Decca. The Decca people called us down and said "Look, this is great; we've got all these machines, and yours is much closer to the original tape than all the others." And they let us use their facilities, which was a great help. We could get one of the CDs and pull the master tape off the shelf and compare them side by side. And with all the modifications that made the MCD into the Pro, we reached a point where the Decca engineers and ourselves couldn't hear the difference between the master tape and what was coming off the CD. When we got through, we knew we had not only made the MCD sound better, but that we hadn't just gone toward a more euphonic sound; we'd actually gone towards precision.

Holt: Accuracy.

Stuart: Yes, accuracy. If another machine sounds different, it's wrong. It sounds less like the master.

Holt: That seems reasonable (footnote 3).

Stuart: Yes, of course. Quite recently at Decca, we had a chance to hear the Sony two-box machine and some other competitive machines, and they do deviate from the master tape sound.

Holt: What does that say, though, about the quality of the electronics they're using in the playback part of their digital mastering machines?

Stuart: Decca uses a very high-quality unit, but of course that is a question. They don't use Meridian electronics.

Holt: I was wondering when the time will come when home CD players have a better playback analog section than the professional digital mastering decks?

Stuart: It's right now. That time has come. What's happened is, we've evolved the replay part to the point where it is better than that of most PCM mastering machines. Decca is unusual because they use their own custom machine, which is pretty competently designed. Most recording companies are using Sony's 1610 or 1630, or—actually, the best-sounding one seems to be the Mitsubishi.

Holt: Doug Sax of Sheffield Lab opted for the JVC, I believe.

Stuart: Yes, and then I understand the first thing he did when he got it was rebuild all the analog electronics. What we've found is that most CD manufacturers who want to know what their discs sound like have to go ahead and make them and then listen to them on the Meridian Pro. They can't get it back through the (mastering) tape machine. In fact, we're doing some work right now in England with a couple of recording companies, producing Pro machines with a digital input so they can feed the digital mastering machine into it, allowing them to switch from the CD to the tape, both using our D/A converter and audio section.

Holt: Clever!

Stuart: But it seems to me that the next major step has to be in the A/D converter.

Holt: What will you be doing in that area?

Stuart: We're trying to build a four-times-oversampling A/D converter, running at 176kHz. Then the anti-aliasing filter could be digital, and it would be simple to digitally translate down to 44.1kHz for the tape encoding.

Holt: Most of our readers are familiar with how four-times-oversampling works in playback, where each digital sample from the disc is sampled four times. Please explain how it works in recording?

Stuart: It's even simpler at the recording end. You just take your amplitude samples from the analog signal four times more often. This gives all the advantages in anti-alias filtering that it gives you in playback filtering. Except that when recording, you're trying to filter out difference tones produced by signals of too high a frequency for the sampling to resolve, and in playback you're trying to filter out the corners of the stepped output pulses, whose frequencies aren't related to the signal at all.

Holt: No one, at least as far as I know, has questioned the recording end of CD. Four-times-oversampling when recording might even meet the criteria of digital critics who maintain that 44.1 thousand samples per second don't provide high enough resolution.

Stuart: Perhaps.

Holt: That means, then, that Meridian will be getting involved in the design of recording-equipment electronics.

Stuart: Yes. Or digital preamps. That's the way I think it's going to go. It's only a question of time before the A/D conversion takes place right at the microphone interface, and the signals stay that way right up the the loudspeakers. A couple of years ago, we built a digital version of our M-10 active loudspeaker. We never produced it, but it was exhibited at several shows. The digital converter was in the preamplifier, and the signal was handled in digital form all the way to the loudspeaker. It didn't have to concern itself with amplifier nonlinearities or considerations of interconnecting cables. That's the future as far as I'm concerned: digitization right up to the loudspeaker. I can well see systems evolving that way, particularly as we get more and more digital sources.

Holt: Do you see the possibility of using the loudspeaker itself to do the D/A conversion?

Stuart: Yes, it's possible. Certainly, a digital crossover would be advantageous. It would have no phase shift, and could use very steep curves without ringing. I see the speaker of the future—and I don't know whether I'm talking five or ten years from now—as being part of a completely digital system, with all parameters such as volume, equalization for analog discs, even corrective EQ for badly made recordings, performed digitally.

Holt: Let's get back to that business about the tracking servo modulating the power supply. Besides isolating the servo power supply from the other circuits, you also provide a soft plastic disc-damping mat with the Pro. Isn't that superfluous?

Stuart: Not really. No matter how much you decouple the supplies, the servo supply is still within the system.

Holt: At least one manufacturer is selling a hard disc damper painted flat black, to absorb stray light as well as inhibiting disc wobble. Do you think that is a valid approach to the problem?

Stuart: Well, a hard damper is not going to inhibit wobble any more effectively than a second CD on top of the one you're playing, because it is not going to contact the playing disc's surface all that well. That's why we use a soft damper.

Holt: What about the stray light? They claim that that's a problem because some discs are less opaque than others.

Stuart: I don't see how that can have any relevance at all. After all, we're dealing here with a digital system. . .

Holt: Go or no-go. . .

Stuart: Exactly. The light sensor either reads reflected light or it doesn't, and a small change in the level of either one won't make any difference. If there is enough light scattering to upset things, you'll just get too many uncorrectable errors and the system will mute.

Holt: So the lack of opacity is unimportant.

Stuart: I would think so.

Holt: A change of topic here. I cannot help but wonder how it is that a manufacturer whose products have generally gotten only lukewarm reviews in the English perfectionist press has managed to come up with what is widely acknowledged to be the best-sounding CD player ever made?

Stuart: That's a very hard question to answer. Over the years, we have had a very good reputation in the UK for our amplifiers and speakers, although we haven't done too well during the last couple of years because our modular system was basically too expensive. One's experience in the marketplace goes up and down.

Holt: Actually, the main criticism I have seen of Meridian products in the UK press had to do with value for the dollar—or pound. Then there's the question of Meridian's presence in the American marketplace. Until the MCD came along, the American press had rarely even mentioned the name Meridian. Is this because of any reluctance on Meridian's part to actively solicit American reviews?

Stuart: Not really. When we first came into the US market we had a different distributor, who just wasn't very aggressive about promoting our products. You see, many Britons seem to feel that if you have a good enough product, it will sell itself. But the world doesn't work that way. And we had rather more of a job of promotion to be done here than usual, because Americans are not too enthusiastic about the idea of self-powered loudspeakers.

Holt: I have felt for some time that the mix'n'match approach to component selection that is so dear to the heart of audiophiles is no longer a viable approach—that it is necessary now to look at amplifiers and loudspeakers, for instance, as interrelated parts of the same component.

Stuart: It's just a completely logical design approach, because one can eliminate all the compromises that must otherwise be made to have a speaker, for example, work well with the wide range of source impedances, power capabilities, and feedback configurations provided by different power amplifiers. There are so many advantages to the active loudspeaker approach.

Holt: How long have you pursued that approach?

Stuart: For about seven years now. We feel the designs have been successful, but the company went through some evolutionary difficulties—financial, management—that inhibited its growth. Then the modular system came out, and it was a bad value.

Holt: The point I've been skirting is that, when the people at Hi-Fi News, for instance—Martin Colloms or John Atkinson (footnote 4)— discuss their tests on the latest cartridges or turntables or whatever, they never seem to mention your products among those used for reference standards.

Stuart: We avoided the UK press for about 12 months, partly because we knew that we had amplifiers coming along that would supersede our current line, and because we were rather preoccupied with reorganizing our company. I'm friends with these people, and they come by from time to time, so what we're doing is no news to them. But the modular system just didn't catch on; they wouldn't be using that, and what else was there? They all like the active speakers, though. The M-20 is getting very good press coverage now.

Holt: So your market presence, your visibility, is going to be substantially greater in the near future.

Stuart: You're going to see a marked change, now that we really have something worth talking about. Before that, we had speakers which were five years old. Magazines don't like to write about things that are five years old.

Holt: I'm curious: What is your background? Did you come out of engineering?

Stuart: Yes. I have a degree in electronics and psychoacoustics, and took a second degree in business.

Holt: How much are you involved in the musical end of audio?

Stuart: Only as a music lover. When I left the University I spent some time working for Marconi, doing development work on transmitters and television color cameras and so on.

Holt: How did you get into audio?

Stuart: Audio has been a passion of mine for many years. While I was in College I built my own system, designed a tape recorder, had articles published in Wireless World about tape recorders and noise-reduction systems. I've been in the audio business since 1972, when I was invited to design a range of products which were called Lecson—very distinctive looking. That's where I met my partner, as he was also called in on the project. That's how it began. We designed Lecson, then something called [Orpheus], then decided to form our own company. I find being a consultant brings little satisfaction— you're always being called in by companies that are already a bit sick.

Holt: They call you in when it's too late.

Stuart: Yes. They haven't had their own planning right to do their own development, and then they expect you to breathe new life into their company after it's already earned a bad reputation in the marketplace.

Holt: And when it doesn't happen, it makes you look bad.

Stuart: It doesn't make one look good.

Holt: What kind of music do you prefer to listen to?

Stuart: Mostly classical: chamber, symphonic, and choral.

Holt: I've noticed something at these shows: Exhibitors rarely play symphonic music, except for the occasional high-powered showpiece like a Sheffield Firebird or a Reference Recordings Symphonie Fantastique. Some exhibitors have said this is because there are very few good symphonic recordings. Do you agree with this?

Stuart: No, I don't. That was certainly the case with LP, though. It was very hard to find a symphonic or choral record that was truly satisfying, whereas now there are custom CDs that are much more enjoyable.

Holt: By "custom" you mean products of small record manufacturers?

Stuart: Yes. Discs that aren't aimed at the mass-market buyer.

Holt: Telarc and M&K Realtime for example.

Stuart: Yes. But I think another reason symphonic material isn't often played at shows is because most listeners have such a short attention span under the pressured CES conditions that it's more appropriate to use music on a smaller scale, or short interludes of high-powered material. A single symphonic crescendo may last longer than a casual visitor is prepared to spend in any one exhibition room.

Holt: Your listening room here at CES is, what, about 24 feet square. What would you say is the average listening room size in England?

Stuart: More like 15 foot square would be average, although plenty of people have rooms which are 30 feet in one direction. But the rooms are usually very solidly constructed. Most British homes are built of brick, with plaster interior walls, rather than the wood frame which is so popular in the US.

Holt: I've noticed that British exhibitors tend to demonstrate at much lower volume levels than American exhibitors. Are listening habits different in the UK? And I've always assumed, from the popularity of the Quad speakers, that Britons listened at much lower levels than Americans.

Stuart: The Quad is marginal even for the UK. But yes, it's customary in England to try and listen at a realistic level, more near the original level.

Holt: But the original level is going to depend on how closely the instruments were miked, and, as miking has gotten closer, that realistic level has risen to around 100dB or more.

Stuart: Oh yes, that is true.

Holt: But there is still a cultural difference, as with the Japanese.

Stuart: The Japanese taste is quite extraordinary. It explains the way their loudspeakers sound.

Holt: Shrill and strident, to Western ears. Yet American audiophiles often find English loudspeakers to be a little too polite at the high end.

Stuart: That's why our speakers have HF balance controls on them.

Holt: Each to his own taste, eh? Or lack of it.

Stuart: There's no accounting for it.

Footnote 3: It's fascinating to hear the assurance that any difference from the MCD Pro is an error, and yet the acknowledgement that the best CD players are better than the tape decks used to make the master tapes. Who's to know that the reference standard, in this case the Decca tape deck, won't be significantly bettered? In that event. who's CD player is best; the one that matches the old Decca or the new Decca? No one yet knows how good digital can sound, even with the current recording electronics.—Larry Archibald

Footnote 4: Actually, in the 1980s I was was an enthusiastic owner of the original Meridian 101 preamplifier.—John Atkinson