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Inside Views: Ray Dolby

The world's best known engineer | Ray Dolby

Ray Dolby's name appears on almost every recording device imaginable, yet few people outside the industry know much about this most famous engineer. In a rare interview he talks to David Mellor and explains the evolution of Dolby noise reduction.

Continuing our series that looks at hi-tech companies and design personnel working in the field of music and recording technology, David Mellor talks with Ray Dolby, founder of Dolby Laboratories - the man who has done more to silence noise than the Speaker of the House of Commons.

Ray Dolby

Someone once defined 'fame' as being when you are known by more people than you know yourself. This must be the case with Ray Dolby, whose name appears on nearly every hi-fi cassette recorder in the world. Most people associate Ray Dolby's name with noise reduction, so it may come as a surprise to learn that his early work was in the development of the first practical video recorder for the Ampex company in the USA. I caught up with the man himself at the recent Audio Engineering Society convention in London and began by asking how he came to be involved in such a project:

RD: Basically, I was in the right place at the right time, and I was able to start on the ground floor of the project at its inception and was able to see it through to its first use 'on the air'.

You helped develop the rotary head quadruplex recorder for Ampex. How does it compare with today's domestic video machines?

RD: The picture quality in those days was somewhat better than VHS but was only in black and white, of course. Not as good as the best U-matic - somewhere in between. It had a resolution of something over 250 lines on the American NTSC system.

Did you work on rotary heads from the beginning?

RD: At Ampex we started from the outset using rotary heads, beginning in 1952. However, I did make a couple of longitudinal recordings using instrumentation recorders, running the tape at 60 inches per second, which gave the recorder a response of something over 100kHz. Needless to say, the pictures were not very good!

I left Ampex to go to Cambridge University. (Cambridge, England - not Cambridge, Massachusetts!)

How did you become interested in noise reduction? Did you think of it as an engineering problem or as a musical requirement for successful tape recording?

RD: I was interested in it from a combination of the two. As a youngster I took piano lessons, played clarinet in the school orchestra and was interested in music generally - symphonic music, opera... From the very earliest availability of tape recorders I had been interested in tape recording. One of my uncles had a disc recorder that I played with when I was around nine years old, then came the wire recorders when I was twelve or so. At about fifteen, the 'Sound Mirror' was introduced, which was the first American tape recorder. It had a paper tape. This would have been 1946-7.

Did you start on noise reduction as your own pet project?

RD: Yes, when I was at Ampex I had the opportunity to buy an Ampex Model 600 at a very low price. It was a playback-only machine so I had to build my own record electronics for it. I took that with me to Cambridge University and with a pair of STC microphones I recorded many of the musical groups at Cambridge such as chamber music, symphonic, choral, jazz, pipe organ. I had a room in the old part of Pembroke College - room E5. It was very nicely situated because it was only fifty yards away from the chapel, so I ran microphone lines over so I could record whenever I wanted to. There was another room called the Old Library, next door to my room, so when there was any chamber music going on there I could record that too. I had the opportunity to do live line-in/line-out comparisons under quite good conditions. I had one Quad electrostatic and one Ampex loudspeaker rigged up in stereo. I became quite fanatical. I could hear the difference between line-in and line-out signals on the recorder, and the later at night and the more the traffic had died down, the more obtrusive the tape hiss became. It used to drive me crazy! I would bias and equalise my recorder to the nth degree, go through batch after batch of tape, trying different brands. It was very, very difficult to improve the situation.

But tape wasn't as good as it is today surely?

"I was quite surprised to find that what I produced was met either with a shrug of the shoulders or even a little bit of hostility. People didn't seem to care. They would say things like, 'We don't have a noise problem...'"

RD: It was a few dB worse, but not all that different really.

All that was around the years 1960 to 1963, then I went off to India to work for UNESCO on a United Nations special fund project. I helped to set up a new scientific instruments organisation in the Punjab. While I was there I did a lot of recording of street musicians and any other Indian musicians I could persuade. I took all my gear to India with me.

I kept thinking about the problem of noise. I had books on sound recording technology, which described various noise suppressors. So I decided to calculate the distortions in one particular design of noise suppressor, which was a multi-band device using non-linear diodes. While thinking about this particular suppressor design it suddenly hit me that all the problems with that noise reduction system, and many others, could be bypassed by using a dual circuit approach that has characterised all of my own noise reduction systems so far. The dual path approach is where all the high level signals go straight through the system without any dynamic processing and all the dynamic processing takes place in the sidechain.

Is this system peculiar to Dolby?

RD: Oh yes. I felt it was of particular importance to keep all the high level signals unprocessed. That's where all the troubles had been coming from-the high level distortions, the overshoots. All of these problems disappear if you avoid processing the high level signals.

I had to finish my work there in India but I knew that I wanted to start my own research laboratory. That had been in my thinking for many years. My first thoughts were to establish a lab based on the work I had done in Cambridge, which involved X-ray analysis systems. For my PhD research I had designed an X-ray microanalyser which I was quite proud of. The nuclear energy authority asked me to design a system for them and I spent about a year doing that. This machine could analyse elements and the impurities in them.

I had this plan, on leaving India, of setting up a lab in London making these machines. They are very complicated and expensive, as you can imagine. I didn't have the money to be able to produce something like that straightaway, so I saw noise reduction as a way to get started.

So you set up a lab to develop a noise reduction system?

RD: Yes. The first one was in Fulham in the corner of an old dressmaking factory in around 1965. I stayed there for about five months before the landlord pushed me out because he wanted to do something else with the building. Then I found some space on Wandsworth Road. It was there that I finished off the design of the Dolby A type system.

When you started your lab did you already have the idea of a four-band noise reduction system or was it something that grew out of your research?

RD: I knew that there needed to be more than one band but I wasn't sure how many there should be. That's what I had to investigate in the last half of 1965.

"I think one reason we have been able to survive for twenty-two years is that we have remained specialised. Other companies that have dabbled in noise reduction have seen it more as a side issue."

Did you involve any music producers in your research?

RD: No - no money to do that! I demonstrated a prototype of the A type system in November of that year to the Decca record company. They were impressed by it. I had made contact with them before, during my time at Cambridge. Some of the recordings I had made there I took down to Decca in London to transcribe to disc, so I came to know Cyril Windeybank (the chief engineer) and Bob Goodman. When I returned from India, even before I set up shop in Fulham, I went along to Decca and said: "What would you think of a system which could reduce the noise coming from tape without changing the sound?" Windeybank replied that he thought it would be wonderful but they were already testing a couple of systems like that. That came as a big shock to me, but I decided to take a chance and develop my own system anyway because I felt that it would be extraordinary if these other companies could have hit on the same principle that I was going to base my system on. As it turned out, their systems did work on different principles so I was in the clear. Decca asked me to come back when I had something to demonstrate to them.

This would have been one of the first production models?

RD: No, just a very crude prototype. It was packaged up neatly enough to demonstrate the principle and it worked quite well. With that unit the Decca people made test recordings on piano, guitar, voice and symphony orchestra. They made test pressings - one side of the disc with noise reduction, one without - and submitted them to Sir Edward Lewis, the chairman of Decca. He could hear the difference on his Deccola unit or whatever it was he had in his office. Decca were a very technology oriented company, especially with their involvement in navigation systems for ships.

Do you think it was fortunate for you that they were receptive to your ideas?

RD: Yes indeed, because I went to various other companies after I delivered the first units to Decca. I was quite surprised to find that what I produced was met either with a shrug of the shoulders or even a little bit of hostility. People didn't seem to care. They would say things like, "We don't have a noise problem. We use the best tape, the best machines lined up every morning. Noise isn't a factor in our work."

Presumably you knew you had a good product?

RD: Yes, but only certain people were sensitised to the noise problem.

We all have different sensitivities. I think at that time most people felt it would hamper their enjoyment of recordings if they started getting worried about noise problems. In those days it was very popular to monitor on tiny loudspeakers, much smaller than these little loudspeakers that you find sitting on mixing consoles now. A check would always be done through a very small tinny-sounding monitor speaker - I mean really tinny! These Yamaha NS10s that you see nowadays are relatively high quality loudspeakers by comparison. In that 1965 period there would always be a transistor radio loudspeaker in the studio.

When did the first Dolby product - the Model 301 - come on to the market?

"An American domestic reel-to-reel tape recorder manufacturer called KLH was interested in producing a machine that would record at 33/4 inches per second and would still sound good, so I developed the Dolby 6 system for them."

RD: In April 1966.

Did it have the Dolby tone then? (The line-up signal to aid in setting the correct Dolby level.)

RD: No.

It had a meter for level setting, surely?

RD: No, no meters. And no switches, or indicators. You see, other people had previously tried to build noise reduction systems - there was a history stretching back some thirty years - but mine was intended to be a system which was installed and didn't need adjustments. The Decca people were always very precise in lining up their tape machines, so when we prepared a unit for them we would know exactly what levels to set. When we started selling to other companies who were not so precise, it became necessary to make our units adjustable so we provided a built-in meter to line up tone to. The Dolby tone came later; only the very last 300 or so units - we only made 1,200 or so - had Dolby tone on them.

What about Dolby B? How did that come about?

RD: Dolby B wasn't originally intended for cassette recorders. There weren't any what you would call 'quality' machines around at that time. An American domestic reel-to-reel tape recorder manufacturer called KLH was interested in producing a machine that would record at 33/4 inches per second and would still sound good, so I developed the Dolby B system for them.

How did you persuade Japanese manufacturers to adopt the system?

RD: We demonstrated the Dolby B system on a modified Harman-Kardon cassette recorder at the Audio Engineering Society's convention in New York, 1969. Harman-Kardon and two other manufacturers contracted Nakamichi of Japan to build cassette recorders for them, so that's how the connection was made.

Coming up to date now, I have to ask if you see the new Dolby SR (Spectral Recording) system as a challenge to digital recording methods?

RD: I've always preferred to work independently. I want to do my thing my way. Other people can do things their way if they want to. You may have noticed that in our advertising we never make reference to any other noise reduction systems. We only talk about ourselves, not what other people are doing. Regarding digital recording, I would like to avoid having to say we can outperform any particular machine. I don't think it is good for the industry to do that.

Is there any way to improve analogue recording further after SR?

RD: Right now we seem to be limited by the source material. I believe it is impossible to find a microphone that's quiet enough. In every experiment we've done, the tape is not the limiting factor any more - it's microphone noise. Even if you stuff the microphone right inside the instrument to get the very best signal-to-noise ratio - a microphone inside a piano, for example - the noise you hear during playback is just microphone noise.

"I believe it is impossible to find a microphone that's quiet enough. In every experiment we've done, the tape is not the limiting factor any more - it's microphone noise."

So if you took the quietest microphone available, put it into the quietest preamp - no mixer - and recorded it with Dolby SR noise reduction, you are saying that the tape would outperform the mic?

RD: Yes, at least until someone devises a quieter microphone, so we can relax for a little while.

Somehow I don't think there can be much chance of that - there always seems to be some new Dolby product on the market. I have heard that Dolby Laboratories are now involved with digital work in connection with satellite broadcasting. Is that true?

RD: Yes. We first got involved with digital work in connection with our cinema 'surround sound' processors.

We needed a way of providing a relatively high quality delay for the rear channels - the surround channels. That requires a delay of up to 100 milliseconds, so we used digital techniques for that. That work started around 1976. Ever since then we have had digital projects in development as well as analogue projects.

You are not using the same industry-standard digital system that's employed in the compact disc?

RD: No. We use adaptive delta modulation. It's a kind of one-bit digital system. Instead of having sixteen bits, as with compact disc, you have only one bit. The bit is either there or it's not there, and that causes the waveform to either go positive or negative, describing changes in the signal rather than steady state values. It has certain advantages, one of which is economy. It's much more economical than a PCM (pulse code modulation) system.

Do you expect Dolby Laboratories to stay in noise reduction or to diversify into other fields?

RD: We are pretty well diversified in this field of noise reduction already. There are so many different products aimed at so many different markets - we have cassette recording, tape duplication, recording studio equipment, equipment for motion picture studios and the cinemas themselves, and the satellite equipment which uses a combination of analogue and digital systems. It's not just purely digital, it's 'smart' digital using analogue techniques similar to our noise reduction techniques to give improved efficiency. Somehow or other, all these things have really kept us jumping. The idea of branching out, making mixing desks for example, just doesn't seem necessary. I think one reason we have been able to survive for twenty-two years is that we have remained specialised. Other companies that have dabbled in noise reduction have seen it more as a side issue. We have 150 people in London and the same number in San Francisco and they are all working on these things. We are all working flat out. If people see that you are dedicated, committed and concentrated, they tend to shy away from competing with you.

How heavily involved are you personally in research and development?

RD: The SR system has been my obsession now for around seven years.

You headed the design team?

RD: I designed it myself. You know, designing something like that is a lonely kind of thing. It's not something you can parcel out to different people. It's a bit like writing a novel - in fact, I have often thought of it in those terms. I can see how the writer of a novel had to do it all by himself; he couldn't say "You write chapter seven" and someone else take care of this episode.

It doesn't work. Everything has to interlock and work together as a total organism. A complicated system like Dolby SR is like that too. That's been my obsession. I'm just now feeling that I'm out of the woods. Of course, when I say I designed it I must give credit to the engineers who put it together as a production package, the people who put the system together into a finished module.

Right now we are working flat out on SR production, both in London and San Francisco. We have delivered around 2,000 channels so far and there are about 2,500 on back order. As soon as we start delivering the multitrack version the whole thing is going to explode! It's a happy thought.

I left Ray Dolby to resume the helm at his stand at the AES exhibition and went home to transcribe his words recorded on my small portable cassette recorder - with Dolby B noise reduction, of course!

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Fix it in the Mix

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Yamaha DMP7 Digital Mixer

Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.


Sound On Sound - Jul 1987

Interview by David Mellor

Previous article in this issue:

> Fix it in the Mix

Next article in this issue:

> Yamaha DMP7 Digital Mixer

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