Mondo Audio by Ken Kessler -- Interview: Stan Kelly (Jan. 1995)

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above: Stan Kelly's fully functioning workshop in his garden is also an Aladdin's cave of audio artifacts.

When Gene Pitts asked me if I'd like to conduct a series of conversations with the greats of British audio, I jumped at the opportunity. In my time as a hi-fi journalist in the U.K., I'd been saddened by the passing of Donald Aldous, Arthur Radford, John Gilbert, and other giants of audio lore; here was an opportunity to reminisce with the surviving founding fathers of the industry.

For American readers, this should provide an intriguing view of the birth of the audio scene on the other side of the Atlantic. As I learned upon moving here in the early 1970s, the U.S. and the U.K. were prior to the appearance of the Japanese manufacturers-responsible for the bulk of audio development and manufacture, with a few notable exceptions (such as Thorens, Studer/Revox, and Dual And yet, Great Britain and the United States operated virtually in isolation from each other until the 1960s Although numerous British companies exported products to the U.S from the early 1950s onward (QUAD, Tannoy, Leak, and other had a presence in the States), a stud of British hi-fi magazines and year books from the 1950s reveals the presence of almost no America components whatsoever. British de signers were, however, familiar with American developments, even if the British public knew only of native hardware. For example, David Hafler, while at Dynaco, was an early audio ambassador to the U.K. and even sourced transformers from Radford. Bud Fried was (and still is another Anglophile; he imported Decca cartridges and other products into the States.

To continue this interview series, I chose to speak with Stan Kelly.

Many individuals have companies which bear their names; fewer are those whose name has come to stand for a specific product. British audiophiles still refer to Stan's horn loaded ribbon tweeter as the Kelly Ribbon, not the Decca Ribbon, even though that company took over the manufacture of the ribbon at an early date. Stan also can take credit for inventing the "flipover needle" for budget record players when 33 1/3 rpm joined 78 rpm. And he even helped Miles Henslow establish Hi-Fi News, the first British hi-fi magazine; Betty Kelly, Stan's wife, guaranteed Henslow's bank loans!

A spry 80-something, Stan still acts as a consultant and maintains a fully functioning workshop where he makes his own prototype drive units for various manufacturers, including the magnet assemblies and speaker baskets. The workshop in his garden is an Aladdin's cave, with some desk drawers full of ancient cartridges and others with what look like modern Infinity EMIT tweeters.

"Those? I made them myself in 1956." And when Stan's memory can't be jogged, his charming wife is there to fill in names, places, and dates. The following interview is taken from conversations with Stan Kelly in November 1992 and September 1994, the latter inspired by the sudden appearance of a new source for Kelly replacement ribbons. [ See sidebar.]


New Ribbons for Old

The manufacturer of new re placement ribbon elements for Kelly speakers is H. Dawson, 16 Copeman Rd., Aylsham, Norwich NR11 6JL, England. To confound matters a bit, Presence Audio, which has the license for the manufacture of Decca products, also makes replacement ribbons; the U.S. agent for Presence is Pro Audio Ltd. ( 111 South Dr., Barrington, Ill. 60010; 708/526-1660).




above: The very first Kelly ribbon tweeter (left) and a later version.

How did you react when you learned that an independent individual had put the ribbon element back into production?

Frankly, I had no reaction. The thing is that I wasn't making it. Decca--or the people who have taken over Decca--aren't interested in making it. If he wants to have a bash, good luck to him.

Did you not retain any rights to the ribbon at all?

I can't, you see. All patents lapse after 17 years. The only thing I have any individual title to is my name. If we'd have taken out a copyright on it, as distinct from or in addition to the patent, well, the copyright could have lasted forever. But we didn't.

So what can people call this new ribbon element without your permission?

Well, they can't call it a Kelly Ribbon with out my permission, and they can't call it a Decca Ribbon without Decca's permission.

What led you to produce a horn-loaded ribbon system in the first place ?

I wanted to make a wide-range, high-frequency transducer. At that time, I was out a scrapbook which itself would warrant facsimile reproduction.] At Cosmocord, where I was technical director from 1947 to 1953, we were making tonearms, pickups, and microphones. That included the first pickup ever made to play at eight grams, but I designed it to play at five. It became a standard. These [pointing to the book] were rather more ancient. And these featured the first cantilevers. Before that it was needles; I started making sapphire-tipped rods to use in place of steel needles. They were fine for playing weights of less than 20 grams. This pickup, for example, had a playing weight of 120 grams.

How much?!

Four ounces. EMI and Decca produced their pickups at 'round about 40 to 50 grams. This was for the first LPs. I then produced the GP15 to play at eight grams.

And that meant that the vinyl now had a reasonable life. Then I produced this unit, the GP20, for 78 and 33 1/3, with two styli, one on either side.

Had no one else thought of that before? The Americans or the Germans?

No, no. This was a first.

How did that idea hit you?

It was obvious. Look, if we started with a torsion crystal instead of a bending crystal, it was quite obvious that if, on the end of the crystal here, you put a bar at the back end and pushed it that way, it was twisting the crystal. If you pushed it the other way, it was also twisting the crystal. So you put two styli on it. We made a lot of 'em-this was around 1950; I left Cosmocord in 1953 and went on to start my own company, Kelly. And the first thing I manufactured was that. [He shows me the original ribbon.] The RLS-1, 3k to 20 kHz.

Prior to introducing this drive unit, what ribbons were commercially available to audio enthusiasts ?

There was the QUAD, in production quite early. It was a much larger ribbon. But the QUAD was extremely expensive, and you had to buy a complete full-range system; you couldn't buy a single ribbon tweeter. So when I made the ribbon, I also produced a bass unit for it and a crossover network--but these were for the home constructor.

Was the home-constructor market more important than the assembled-unit market in the mid-1950s ?

In terms of real hi-fi, yes, because with the exception of QUAD and one or two others, you couldn't buy a complete system made up of separate components. You had to go to a specialist hi-fi dealer who had a range of amplifiers, a range of tuners, and a range of speakers and hope that he'd got the right combination.

So how was the mass market being served?

There was no mass-market hi-fi. Radios, radiograms, and record players. If you went to a radio shop, you could buy a radiogram, which was a tuner, record player, and speaker all in one box. And there was a whole range of those, from bad or indifferent to quite good.

The enthusiast market to which you were addressing your products, was that an immediate postwar phenomenon or did it not take off until well into the 1950s?

There was a hard core of "hi-fi enthusiasts" from before the war, with Donald Aldous, who later worked for Hi-Fi News & Record Review, handling the information side.

Percy Wilson was another one, the technical editor of The Gramophone. Before the war, Gilbert Briggs at Wharfedale pioneered the individual loudspeaker driver, one of the first permanent-magnet, moving-coil designs. They developed the hobby from the acoustic gramophones before the war to the very crude electronic gramophones immediately before the war. Then everything went into limbo for the next five years. After the war, with all the technical developments from military electronics and the mass production of equipment, it became possible for the man in the street to buy a good audio amplifier.

Military surplus?

No, not military surplus. Some of the manufacturers who were making military equipment immediately went over to civilian production; they'd got the technical know-how and the production facilities to make civilian equipment.

So when you decided to go into speaker manufacture in the early to middle 1950s, there was a ready market?

Oh, yes. There were companies like Celestion who'd been manufacturing pre-war, mainly for the domestic radio market. They had played with better speakers before the war, but after the war they then had the technical and commercial facilities to produce good-quality loudspeakers. Of course, this was very much tied up with the cones.

The normal tweeter purchase for the home constructor, before the ribbon was introduced, would have been a little three or four-inch cone with a little dust cover which was your dome, of course-and these were usually good for five watts. But you must realize that the sensitivity was about 85 dB for one watt. Yet because of the limitation in broadcast frequency range--we're talking about AM, not FM, everything was on medium wave-you were limited on the frequency response and the signal-to-noise ratio. And you were limited in exactly the same way on 78-rpm records. The speakers of the day were consistent in quality with the records and broadcasts available at the time. And then LP and FM radio triggered each other.

So you came out with a tweeter good for 3k to 20 kHz.


Were you the first to put a ribbon in a horn?

As far as I know. It had a 3k to 20 kHz signal, and I wanted at least half an octave on each side; on the high end this immediately outperformed any voice-coil-cum-dome or what-have-you, just because of mass and also because of the limitations on the mag net. The neodymium magnet was-well, you couldn't afford it. You had access to it, but it was like buying gold. These are cobalt. [He points to the Kelly speaker magnets.] I had to keep an eye on price, even though I was trying to go for the best performance.

The price of the original drive unit was 12 guineas in 1955. That's equivalent to .. .

Fifty pounds in today's money.

That's still not very expensive, even by '50s standards.


How long did you work on the ribbon before making the first production version ?

Less than a year. The first problem was get ting an efficient magnet. I didn't make many of the first type, because, by redesigning the magnet, I added another 6 dB to the efficiency. It reduced the mag net's cost, too. The ribbon, the trans former, and the horn remained constant ever since. The ribbon itself was an aluminum alloy that stayed constant; I never altered it. The horn was cast.

Had you tried other topologies?

Not electrostatic. I had two things against it. It was high-impedance. And high-impedance transformers are very difficult to make because of self-capacitance and things like that. Then you've got to have polarizing voltages on it, and your high-voltage production equipment was very, very costly compared to a magnet.

So cost ruled out using electrostatics?

And simplicity. There's nothing to go wrong in this ribbon. If you've got a high-voltage thing with valves in it, something can go wrong. You need a power supply for it. Instead of two leads going to your loud speaker, you had four.

And what of the existing dynamic tweeters of the day? Well, they were domes. And if you had them sufficiently large enough to give you the radiation, then you were severely limited on the high-frequency side. And you had all the resonances of the dome and the suspension added to it. It worked well enough so that, during the peak of production, we were probably making about 500 drivers per month.

How was Decca involved?

Decca came along and said, "We want to use your speaker in our equipment."

So they already had their own line of loudspeakers?

Oh, yes. So I said yes, and they if we make 'em, we can make them for half the price you can, because we can make four times as many. We'll take over the manufacture and give you a royalty." That was in the early '60s. MI the manufacturing moved up to their factory in the Midlands.

I then played around with tape recorders, made microphones, and then moved on to complete loudspeaker systems. We closed down Kelly in the mid-'60s, after I'd had my fill of it.

Did you keep an eye on Decca after they took over manufacture?

I was forbidden to. They didn't say so in so many words, but when I said I'll go up and see how they were getting on in the Midlands, they said you bloody well won't.

So you took their word on the royalties.

Look, I'm an engineer, not a businessman.

That's the story of my life! But I was happy with Decca's drivers; they were exactly to spec. There was no way that you could complain about the quality.

But once they took over, the name changed to Decca London?

Yes. It was Decca-Kelly originally. And then Decca London.

(adapted from Audio magazine, Jan. 1995)

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