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For more than 40 years, the Thiele-Small (T-S) parameters of Neville Thiele and Richard Small have been the standard for designing and assessing the performance of loudspeakers. Their unified parameter based approach analyses the electromagnetic, electromechanical and acoustic behaviour of transducers, enclosures and filters. The resulting equations are mathematically equivalent to those describing an electric circuit, thus the term ‘Equivalent Circuit’. Thiele and Small showed how sound produced by the loudspeaker at low frequencies could be modelled by a simple circuit analogue. By using the T-S parameters in computer simulation models, users are able to design loudspeakers without having to physically build the enclosure. Last issue, we published an interview with Neville Thiele. This issue, Steve Mowry catches up with Richard Small…
SM: Dr Small, thank you for this opportunity to talk with you today. Firstly, are you an Australian or an American citizen?
RHS: I was born and raised in California, Steve. My mother told me I was a fifth generation Californian on her side. Australia gave me the opportunity and means to extend Neville Thiele’s groundbreaking work, and I love the place. I spent 21 wonderful years there. My wife, born in England, also has an Australian passport. With a total of 30 years outside my native country, I think I qualify as an adopted foreigner. But I have only a US passport.
SM: Do you consider yourself to be a loudspeaker pioneer?
RHS: Goodness, no. Just lucky. It really helps to be in the right place at the right time. If you can see me, it’s because I’m standing on the shoulders of Neville Thiele, Jim Novak, Leo Beranek and others.
SM: What do you consider to be your greatest achievement in your career as an engineer?
RHS: Getting lucky again and finding a good wife.
SM: Could you please explain your passion for loudspeakers to the readers?
RHS: I couldn’t call it passion, more a long-term interest. My father was an amateur pianist who played everything by ear, and he loved music and was keen on music reproduction. We had wired music all over our house in Altadena, California, and I helped to run the wires through the basement, attic, drop spaces and walls. I had a keen interest in electronics and built the amplifiers that drove our music ‘network’. Dad had a fine circular bench saw and built various enclosures for the living-room loudspeakers, following the trends of the times. One day, he found that the local lumberyard had a sale on 1-1/4-inch marine plywood for the price of quarter-inch. He bought a few sheets and then went wild and got some JBL components: a 130A 15-inch woofer, an eight-cell horn tweeter and a ‘1,200 cycle’ crossover network to match. He built a beautiful 16 cubic-foot corner enclosure (this was mono days) for the components. It had a 64 square-inch port. It had to be the speaker system to beat all speaker systems. Trouble was, it never had good bass. I never knew why until after I had done my research in Sydney and then had the opportunity in 1977 to measure the parameters of a 130A. The Qt was really low, about 0.2. It was designed for horn loading, not for direct-radiator use. The enclosure was beautiful though!
SM: How did you happen to meet Neville Thiele and Ernest Benson?
RHS: I’ll try to keep a long story short. When I worked at Bell and Howell, I met Andrew Nowina-Sapinski, an industrial designer who became my social mentor. He did a lot to humanise this awkward engineer. He went to Japan in 1963 and invited me to come along. Nine months later, we both moved to Sydney and I got a part-time job at The University of Sydney, as a teaching assistant in the electronics lab. Andy did consulting in product design. One of his clients wanted a design for a loudspeaker system for a modular storage system, and Andy recommended me. I didn’t know how to design loudspeaker enclosures, but the university had an excellent engineering library, so I figured I could learn. I failed, initially. Then one of the professors suggested I should read Neville’s 1961 Australian paper, which I hadn’t found in my searching. I read it. As Neville likes to quote Einstein when told that his theory of relativity was difficult to understand, ‘it isn’t difficult to understand, just difficult to believe’. That’s what Neville’s paper was. I got his references and studied them, and it was all correct, so I had to believe it. So I tried it, and it worked! I wish I had a dollar for all the times other people have said the same thing to me about Neville’s paper. Some time later, I went to a lecture that Neville gave and introduced myself. That was the start of a long and wonderful friendship. Of course, Neville knew Ern Benson, who edited (and wrote for) the AWA Review, the Australian version of the RCA Review. Ern’s loudspeaker papers are classics. He designed the first really successful electrically- tapered arrays, using both amplitude and bandwidth tapering plus overall equalisation, for the Sydney Opera House.
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