We recently heard of the passing on Oct. 1 of Dr. Albert Neville Thiele, one of the great names in the development of our understanding of transducers and speaker enclosure design. Thiele, pictured here, left, with fellow audio specialist Richard Small, was 91.
Speaker design has long been considered some kind of black magic. Yet over the years, the increased application of solid science to loudspeakers has brought true predictability (rather than simple trial and error) to the process.
In 1961, while a broadcast engineer, Thiele published a paper in an Australian radio/electronics journal describing his work in simulating loudspeaker response as electrical filters as a means for speaker design.
A decade later, Richard Small, an American studying in Sydney read the paper and convinced the University of Sydney to let him enroll for a Ph.D, expanding and refining its premise.
With the help of colleague Robert Ashley, Small convinced the AES to reprint Thiele’s original paper in the May and June 1971 issues of the Journal of the Audio Engineering Society and followed it up with a series of his own AES papers in 1972 and 1973.
Following earlier work by Leo Beranek, a major advancement in the understanding of enclosure design came from Thiele and Small’s research regarding the relationship of loudspeaker parameters to low frequency performance in vented cabinet enclosures and simple methods of measuring them. Among these parameters were the driver’s free air resonance, electrical and mechanical Q, DC resistance, efficiency, piston area, thermal power rating, etc.
The effect of the Thiele-Small research was dramatic, not only influencing manufacturers to provide more details about the drivers they built, but also bringing about a new era in the predictability of loudspeaker response based on enclosure volume and port dimensions. Today, the Thiele-Small parameters (TSP) are adopted and provided by nearly every raw loudspeaker supplier.
Thiele continued to be active in the industry for many years, and, until very recently, he was still teaching graduate level courses in loudspeaker design and acoustics at the University of Sydney.
Small remained in Australia for many years and eventually returned to his native America, where he is currently a senior engineer with Harman/Becker Automotive Systems.
The audio world mourns the loss of Albert Neville Thiele and is indebted to both of these great men for their work in recognizing and understanding the importance of the Thiele-Small parameters.
