Most of the best hi fi transducers and systems by University in the 1950s and 1960s were the work of Abraham Cohen, their chief engineer. This guy was good! He also wrote very well, authoring numerous magazine articles and his essential book "Hi Fi Loudspeakers and Enclosures" in at least two editions. Somewhere I have the article he wrote explaining the Diffusicone series. Basically a wide range dual cone driver a la Lowther, the whizzer is damped by being tied back to the main cone at its periphery. I believe Cohen may have been following up on earlier work by Dr. Harry Olson of RCA, who described such a driver in the late 1930s. I once had a pristine Diffusicone 15 and let it go cheap on ebay... bad move. My brother and his family are still using the Cohen-designed University Classic three way horn systems I fixed up for them years ago, though.