A leading authority on loudspeaker technology, D.B. “Don” Keele has done it all, from his dozens of published technical AES papers, to his design work for leading manufacturers — among them Electro-Voice, JBL and Klipsch —an AES board member and even as a journalist, reviewing loudspeakers forAudio magazine. Products he’s contributed to are familiar names to audio pros, such as his work on JBL’s famed Bi-Radial horn series and programming for Crown Techron’s TEF systems. 

As a senior designer with Electro-Voice, he conceived and patented the Constant Directivity (CD) loudspeaker horn in 1975. In addressing the issue of beamwidth varying at different frequencies, Keele’s CD horn design employed a hybrid horn with an exponential expansion rate near the throat followed by a conical expansion section and ending with a rapidly flaring flange at the mouth. Even today, some 45 years later, his landmark patent remains a standard design concept throughout the professional loudspeaker industry. In fact, in 2002, Keele was honored with a Scientific and Engineering Academy Award from the Academy of Motion Picture Arts and Sciences for work on Constant Directivity loudspeakers for cinema applications.