Videos

AES Interview with Don

This video is an essential piece of audio engineering history, capturing an interview with the legendary D.B. (Don) Keele, Jr. by Irv Joel, recorded at the 111th Audio Engineering Society (AES) Convention in New York.

The interview covers Keele’s extensive career and his contributions to the loudspeaker engineering community. Below is an overview synthesizing the video’s context with the key technical achievements he is known for:

🎙️ The Interview Context

The interview format allows Don Keele to speak candidly about his professional journey and experiences in the high-fidelity and professional audio industries. He discusses his work at several major companies and his evolution as a loudspeaker designer, giving insight into the challenges and innovations of the era. The discussion often circles back to his most influential technical contributions that shaped modern sound reinforcement and home audio.

The video provides a valuable oral history from one of the industry’s most influential engineers.

The CBT Chronicles

The playlist, “The CBT Chronicles” by Don Keele, is a comprehensive, nine-part video series detailing the history, technology, and performance of CBT (Constant Beamwidth Transducer) loudspeaker arrays.

Here is a brief overview of the content:

• Introduction to CBT (Parts 1-5): These videos cover the general background, history (including its military roots and associated patents), and theory of CBT arrays. Key topics include:
  • Ways to implement a practical CBT system, including shading.
  • The features of the CBT36 ground-plane system.
  • Discussions on how CBT technology manages floor reflections and the concept of a constant, wide beamwidth.
• Comparative Measurements (Parts 6-9): The latter half of the series consists of real-time measurements over a reflective tile floor, comparing:
  • A traditional, well-designed three-way speaker system.
  • A two-way CBT array system.
  • The measurements demonstrate how the CBT array maintains a consistent frequency response regardless of listening location (sitting, standing, near, or far), unlike the traditional system, which suffers from significant changes and detrimental comb filtering from floor bounce.

The videos are presented as an extemporaneous lecture by Don Keele, featuring real loudspeakers and props rather than a typical PowerPoint presentation.

Don Keele’s CBT Presentation for Parts Express

Don Keele’s Keynote Speech for Parts Express, delivered at the 2010 Midwest Audio Fest, focuses on the groundbreaking concept and practical application of CBT (Constant Beamwidth Transducer) Line Array Speakers.

The presentation covers:

• Origin of CBT Theory: Keele introduces the foundational work on the CBT concept, which originated from research on underwater transducers at the Naval Research labs [00:42]. The key to the design involves a spherical cap surface that uses a specific shading function (based on Leander functions) to control the sound pattern.
• Broadband Constant Directivity: The central theme is the development of a loudspeaker array that achieves broadband constant directivity [06:00]. This means the speaker’s sound coverage pattern remains invariant with frequency and does not change significantly as a listener moves further away from the array.
• Comparison to Other Speakers: Keele uses examples of traditional loudspeaker designs—such as straight line arrays, horns, and point sources—to illustrate why they fail to maintain a consistent directivity pattern, positioning the CBT array as a superior solution [06:29]. The CBT design is presented as an “absolute yes” for achieving the goal of uniform sound coverage [09:40].

Don Keele Award

D.B. (Don) Keele, Jr. accepted the Gold Medal at the 141st AES Convention in Los Angeles, CA on September 29, 2016 “for outstanding and significant research, design, and product development, over a period of more than 45 years, of loudspeakers and loudspeaker systems providing broadband constant-coverage performance.”

The AES Gold Medal Award (formerly known as The John H. Potts Memorial Award) is given in recognition of outstanding achievements sustained over a period of years in the field of Audio Engineering.

This was the 35th award given in the 75-year history of the AES.

JBL First with the Pros

JBL First with the Pros is a promotional video created in the mid 1980s that showcases the quality of both the engineering and manufacturing of JBL home and professional products at the time. This video features factory workers and engineers like Don Keele and Mark Gander plus others.