Patent Review: Passive Radiator with Dynamically Adjustable Resonant Frequency

This review addresses an important patent awarded to Joseph F. Pinkerton (Austin, TX), on behalf of Clean Energy Labs, LLC. The patent describes an audio speaker having one or more passive radiators, and more specifically, an audio speaker having a passive radiator with dynamically adjustable resonant frequency. Croft reviews the patent and compares it with previous attempts to achieve this useful development, with significant potential if its full capability is realized.

The driver featured in this Test Bench is the new E0060-08/06 6.5 “King Coax” from SEAS. Recognized for several years for its high-performance coaxial midrange/tweeter drivers, SEAS developed this new driver at the request of a studio monitor customer who wanted a compact three-way monitor and asked SEAS to develop a midrange + tweeter coax. The King Coax received its name from the copper ring under the tweeter, which resembled the look of a crown. This article was originally published in Voice Coil, June 2017.

For this Test Bench, Vance Dickason characterizes an Eminence N151M-8 1” throat ring radiator compression driver coupled with the Eminence STI1 90° × 40° constant directivity horn. The N151M-8 includes a mylar diaphragm driven by a 1.5” voice coil wound on a polyimide former and cast aluminum body, neodymium ring magnet motor, and field-replaceable diaphragm. This article was originally published in Voice Coil, June 2017.

Shannon Becker conducts an interview with Dave Thomson, CEO and founder of Raven Audio, a tube amplifier company based in Texas, which has successfully created a thriving business with high-quality tube amplifiers and preamplifiers. Raven Audio just opened a new facility in Onalaska on Lake Livingston, 100 miles north of Houston, and continues to expand its engineering staff. This article was originally published in audioXpress, June 2017.

Now available for download, Voice Coil June 2017 features a report on new earphone and headphone technology developments, compiled by Mike Klasco (Menlo Scientific); a directory of manufacturers; and a summary of recommended related trade shows. James Croft reviews a patent for a passive radiator with dynamically adjustable resonant frequency, while Vance Dickason tests Eminence’s new 1” compression driver and SEAS’ 6.5” “King Coax.”

If you have a passion for high-quality audio experiences you know this is a continuous learning process. In audioXpress June 2017, you will learn more about binaural recording, how you can tune your listening to your own hearing when using earphones and headphones, and we explain how to assess audio quality in any acoustical environment with the MATT Test. That and much more is now available in audioXpress June 2017.