Patent Review: Smart Bass Reflex Loudspeaker

James Croft (Croft Acoustical) reviews a very curious patent from Amazon Technologies, Inc. (Reno, NV), filed in 2013, and awarded in April 2017. Basically, the patent discusses a new technique to tune a port of a loudspeaker, in this case multiple ports that will be open or selectively closed, in function of an analysis of the frequencies of the signal being played. This article was originally published in Voice Coil, June 2018.

Our readers that follow Richard Honeycutt's column Sound Control know how this series of articles covers the most fundamental topics in acoustics and electroacoustics. Most people who have been around acoustics or acousticians have heard of the Helmholtz resonator. In this article, Honeycutt discusses the extraordinary scientist for whom this device is named - Hermann Ludwig Ferdinand von Helmholtz (1821–1894) - and examines how the resonator works, as well as its uses. This article was originally published in audioXpress, January 2017.

Voice Coil March 2019 is now available and this issue focuses on the vital, but seldom addressed, topic of loudspeaker enclosure materials. Mike Klasco reviews and looks ahead at all the materials and design approaches for loudspeaker enclosures, and the edition also includes a complete directory for sourcing vendors in this area. James Croft reviews a Coaxial Centerbody Point-Source (CCPS) Horn Speaker System patent, and Vance Dickason characterizes three new tweeters on Test Bench.