Industry Insights, Expert Views, and Loudspeaker Test Bench. Voice Coil June 2020 Is Now Available

May 22 2020, 14:10

From an overview of the latest headphone test & measurement equipment, to a massive 21" tour-grade woofer from Eminence, a precise, horn-loaded ribbon planar driver from Radian, and a discussion of a controversial and wide-ranging patent on low-mass transducers, there's a lot to discover in the June 2020 edition of Voice Coil. Available now in print and digital. Download now.

Voice Coil June 2020 is now available and provides great industry insights on the headphone market, followed by an updated Headphone Test & Measurement Equipment overview and directory, compiled by Mike Klasco and Nora Wong (Menlo Scientific, Ltd.).

And for this edition, our loudspeaker patent expert and reviewer James Croft found an interesting and controversial patent to investigate and discuss. 

US Patent 9,247,339 submitted by (and assigned to) Eric Jay Alexander (Orem, UT) in 2014, and granted in 2016, claims in its short and simple abstract that "Improved speakers are better able to accurately reproduce sound through the use of low-mass transducers." How and why such a generic claim was the subject for a patent is the starting point for a detailed and entertaining review by James Croft. As the patent text details "new and improved transducers are specifically designed to match or more closely match the mass of the musical instrument reproduced from a recording." And also "a very low mass mid-range and high frequency type transducer is specifically dedicated to reproducing efficiently the overtone spectra contained in music." The author of the patent has effectively implemented speaker designs using one or more array(s) of very small transducers with minimal moving mass work, grouped closely together to reproduce the lowest audible frequencies while keeping all related overtones completely intact.

As James Croft also notes, Eric Alexander applies this (patented) theory in actual high-performance loudspeakers sold by his own company, Tekton Design (, offering speakers "that consistently punch above their weight," in the inventor's own words.

And because the work of Vance Dickason in Test Bench is increasingly recognized as a much needed benchmark for driver characterization, this June edition of Voice Coil jumps straight to those essential measurements, starting with the Eminence NSW6021-6 21” neodymium low-frequency woofer, part of the company's recently announced Tour Grade series. The Eminence  Tour Grade family of pro woofers consists of two 18” options, including the Ferrite  Magnet FSW4018-8, and the Neodymium Magnet NSW4018-8 that appeared in the March 2020 Test Bench. The NSW6021-6 is a very high power handling 21” woofer, designed over the past two years to support the requirements of touring sound professionals who want to move more air, more efficiently, and without failures in a wide range of applications and venues. 

Next up, Vance Dickason measures the latest Radian Audio Engineering's LT6 Horn-Loaded Ribbon Device, part of an expanding series designed by 35-year loudspeaker engineering veteran Igor Levitsky for the Californian manufacturer. Since the change of Radian's ownership in 2017, the company has worked consistently in the consolidation of its renowned compression driver range and diaphragms, followed by an ambitious expansion of its coaxial line, and more recently the introduction of the LT Ribbon high-frequency series, already with four models, all complemented with matching waveguides.

The LT6 is a pro sound driver but was designed to be a more hi-fidelity substitute for 1" compression drivers, and that is a direct result of Levitsky extensive experience in designing high end residential, and cinema sound systems, having worked since 1995 with companies such as Hi-Vi Research, where he developed a complete production process for manufacturing ribbon diaphragms, and over the subsequent 20 years developing planar ribbon drivers and complete speaker systems for the famous BG Radia brand (acquired by Christie Digital in 2014) and for SLS Audio (acquired by Dolby in 2014). Before joining Radian, Levitsky also worked with OPPO and Dai-Ichi on the development of the award-winning OPPO PM1 and PM3 planar magnetic headphones. He also holds a total of six patents on planar ribbon driver and speaker design.

And for this edition's Industry Watch, among other highlights, Dickason references product and corporate updates from Listen, Inc., LoudSoft, and the Audio & Loudspeaker Technologies International (ALTI) association.

The June 2020 edition of Voice Coil is available for download and already in the mail for print subscribers. Subscribers can go to - - to download this issue.

Remember, Voice Coil is available in print and download for all registered subscribers, free for industry professionals. To qualify for a free subscription to Voice Coil, or renew your subscription, go to:

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