Free Tutorials and Speaker Design Advice from Experts in August 2020

July 24 2020, 06:30

In this edition, Voice Coil is proud to feature an article by experienced speaker designer Igor Levitsky on “The Advantages of Thin-Film High-Frequency Transducers.” Levitsky is highly recognized in the industry for developing some of the best planar magnetic speaker and headphone drivers for some of the most reputed brands, focusing precisely on this type of technology. As he mentions in this article, over the years, the audio community has acknowledged that speakers based on drivers with thin-film diaphragms deliver exceptional sound quality in mid- and high-frequency ranges. And it seems clear that we will continue to see more headphones and speakers using thin-film drivers, as the industry is now perfecting the use of different types of diaphragms and materials for electrostatic, planar magnetic, ribbon, and air motion transformer (AMT) designs. The August 2020 edition of Voice Coil includes just the first part of this article, with the second part next month, detailing the latest Radian LT2/LT6 ribbon transducers - the two latest products that Igor Levitsky designed for the Californian manufacturer.

Mike Klasco (Menlo Scientific) wrote a tutorial where he provides an overview on how to specify or fabricate voice coils. A topic that is addressed regularly in this magazine, and yet it's been almost five years since the last tutorial on voice coils was featured. Usually the magazine focuses on the latest market trends and changes in vendors, which have seen dramatic changes from 2010 to 2015, as the voice coil winding industry moved predominantly to Asia. This month, Mike Klasco recaps on voice coil basics, bobbin materials and sizes, collars, winding techniques, configurations, tips and tricks and wire types and considerations - a valuable, concise compendium of unique knowledge.

Then, Nora Wong provides the latest global directory of voice coil winders and converters, covering what is still possible to do in the US, who are the main Asian voice coil winders, and which Asian vendors are “converters” and sell coated bobbin materials, coated magnet wire, collar materials, adhesives, and such to other independent coil winders and speaker manufacturers that wind their own coils. Finally, there's an overview of European and Indian voice coil manufacturers.

In this month's Acoustic Patents column, James Croft (Croft Acoustical) covers a fairly recent patent of a "Speaker Device". Claimed by Toshiyuki Matsumura (Osaka, Japan), Akihisa Kawamura (Osaka, Japan), and Shuji Saiki (Nara, Japan) as the inventors, on behalf of Panasonic in Japan, this modestly titled patent does indeed show merit - basically describing a novel type of coaxial configuration, including a woofer and a high-frequency transducer arranged in a front-to-back, coaxial relationship. Exploring recommended.

And for this edition's Test Bench, Vance Dickason served a generous dose of measurements while characterizing two different high-frequency drivers.

The first one is the LT2 Ribbon Transducer and corresponding waveguide from Radian Audio Engineering. This is effectively a smaller version of the LT6 ribbon transducer reviewed in the July 2020 issue of Voice Coil, but offering much more diverse possibilities, as Dickason discovers. While Radian is recognized for its pro sound OEM drivers, and particularly known for great sounding compression and coax drivers, this new-generation waveguide planar transducers pave the way to an entirely new range of applications. And as the compact LT2 shows, this was designed to be more of a hi-fi or home theater substitute for any high-frequency driver. The LT2, like all of the other new Radian ribbon high-frequency devices, was designed by 35-year loudspeaker engineering veteran Igor Levitsky, who also designed consumer systems for famous brands, including BG Radia speakers and the OPPO PM1 and PM3 planar magnetic headphones.

The second Test Bench in this edition is the 140FCD 1" compression driver from REDCATT. This is a relatively new OEM pro sound driver manufacturer - a privately held, international company established in 2014 and based in FuMing Industrial City, DongGuan, China. The core management team at REDCATT has been sourcing and building transducer components, sub-assemblies and systems in China for more than 25 years, and its team members have been working around the world for the biggest companies in the audio market with direct R&D and manufacturing experience. The self-stated objective for REDCATT was to create a true state-of-the-art facility, focusing on production quality audio products. 

And the 140FCD is a truly impressive compression driver. Designed for use with 1" throat horns, the REDCATT 140FCD is definitely in the running for this year’s best looking driver packaging! It is driven by a 35.5 mm (1.45”) diameter voice coil wound with edge wound copper-clad aluminum wire (CCAW) on a non-conducting Kapton-type former, driving a polyimide composite diaphragm and vented surround. 

The August 2020 edition of Voice Coil concludes with the usual Industry Watch section where Dickason pays tribute to Albert von Schweikert (1945-2020), the high-end loudspeaker engineer and founder/chief engineer of Von Schweikert Audio in California. Von Schweikert worked at ESS Laboratory for a number of years, most of which was spent as Dr. Oskar Heil’s research assistant, and he also worked or designed systems for Polk, Klipsch, JBL, Infinity, Apogee, Cerwin-Vega, Jensen, NHT, and many others.

The August 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.

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