Voice Coil March 2018 is Now Available!

February 26 2018, 05:00
This month, in Industry News & Developments, Vance Dickason highlights the forthcoming Audio Expo North America (AXPONA), which will take place April 13-15, 2018, at the Renaissance Schaumburg Hotel & Convention Center in Schaumburg, IL.

This edition also includes our AISE 2018 Report, written by Mike Klasco, Nora Wong, and Touy Ken. If you attended the Association of Loudspeaker Manufacturing and Acoustics (ALMA) International’s AISE 2018 at the South Point Hotel in Las Vegas, NV, you probably experienced two days filled with networking, education, networking, exhibitors, new products, and a lot of fun. The detailed Voice Coil Spotlight article, provides an overview of the exhibition and this year’s presentations.
Also in this edition, Christopher J. Struck (CJS Labs) discusses “Efficiency Bandwidth Product for Loudspeaker Drivers” in a Technical Notes article.
And James Croft (Croft Acoustical), discusses a patent originally claimed in 2013 on a Double Coil Speaker design, which was recently granted to Friedrich Reining (Vienna, Austria), on behalf of Sound Solutions International from China. The abstract from the patent details an audio system comprising an electro-acoustic transducer having two stacked voice coils mechanically linked to a membrane. The voice coils are oscillatingly suspended in the magnetic field of a permanent magnet focused by a pole plate and are mechanically arranged symmetrical to the pole plate while in a rest position. The audio system further comprises two driver circuits connected to the electro-acoustic transducer. James Croft discusses multiple approaches in similar concepts, which apparently have never resulted in practical applications, but notes that the current state of technology, and notably the evolution in Class D amplification, might finally create a way to explore it in commercial products.
In this month's Test Bench, Dickason examines two 1" compression drivers. The first one is a new PEEK diaphragm compression driver from Precision Devices, the PD.CD1N. The second unit on Test Bench is the Peerless by Tymphany DFM-2544R00-08.
About the Precision Devices compression driver, Dickason notes that this is a unique design in the UL brand's portfolio, using a PEEK diaphragm/surround material, which also incorporates a three-slot optimized phase plug design and a 44 mm (1.73”) diameter voice coil wound with copper-clad aluminum wire on a Kapton former. Other features include a radial neodymium magnet motor structure, an aluminum three-slot phase plug, nominal 40 W (AES) rated power handling, a 1.6 kHz recommended crossover frequency, and color-coded chrome push terminals.
About the Peerless by Tymphany DFM-2544R00-08, which is part of the brand’s new three model compression driver series, the compression driver features a 1” throat exit diameter, but with a 1.75” titanium diaphragm and the same type of polyimide surround. As Dickason notes the DFM-2544R00-08 is driven by a 44.4 mm diameter voice coil wound with aluminum wire on a Til film non-conducting former. Other features include a ferrite ring magnet motor structure, nominal 60 W rated power handling (50 W continuous), an injection-molded black heatsink, and solderable terminals. I should also note that the titanium diaphragm is coated with a light, thin layer of unique damping material giving the driver, according to the company, an unusually smooth sound at high SPLs. All of the materials resist environmental factors of heat, vibration, and aging and is purported to ensure many years of stable performance.
The March 2018 issue of Voice Coil wraps up with the usual mix of Industry Watch stories, this month we discuss the disappearance of Thiel Audio and highlight QSC’s 50th anniversary, among other updates.
Voice Coil March 2018 is available in print and download for all registered subscribers. If you already subscribe, go to - www.gotomyvcoil.com - to download this issue. 
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