Expand Your Horizons in Speakers with Voice Coil September 2020

This is certainly a very heterogeneous edition of Voice Coil. Delivering on its promise to be the Periodical for the Loudspeaker Industry, Voice Coil's September 2020 edition features a special report about manufacturing in Vietnam, complete with a directory and a list of trade shows. Igor Levitsky returns to offer valuable details about the latest Radian Audio Engineering LT2/LT6 Ribbon Planar transducers. James Croft reviews a "Venting System for Vehicle Speaker Assembly patent," recently granted to Harman. And, Vance Dickason characterizes the ND45 1" compression driver from Oberton, and the TW29TXN-B-4 TeXtreme diaphragm tweeter from SB Acoustics' Satori line. Voice Coil September 2020 is now available online and in print.

In "Audio in Vietnam: An Introduction to a Brave New World" by Mike Klasco and Nora Wong (Menlo Scientific), Voice Coil readers will gain a valuable perspective about one of the most promising manufacturing opportunities in the near term. As Klasco describes, "While there has been speaker parts manufacturing and speaker assembly for more than 20 years in Vietnam, in the last year there has been an influx of speaker and audio OEM/ODMs that are expanding satellite factories through the country." And this is particularly true for companies looking to counter the trading tariffs imposed in the United States even if, as Klasco also details, "most welcome Chinese transplants in Vietnam and elsewhere, just without the tariffs." This is a very timely report and a must-read under the current circumstances.

As a valuable follow-up, Nora Wong also compiled an updated directory of Vietnamese Audio Industry Vendors, followed by a guide of the audio industry trade shows existing in the region. Everything any loudspeaker company will need to know before scheduling a visit to the region once it again becomes possible. Vietnam has managed to keep COVID-19 under control after closing its borders in March 2020. Less than 1,000 cases have been reported through August 2020, which has allowed local factories and logistics to remain fully in operation.

In a follow-up Spotlight article about Thin-Film High-Frequency Transducers, Igor Levitsky returns to Voice Coil to explain the development and design aspects of the Radian Audio LT2/LT6 Ribbon Planar transducers. "In the heart of Radian planar ribbon technology lays a symmetric push-pull, FEA-optimized magnetic structure based on very high MGO energy neodymium magnets with very even magnetic flux distribution. A lot of care has been applied to metal parts design to minimize stray flux, maximize efficiency, and reduce and even eliminate distortion related to magnetic structure," Levitsky details.

For this month's Acoustic Patents article, James Croft (Croft Acoustical) writes about a "Venting System for Vehicle Speaker Assembly," recently granted to Brandon Wheeler and Christopher Ludwig on behalf of Harman International Industries. In the abstract, the patent details a venting system for a vehicle speaker assembly that includes an internal enclosure, having a vent and a port, allowing for an output generated by the vehicle speaker assembly to be transmitted from the internal enclosure to the exterior of the vehicle. James Croft compares this recent patent with others reviewed in his column and existing prior art, which apparently were not considered or known by either the inventors and the reviewers who decided to grant it. But as Croft also comments, the new Harman patent also shows the potential for performance gains comparable to previous approaches. Clearly, a direct sign of the intense level of activity currently in automotive audio.

For this month's Voice Coil Test Bench, Dickason worked with two cutting-edge products, one with applications in pro audio and another clearly targeting high end home audio.

The first is the ND45 compression driver from Oberton, which has been in development for some time. Oberton is recognized internationally for its innovative work in high-frequency drivers, offering a strong combination of multiple diaphragm materials, which include composite formulas perfected in its own research. Oberton is probably more vertically integrated than a lot of pro sound OEMs, producing all the important parts (e.g., voice coils, diaphragms, and metal parts) for all low-frequency loudspeakers and high-frequency drivers in its own factory, with 100% quality control. The Oberton ND45 1” compression driver submitted was sent along with the H-960 1" throat PBT-PET 90x 60º constant directivity horn. The ND45 has a 44 mm (1.75”) diameter two-layer voice coil wound with aluminum wire wound onto a Kapton former driving a polyester sandwich diaphragm and vented surround, with the entire assembly being field replaceable.

The second driver characterized in Test Bench is a home audio TeXtreme diaphragm tweeter from SB Acoustics' Satori line, the TW29TXN-B-4. What makes this tweeter so special is that it has a new TeXtreme diaphragm, the same material used in the latest Eminence N314X, characterized in the May 2020 issue of Voice Coil, which was the first compression driver commercially available in the industry to use a TeXtreme diaphragm. SB Acoustics has been experimenting with the new-generation material in different designs (including the upcoming Satori MW16TX-4 woofer with a TeXtreme cone) and, likewise, the Satori TW29TXN is the first home audio tweeter that uses a TeXtreme diaphragm.

TeXtreme thin-ply carbon is a novel type of material that is used in applications that require a high degree of stiffness performance in combination with ultra-light weight (read Mike Klasco's detailed article here).

Features for the Satori TW29TXN include a 29 mm TeXtreme diaphragm with a 8 mm wide surround, an non-reflective cast aluminum rear cavity, a two part aluminum faceplate with integrated mechanical decoupling, dual balanced compression chambers, high saturation neodymium ring type motor magnet with a T-shaped pole and dual copper shorting rings (Faraday shields), copper-clad aluminum wire (CCAW) voice coil, foam mounting gasket, silver tinsel leads, and gold-plated terminals.

In Industry Watch, Voice Coil discusses the new Klippel software update for dB-Lab 210 & QC 6.6 software, and the 50th anniversary of Scan-Speak. Congratulations!

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

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