In the first Voice Coil issue of 2022, loudspeaker industry professionals will find a valuable treasure trove of valuable content and resources. Starting with an article about a topic that is top of mind for all loudspeaker manufacturers at the moment, again facing the perspective of rising costs for neodymium and the alternative of using ferrite magnets instead. Mike Klasco and Salvador Magdaleno-Adame discuss in the detail the most promising Next-Generation Rare-Earth-Free Magnets and specifically the benefits of using Iron Nitride (FeN) as it will soon be available from Niron Magnetics.For this edition, Nora Wong (Menlo Scientific) compiled an updated directory of Earphone and Headphone Manufacturers, starting with an updated list of many of the leading OEM/ODM headphone and earphone factories, and a complementary directory of headphone parts vendors. In this detailed overview of parts, Voice Coil readers will be able to identify recognized Acoustic Resistance Wovens and Non-Woven vendors and sources for Diaphragms, Drivers, Headbands, Ear Cushions, and Ear Tips.
And a dedicated directory related to the topic of earphones and headphones details the specific suppliers for Microelectromechanical Systems (MEMS) and other unique earphone drivers. In this industry overview, Mike Klasco and Nora Wong detail vendors for MEMS transducers, as well as application-specific integrated circuits (ASIC) and specialized solutions for application-specific designs.
And since this edition focuses on the headphone and earphone supply chain, David Lindberg (dB Enterprises) contributed an article for Voice Coil discussing Liquid Injection Molding Silicon for Next-Generation Headphone Surrounds. His article details VM Sound’s proprietary approach using injected Liquid Silicone Rubber (LSR) with optical-grade precision to form the surround in 3D and bond the diaphragm to the frame in a single step. A solution that delivers a superior production yield, reduces the bill of materials by more than 20%, and delivers a level of consistency that allows reducing labor costs on the required tuning process for active noise cancellation (ANC) devices, currently in very high demand and bound to become a standard feature in consumer headphones.
In this month's Acoustic Patents column, James Croft reviews a phase independent surround speaker, a patent granted in 2016 to David S. Wilkes, Jr, on behalf of Klipsch. The interesting design discloses a speaker using four drivers with a high-pass filter connected with the first and third drivers, which are wired out of phase by 180 degrees. The second and fourth drivers receive the output of a low pass filter and a lattice filter with signals shifted in phase by -90 degrees and -45 degrees, respectively. These drivers are configured in the surround speaker in a dipole/bipole type configuration, which early designs and research has proven to be the most effective for perception of surround sound. This is an area of research where James Croft was involved directly, allowing him to provide a unique perspective on the merits of this specific Klipsch patent and potential improvements to the concept.
And of course, this edition of Voice Coil offers a generous dose of Test Bench characterizations by Vance Dickason, starting with the Satori MW13TX-4, the latest 5" TPCD cone midbass driver from SB Acoustics. TPCD is the acronym for Thin-Ply Carbon Diaphragm, which is essentially the technology developed in Sweden by Oxeon to create a new-generation material with properties that are now well-proven for speaker cones and domes. This technology is marketed under the brand TeXtreme, which is now recognized in the loudspeaker industry, and its success led Oxeon to spin off its business and create a dedicated company, which is now Composite Sound.
The Satori MW13TX-4 TPCD cone 5” woofer is the fourth TPCD diaphragm transducer to be explicated in Test Bench. The first, being an Eminence compression driver, and the following two speakers in the prestigious Satori family from SB Acoustics. The MW13TX-4 has a substantial feature set that begins with a proprietary six-spoke cast aluminum frame, comprised of narrow spokes, completely open below the spider mounting shelf for cooling an inverted, single piece bowl-shaped TPCD cone and NBR surround. The FEA-optimized neodymium magnet is coupled with a 1.2" voice coil wound with round copper clad aluminum wire (CCAW) on a non-conducting fiberglass former.
Next in Test Bench, Vance Dickason explored the latest WF275BD01 10.75” woofer from Wavecor, a new high-power design targeting home audio and home theater applications, including two-way (with larger ribbon/AMT drivers, or compression driver/horn combinations) and three-way speakers. This woofer, which could also be advantageous in high-powered studio monitors, is part of a new series of products announced in October 2020 by Wavecor. The feature set for the WF275BD01 is like most high-performance two-channel/home theater drivers, fairly substantial.
Starting with the frame, the WF275BD01 uses a proprietary eight-spoke cast-aluminum frame incorporating rectangular vent holes in the area below the spider mounting shelf for enhanced voice coil cooling. This series of cooling vents allows air to move past the voice coil and across the front side of the ferrite motor assembly. The cone assembly consists of a curvilinear proprietary paper/glass fiber mix cone along with a 2” diameter paper/glass fiber dust cap. Compliance is supplied by an NBR surround and a rather large flat profile 6” diameter black Conex spider (damper). Details of the motor design include the normal feature set included in all of Wavecor’s Balance Drive motor, which includes a shaped, extended pole piece and copper cap-type shorting ring. The ferrite magnet motor was FEA designed using a 1.5” diameter voice coil wound with round copper-clad aluminum wire (CCAW) on a non-conducting heavy black glass fiber former.
And finally, there's the traditional serving of Industry Watch stories of interest to loudspeaker industry professionals. This edition of Voice Coil is available for download and already in the mail to print subscribers. Subscribers can go to - www.gotomyvcoil.com - 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: audioxpress.com/page/Voice-Coil-Subscriber-Services.html
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