Voice Coil January 2021 Is Now Available in Print and Digital!

This edition of Voice Coil dives deep into Headphone OEM Devices and Parts, with a special overview prepared by Mike Klasco and Nora Wong (Menlo Scientific, Ltd.), benefiting from their extensive industry experience in the segment. The headphone focus is highlighted by Mike Klasco for the resiliency that this product category is showing under adverse global conditions. While sound reinforcement, commercial sound, and other audio gear for public spaces is suffering from restrictions, headphones and earphones are on a roll, Klasco notes. "For some time, many speaker product developers have found themselves designing headphones. The headphone vendors are rarely the same vendors as those for speakers, but of course a few of the giant vendors do most of everything. Information on earphone and headphone sourcing components and materials - from selection options to specialized vendors... is more obscure."

And precisely focusing on earphone/headphone sourcing, this edition features an updated directory of key suppliers that either have a strong share of the business (usually for good reasons!) or up and coming alternatives that deserve their share of attention. That directory of OEM/ODM headphone and earphone factories, compiled by Nora Wong (Menlo Scientific) is complemented with another specific directory on Headphone And Earphone Parts, including Headbands, Ear Cushions, Ear Tips, Headphone Drivers, and Acoustic Resistance Wovens and Non-Woven Vendors.

And Mike Klasco also wrote another must-read Voice Coil Focus article on the topic of headphones. In "Headphone Engineering: A Helpful Cheat Sheet," he updates an article written in 2015, detailing a “10-point” cheat sheet. This introduction to headphone engineering needed some crucial updates, given how much the technology has evolved and how the design concepts and form factors have changed. "After taking a trip down memory lane, I dusted my notes off and decided to revisit what to consider for products in their design stage for 2021," Klasco writes.

This strong first 2021 edition also includes a Spotlight article on speaker design, written by Brian Cho, the CEO of Resonado Labs. The technology startup founded at the University of Notre Dame, Indiana, and now based in Chicago, IL, is now ready to bring to market its patented speaker technology. Describing "A New Standard of Low-Depth Racetrack Speaker Drivers with Flat Core Speaker Technology," Cho writes about Resonado's core Flat Core Speaker (FCS) technology. The company developed a reconfigured speaker with a planar voice coil mounted perpendicularly to its flat “race track” diaphragm, an ingenious architecture that enables slightly thinner, lighter, and more efficient speakers than conventional equivalents. Applications are wide-ranging from soundbars, home theater, column speakers, automotive to headphone drivers. "This enables manufacturers to produce not only sleeker and more compact products, but also enables them to introduce entirely new designs into the market," Cho writes.

On his first Acoustic Patents column in 2021, James Croft writes about the “Signal Processor for Loudspeaker Systems for Enhanced Perception of Lower Frequency Output.” Another patent he submitted as inventor, and which was granted in October 2018. As a speaker industry expert with a unique historical perspective of the technologies and design topologies involved, Croft is not only frequently requested to review patent submissions and advise companies on patent issues, but he is also an inventor. In this article, he details the reasoning behind this signal processing system, allowing users to control a lower frequency acoustic range of a loudspeaker system.

And Vance Dickason kicks off his Test Bench characterizations with two drivers focused on home audio. First up is the new Bold North Audio BWX-6502 Midbass, one of a series of exciting new drivers designed and manufactured in the US by MISCO (Minneapolis Speaker Company), the oldest OEM driver manufacturer in the US, founded in 1949. The Bold North lineup was recently expanded to include a new 29mm dome tweeter, a woven carbon fiber 4” bass/midrange, and two new 6.5” XBL2 motor woofers. In the December 2020 edition, Voice Coil featured the new BDT-2901 high-end tweeter, and the equally high-end BWX-6501 6.5” XBL2 woofer/midbass driver.

For this Test Bench, Dickason focused his set of measurements on the BWX-6502, which is built on the same platform with a similar XBL2 "dual-gap" motor design structure to the BWX-6501 but with a cone assembly consisting of an Abaca fiber (paper) cone and a 60mm (2.4") diameter Abaca fiber dust cap, with compliance provided by a wide high excursion NBR surround, and a 3.5" diameter flat cotton spider (damper). Driving the cone assembly is a 1.5" diameter voice coil wound with round copper-clad aluminum wire (CCAW) on a nonconducting Kapton former.

The next driver in Test Bench is the Wavecor TW022WA09 22mm high-end textile dome tweeter. The TW022WA09 was recently unveiled by Wavecor together with the new TW022WA08/10 high-end tweeter, a new series of 22mm chambered neodymium drivers with increased sensitivity. The precision cloth (textile) dome ensures an extended frequency response, while the voice coil design offers higher power handling and low resonance frequency. Features for the TW022WA09 tweeter include a neodymium magnet motor structure, copper foil-clad pole shorting ring (Faraday shield) vented to a damped rear chamber, a compact injection-molded 70mm (2.6") diameter faceplate and rear cavity, a 4Ω 22mm diameter voice coil with a vented aluminum former wound with copper-clad aluminum wire (CCAW) wire, built-in cavities beneath the dome surround, a foam mounting gasket, and gold-plated terminals.

Finally, in Industry Watch, Dickason highlights the 25th anniversary of Listen, Inc., which was signaled in 2020 but could not be celebrated as it deserved. During the past year, the company founded by Steve Temme has continued to thrive, and is better prepared than ever to continue its successful path. During 2020, its engineering team focused on updating the SoundCheck software, and reinforcing the range of educational and technical support materials. As Temme writes, "I am immensely proud of what my company and employees (both past and present) have built over the years, and feel honored to be able to refer to so many leading names in the audio industry, both companies and individuals, as my friends, colleagues, and customers."

The January 2021 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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