Voice Coil Patent Review: Bidirectional Speaker Using Bar Magnets

In this article James Croft reviews a patent claimed by Leeg Hyun Cho (Gyeonggi-do, Korea), Youngil Cho (Chicago, IL), and Christian Femrite (Westminster, CO) on behalf of Resonado. The patent in question will be familiar to many Voice Coil and audioXpress readers who have followed the news about this young company's developments. As an experienced patent reviewer and speaker technology expert, Croft adds valuable context to the awarded patent. This article was originally published in Voice Coil, July 2021

In the October 2023 issue of Voice Coil, James Croft reviews an active noise control enclosure system, and Mike Klasco and Nora Wong provide an updated directory of Integrated Electronics for Loudspeakers. Vance Dickason offers three different driver characterizations, starting with the AMT100H driver from Eighteen Sound. Next up, he tests an updated version of the popular TW030WA23/24 tweeter from Wavecor. And finally, measures the Scan-Speak D2008/2010, the revised version of the classic dome tweeter from the Danish brand.

Lenbrook Corp., the privately-owned Canadian audio company that owns NAD Electronics, PSB Speakers, Bluesound, Bluesound Professional, and BluOS, has acquired the assets of UK-based company MQA. The deal adds significant audio patents and codecs to Lenbrook’s IP portfolio, including MQA's high-resolution audio encoding and the latest SCL6 Scalable Codec for wireless audio applications, which is implemented in the upcoming line of PSB headphones and earbuds.

This article reviews two patents titled simply "Speaker Device" from four Japanese inventors, on behalf of Pioneer Corp. of Japan. The original and expanded patent describes a flat speaker device capable of emitting loud reproduced sound, using a mechanical structure that converts a linear voice coil motion in one axis to an orthogonal mechanical diaphragm displacement. The system functions much like a scissor-jack you would use to raise your automobile to change a tire. The linear motion of the threaded rod coverts the axial force to a 90° lift movement.

Voice Coil June 2023 features an extensive patent review in James Croft's Acoustic Patents column. The topic is a 2014 patent awarded to Nokia, offering an opportunity to revisit the history of electrostatic loudspeakers, with insights from Tim Mellow, one of the two listed inventors. In Test Bench, Vance Dickason focuses on the D8404-552000 Ellipticor cloth diaphragm dome midrange from Scan-Speak, and characterizes the SB Acoustics TW29BNWG beryllium dome and waveguide from the brand's prestigious Satori line.

This review looks at a speaker patent, awarded to inventor Shengbo Li from Guangdong, China, on behalf of Harman International. The abstract from that patent details a speaker including one or multiple transducers, an enclosure, and a suspension mounted on the enclosure, wherein the suspension and the enclosure are configured such that the enclosure is capable of vibrating as a result of operation of the transducer so as to produce audible sound. You read it right, the enclosure is also a passive radiator!

This article examines an important patent filed in 2014 by F. Bruce Thigpen (Tallahassee, FL) and granted in June 2016. Appearing both as the inventor and assignee, Thigpen describes a rotary sound transducer having an improved output at higher frequencies. Thigpen has been working on this type of device for more than a decade and has advanced what was already a very difficult engineering achievement, to a more sophisticated structure that apparently raises the general performance and high frequency limits beyond what was thought possible with this architecture. This article was originally published in Voice Coil, July 2017.

The April 2023 issue of Voice Coil reveals the genesis of Echo Test + Measurement and its AIO Test System. As scheduled, there's an updated industry directory of Cable and Connector vendors, James Croft reviews a key Polk Audio patent that expands on its Polk SDA loudspeaker prior art now in a more compact enclosure. And on Test Bench, Vance Dickason focus on the characterization of the innovative TW045WA01 dual-diaphragm tweeter from Wavecor.

AntennaWare Ltd, specialists in solving body-blocking problems normally associated with close-range RF designs, has been awarded a European Patent which is expected to have important implications for enabling implantable devices within the human body. The new multi-mode antenna from AntennaWare enables reliable and continuous communications even in next-generation medical applications or from sensors inside obstructed structures.

In this issue of Voice Coil, Mike Klasco shares his experience dealing with sustainability and other noble goals, an article that was greatly inspired by the effort to compile another updated Speaker Enclosure Vendor Directory for 2023. In Acoustic Patents, James Croft explains how Yamaha recently invented a clever way to use a Class-D amplifier to bend the infamous "Hofmann’s Iron Law." And Vance Dickason takes the new 10HX230 10" coaxial professional driver from Faital Pro to his Test Bench.