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 this valuable review for product developers, Brent Butterworth shares what he learned about two evaluation solutions intended for designers of true wireless earbuds, the fastest growing product category in the audio industry. With this reference design and developer kit, Knowles made it easier for companies to add sophisticated true wireless earphones to their lines — whether they develop their own design or adopt one that’s ready to go. audioXpress tried out both options.

Any form of audio and entertainment content today is produced and distributed as files, which are then streamed to consumers. MC Patel, the founder and CEO of Emotion Systems, explores immersive audio from the deliverables standpoint. The article discusses the evolution of immersive audio and all the implications of dealing with its formats and unique requirements. The article was originally published in audioXpress, September 2023.

The SonicEdge transducer - a cutting-edge microspeaker based on a unique MEMS technology that generates sound using active ultrasound modulation - introduces a completely new class of devices that can deliver constant volume velocity across audio frequencies and beyond. The article details how to model the transducer in lumped-element and finite-element acoustic simulations and how to tailor a desired SPL response using acoustic features. As originally published in audioXpress, August 2023.

The Hypex Nilai500DIY 500W Mono Power Amplifier Kit is new DIY benchmark from the company's dedicated DIYClassD brand. The kit is specified to deliver 500W with 1% THD at 4 ohms, improves output noise and idle losses significantly, and comes with a discrete buffer stage and voltage regulators. The article, originally published in July 2023, offers an extensive review with measurements of the full kit, including the PS500 DIY power supply and DIYClassD preamplifier kit.

In this article, James Croft discusses a patent granted to Curtis Graber (Woodburn, IN) that describes a radial acoustic speaker assembly including a transducer and a plurality of segmented spiral horns acoustically coupled to the transducer, each with its acoustical path. This new patent by prolific audio inventor, Curtis Graber, uses a new multi-spiral waveguide structure driven by a single transducer and has clear advantages over prior art. This article was originally published in Voice Coil, May 2018.

This article discusses a patent originally claimed in 2013 on a Double Coil Speaker design, which was granted in 2017 to Friedrich Reining (Vienna, Austria), on behalf of Sound Solutions International. The abstract from the patent details an audio system comprising an electro-acoustic transducer having two stacked voice coils mechanically linked to a membrane. James Croft discusses multiple approaches in similar concepts, and notes that the current state of technology might finally create a way to explore it in commercial products. This article was originally published in Voice Coil, March 2018.

Linkplay Technology is recognized for its widely adopted wireless audio streaming modules, smart home, and connected AI products. The new WiiM Pro is a versatile music streamer that combines all the latest technologies and protocols, making it the ultimate (and most affordable) home audio hub available. audioxpress received a pre-launch unit to review subjectively and objectively. This article was originally published in audioXpress, July 2023.

Renowned audio speaker design, David W. Gunness, now with Fulcrum Acoustic, and previously with Electro-Voice and Eastern Acoustic Works, is no stranger to this field of research where he holds numerous patents.This review is a fascinating read, especially given that Fulcrum has already proven the validity of the proposed designs in actual products. It seems clear that Gunness achieved “a very good design that should advance the art in the category of cardioid devices,” as Croft notes.

audioXpress visited Grimm Audio in The Netherlands to learn more about the people behind this unique company, its products, and philosophy. There's nothing better to learn about product development than to visit an audio company and learn from its history and business journey. As a relatively young company, Grimm Audio has consistently put its mark on both the pro audio and hi-fi scene and Jan Didden shares what he learned about their unique in-house development philosophy. This article was originally published in audioXpress, July 2023.