Patent Review: Inverse Horn Loudspeakers

This article reviews a patent originally granted to inventors Philip R. Clements; (Tempe, AZ), Boaz Shalev; (Needham, MA), and James Joseph Croft, III; (Bellevue, WA), which has now expired. The patent describes a low-frequency transducer system with a multi-compression chamber, where an inverse horn structure is employed in combination with a resonance-distortion filter chamber. This was the third patent granted on Atlantic Technology’s low frequency system known by the trademark name H-PAS (High Pressure Acceleration System). This article was originally published in Voice Coil, September 2016.

Exploring some pressing topics in headphone technology, in this article Hans W. Gierlich addresses the requirements for effective performance testing of communication headsets that use active noise cancellation (ANC) technologies, test setups, testing equipment, and setup conditions needed to correctly assess ANC performance. From the right choice of artificial ears and the latest ITU-T recommendations in that domain, to ANC performance measurements and talk-though performance. This article was originally published in audioXpress, June 2022.

This important article revisits the evolution of Rub & Buzz measurements in loudspeakers, headphone drivers, and microspeakers production lines, and how these are being addressed using the next-generation of perceptual algorithms. Steve Temme offers a valuable comparison with what can be accessed today using modern methods, and what to apply to access production faults, determine thresholds for production yields, or understand the real impact on consumer's perception. This article was originally published in audioXpress, April 2022.

This review looks at an independently patent submitted in 2013 and awarded in 2016 to Jack Nilsson (Canton, OH), describing a system and method for an audio system including a first speaker that reproduces sounds in a first frequency range and a second speaker that reproduces sounds in second frequency range. As James Croft comments, the patent is interesting in its purposeful application of breaking currently established rules and may be useful in certain applications or environments. This article was originally published in Voice Coil, August 2016.

In this review of the GaN Systems amplifier evaluation kit, Stuart Yaniger shares his explorations of the features and benefits of GaN (gallium nitride) power semiconductors, and explains why the technology is not only enabling great sounding audio amplifiers but is also bound to completely disrupt the Class-D segment in high power ratings. This article was originally published in audioXpress, April 2022.

This article reviews a patent application submitted in 2010 by to two inventors, on behalf of Jazz Hipster Corp. (Taiwan), regarding an improved structure of a speaker using the surround to reduce the resistance of the diaphragm excursion, which helps to generate a more linear diaphragm movement, with less resistance, and reduced distortion. As James Croft noted, the approach had been used in the past, but its use decreased due to the high-performance achieved with well-designed roll-surrounds, at a lower cost. No surprisingly this patent was subsequently abandoned.

This article addresses the practical approach to testing and evaluation of multichannel MEMS microphone arrays. The simultaneous acquisition and measurement of signals from a microphone array presents a variety of challenges to developers seeking to evaluate their designs. This article explains the fundamentals to address challenges in smartphones, smart speakers, and all sorts of voice-activated devices, typically using two, and up to seven or more microphones. This article was originally published in audioXpress, March 2022.

An overview of Loudsoft's latest FINE Suspension Nonlinear FEA Spider and Surround Design software. This new transducer engineering tool, specific to the development of speaker surrounds and spiders (dampers), allows for the simulation of different types of surrounds and spiders from imported DFX files or created from templates with parameters selected by the user, and then outputs the compliance curves similar to the Kms and Cms curves measured by Klippel DA2 or KA3 analyzers.

This review discusses an intriguing speaker design patented by Walter Ka Wai Chu, from Taiwan. The design allows the speaker device to potentially improve the bass performance in the entire low-frequency band instead of being limited to only a few low-frequency points, the inventor claims. While James Croft confesses to being somewhat skeptical of whether, in its current disclosed form, the device will provide a useful advantage, he found the design sufficiently interesting to be analyzed in more detail.

Following the review of the KEF LS50 Meta speakers for audioXpress, this article offers a detailed review of the KC62 compact subwoofer, which combines KEF's force-canceling and Uni-Core technologies in a new approach to allow maximizing bass in a minimum space. Masciarotte did the listening and spoke with Jack Sharkey, Senior Technical Engineer at GP Acoustics, about this fascinating design. The subwoofer was also measured by Peterson at Warkwyn’s facility using the Klippel measurement system.