All items written by James Croft

Patent Review: Head-Related Transfer Function Equalization and Transducer Aiming of Stereo Dimensional Array (SDA) Loudspeakers

June 26, 2024 by James Croft

Patent Review: Head-Related Transfer Function Equalization and Transducer Aiming of Stereo Dimensional Array (SDA) Loudspeakers

This patent, awarded to Polk Audio, describes a very specific loudspeaker design that claims to be able to achieve better stereo sound reproduction with “a realistic ambient field and a larger, and more stable acoustic image.” This obviously aims at achieving something that Polk Audio actually patented nearly 40 years ago, with its original Stereo Dimensional Array (SDA) loudspeaker, and for which the new updated patent now provides a new improved version. This article was originally published in Voice Coil, February 2019.

Patent Review: Multi-Layer Voice Coil Plate and Flat-Type Speaker Comprising the Same

June 19, 2024 by James Croft

Patent Review: Multi-Layer Voice Coil Plate and Flat-Type Speaker Comprising the Same

In this patent review, James Croft (Croft Acoustical) looks closely at a new patent of a multilayer voice coil plate and a flat speaker including the same type of multilayer voice coil plate, granted to three inventors from South Korea, on behalf of ICUBES Co., Ltd., Gyeongi-do, Korea. Detailing multiple configurations of this interesting concept, this patent offers an interesting take on the quest for the realization of a high-performance, one way, full-range electrodynamic transducer.

Patent Review: Acoustic Passive Radiator Rocking Mode Reducing

June 12, 2024 by James Croft

Patent Review: Acoustic Passive Radiator Rocking Mode Reducing

With the increasing popularity of miniaturized systems, the application of the passive diaphragm radiator, as the acoustic mass component in a bass reflex enclosure, is becoming standard practice in the low-frequency portion of the system. And these systems have a few parameter demands that can exceed the capability of many conventional approaches to passive radiator design. In order to solve those challenges, including rocking modes, Bose proposed an effective design.

Patent Review: Acoustic Filter for Omnidirectional Loudspeaker

June 5, 2024 by James Croft

Patent Review: Acoustic Filter for Omnidirectional Loudspeaker

This is an interesting patent awarded to Lakshmikanth Tipparaju, Allan Devantier, William Decanio, and Andri Bezzola, on behalf of Samsung Electronics - effectively the audio research team that Samsung created in Valencia, CA. The industry has attempted to achieve a successful implementation of acoustic radiation closely coupled to a boundary surface for omnidirectional and subwoofer applications - unfortunately, mostly plagued by resonances generated by the waveguide or reflector surface. This new approach appears to be an effective solution.

Voice Coil Patent Review: Controlled Passive Radiator

March 27, 2024 by James Croft

Voice Coil Patent Review: Controlled Passive Radiator

James Croft has fun reviewing a Controlled Passive Radiator patent awarded to inventor Tony Doy, on behalf of Sonos (Santa Barbara, CA.) The patent details multiple techniques to control a passive radiator, including a device buffering successive samples of audio content and predictive techniques on active designs. With this extensive review, Voice Coil readers will gain a valuable perspective on key possible innovation areas. This article was originally published in Voice Coil, October 2018.

Patent Review: Dual Coil Electrodynamic Transducer with Channels for Voice Coil Cooling

March 20, 2024 by James Croft

Patent Review: Dual Coil Electrodynamic Transducer with Channels for Voice Coil Cooling

James Croft reviews a published design submitted on behalf of Harman International Industries on January 2017. The design details an important approach to solving the everlasting problems of heat generation that limits the power handling capacity and the distortion-free acoustic output capability of loudspeakers, as well as their efficiency as electroacoustical transducers. This article was originally published in Voice Coil, September 2018.

Patent Review: Air Motion Transformer Passive Radiator for Loudspeaker

January 10, 2024 by James Croft

Patent Review: Air Motion Transformer Passive Radiator for Loudspeaker

In the August 2018 issue of Voice Coil, James Croft combined the review of two important independent patents, having in common the fact that they try to address the shortcomings of the work of Dr. Oskar Heil with his Air Motion Transformer (AMT) woofer system. Following a review of a Tymphany patent, Croft reviewed a related patent for an Air Motion Transformer Passive Radiator, invented by and awarded to Eugene Julius Christensen (Aspen, CO).

Patent Review: Acoustic Transducer Comprising a Plurality of Coaxially Arranged Diaphragms

January 3, 2024 by James Croft

Patent Review: Acoustic Transducer Comprising a Plurality of Coaxially Arranged Diaphragms

This is a review of a design patent, submitted on behalf of Tymphany, trying to address the shortcomings of the work of Dr. Oskar Heil with his Air Motion Transformer (AMT) woofer system. The patent describes an acoustic transducer comprising one or more electromagnetic motors that drive one or more sets of multiple diaphragms to provide acoustically efficient loudspeaker systems in compact dimensions.

Patent Review: Self-Bias Emitter Circuit

November 1, 2023 by James Croft

Patent Review: Self-Bias Emitter Circuit

This article reviews an intriguing new patent awarded to Turtle Beach Corp. addressing a new emitter circuit for providing a bias voltage, which is key for the development of electrostatic loudspeakers. Extremely aware of the techniques and historical perspective of the development in this area, Croft provides a complete overview of all the challenges, implications and merits of this patent and prior art. This article was originally published in Voice Coil, July 2018.

Patent Review: Smart Bass Reflex Loudspeaker

October 25, 2023 by James Croft

Patent Review: Smart Bass Reflex Loudspeaker

James Croft (Croft Acoustical) reviews a very curious patent from Amazon Technologies, Inc. (Reno, NV), filed in 2013, and awarded in April 2017. Basically, the patent discusses a new technique to tune a port of a loudspeaker, in this case multiple ports that will be open or selectively closed, in function of an analysis of the frequencies of the signal being played. This article was originally published in Voice Coil, June 2018.

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