All items in category Magazine Articles
Measuring Loudspeaker SPL Response and Harmonic Distortion at Low Frequencies
by Reinhold Lutz

Measuring Loudspeaker SPL Response and Harmonic Distortion at Low Frequencies

This article discusses how to measure loudspeaker SPL response and harmonic distortion at low frequencies in a standard environment, full of reflections from acoustically hard boundaries (e.g., walls, floor, and ceiling), room resonances, and even ambient noise reducing the dynamic range and accuracy of the measurements. The method combines near-field measurements with two identical microphones. This article was originally published in audioXpress, October 2023.
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Patent Review: Self-Bias Emitter Circuit
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.
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Patent Review: Smart Bass Reflex Loudspeaker
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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Simulation Techniques: Loudspeaker Driver Displacement Decomposition
by René Christensen

Simulation Techniques: Loudspeaker Driver Displacement Decomposition

This article by René Christensen (BSEE, MSc, PhD), offers a valuable tutorial that discusses the unique possibilities of three-dimensional analysis of loudspeaker driver displacement, using Phase Decomposition and Axial-Symmetrical Decomposition techniques. The article demonstrates how a total displacement on a cone surface can be decomposed into different components directly in COMSOL Multiphysics, and how this can reveal some of the underlying mechanisms of the driver.
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Voice Coil Patent Review: Two Key Resonado Patents
by James Croft

Voice Coil Patent Review: Two Key Resonado Patents

James Croft looks at two patents from Resonado Labs, the young speaker company that has been pursuing a new speaker topology — originally called Flat Core Speaker (FCS), and now rebranded as Res-Core — using a reconfigured speaker with a planar voice coil mounted perpendicularly to its flat diaphragm. This review covers two of the company's patents granted in 2022, titled "Speaker Comprising Split Gap Plate Structure," and "Flat Speaker Driven by a Single Permanent Magnet and One or More Voice Coils.".
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Simulation Techniques: Dinaburg C2S Concentric Coplanar Stabilizer Analysis
by Roger Shively

Simulation Techniques: Dinaburg C2S Concentric Coplanar Stabilizer Analysis

Dinaburg Technology developed a unique patented integral coaxial speaker cone approach that features the advantages of a passive radiator in a small volume and takes advantage of a back wave from the loudspeaker’s diaphragm to optimize the passive radiator’s response and the off-axis performance of the active driver. The advantages are clearly audible, and this article dives into the mathematical simulation, and integrating the mechanical, acoustical, and electrical simulations.
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Voice Coil Patent Review: Bidirectional Speaker Using Bar Magnets
by James Croft

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
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Fresh From the Bench: Knowles KN2 True Wireless Reference Design and Franklin 2 Developer Kit
by Brent Butterworth

Fresh From the Bench: Knowles KN2 True Wireless Reference Design and Franklin 2 Developer Kit

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.
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Immersive Audio Explored - Really, What Is Immersive Audio?
by MC Patel

Immersive Audio Explored - Really, What Is Immersive Audio?

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.
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Simulation Techniques: SonicEdge Ultrasound Speaker - Modeling and Application
by René Christensen

Simulation Techniques: SonicEdge Ultrasound Speaker - Modeling and Application

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.
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