All items in category Magazine Articles
Patent Review: Knurled Speaker Diaphragm
by James Croft

Patent Review: Knurled Speaker Diaphragm

This patent, granted to MrSpeakers, the company from San Diego, CA that is now Dan Clark Audio, was granted in the same month that this review was published in Voice Coil. The patent details a headphone driver that should also be of note for the speaker industry. As Croft notes, the patent office initially rejected the claims due to prior patents, eventually accepting the inventor's arguments, in 2016. The review provides the historical context for planar magnetic transducers, and explains why this is an important patent.
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Book Review: Learning Audio Testing and Measurements
by Jan Didden

Book Review: Learning Audio Testing and Measurements

For those who need to refresh their knowledge or learn about audio test and measurements, Jan Didden reviews a great - and big! - book on the topic. Audio Tests & Measurements by Igor S. Popovitch is one of the many self-published works by this proficient writer based in Australia, also the author of several popular books on vacuum tube amplifiers. This particular book runs about 180 pages, but that is deceiving as the book’s format (A4 size) is about twice the size of most soft cover books.
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Patent Review: An Advanced Loudspeaker System
by James Croft

Patent Review: An Advanced Loudspeaker System

This article examines a notable patent from VUE Audiotechnik, describing a loudspeaker system with one driver providing a direct radiating output from the front, and a second driver on a ported side chamber, sharing a ported common chamber, where at least one port of the ported common chamber exits the front of the loudspeaker system. As Croft notes, this is an innovative advanced system - that was patent-pending at the time - and provides a unique combination of technology, offering real-world advantages. The patent was granted in 2021.
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Fresh From the Bench: The Hypex NCORE NCx500 Amplifier Module - Doubling Down on a Flagship
by Stuart Yaniger

Fresh From the Bench: The Hypex NCORE NCx500 Amplifier Module - Doubling Down on a Flagship

The new NCx500 amplifier board from Dutch manufacturer Hypex Electronics is the first of a new NCOREx family of modules that evolves from the extremely popular NCORE Class-D amplifier technology, one of the most successful options among high-end audio and studio monitor brands. Stuart Yaniger was able to spend a few weeks with this next flagship for OEM applications. How will this improved NCOREx technology measure up? And will it deliver the "x" times improvements over the proven NCORE? Stuart shares all the juicy details.
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Book Review: Burkhard Vogel’s Slopes and Levels. Spice Models to Simulate Vintage Op-Amp Noise
by Marcel van de Gevel

Book Review: Burkhard Vogel’s Slopes and Levels. Spice Models to Simulate Vintage Op-Amp Noise

Interested in accurately simulating the noise of op-amp circuits? Audio electronics expert Burkhard Vogel wrote a book that addresses this relevant topic for any audio circuit designer that doesn't want to rely just on manufacturers own models. In this review, Marcel van de Gevel explored the full book after he read Vogel's introduction, explaining that some manufacturer-supplied simulation models are way off.
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Voice Coil Focus: A Fresh Take on Green Audio 2023
by Mike Klasco

Voice Coil Focus: A Fresh Take on Green Audio 2023

Good intentions for sustainability, circularity, or simply reducing your carbon foot-print in the development or manufacturing stages not always produces the intended results. Mike Klasco reminds us how things are not always as simple as we would like, and that having good intentions and throwing empty claims might work on paper, but not actually work in the real world.
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R&D Stories: Developing an Electrostatic Transducer
by Comsol Multiphysics

R&D Stories: Developing an Electrostatic Transducer

This article discusses how Warwick Audio Technologies designed a completely new type of transducer for high-end electrostatic headphones using the latest materials, validated with computer simulation tools from Comsol. The design process for the High-Precision Electrostatic Laminate (HPEL) transducer was first available in the outstanding Sonoma Model One, the world’s first headphones to use HPEL audio transducers, and all subsequent Warwick products, now expanding also to automotive applications. This article was originally published in audioXpress, April 2018.
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Patent Review: Acoustic Resistive Elements for Ported Transducer Enclosure
by James Croft

Patent Review: Acoustic Resistive Elements for Ported Transducer Enclosure

This review highlights a patent granted to Bose Corp, part of an interesting series of bass reflex and tuned pipe enclosure architectures explored by Bose, which James Croft reviews and explains in detail. The patent describes a single chamber, single tuned, bass reflex enclosure system, using a more advanced, single Helmholtz tuned bass reflex design, with a port that is folded and extended. A great patent review with lots of informative details. This article was originally published in Voice Coil, October 2017.
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Patent Review: Simply A Speaker by Harman
by James Croft

Patent Review: Simply A Speaker by Harman

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!
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Patent Review: Bass-Reflex Speaker Cabinet Having a Recessed Port
by James Croft

Patent Review: Bass-Reflex Speaker Cabinet Having a Recessed Port

This patent awarded to inventor Matthias Larrieu, on behalf of French company NEXO (owned by Yamaha Corp.) was the topic of this detailed review by James Croft. From the abstract it might be difficult to visualize what exactly differentiates the patented design from a standard bass reflex system. Basically, Larrieu created two V-shaped slices at the opening either centered or with one at each side of the port, helping to reduce amplitude and phase anomalies in the midrange due to port resonances, while improving mid-band directivity.
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