The March 2022 issue of Voice Coil opens with Industry News & Developments reporting on the latest generation Balanced Mode Radiator (BMR) driver designs from Tectonic Audio Labs. As it was announced at CES 2022, Tectonic has optimized the basic concepts of the BMR technology and created new advanced iterations that are more powerful, more compact, and more cost-effective. Those include the latest BMR High Aspect Ratio Panel (HARP) transducers, using the company's latest dual drive/single motor patented design, and the next-generation Tectonic BMR-k drivers.
This edition of Voice Coil focuses on speaker enclosures, and the topic is addressed in a new article by Mike Klasco (Menlo Scientific) discussing options for plastic enclosures. Addressing loudspeaker driver design in general, this article explores enclosure characteristics, construction features, advantage comparisons between wood and wood particle board cabinets, and production techniques. He also discusses the fact that tooling for injection molds for plastic parts can now be done directly from 3D modeling files on remote CNC machines, which can be anywhere in the world, making plastics an increasingly viable option. The article addresses various options to meet the challenges in different speaker designs, from conventional injection-molded plastics to composites, and the latest material formulations supporting sustainability and design to manufacturing options.
As Voice Coil tradition mandates, this issue also features an updated directory of Speaker Enclosure Vendors, meticulously compiled by Nora Wong (Menlo Scientific), including updated characterizations of many companies. As factories increasingly expand from making quality speaker enclosures directly to supplying complete loudspeaker system assembly, including the electronics, it's always good to know that highly specialized companies continue to offer cabinet manufacturing all over the world.
And this issue includes another Acoustic Patents article from the Archives of James Croft, selected by Vance Dickason. This is the second patent review to be revisited that examined rear cancellation passive cardioid loudspeaker design as a way of compensating for the "Allison Effect". In this case, a patent granted to Dutch & Dutch B.V. (Netherlands), and listing as inventors the names of Koenraad August Jan Knaapen, Eric Van Duin, Martijn Gerardus Mensink, Kevin Ivan Kleine, and George Ortega. An interesting read of a design submitted in 2014.
Vance Dickason also offers a generous Test Bench characterization of the U80W Air Motion Transformer from Mundorf's new high-end U Series. This is a timely opportunity to learn more about the Mundorf range of AMTs given that the German company is traditionally very mysterious and doesn't send out press releases when it introduces a new product. Traditionally a much respected manufacturer of high-quality condensers and crossover components, Mundorf is also capitalizing on the industry's “renaissance” in AMTs and now offers five models in this updated U series, each driver having the same width, but different heights.
The U80W AMT model features a 63mm x 19mm pleated proprietary AMT diaphragm, an optimized rear chamber, a flat face plate with an optional secondary aluminum face plate, and is rated for 80W power handling and 94dB sensitivity. The U Series is the fourth in Mundorf's AMT portfolio, which also includes Pro drivers (currently being updated), the HiFi AMT Dipole series, and the high-end audio AMT Concert series.
This issue of Voice Coil also includes a Test Bench on Eighteen Sound’s NSD1095N Compression Driver and XT120 Horn. This a very refined design from the company that now is part of the B&C Speakers group, but remains an independent operation. The NSD1095N is a 1" throat compression driver with a compact footprint for “high quality” sound applications in professional audio, from studio monitors or stage monitors to high-power sound reinforcement cabinets.
The Eighteen Sound NSD1095N compression driver is driven by an optimized neodymium ring magnet motor structure and 44mm (1.75”) diameter edge-wound voice coil wound with copper-clad aluminum wire (CCAW) on a non-conducting Nomex former with a proprietary treatment. This specially treated Nomex former shows a 30% higher value of tensile elongation at operating temperatures (200 C) when compared to Kapton. This assembly drives the field replaceable True Piston Motion (TPM) TiN coated titanium diaphragm, extending the frequency response by 25%. The NSD1095N also incorporates a proprietary phase plug architecture that has been designed to give a smooth coherent wave front at the horn entrance across the whole working frequency range.
Finally, this issue also includes a generous dose of Industry Watch stories, discussing some cutting-edge research regarding a new type of sound wave propagation, generated by Associate Professor of Physics Dr. Shubo Wang, of the City University of Hong Kong (CityU), and described in a paper recently submitted to the scientific journal Nature Communications. Also discussed by Vance Dickason is the latest Consumer Technology Association (CTA) market indicators and forecast, plus industry event updates.
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