Here for You: Voice Coil May 2020 is Now Available

April 27 2020, 08:10

This month's edition of Voice Coil features an important article update regarding "The Speaker Industry Supply Chain," by Mike Klasco (Menlo Scientific, Ltd.). In last year’s May issue, with the tariff war still running hot, Voice Coil surveyed the landscape of the Asian speaker factories with a focus on the growing strength of China’s neighbors. Today, the pressure, challenges, and geographical competition in the supply chain is far more intense, and in this Voice Coil Focus feature, Klasco looks at some of the most important “Asian alternative” manufacturing options, with country by country strategic characterizations.

Next up, there's a fascinating Voice Coil Spotlight article: "Comparative Studies on the Behavior of Beryllium, Titanium, and CN Fiber Hybrid Dome in the Last Octave," by Oberton engineer Peyu Vlaevski. For some years, Oberton has been conducting efforts in the development of a new composite fiber diaphragm, combining a low relative weight and a high damping factor as in beryllium, with mechanical characteristics similar to titanium. The result lead the respected Bulgarian loudspeaker manufacturer to perfect a composite diaphragm material, combined with a suspension for the diaphragm periphery based on carbon fiber (CN fiber). This article details how this carbon composite dome - already implemented in Oberton's latest ND72CN and ND100 compression drivers, behaves compared with other 4" compression drivers that use beryllium and titanium diaphragms.

In Acoustic Patents, James Croft (Croft Acoustical) discusses one of his favorite topics - and certainly one of the most popular topics among loudspeaker engineers - a new electrostatic loudspeaker (ESL) design. The patent under review this month describes an "Electrostatic Loudspeaker Capable of Dispersing Sound Both Horizontally and Vertically," and was submitted by inventor Murray R. Harman (Ottawa, CA) on his own behalf - granted in May 2012. The abstract describes an ESL assembly providing curvature in two directions for improved dispersion of sound waves, where the two-axis curved structure enables a compact form of ESL to be realized, including bookshelf type loudspeakers. The individual curved ESL panels can also be readily combined to create larger transducer assemblies including omni-directional units. This patent is a great opportunity for James Croft to revisit the story of electrostatic loudspeakers and to compare the merits and possibilities for creating new products based on the technology.

For this month's Test Bench, Vance Dickason focuses on the latest innovations coming from Eminence, one of America's premier loudspeaker manufacturers in activity since 1966. And those innovations couldn't come in more extreme categories!

In the first Test Bench, Dickason characterizes a very high power handling 18" woofer from Eminence’s recently announced Tour Grade pro sound product line, the NSW4018-8. The Tour Grade family of speakers consists of two 18" options, including the ferrite magnet FSW4018-8, the neodymium magnet NSW4018-8, and the massive neodymium magnet 21” NSW6021-6, and was developed over the past two years to support the undisputed growth of professional audio.

Applications for the new Eminence NSW4018-8 include use as a bass driver in multiway systems, or as a dedicated subwoofer in bass reflex designs. The feature set for the NSW4018-8 is like most high-performance pro sound drivers, rather substantial. Starting with the frame, the series of cooling vents, or the impressive cone assembly that consists of a straight profile thick “X5” pulp paper ribbed cone along with a 5.75” diameter convex paper dust cap. The entire cone assembly (cone, surround, and spider) is water resistant. The Eminence NSW4018-8 motor is based on a FEA-designed neodymium magnet structure using a 102 mm (4”) diameter voice coil wound with round copper wire on a non-conducting fiberglass former. Factory-rated power handling for this driver is 1600 W AES, 3200 W program, and 6400 W peak power!

The second Eminence product to be characterized this month, the new N314X 1.4" compression driver is also something special, in that it is the first compression driver that uses TeXtreme composite for a diaphragm. TeXtreme thin-ply carbon is a novel type of material that is used in applications that require a high degree of stiffness performance in combination with ultralight weight. Designed for use with 1.4” throat horns, the N314X compression driver has a 35.6 mm (1.4”) throat diameter driven by a 3" diameter voice coil wound with round copper-clad aluminum wire (CCAW) on a non-conducting polyimide former driving the TeXtreme diaphragm and PEN surround. The N314X also incorporates a three-slot annular phase plug and an acoustically damped black die-cast aluminum cover with heatsink fins. Other features include a FEA-optimized neodymium magnet motor structure, a continuous power handling of 300 W with a 75 W (AES) power handling rating, a 800 Hz recommended crossover frequency (with a minimum 12 dB/octave high-pass network), and 1 W/1 m 110.5 dB sensitivity (average output across the operational frequency range).

And for this edition's Industry Watch, among many other highlights, Dickason references two important product launches for loudspeaker measurement: the Listen SoundCheck 18 software and Audiomatica's latest CLIO 12.5 and CLIO Pocket 2.1 updates.

The May 2020 edition of Voice Coil is available for download and already in the mail for print subscribers. Subscribers can go to - - to download this issue.

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