Voice Coil December 2014 available online

November 22 2014, 16:32
The December 2014 edition of Voice Coil is already available. Remember, a print and digital subscription is free for qualifying members in the US and the digital edition is available globally.

In this edition, Vance Dickason anticipates the excitement of the 2015 International Consumer Electronics Show (CES), to be held from January 6–9, 2015 in Las Vegas, NV. The show, now in its 47th year, first launched in June 1967 in New York, NY, with 200 exhibitors and 17,500 attendees. This year’s International CES will feature product debuts from more than 3,200 exhibitors, covering more than 30 product areas, including the latest in content, wireless, digital imaging, mobile electronics, home theater, and audio, including a continued focus on electric vehicles and in-vehicle technology.

This month Industry News & Developments also highlights the Association of Loudspeaker Manufacturing & Acoustics (ALMA) International Winter Symposium 2015, preceding the CES 2015 Show. The event, titled “Digitally Driven Loudspeakers. A New Paradigm Demands New Designs,” is scheduled for January 3–4, 2015, at the Tuscany Suites and Casino in Las Vegas, NV and will feature a Technical Track features with industry luminaries as Wolfgang Klippel, Sean Olive, Steve Temme, Christopher Struck, and many more!

This month Test Bench analysis discusses two very different woofers — the 18” Celestion CF1840JD pro sound subwoofer and Dayton Audio’s 7” ES180Ti-8 home audio woofer.
Designated as a woofer/subwoofer, the CF1840JD is a fairly high power-handling woofer rated at 1,000 WRMS (AES standard) and weighs a moderate 25.5 lb. The CF1840JD’s features include a proprietary seven-spoke cast-aluminum frame. However, Celestion’s approach on this model, as with the previous CF18VJD model (examined in Voice Coil, November 2013), does not include venting below the spider mounting shelf at the top of the front plate, which is a common feature built in to high power handling woofer frames. Instead, Celestion uses a series of eight 9-mm diameter peripheral vents located on the top of the back plate in conjunction with a 40-mm diameter pole vent.

The Dayton Audio 7” ES180TI-8 midwoofer is a new member of the Esoteric Series of drivers. Starting with the frame, Dayton Audio used a nicely configured sixspoke cast-aluminum frame with narrow 9-mm wide spokes to minimize reflections back into the cone. The area below the suspended spider mounting shelf is almost completely open, resulting in effective cooling of the motor and the voice coil. For the cone assembly, Dayton Audio chose a rather stiff flat profile woven glass fiber cone with a 2.75” diameter convex woven glass fiber dust cap. Compliance is provided by a nitrile butadiene rubber (NBR) surround, which is nicely designed with a shallow discontinuity where it attaches
to the cone edge. Remaining compliance comes from a 4.5” diameter elevated black cloth spider. The Dayton Audio ES180Ti’s motor design is well thought out and incorporates dual copper shorting rings (Faraday shields) and a neodymium ring magnet.

In Acoustic Patents, James Croft (Croft Acoustical) reviews two loudspeaker-related patents, filed by Dolby Lab Licensing Corp. (US) primarily under the Office of Patent and Trademarks classification 181 for acoustical devices and 381 for electrical-signal processing systems and HO4R for international patents. The first one is named “Reflected Sound Rendering for Object-Based Audio” (Publication Number: WO2014036085) and the second is called “Virtual Height Filter for Reflected Sound Rendering Using Upward Firing Drivers (Publication Number: WO2014107714).

James Croft also comments on its own Transducer With Improved Electro-Magnetic Circuit patent, which was granted September 18, 2014. The invention provides a planar-magnetic transducer with a frame and a primary magnet row structure of elongated magnets adjacent and air gapped from a first surface side of a mobile portion of a thin film or thin structure diaphragm with conductive traces incorporated with the diaphragm.
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