Voice Coil February 2018 is now ready for download. This month Voice Coil discusses new developments from HEAD acoustics and PRV Audio in Industry News and Developments, and Mike Klasco (Menlo Scientific) follows with an update of our annual Loudspeaker Cone Industry Suppliers Directory for 2018. For 2018, the scope of this year’s cone industry directory has been expanded to incorporate relevant materials suppliers and component vendors such as specialized surrounds, spiders (dampers), and cone additives.And for our readers who never miss James Croft’s column on Acoustical Patents, this edition of Voice Coil offers a very interesting analysis of David Gunness’ patent submission of a new Passive Cardioid Speaker design, still waiting patent prosecution. Renowned audio speaker design, David W. Gunness, now with Fulcrum Acoustic, LLC, and previously with Electro-Voice and Eastern Acoustic Works, is no stranger to this field of research where he holds numerous patents.
So, when our acoustic patent specialist learned about the publication of this new patent, he was naturally interested in providing a review of the submission, to understand what makes the “improved acoustical circuit,” which “allows improved efficiency, as well as greater flexibility with regard to the size, maximum output, and effective frequency range of the loudspeaker, as compared to prior art,” as the patent abstract claims. This is a fascinating read, especially given that Fulcrum has already proven the validity of the proposed designs in actual products. It seems clear that Gunness achieved “a very good design that should advance the art in the category of cardioid devices,” as Croft notes.
For this month’s Test Bench, Vance Dickason characterizes a new Precision Devices 1.4” Titanium Diaphragm Compression Driver, the PD.CD2N and Wavecor’s new 10” PA woofer, the WF259PA01.
The new driver from prestigious UK Pro Sound OEM manufacturer, Precision Devices, is part of a seven model lineup of high-performance neodymium compression drivers. Six of the models, including the PD.CD2N feature titanium diaphragms (one uses Peek diaphragm material), as well as utilizing a three-slot optimized phase plug design. The PD.CD2N has a 50.8 mm (2”) throat diameter, with a radial neodymium magnet motor structure, an aluminum three-slot phase plug, and nominal 105 W (AES) rated power handling.
Next, we have Wavecor’s new 10” PA woofer, WF259PA01. This is an interesting driver since, until now, Wavecor has been known mainly for its high-end home hi-fi drivers. However, the company has decided to expand its coverage in the loudspeaker market and has introduced a well-designed 10” OEM pro sound PA woofer. The WF259PA01 is for now available only as an 8 Ω model, and has a generous feature set that includes a proprietary four double-spoke cast aluminum frame with parallelogram-shaped vents, uses a very stiff flat black coated curvilinear paper cone, and an innovative low-loss surround, driven by a 76 mm diameter (3”) voice coil wound with round wire on a vented black fiber glass non-conducting former. The motor structure powering the cone assembly utilizes a single 25 mm thick, 190 mm diameter ferrite magnet sandwiched between a black plated 8 mm thick front plate and a black-plated and shaped T-yoke that has 30 mm diameter a pole vent that is flared at both ends to suppress vent noise. As part of Wavecor’s Balanced Drive motor format, the WF259PA01 further incorporates an aluminum shorting ring that reduces distortion. Read the full review now.
This edition is complemented with the usual dose of “Industry Watch” stories and can be downloaded now. Voice Coil February 2018 is available in print and download for all registered subscribers. If you already subscribe, go to - www.gotomyvcoil.com - to download this issue. Remember, Voice Coil is free for industry professionals. To qualify for a free subscription to Voice Coil, or renew your subscription, go to: audioxpress.com/page/Voice-Coil-Subscriber-Services.html
