Voice Coil December 2021 Helps You Tune Your Loudspeaker Responses

After briefly introducing F.MonteiroScience and its CrossLite + FIR/IIR software DSP filter simulator and analyzer in the Industry Watch section of Voice Coil’s October 2021 issue, in this edition, Vance Dickason highlights the possibilities for a "Two-Way DSP Filter Design" using this software package. Under development by the Brazilian pro audio company since 2009, CossLite+ is a dual-channel FFT analyzer that will function with basically any USB-type recording interface. CrossLite+ is intended primarily for product development of DSP-powered pro speakers and for use in live sound PA systems. And measured data can also be imported from other analyzer as Rational Acoustics Smaart, Audiomatica CLIO, Klippel KA3, and ARTALabs ARTA.

Voice Coil readers will also find an updated Measurement Microphone Directory, compiled by Nora Wong (Menlo Scientific), detailing the latest solutions from a variety of global vendors, with special attention to speaker measurement and emerging applications (e.g., noise cancellation and frequency response calibration). The directory not only details the traditional "microphone" manufacturers but also related testing instruments and complete solutions for audio test and measurement. From ACO Pacific and AV-Leader to Studio Six Digital and Zumi Systems, this extensive directory provides a valuable resource for loudspeaker designers.

In his Acoustic Patents column, James Croft reviews a "Loudspeaker Arrangement" patent, very recently awarded to Lars Goller (Struer, Denmark) as the inventor, and assigned to Harman Becker in Hungary. The abstract explains that this patent covers a loudspeaker arrangement that comprises an enclosure, with at least one speaker driver with two passive radiators, and "a connecting element connecting the first passive radiator to the second passive radiator." The intent is to allow "a symmetrical movement of the pair of passive radiators" by coupling the two membranes and effectively improve the low-frequency response in environments that are prone to vibrations, such as in automotive applications. The patent covers the ingenious "connecting element" with two rods connected to a counteracting plate, or a more advanced hydraulic coupler for the same effect.

As James Croft mentions in his review, the inventor, Lars Goller, is best known for his work in the field of high-frequency transducers and ring-radiators while at Vifa and Sinar Baja Electric (SB Acoustics), among other manufacturers. In this patent, Goller focuses on the bass response and shows an extensive research in automotive-specific applications.

Voice Coil December also includes two interesting driver characterizations by Vance Dickason. Basically two woofers, one more focused on home theater applications from Dayton Audio, and the other clearly oriented toward sound reinforcement applications, from B&C Speakers.

The first Test Bench explication focuses on the Dayton Audio Epique MMAG E150HE-44 "full-range subwoofer," in itself an interesting concept. Like its larger E180HE-44 brother in the Epique line, the E150HE-44 is based on the patented Multiple Magnet Air Gap (MMAG) technology invented by Enrique Stiles. The two new Dayton Audio Epique MMAG woofers were designed with direct support by Enrique as an independent transducer engineering consultant, working in conjunction with the engineering team at Dayton Audio. The "full-range subwoofer" concept is ideally suited to the MMAG technology given the typical high-excursion/low inductance aspect of this motor design.

The primary magnetic drive in the Dayton Audio EP150HE is provided by the 121mm×25mm ferrite rear ring magnet, directly providing flux to a second rear 7mm gap. However, the secondary magnet system is comprised of six 28mm×8mm ferrite disks. These magnets do not add flux to the upper 7mm gap, but rather act as magnetic “diodes” pulling the flux from the main magnet into the top 7mm gap. These disks also provide an 8mm space between the two 7mm gaps as well as a convention cooling path for the voice coil as it travels between the two gaps. The cone assembly consists of an extremely stiff curvilinear shaped carbon fiber cone and dust cap, with compliance provided by a 21mm wide NBR surround and a 4" diameter flat cloth spider. Driving the cone assembly is a 1.5" diameter dual voice coil (two 4Ω coils) wound with round copper-clad aluminum wire (CCAW) on an aluminum former. RMS power handling is rated at 200W.

The second driver on the Test Bench bench is the 10NW76 high-SPL 10” woofer from B&C Speakers, clearly designed for professional audio. The 10NW76 was designed for uses in line arrays, small two-way monitors, and as a subwoofer, or as a midbass driver in multiway systems. The 10NW76 uses a proprietary 12-spoke (six double spokes) cast-aluminum frame with a series of cooling vents that allow air to move past the voice coil and across the front side of the neodymium motor assembly. Additional cooling is provided in a tapered and flared 1.5” diameter pole vent in conjunction with eight 6.5mm diameter peripheral vents located on the milled back plate.

The cone assembly consists of a curvilinear waterproof coated paper cone and dust cap, with compliance supplied by a pleated coated polycotton cloth three-roll-type surround and from a cloth type 5.5” diameter flat spider. Details of the B&C Speakers 10NW76 motor design include a neodymium ring magnet structure sandwiched between a 9.8mm polished milled front plate and the polished milled and shaped back plate/return cup. The neodymium magnet motor was FEA-designed using a 3" diameter voice coil wound with round copper-clad aluminum wire (CCAW) on a non-conducting glass fiber former. Rated power handling is 400W (800W continuous), making the 10NW76 the highest power handling 10” in the B&C Speakers line-up.

This December 2021 edition concludes with the traditional dose of Industry Watch stories. This edition of Voice Coil is available for download and already in the mail to print subscribers. Subscribers can go to - www.gotomyvcoil.com - to download this issue.

Remember, Voice Coil is available in print and download for all registered subscribers, 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

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