Voice Coil February 2021 Focus on Cone Industry

For this edition of Voice Coil, Mike Klasco and Nora Wong prepared a complete overview of the Cone Industry in 2021, an essential component in loudspeaker design and manufacturing. With most of the manufacturers activities affected by the pandemic restrictions globally, they discuss how things progress in terms of research and development activities. This edition offers a perspective from key suppliers YuonYunn (YY), Guangzhou Istaray Trading, Kurt Mueller, Textreme, Teijin, and Clarasonic.

This world tour is followed with an updated directory of Loudspeaker Cone/Diaphragm Industry Suppliers 2021, incorporating suppliers of relevant materials and components, such as specialized surrounds, spiders (dampers), ribbon diaphragms, and cone additives.

In this month's Acoustic Patents column, James Croft (Croft Acoustical) reviews a Directional Loudspeaker European patent claimed in 2014 by inventors Koenraad August Jan Knaapen, Eric Van Duin, Martijn Gerardus Mensink, Kevin Ivan Kleine, and George Ortega, on behalf of Dutch & Dutch BV (The Hague, Netherlands), published in 2016 and granted in 2018. The patent describes a directional loudspeaker for use in the mid-frequency range of the audio spectrum, comprising a housing using an acoustic resistive material wherein at least one acoustic transducer is mounted and, with one or more openings in the side panels of the housing, and, optionally, in the back panel, allowing at least part of said back waves to exit and introduced a phase delay, an attenuation and an amplitude, generating an attenuation at the backside of 15dB or more. In summary, obtaining desired frequency or directional characteristics for obtaining a phase-shift between the front and back acoustic wave, by using a single transducer.

In his review, James Croft revisits all the relevant research in the acoustic and electroacoustic design domains that were or weren't considered in this invention, and the fascinating efforts related to the concept - going back as much as 40 years. "The centerpiece of the patent is the midrange driver and enclosure system, which is a passive cardioid configuration with a forward firing midrange driver loaded into an enclosure with resistive, side-firing rectangular shaped ports..." he writes, reminding us of previous reviews of passive cardioids patents from David Gunness, Bobby Beavers, and John Meyer. As always, a fascinating voyage, which in this case has resulted in an actual existing product by Dutch & Dutch.

For this month's dose of Test Bench, Vance Dickason focuses on two small-sized loudspeakers that represent typical drivers used in portable speakers, smart speakers or soundbars. "Today, 2" to 3" diameter full-range drivers and woofers are without a doubt some of the most popular transducers in consumer electronics," Dickason notes.

The first one to be characterized is Wavecor’s FR070WA05, a 2.75" full-range driver with a black anodized aluminum cone, built on a proprietary injection-molded polymer four-spoke frame. Like most contemporary drivers, the area below the spider mounting shelf is totally open for increased cooling. The cone assembly with a 27mm diameter also features a black anodized aluminum dust cap (directly coupled to the 26mm vented black non-conducting black fiberglass voice coil former), and suspended with a low loss (high Qm) NBR surround and a 45mm diameter flat Conex spider (damper). Powering the cone assembly is a dual neodymium motor and a milled return cup with black emissive coating and 6mm diameter flared vent. Tinsel leads connect on one side of the cone to a pair of solderable gold-plated terminals.

The second product to be characterized is the AUGWL0006-JN01, a new 2.25" woofer from Eastech’s Punktkilde lineup. With a depth of 7/8", the AUGWL0006-JN01 is part of the Ultra-Thin Series and is built on a proprietary die cast four-spoke aluminum frame. The cone assembly consists of a black anodized aluminum cone, with a 20mm diameter black anodized aluminum dust cap, and suspended with a NBR surround. Instead of using a spider assembly, this woofer has a 25mm round foam surround to supply the additional compliance and centering for the cone assembly. The inside diameter of the foam surround is attached with an aluminum collar to the underside of the dust cap, so fairly clever. This driver has a rather unusual motor structure comprised of a large (for a 2.25” woofer) 35.5mm diameter under hung voice coil that rides inside a double set of neodymium ring magnets. A chrome-plated return cup has four 3mm diameter vents for additional cooling. Tinsel leads connect on opposite sides the cone to a pair of solderable terminals.

In Industry Watch, this edition of Voice Coil highlights the recent introduction by SEAS of a new Excel Nextel paper cone woofer, model W18NX003, and the latest Scan-Speak D2404/552000 Ellipticor 24mm textile dome tweeter.

The February 2021 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.

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