As scheduled around this time of the year, Voice Coil September 2023 features our annual overview of the state of Magnetic Materials for the Loudspeaker Industry. Salvador Magdaleno-Adame (Salvador Consultant) and Mike Klasco (Menlo Scientific) compiled another valuable analysis of this fascinating field. From material science to speaker application-oriented innovations, this update discusses the alternatives to the essential ferrite, alnico, and neodymium magnets, as well as low carbon steel for the magnetic return structure. Among the topics our readers will enjoy, there are updates on the latest in Nitride Iron Magnets, Clean Earth Magnets and even the unobtainable Tetrataenite, "The Cosmic Magnet" discovered in meteorites. Next up, Mike Klasco writes about Upcoming Technologies for Voice Assistant Smart Speakers, which he basically used as an excuse to provide updates on all the exciting technologies that are being explored for the most innovative categories of consumer speakers, most of which are wireless. Expanding on a topic Klasco wrote for Voice Coil in the past, this article is full of valuable insights on low-power solutions, GaN components, Exeter's Powerfoyle light energy source solution, and other more exotic wireless power approaches that are now making their way to the market. And of course, he discusses voice input front ends, microphones, and wake-word and voice recognition technology.
Included in this issue is the final part of "A FINE Circle Hardware/Software Tutorial" that Peter Larsen (Loudsoft) wrote specifically for Voice Coil. This third article is focused on the Crossover for the speaker project he started to design in the two previous articles. The first two parts of this Loudsoft simulation software system design tutorial series demonstrated the development of a 6.5" woofer and vented enclosure along with the high-frequency transducer, a 1" silk dome tweeter. The final step is an appropriate passive network design, which is where FINE X-over software comes to the rescue.
Jumping straight to the always highly anticipated Test Bench characterizations, Vance Dickason has written about three new drivers.
We start with the Fountek NeoCD2.0 high-end ribbon tweeter from this China-based OEM. The Fountek brand is now being manufactured by Shanghai Nada Technology (formerly Fountek Electronics), updating a large portfolio of high-end range of transducers (woofers, midbass drivers, full-range drivers, and ribbons high-frequency devices). The device that was sent to Voice Coil is the company’s current iteration of its Fountek NeoCD 2.0 ribbon tweeter, which uses a 120mm × 8mm 0.015mm thick reinforced sandwich diaphragm. The NeoCD2.0 has a closed-back injection-molded rear cavity with two aluminum heatsinks and a built-in transformer and features a cosmetically attractive thick black aluminum faceplate with a black mesh screen. This Test Bench includes a complete characterization of this heavy high-frequency device.
Next in line for Test Bench is another significant product from SB Acoustics' Satori Line of high end drivers. The WO24TX-4 9.5" Midbass Woofer is the latest product from Sinar Baja to feature a Composite Sound Thin-ply Carbon Diaphragm (TPCD) cone. Clearly a material choice that is starting to conquer a growing number of speaker manufacturers in all application segments. The SB Acoustics WO24TX-4 Satori has a substantial feature set that begins with a proprietary six-spoke cast-aluminum frame, comprised of fairly narrow spokes, completely open below the spider mounting shelf for cooling. Additional cooling for this driver is provided by a 21mm diameter pole vent with a flared exit. The cone assembly consists of a curvilinear inverted single piece “bowl” shaped cone. The cone is glued to a conventional-looking conic section of TPCD joining the cone to a normal-looking voice coil next joint. Compliance is provided by NBR surround that has a shallow transition to the cone attachment. The motor is a FEA-optimized neodymium magnet-type with milled plates and an undercut pole piece with dual copper shorting rings. Driving the cone assembly is a 1.95" diameter voice coil wound with round copper-clad aluminum wire (CCAW) on a nonconducting vented fiberglass former.
The third driver to deserve the Test Bench podium is another high-profile product launch for hi-fi, high-end audio and even studio monitor manufacturers and speaker builders. We are talking about the new SEAS L22ROY2 8" Subwoofer from its Extreme line. This latest driver from Norwegian OEM manufacturer SEAS is currently only available in an 8Ω two-layer voice coil version. The new L22ROY2 subwoofer offers a well-appointed feature set that includes a proprietary cast 16-spoke (8 twin spokes) cast-aluminum frame, completely open 1" deep below the spider mounting shelf. Other features include the incorporation of a very stiff black anodized aluminum curvilinear shaped cone, further stiffened by a 3.1" concave black anodized aluminum dust cap. Compliance is provided by a FEA-optimized 13mm tall NBR surround plus a 5.2" diameter black flat textile spider. All this is driven by a 2" voice coil wound with round wire on a titanium former. The motor system powering the cone assembly utilizes a single ferrite magnet sandwiched between a black emissive-coated 8mm thick front plate and T-yoke that incorporates a bump-out and flared pole vent for enhanced cooling.
This issue of Voice Coil concludes with the usual dose of Industry Watch updates and is now 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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