Magnets being one of the topics scheduled for this Voice Coil September 2025 issue, Mike Klasco (Menlo Scientific) has been deeply committed to gathering all the latest information on what’s happening around the world in this critical field for speaker design and manufacturing. In “Magnetics in 2025 - Fasten Your Seatbelts and Get Ready for Turbulence!” Klasco offers valuable history lessons about the evolution of material selection and magnet materials over time - from ferrite and alnico to neodymium - also under a geopolitical perspective. From that historical perspective, this valuable Voice Coil Focus article summarizes the efforts taking place worldwide, from neodymium-related news, ongoing developments at California’s Mountain Pass, and the progress with other non-China magnet facilities, and commercial production of neo magnets from recycled feedstock. In this report, analyzing the importance of rare earth metals - a key factor in speaker magnets as neodymium was commercially introduced - there are also important updates on recycling neodymium efforts, and respective supply chains.And a perfect complement to this magnets overview, Mike Klasco and Danny Ken (Menlo Scientific) have also prepared an update on “Materials Manufacturers for Consumer Audio Products,” an area that continues to evolve at a constant pace. While materials used for mainstream consumer audio products remain pretty much the same, with plastic still used in most commodity products, there’s been important progress in exploring other options for fast-growing product categories such as headphones and portable speakers. This resource directory describes that progress and identifies key players that speaker manufacturers need to consider, from Alpine Advanced Materials and the possibilities of the revolutionary HX5 injection-molding composite material to Oerlikon Balzers Surface Solutions and Yuonyunn Membrane, which has used graphene oxide material for speaker membranes, but also for microspeakers, headphones, and earphone diaphragms.
Another valuable directory for this issue focuses on "Innovative Transducers for Soundbars and Bluetooth Speakers," benefiting from Mike Klasco’s extensive industry contacts. Anyone looking for innovative speakers as well as relevant techniques to enhance performance for these popular speaker form factors, this directory offers an updated listing of some of the manufacturers with details about their offerings. In this update, those include examples from Dinaburg Technology, Premium Sound Solutions (PSS), Tectonic Audio Labs, and Trulli Audio.
For this month’s Test Bench, Vance Dickason characterized the new BGW-D182-86-4-001 6.5” glass cone woofer from Glass Acoustic Innovations Technology (GAIT). This relatively young company created an extensive foundation on R&D and patented glass diaphragm technology, now benefiting from a state-of-the-art production facility in Taipei, Taiwan. The GAIT glass diaphragm is now being offered in a comprehensive product line that includes examples such as this woofer, targeting hi-fidelity and home audio applications, as glass is a stiffer and better damped material with the first break-up mode higher in frequency and lower in magnitude compared to an aluminum cone.
The transducer GAIT submitted is the BGW-D182-86-4-001 6.5” woofer, fitted on a cast-aluminum frame, with a very open area below the spider mounting shelf for cooling, and a cone assembly comprised of a patented 3D ion-strengthened ultra-thin glass (UTG) - 0.2mm thick - diaphragm suspended on an NBR (CBR) surround that includes a nice shallow transition to the cone attachment area. Remaining compliance comes from an elevated cotton 20S/2 spider. This glass diaphragm is powered by a 35.6mm diameter voice coil wound with round copper wire on an aluminum former, and a thick Y30 ferrite magnet. The BGW-D182-86-4-001 woofer rates 87dB sensitivity (1W/1m at 1kHz), and a 50W continuous power handling (140W peak).
Another similar-sized 6.5” woofer characterized in this issue of Voice Coil is the W 174.38 Fibonacci Woofer from RS Speakers, the new separate brand recently created by SICA Altoparlanti, addressing high-end home transducer applications. The RS lineup already includes an 8” woofer, plus 6.5” and 5.5 woofers and midwoofers in this Fibonacci range, apart from different tweeter models. Having measured the 28mm RS TW 104.28 N/Ag soft dome tweeter in the March 2025 issue, Vance Dickason received the W 174.38 Fibonacci 6.5” woofer, with 80W RMS power handling.
Features for the RS Speakers’ W 174.38 Fibonacci Woofer start with a proprietary cast-aluminum frame that incorporates 12 narrow spokes to minimize reflections back into the cone. The area below the spider mounting shelf is totally open, with additional cooling provided by a 12mm flared pole-type vent plus eight 4mm diameter peripheral vents located on the front plate instead of the back plate. The diaphragm features a custom para-elliptical profile, further made stiff by using the downward folded 90° edge technique. The patented “Fibonacci” technology involves a precise erosion of the cone’s outer surface by laser marker, following a path inspired by the Fibonacci sequence, named after the Italian mathematician. The primary advantage of this technology is the reduction of unwanted resonance modes in the cone.
The diaphragm is treated with an acrylic coating on the front and a damping layer on the back, creating a “sandwich” structure that balances rigidity and damping. The dust cap is made with the same coated paper material as the cone. Compliance is controlled by a 12mm wide NBR (CBR) type dual roll “M” surround that has a fairly shallow transition to the cone, and by a 4” diameter black conex progressive profile cloth spider. This assembly is connected to a 1.5” diameter voice coil, on a non-conducting vented fiberglass former wound with round copper wire. The motor assembly is powered by a FEA-optimized Ferrite motor design and incorporates an aluminum shorting ring around the inside diameter of the ring magnet.
This issue includes another set of Industry Watch articles of interest for loudspeaker professionals, with updates from Loudsoft, Hypex, and Klippel.
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