Voice Coil June 2025 is now available, and you will want to dive right in with a great amount of new product overviews, starting with the latest Klippel dB-Lab software release, now with Fast Large Signal Identification Professional (FLSI Pro), significant revisions, and extended analysis capabilities. Another highlight in this month's Industry News is an extended overview of Dayton Audio's new OmniMic 40k and the Digital Audio Test System Loudspeaker Analyzer (DATS LA). The OmniMic 40k is a substantial upgrade from the original Dayton OmniMic V2 measurement system, while the new DATS LA is an entirely new loudspeaker measurement analyzer and software, using a patented DC offset bias technique to derive both small and large signal parameters, including both linear and nonlinear output capability.Although this issue of Voice Coil is focused on test and measurement, which naturally should be mainly addressing loudspeaker measurement solutions - and there are some - Mike Klasco (Menlo Scientific) opted to recap the latest Headphone Test & Measurement Equipment, with a complete list and updates on all the companies active in that space. From Audio Precision to Audio and Crysound, all the way to MegaSig and Zumi Systems, all the key suppliers are featured with valuable details.
And for this issue's Test Bench, Vance Dickason prepared a large characterization. Large as in Celestion's new TSQ2145 21" Pro Sound Subwoofer, the latest example of a neodymium, low-frequency loudspeaker from the British company, which recently celebrated its 100th anniversary (1924-2024). This new 21" subwoofer from Celestion's 10 Squared line-up (TSQ for short) is rated for 1800W AES (3600W continuous) power and was designed to be integrated in large power multi-way sound reinforcement systems, or to be used as a dedicated subwoofer in bass reflex designs.
The feature set for the TSQ2145 is like most high-performance pro sound drivers, rather substantial, with a cast-aluminum frame with advanced temperature control achieved using a three-channel tuned venting system that typically operates up to 80° C lower temperature than other leading drivers in its class. The cone assembly consists of a straight profile thick pulp paper ribbed cone, weather-proofed front and back, along with a coated convex paper dust cap. Compliance is provided by a unique suspension structure proprietary to Celestion, using two layers of coated cloth material with a center layer of polysiloxane. The remaining compliance is supplied by a three-roll pleated coated surround. The 115mm (4.5") diameter voice coil is wound with round copper wire on a non-conducting fiberglass former, and all motor parts are coated with a black heat-emissive coating for improved cooling.
The second Test Bench for this June issue is equally impactful in a totally different way and is the new C16NX001/X, an advanced 5.25" coaxial driver from SEAS. This new coaxial speaker is another high-end home audio/studio monitor driver that uses the latest metamodal thin-ply carbon diaphragm (TPCD) technology and was developed in close cooperation with Composite Sound, the company that licenses and manufactures diaphragms and cone materials. Given the C16NX001/X’s 5.25" diameter woofer, it works well as a stand-alone coax product, but also certainly in applications where it could be used as a mid/hi driver in a three-way application.
The C16NX woofer is built on a rather stylish and aerodynamic-looking proprietary six-spoke injection aluminum cast frame that minimizes reflections back into the cone. The frame is totally open below the spider (damper) mounting shelf, which allows substantial airflow past the voice coil over the front plate. Attaching the cone to the frame is a NBR surround with the remaining compliance provided by a 3.75" diameter flat black cloth spider (damper) with the tinsel leads attached to a set of gold-plated terminals. The cone assembly is driven by a 39mm (1.54”) diameter voice coil wound with a copper-coated aluminum wire (CCAW) on a non-magnetically conducting Titanium former. The motor assembly is made up of a fairly large (for a 5.25" driver) 110mm × 25mm ceramic magnet sandwiched between a 6mm thick front plate and back plate. Like the SEAS "King" coax, the C16NX has a T-shaped pole with heavy dual copper-type shorting rings (Faraday shields) mounted above and below the gap.
The high-frequency device is mounted on the woofer T-pole via the upper crown-shaped shorting ring and damps the vibration associated with the tweeter housing and the woofer voice coil former. The tweeter is comprised of a 26mm (1") diameter metamodal TPCD diaphragm suspended by a SEAS proprietary Sonomax plastic surround. Powered by a neodymium slug, the tweeter motor incorporates a resonant back chamber design that gives the tweeter a 1.49kHz resonance that is magnetic fluid damped (1000cp). The voice coil for the tweeter is wound with round copper wire.
This issue closes with an Industry Watch section containing comments about the current tariffs situation and potential consequences for the industry and the US in particular, followed by updates from Scan-Speak, Countervail, and the Audio & Loudspeaker Technologies International (ALTI) Association.
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