Patent Review: Loudspeaker Apparatus

This article reviews a patent awarded to Teppei Yamada, on behalf of Zorzo Co., Ltd. (Tokyo, Japan), describing an original design of a low-frequency enclosure system incorporating multiple woofers inter-coupled in a manner similar to what is known as an isobaric or compound woofer enclosure. James Croft reviews other approaches to the concept, starting in 1954 with a patent granted to Harry F. Olson on a dual, compound woofer system and later "reinvented" and popularized by Linn Corp., in 1975. In the new patent, the inventor uses an enclosure with as many as 12 woofers, all seriously coupled through individual air chambers

This article reviews a patent awarded directly to inventors Anthony Allen Bisset (Oakland, CA) and Quang-Viet Nguyen (Aldie, VA), for a coaxial horn speaker design. In his review, James Croft looks back at multiple multi-driver horn topologies and compares the unique aspects of the CCPS Horn Speaker System, highlighting the positive attributes and benefits of the invention, to deliver both increased acoustic quality and increased power density.

This latest MR13TX-4 midrange from SB Acoustics is part of the fast-growing Satori line of high-end transducers. A dedicated 5" midrange driver, the MR13TX-4 is the 10th TPCD TeXtreme diaphragm transducer to be featured in Test Bench. In terms of features, the MR13TX-4 is built on a proprietary two-piece cast-aluminum frame, completely open below the BIMAX spider for cooling. The cone assembly consists of a curvilinear inverted single piece "bowl" shaped TeXtreme cone and an inverted NBR surround, driven by a 1.2" diameter voice coil and a neodymium motor.

The B&C Speakers DE640-16 Compression Driver is a 1.4" exit design, which along with the recent DCM414 midrange and the DE360 models represent a line of two-point suspension ring radiator type compression diaphragms. The DE640-16 features a 65mm (2.6") Polymer diaphragm and neodymium ring magnet and is specified for a recommended crossover frequency around 1kHz, and a 140W continuous power rating. For this Test Bench, the DE640-16 was matched with the Eighteen Sound XT1464 elliptical flare horn.

The fifth article by Claus Futtrup in his series about loudspeaker bass reflex alignments explores the concept of transitional alignments, which is helpful in bridging between filter types. The example details a transitional alignment between Butterworth B4 and Linkwitz-Riley LR4. This article series started in May 2024 with “Computation of Bass Reflex Alignments," the series expanded with classical alignments such as the B4, the LR4, the IB4, and most recently, the CD4 vented alignment, in the August 2024 issue.

In this December 2024 issue there's a new DSP product review of the Marani Pro Audio MIR260A outboard processor, and Lars Risbo shares his expertise in Numerical Optimization applied to Speaker Box Alignments. Essential resources are the updated directories of Test and Measurement and of Simulation and CAD Software vendors. On Test Bench, Vance Dickason characterizes the Faital Pro HF110 1" Neodymium Motor Compression Driver and the SB Acoustics Satori MR16TX-8 6.5" TPCD Midrange.

In this article Mike Klasco shares his extensive knowledge about voice coils, and how this critical part of loudspeaker technology has evolved - the result of decades of walking factory floors all over the world . As noted in his introduction, "Winding some wire into a coil should be simple enough and after a century of loudspeaker manufacturing, there shouldn’t be any new surprises. But voice coil materials, process control, and topology continue to evolve and here we discuss half a dozen noteworthy new tricks."

The Scan-Speak D3004/606200 is a 1" compact tweeter from its Illuminator Line, and features the new generation of Metamodal TPCD diaphragms. Scan-Speak has been participating in Composite Sound's metamodal development program, and the new D3404 tweeter is the first to be released. It features a low resonance, injection-molded rear chamber, SD-2 neodymium motor, large-roll coated cloth surround, and black anodized machined aluminum faceplate. This article was originally published in Voice Coil, July 2024.

This Test Bench characterizes the new Scan-Speak 15W/8534T00 woofer, which fills the gap in the Classic family for a compact high-performance 5.5” (15cm) midbass driver. It is based on the design principles of the popular 18W/8545 continuing the tradition with a slim frame aluminum chassis, Symmetrical Drive (SD) motor system, low loss linear rubber suspension, and updated with a brand-new cone material called Phenomax.

The 10PR330 is Faital Pro's new high-power handling 10" woofer intended for line arrays and large PA systems, or as a midbass driver in multiway systems — and apparently it has also been also used successfully in bass guitar applications. The cone assembly for the Faital Pro 10PR330 woofer consists of a curvilinear paper cone along with a very stiff coated dust cap. Compliance is supplied by a coated polycotton cloth M-roll type surround and from a cloth-type flat spider.