Voice Coil May 2024 includes valuable speaker design knowledge, courtesy of Claus Futtrup, who writes about Computation of Bass Reflex Alignments. And this issue includes an updated Microspeaker Vendor Directory, with a MEMS Microspeaker Subdirectory, compiled by Mike Klasco and Nora Wong. And Vance Dickason placed the unique W4-2315 4.5” coaxial from Tang Band Speaker, together with Faital Pro's 5HX140 5” pro sound coaxial on Test Bench. Read it in print, digital or online.In this issue of Voice Coil May 2024, Claus Futtrup, renowned for his work with Tymphany, Scan-Speak, and SEAS, and currently working as an Engineering Manager for DALI, offers the first of a series of contributed articles of great value for speaker designers. In a piece about Computation of Bass Reflex Alignments, Futtrup expands on his introductory article “Loudspeaker Bass Reflex Alignments," an historical perspective about the invention and the concept of loudspeaker bass reflex alignments that was published in the January 2024 issue of audioXpress. In this issue of Voice Coil, Futtrup now provides an updated approach for the mathematical presentation of the various alignments, applicable to all computerized development tools. This is effectively an explanation of the code available in the Alignment Chart of the Speakerbench web application that Futtrup developed in collaboration with Jeff Candy.
Next, this issue of Voice Coil expands on the traditional directory resources that Mike Klasco and Nora Wong (Menlo Scientific) diligently compile and update every year. This month features an updated Microspeaker Vendor Directory for 2024, which also includes its own MEMS Microspeaker Subdirectory. The first section includes vendors supplying microspeakers for smartphone and laptops applications, while the additional subdirectory follows for MEMS microspeakers, a class of drivers that is increasingly finding applications in IEMs and true wireless stereo (TWS) earphones.
For this May 2024 issue, Vance Dickason placed two completely different coaxial speakers on his Test Bench. The first driver is the highly original Tang Band (TB) Speaker’s W4-2315 4.5" paper cone coaxial design. This small diameter coincident coax transducer from TB Speaker, is a great new example of this genre for home audio applications, with applications extending to any high-performance small two-way speaker or a studio monitor design.
The W4-2315 woofer is built on a proprietary six-spoke injection-molded two-piece polymer plastic frame with an injection molded aluminum trim plate attached. The woofer cone is a very shallow curved profile bamboo fiber paper cone, which includes a flat copper center ring and is suspended by an articulated NBR (CBR) surround. The cone assembly is driven with a 32mm diameter voice coil wound with round copper wire on an aluminum former, powered by a neodymium ring magnet. The high-frequency section is mounted on a pole inside the long voice coil former that extends about 1" from the top of the front plate of the motor structure. The tweeter features an aluminum inverted dome diaphragm suspended by a cloth surround. Powered by a neodymium slug, the tweeter motor incorporates a resonant back chamber design that gives the tweeter a 1.6kHz to 40kHz operating range, which is impressive for its diameter.
The second driver in this coaxial showcase is the recent 5HX140 5" pro sound coaxial from Faital Pro. In terms of features, the 5HX140 woofer is built on a proprietary six-spoke cast-aluminum frame, with the woofer paper cone with a water-resistant coating on the front side, a coated pleated M-type fabric surround, and a porous acoustically transparent cloth dust cap over the compression driver conical horn. A flat cloth spider is combined with a 37mm (1.46") diameter voice coil, wound with round aluminum wire on a Kapton former. Driving the cone assembly is a neodymium ring magnet sandwiched between a 6mm front plate and an 18mm milled back plate that forms the throat for the conical compression driver horn. This substantial motor mass greatly contributes to the voice coil cooling mechanism and accounts in part for the substantial (for a 5" woofer) 120W AES power handling rating.
The high-frequency compression driver for the Faital Pro 5HX140 coaxial has its own neodymium ring magnet motor system that drives the 25mm Kapton Polymer dome shaped diaphragm, with a voice coil also wound with aluminum wire on a Kapton former. This Kapton Polymer diaphragm fires into a short 90° aluminum conical-shaped horn, which brings the sensitivity to 101dB, with a recommended crossover frequency of 1.5kHz to 2kHz and a rated AES power handling of 15W.
And finally, for Industry Watch, Vance Dickason looks at the recent announcement from Masimo, and the fact that the company's own board of directors "authorized" the management to spin-off of its consumer business, which includes the recently acquired Sound United business and its valuable brands. This section also highlights the availability of the Nuvoton NAU83G60 2×30W amplifier with Klippel Controlled Sound (KCS) nonlinear adaptive speaker control technology.
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