Test Bench: The M3 Carbon Midrange Car/Home Audio Transducer from Stereo Integrity

This Test Bench explores an interesting transducer from Stereo Integrity, a company founded in 2001, targeting the home and automotive audio markets. The Stereo Integrity M3 is a 3.5" carbon fiber midrange driver with neodymium motor, only 52mm (2") in depth. The M3 includes a black woven carbon fiber/paper sandwich curvilinear cone and 1.1 convex dust cap, with suspension provided by a synthetic copolymer surround plus a flat 55mm diameter cloth spider.

The DH450-8 ultra-compact compression driver from B&C Speakers incorporates a 1.7" high temperature Polymer diaphragm driven by a 44mm voice coil wound with aluminum wire on a high Qm Kapton former. Its most fascinating feature is the patent-pending phase plug with a deliberately twisted internal channel, which is intended to improve the overall frequency response. For this characterization, the DH450-8 1" neodymium driver is measured along with the B&C Speakers ME10v2 90x60 hyperbolic cosine flare horn, made from injection-molded ABS. This article was originally published in Voice Coil, August 2024

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."

In the second article about the latest generation A2B technology from Analog Devices - expanded with the release of the AD2437 chip - Brewster LaMacchia explores the latest possibilities for audio applications in many other areas other than automotive audio. After reviewing the three generations of A2B technology, LaMacchia expands on the alternative power schemes that deserve some investigation for multichannel digital audio applications. This article was originally published in audioXpress, August 2024.

In the fourth article from Claus Futtrup in his series about the invention, concept, and historical perspective of loudspeaker bass reflex alignments, he explores the Critically Damped Fourth-Order (CD4) bass reflex alignment. This alignment remains one of the least known and hasn't been discussed in literature related to loudspeaker design, even though it allows for interesting output properties. This article was originally published in Voice Coil, August 2024.

With the ARC Studio, IK Multimedia introduced a new DSP market contender for room and speaker correction. The solution combines a processor bundled with the company's ARC MEMS microphone and new ARC 4 software. Although ARC Studio was designed essentially for the home studio, the market served by the Italian company, this review also explores the possibilities for stereo system users, seeking playback chain improvements.

In this issue, Vance Dickason kicks off a series of outboard DSP processor reviews, starting with the Danville dspNexus. Next, Claus Futtrup writes about the Critically Damped Fourth-Order (CD4) bass reflex alignment. As scheduled, Mike Klasco writes about New Materials and Technologies for Voice Coils, and there's an updated directory of 2024 Voice Coil winders, converters, lead out wire, and more. On Test Bench, Vance Dickason assesses the new B&C Speakers DH450-8 1" compression driver and the Stereo Integrity M3 3.5" carbon midrange driver.

audioXpress August 2024 features our traditional Acoustical Solutions Round-Up, while Active Acoustic Enhancement Systems are also discussed in the Sound Control column. Oliver Masciarotte reports from AXPONA 2024, Philipp P. Klose reviews the new IK Multimedia ARC Studio solution, and Brewster LaMacchia expands on alternative power schemes for audio applications with A2B. On audio electronics, Charlie Laub explores Notch Filters, and Todd Schneider details his High-Fidelity Active Direct Box project.