Test Bench: The AMT100H Driver from Eighteen Sound

The AMT100H driver from Eighteen Sound is the "little brother" of the AMT200P (with the XMT200 horn) air motion transformer (characterized in the November 2021 issue). Features for the AMT100H, include a rectangular throat with a Kapton diaphragm, a neodymium magnet structure, and a net weight of 1.84lb (0.835kg). This driver has a recommended crossover frequency of 1.2kHz at 24dB/octave. This article was originally published in Voice Coil, October 2023.

For this Test Bench, Vance Dickason measures the Scan-Speak 18ME/9642T00 Ellipticor 6.5" Midrange, the first driver to be offered only to Scan-Speak's OEM customers, not available on the DIY retail market. Benefiting from the oval (elliptical) voice coil shape that characterizes the Ellipticor range, this midrange also features the AirCirc motor structure, and Symmetrical Drive SD-2 motor format.

The Wavecor WF182BD13 is a midbass driver that utilizes a unique proprietary cone material made with interwoven Kevlar/Carbon fibers with beneficial properties for midrange reproduction - a combination of low mass, rigidness, and damping. Unique features include a vented inverted dome-type phase plug (no dust cap), a shallow profile low loss high Qm NBR surround, accompanied by a flat 4” diameter black cloth spider.

Beyma's Near and Mid Field (NMF) line includes this compact woofer aimed at the studio/home audio market, one of three models with a similar feature set that includes carbon fiber cones and dust caps, Malt Cross cooling technology, triple aluminum, and copper shorting rings, dual Bimax spiders, and Quattro inside/outside voice coil windings. This article was originally published in Voice Coil, August 2023.

James Croft (Croft Acoustical) reviews a very curious patent from Amazon Technologies, Inc. (Reno, NV), filed in 2013, and awarded in April 2017. Basically, the patent discusses a new technique to tune a port of a loudspeaker, in this case multiple ports that will be open or selectively closed, in function of an analysis of the frequencies of the signal being played. This article was originally published in Voice Coil, June 2018.

Founded in 2001, Stereo Integrity is an OEM speaker driver manufacturer from North Carolina that also designs its own range of hi-fi amplifiers, sold directly to consumers online. The company sent its M25 mkII high-end tweeter, which features a 25mm silk dome diaphragm and surround, a dual-magnet neodymium motor, a black anodized aluminum motor housing with a tuned rear chamber, two-layer CCAW wound voice coil, and a compact 50mm diameter face plate with a steel anodized grill. This article was originally published in Voice Coil, July 2023.

This Test Bench characterizes the innovative TW045WA01 dual-diaphragm coaxial tweeter from Wavecor. This driver's dual-diaphragm assembly combines a 22mm coated textile dome for high-frequency extension and a 45mm ceramic/aluminum cone, which adds low-frequency output and efficiency. The hybrid design incorporates a dual neodymium magnet motor structure and sculpted foam damping ring attached to the faceplate. A very unique driver that is certain to appear in new two-channel high-end audio loudspeakers.

There seems to be a lack of consideration and understanding of the acoustical characteristics of the loudspeaker’s many glue joints. In this article for Voice Coil, Mike Klasco and Steve Tatarunis detail how the influence and use of glue joints and diaphragm treatments can be used as a design tool. The report also details some significant new material options and design and measurement tools available. This article was originally published in Voice Coil, July 2017.

This Test Bench characterizes the 6CXN36 6.5" coincident coax transducer, a professional audio driver from Italian manufacturer B&C Speakers and fairly similar to the company's 5.25” 5CXN44 reviewed in Voice Coil, August 2021, which uses a nearly identical compression driver. The cooling for the 6CXN36 is exclusively provided by the motor mass, which is substantial, and no vents are required for the impressive 200W continuous power handling rating in a small diameter driver such as this.

Happy 36th Anniversary Voice Coil! The November 2022 issue of Voice Coil once again celebrates the launch of this periodical as an information resource for the loudspeaker industry. Also, this month, Mike Klasco writes about technologies and solutions to enhance low-frequency performance, and James Croft reviews a recent patent awarded to Panasonic for a loudspeaker arrangement for a Near to the Ear Subwoofer in a car seat. For this month's Test Bench, Vance Dickason characterizes the 6CXN36 coaxial 6.5” pro sound driver from B&C Speakers, and Wavecor’s FR4X-6WA01 compact oval full-range driver. Now available in print, digital and online.