Test Bench: Eighteen Sound NSD1095N Compression Driver and XT120 Horn

The NSD1095N is a 1" throat compression driver with a compact footprint for “high quality” sound applications in professional audio, from studio monitors or stage monitors to high-power sound reinforcement cabinets. It uses a field replaceable True Piston Motion (TPM) TiN coated titanium diaphragm, extending the frequency response by 25% and incorporates a proprietary phase plug architecture that has been designed to give a smooth coherent wave front at the horn entrance across the whole working frequency range.

The Satori MW19TX-8 TPCD cone 7.5" woofer is the fourth TPCD diaphragm transducer to be explicated in Test Bench, the first being an Eminence compression driver and the remaining all woofers from SB Acoustics. The high-end MW19TX-8 has a substantial feature set with similar features as the rest of Satori series with TPCD cones, impressing immediately by its distinctive cosmetics and subjective performance, which this characterization illustrates.

Part of a new series of drivers announced in October 2020 by Wavecor, this woofer could also be advantageous in high-powered studio monitors. This high-power design targets home audio and home theater applications, including two-way (with larger ribbon/AMT drivers, or compression driver/horn combinations) and three-way speakers. This article was originally published in Voice Coil, January 2022.

TPCD is the acronym for Thin-Ply Carbon Diaphragm, which is essentially the technology developed in Sweden by Oxeon to create a new-generation material with properties that are now well-proven for speaker cones and domes. The Satori MW13TX-4 TPCD cone 5” woofer is the fourth TPCD diaphragm transducer to be explicated in Test Bench, and this one has a substantial feature set, including a single piece bowl-shaped TPCD cone and NBR surround. This article was originally published in Voice Coil, January 2022.

The driver on this Test Bench is from B&C Speakers and clearly designed for professional audio. The 10NW76 was designed for uses in line arrays, small two-way monitors, and as a subwoofer, or as a midbass driver in multiway systems. It uses a proprietary 12-spoke (six double spokes) cast-aluminum frame with a series of cooling vents that allow air to move past the voice coil and across the front side of the neodymium motor assembly. The cone assembly consists of a curvilinear waterproof coated paper cone and dust cap. This article was originally published in Voice Coil, December 2021.

This Test Bench explication focuses on the Dayton Audio Epique MMAG E150HE-44 "full-range subwoofer," in itself an interesting concept. Like its larger E180HE-44 brother in the Epique line, the E150HE-44 is based on the patented Multiple Magnet Air Gap (MMAG) technology invented by Enrique Stiles. The two new Dayton Audio Epique MMAG woofers were designed with direct support by Enrique as an independent transducer engineering consultant, working in conjunction with the engineering team at Dayton Audio. This article was originally published in Voice Coil, December 2021.

This Test Bench article characterizes Eighteen Sound’s AMT200P Air Motion Transformer and accompanying XMT200 6.5” waveguide. This driver is the brand's latest entry into the high-frequency transducer category, specifically designed for the pro sound community. The Eighteen Sound AMT200P includes a rectangular throat with a Kapton diaphragm with a neodymium magnet structure, and is rated for a power handling of 90W AES above 1.2kHz, with a sensitivity of 105dB, and a recommended crossover frequency of 1.2kHz at 48dB/octave. While the AMT200P can be used as a standard planar device it can be also coupled with a dedicated constant directivity horn, the 90°x 20° XMT200, featured in the characterization.

This Test Bench addresses Purifi Audio’s PTT4.0X04-NFA-01 4” midbass, which is very similar to the PTT6.5X reviewed in Voice Coil July 2021, and includes the same constant Sd surround and low magnetic hysteresis motor design. The distinct cone assembly for this driver consists of a flat profile paper cone made with a proprietary fiber mix, a concave dust cap that covers about 90% of the cone surface, plus the addition of a V-shaped edge reinforcing ring glued around the outside rim of the back side of the cone. Compliance is provided by a unique NBR surround, which as in the PTT6.5X surround, deserves to be explored, motivating Vance to discuss it with Purifi’s co-founder Lars Risbo.

While Voice Coil Test Bench reviews only make use of the Large Signal Identification (LSI) data from the Klippel analyzer, the reality is that there is an amazing list of 30 modules available for the KA3 that are seriously valuable for transducer and system development. As space permits, I will be covering a number of these modules in future issue of Voice Coil. The first module in this series is the Time Frequency Analysis (TFA) module. This article was originally published in Voice Coil, October 2021

We're off to a great start in 2022. Starting with details about the promise of Iron Nitride (FeN) magnets, followed by an article about Liquid Injection Molding Silicon for Next-Generation Headphone Surrounds. Next up, James Croft reviews a surround speaker patent granted to Klipsch, and Vance Dickason characterizes the Satori MW13TX-4 TPCD-cone woofer from SB Acoustics and the high-power WF275BD01 10.75" woofer from Wavecor. All articles now available to read online, PDF and print.