Directivity Measurement of In-Wall Loudspeakers

In this article, the authors share their research on new requirements for the measurement of in-wall installation speakers. The directional characteristics are an especially important factor, because the direction in which a loudspeaker emits sound highly affects the interaction with the listening room and the listening experience. The authors' research addressed the requirement using holographic directivity to address the way the directional characteristics interact with the listening room. This article was originally published in audioXpress, December 2021.

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.

In this exclusive article for audioXpress, Lars-Johan Brännmark (Chief Scientist, Dirac Research AB) describes an approach to the challenge of applying DSP room correction to complex multichannel setups, intended for immersive audio reproduction. Instead of one filter applied to a single channel, he proposes a solution where all speakers work to optimize the reproduction of each input channel in an optimal way. This article was originally published in audioXpress, 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.

In this article, Vance Dickason highlights the possibilities for a two-way DSP filter design using the CrossLite+ software package. Under development by the Brazilian pro audio company since 2009, CrossLite+ is a dual-channel FFT analyzer that will function with basically any USB-type recording interface. CrossLite+ is intended primarily for product development of DSP-powered pro speakers and for use in live sound PA systems. And measured data can also be imported from other analyzers such as the CLIO or Klippel This article was originally published in Voice Coil, December 2021.

For those readers following the fascinating article series by Morty Tarr on "Cascodes, Folded Cascodes, and Current Mirrors," this final article in the series contains an additional section with important aspects of amplifier design. In the first two parts of this article series, Tarr discussed the technical merits of cascodes and related circuits. This useful addendum covers a simple test circuit for matching FET devices, the fascinating story of the Blowtorch Line Stage design, and additional notes on inverting and non-inverting amplifier stages and integrators. This article was originally published in audioXpress, December 2021.

In the December 2021 edition of Voice Coil, Vance Dickason details the possibilities of the CrossLite+ DSP filter software, while James Croft reviews an interesting invention to improve the bass response in automotive audio applications. And this edition includes an updated measurement microphone directory, and two interesting low-frequency drivers on Test Bench, with the Dayton Audio Epique MMAG E150HE-44 subwoofer, and the powerful 10NW76 high-SPL woofer from B&C Speakers.

audioXpress December 2021 is now available. Learn how Room Correction and Speaker Calibration is influencing efforts towards the Self-Calibrating Loudspeaker, Dirac's take on Spatial Room Correction Technology, and how to Measure Directivity of In-Wall Loudspeakers. Richard Modafferi describes his unique crossover design build, Frans de Wit talks about DC Power Supplies, Morty Tarr discusses important aspects of amplifier design, and Michel Nieuwenhuizen offers an Arduino-based motor control for turntables. Start reading online or in print.