Bass Reflex Alignments: Compliance Alteration

After discussing computation of discrete alignments such as B4, BL4, LR4, IB4, and CD4, this new article in the "Computation of Bass Reflex Alignments" article series explores the real-world situation where it becomes impossible to have a system design that exactly matches a certain driver Qt, normally described as an alignment error (or misalignment). The technique presented allows designers to modify tuning towards a desired target response function.

This article offers a timely update about the evolution of measurement microphones and the reasons for common choices for automotive measurement applications. The article also expands on current discussions about standard approaches for automotive in-cabin acoustic measurements, including the recent AES TC-AA proposed measurement techniques for automotive audio. A great overview of how measurement microphones can meet new requirements, given the emergence of new technologies, new infotainment options, improved calls, active noise cancellation, and rising consumer expectations.

In another example of cutting-edge experiments that deserve recognition, Joerg Panzer (R&D TEAM, Germany) and Patrick Macey (PACSYS, UK) detail an investigation of the sound pressure response and radiation impedance of a loudspeaker horn driven by an electro-dynamic transducer. The two authors (and creators of the respective software tools) combined measurements with simulation software using finite and boundary element methods and explored the associated issues with meshing for each method.

Designing Audio Circuits and Systems is a surprising effort by the author and one that deserves careful exploration. A true compendium of lessons in audio that reflects Bob Cordell’s long-standing track record of designing audio equipment as well as advanced test equipment. The vast content contained in this book makes it an essential reference for anyone designing audio circuits, including excellent “hands-on” material for anyone starting to experiment in audio electronics.

Although the sound field in a room at low frequencies is one of the most discussed topics, approaches to dealing with room modes are typically treated as an optimization problem, and not correctly defined. This article explores a different strategy: the so-called Double Bass Array layout, using several subwoofers placed in a pattern, on the front and rear walls. Using advanced simulation techniques in order to understand what truly happens in the resulting room mode behavior, sound pressure levels, and resonances, this article builds upon existing research (Geddes, Welti, Devantier, et al.)

Ask audio industry insiders and audiophiles alike about Joachim Gerhard, and chances are that they mention the many high performance speakers he designed over the years. But he also has a great track record designing phono preamps and this interview explores that aspect of Joachim’s career. In this second part of the interview, Jan Didden explores Gerhard's design ideas and goes into details on his Discrete INA design, a discrete input stage instrumentation amplifier topology.

In Voice Coil October 2024, Claus Futtrup writes about Compliance Alteration, and Mike Klasco and Nora Wong prepared an updated directory of Integrated Electronics for Loudspeakers. James Croft returns with a "Loudspeaker" patent review, granted to industry veteran Michael Levy, and Vance Dickason focuses solely on the eagerly awaited Purifi Audio PTT10.0X04-NAB-01 10" Midbass Woofer.

Read the extended Show Report of the 5th International AES Conference on Automotive Audio. Santiago Rayes (GRAS Acoustics) explains the latest advances in Measurement Microphones for Automotive Testing. Reinhold Lutz writes about Eliminating Speaker Doppler Distortion, René Christensen shares an exercise of Double Bass Arrays, and Joerg Panzer (R&D Team) and Patrick Macey (PACSYS) share their Experimental and Theoretical Investigation of an Unusually Shaped Horn. Jan Didden reviews Bob Cordell’s latest book, “Designing Audio Circuits and Systems”.