Meeting Report

Speaker Design using Parametric Acoustic Modelling

Presented by Graeme Huon (HUONLABS)
Based on work by Graeme Huon and Greg Cambrell

On Monday August 14th the Section held its Annual General Meeting (details here) at the SAE Institute Lecture Theatre in South Melbourne.

The AGM was followed by a presentation by Graeme Huon (HUONLABS) on “Speaker Design using Parametric Acoustic Modelling” in which Graeme described a unique method he developed for speaker design using Spice modelling.

After a brief summary of historical loudspeakers and design processes involving educated guesses and iteration.
He then moved on to Neville Thiele’s work, describing how Neville developed a mathematically model based on a second order electromechanical filter.
Sealed and vented enclosure considerations were then outlined, arriving at the conclusion that there is no magic box design.
Graeme then moved on to Huon/Cambrell’s 1995 Parametric Acoustic Modelling (PAM), describing the complications of multiple reflections in complex resonant structures, particularly given the multiple overtones present in the simplest musical source.

He then described the rules used, recognising guided acoustics as a mesh network, which can utilize network solvers (like SPICE) to resolve a full end-to-end response.

After describing the design process he then went on to describe a typical subwoofer design (Profunder 616), and moved on to enumerate the various speaker design elements that PAM enabled, like crossover and filter parameters, loudspeaker interactions in passive crossovers, protection devices, and time alignment and propagation adjustments.
He also indicated “non-motor” design applications for his methodology – like bass traps. acoustic diffusers, automotive mufflers, and car body design.

He then spoke about the drivers used, noting the excellent work of Mike Barabasz (Lorantz) in designing the low distortion drivers used in the Profunder range of subwoofers.

The evening concluded with a Q&A, covering a diverse range of activities relevant to his modelling methodology.

A video has been assembled of the talk, covering the Powerpoint slides+audio:

This video can also be viewed directly on YouTube at:
https://www.youtube.com/watch?v=uuzVrYK0Aeg

A PDF copy of the slides presented can be viewed or downloaded here.
and
The audio-only recording can be heard or downloaded here.

Thanks to Graham Haynes and his trusty Tascam for the audio recording.

A special thanks to the SAE Institute for the use of their excellent facilities.