Microphone and Loudspeaker Design

Microphone and Loudspeaker Design is a second year module on the BEng Acoustics and Audio Engineering degree at the University of Salford.

Loudspeaker (and microphone) design is the perfect example of a multi-physics problem, requiring an understanding and bringing together of many branches of physics and engineering. In the quest to understand and develop suitable design methods this module covers a broad selection of topics, including: electronics and circuit theory, mechanical vibration and dynamics, magnetism, and acoustics.

This page is primarily to offer my current students a convenient way of accessing lecture material (lecture notes and slides) all in one place, but also as a resource for anybody who might find these materials useful. Their use of course comes with the usual caveats… Whilst I have tried to ensure these notes and slides are free from any errors, I cannot guarantee that this is the case. I can therefore not be held accountable for any poorly designed loudspeakers that have their origins in these notes!

Course notes

Week 1: Module introduction, lumped parameter modelling, AC circuit theory

Week 2: Electronic filters, the mechanical domain, and equivalent circuits

Week 3: Impedance vs mobility analogues, Q-factor

Week 4: Mass-spring loudspeaker model, transient analysis, acoustic domain

Week 5: Mass-spring loudspeaker model, acoustic domain, domain coupling

Week 6: Domain coupling, removing transformers, Norton’s theorem

Week 7: Sound radiation, acoustic loading, directivity

Week 8: Infinite baffle, electrical impedance, Theile-Small parameters

Week 9: The sealed cabinet loudspeaker

Week 10: The vented cabinet loudspeaker (part 1)

Week 11: The vented cabinet loudspeaker (part 2)

Week 12: Performance parameters and magnet/voice coil design