Motional Feedback in a Bass Loudspeaker

Digital Implementation

Bachelor thesis (2018)

Authors

S.A. Hijlkema Electrical Engineering, Mathematics and Computer Science
B. Regmi Electrical Engineering, Mathematics and Computer Science

Contributors

G.J.M. Janssen (supervisor 1)
Faculty
Electrical Engineering, Mathematics and Computer Science
Copyright: © 2018 Sybold Hijlkema, Bishwas Regmi
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Published Date

02-07-2018

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Abstract

This thesis describes the digital implementation of a motional feedback system for a bass loudspeaker. Motional feedback is used to suppress the linear and non-linear distortions produced by the loudspeaker, especially at the low frequencies. An accelerometer is mounted on the cone of the loudspeaker to provide the feedback signal. The controller which consists of a PI controller and an equalizer are implemented on an FPGA. The equalizer, which is the inverse of the linear model of the loudspeaker, is used to compensate for the linear distortion. The PI controller with negative feedback is used to suppress the non-linear distortion. Not all measurement results are available at the moment of submission of this thesis. However, simulations were carried out on the model of the loudspeakers which show that the linear distortion is fully suppressed. The reduction of the non-linear distortion due to the controller can not be seen in the simulations.