Reduction of Audible Transients in Digital Amplifiers

Michael Gade Voss

AbstractA well-known problem in single-ended single-supply power ampli ers is the presence of audible transients when powering up the amplifier. One type of amplifier having this problem is the single-ended digital audio power amplifier. The signal in this type of ampli er is a pulse-width modulated signal, from which the audio signal is restored by passing it through an output filter, which is a second order Butterworth low-pass filter. This thesis deals with the process of starting up the amplifier without the presence of any audible transients. This involves the transition from no input signal and a relaxed output lter to a pulse-width modulated zero signal and a non-relaxed out- put filter.

In the present thesis models of the output stage will be made in SIMULINK and MATLAB. This should provide a platform for simulating the output stage when excited by different input signals, making it possible to optimize an input sequence that should bring the output lter from the relaxed to the non-relaxed state without any audible transients being present. In addition a line of practical experiments will be performed. In these it will be attempted to nd an input sequence that can start up the amplifier without the presence of audible transients.
KeywordsDigital Audio Power Ampli ers, Clicks and Pops, Output stage, Pulse-Width Modulation, Start-up sequence
TypeMaster's thesis [Academic thesis]
PublisherInformatics and Mathematical Modelling, Technical University of Denmark, DTU
AddressRichard Petersens Plads, Building 321, DK-2800 Kgs. Lyngby
NoteThis thesis in not public available. Supervised by Assoc. Prof. Jan Larsen
BibTeX data [bibtex]
IMM Group(s)Intelligent Signal Processing

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