Audio power amplifier design

Abstract: The audio power amplifier is used to amplify low-power audio signals to a level that can be suitable for driving the loudspeakers. Thus the audio power amplifier becomes a kind of essential part in the electronics that could make sounds. In this thesis, a good performance audio power amplifier with tonality control is designed. It consists of three parts: pre-amplifier unit, the tonality control unit and the power amplifier unit. In the pre-amplifier unit, a TL071CP operational amplifier is applied, to amplify the low signal to be suitable for the tonality control unit. For the tonality control unit, a filter is used to achieve bass and treble control, resulting in different frequency response. In the last part, the low voltage power amplifier LM386N-1 is used. The results of simulation in Multisim show a good output waveform and different frequency response with the tonality control. Also the pure sound can be heard by ear clearly. The good simulation result offers the encouragement to build the circuit on the board and do the measurement. The measured results show a good output waveform, the output power 256mW, THD 4.7%, the maximum voltage gain 40 etc. Meanwhile, sound can be heard by ear clearly with the tonality control. Judging from the results, the audio power amplifier is designed successfully.