Here at http://year2ampproject.blogspot.co.uk you will find our year2 project blog titled "Audio Amplifier", by Yixuan Xu, Yingjie Wu and Yu Zhao, supervised by Prof. Steve Hall.
This project is an audio amplifier to amplify low-power audio signals (signals composed primarily of frequencies between 20-2000 Hz, the human range of hearing) to a level suitable for driving loudspeakers. When the input signal is only a few hundred micro watts, the output signal could be tens of watts to drive the speaker.
We designed a circuit consist of three amplification stages and one speaker. An input buffer stage, which will be an emitter-follower circuit, is to be used to reduce the loading effect of the high input resistance. The output stage will also be an emitter-follower circuit to provide the necessary output current and output signal power. The gain stage will actually be composed of a 2-stage common-emitter amplifier that will provide the necessary voltage gain.