An audio signal processing system for enhancing audio signals such as music by providing reverberation, generation of stereophonic or quadraphonic effects, chorusing, flanging, pitch change, vibrato and various combinations of these effects. An audio signal is passed through a compressor, to increase its signal-to-noise ratio,and then through a delay circuit. The delayed audio signal is passed through an expandor to restore the original input level. Preferably, before being applied to the compressor the audio signal passes through a pre-emphasis circuit and, after passing through the expandor, through a de-emphasis circuit, thereby emphasizing desired frequencies. In some embodiments, the processed output signal is blended with the received audio signal to provide a blended audio signal, and in some embodiments the processed audio signal is fed back to the system input for recirculation, providing reverberation. The delay circuit is preferably an analog shift register.