4-Channel stereo recording and reproducing method

A method for recording and reproducing a 4-channel stereo signal wherein the reproduced signal can be used with conventional discrete signal or matrix stereophonic systems. Four related audio signals are matrixed to produce a first main channel audio signal, a first sub-channel audio signal, a second main channel signal and a second sub-channel audio signal. The sub-channel signals are modulated, and the first main channel signal and the modulated first sub-channel signal are recorded on one recording surface of a record. The second main channel signal and modulated second sub-channel signal are recorded on another recording surface of the record. To reproduce the original four related audio signals, the first and second sub-channel signals are demodulated and the first main channel signal, first sub-channel signal, second main channel signal, and second sub-channel signal are matrixed to produce the four related audio signals. The matrix is arranged such that if only the main channel signals are applied to the matrix, an output compatible with a conventional matrix stereophonic system will be produced. If, however, all four signals are applied to the matrix, an output compatible with prior discrete stereo signal systems is produced.