CD-4 IC'S for High-Quality Demodulators for 4-Channel Discs

This paper reports improvements on the CD-4, discrete four-channel stereo system including newly developed integrated circuits. Up to now, the CD-4 systems have been considered to possess several disadvantages in performance compared with conventional two-channel stereo systems. These disadvantages were, for example, unsatisfactory signal-to-noise ratio (S/N), frequency response, distortions and unusual shock noises in the absence of a subcarrier as well as cross-modulation between the main and subchannels.