FOUR-CHANNEL STEREOPHONIC REPRODUCING SYSTEM

摘要

A four-channel stereophonic reproducing system for reproducing CD-4 type four-channel records. At the time of start of playback of a four-channel record and upon appearance of the sub-carrier wave of the sub-channel signal, the muting circuit provided in the sub-channel signal processing circuit is not immediately rendered inoperative lest a large d-c level change take place at the output side of the detector resulting in production of a loud foreign sound from the loudspeakers. To achieve this operation the muting circuit is gradually made inoperative after appearance of the sub-carrier wave of the sub-channel signal. Also, a four-channel record can be reproduced as a two-channel reproduction with passage of the sub-channel signals blocked through operation of a select switch.