AUTOMATIC REGULATING CIRCUIT FOR REPRODUCED SOUND OF AUTOMATIC PIANO PLAYER

摘要

PURPOSE:To make reproduced sound close to that in recording by comparing volume information recorded on a magnetic tape to actual reproduced sound and by automatically correcting a difference in recording level when it is found. CONSTITUTION:Comparators 3a and 3b, and amplifiers 4a and 4b for low-frequency-range volume information signals and high-frequency-range volume information signals are provided. Even in reproduction, the main part of recording circuit 1 is put into operation together with them, outputs of amplifiers 15a and 15b of circuit 1 and those of switching circuits 25a and 25b of reproducing circuit 2 are sent to comparators 3a and 3b for comparison, and their differences are amplified by amplifiers 4a and 4b so as to vary biases of amplifiers 22a and 22b of circuit 2, thereby exercising automatical control over amplification degrees. Therefore, reproduced sound is caught by volume sensor 11 in reproduction and the output of circuit 1 is compared to that of circuit 2 by comparators 3a and 3b to control automatically the amplification degree of circuit 2.