| 摘要 |
PURPOSE:To prevent adverse effect due to rapid stereo/monaural switching by variably controlling the mixing ratio of stereo/monaural decision output between a stereo sound field expansion output signal and a monaural sound field expansion output signal with the aid of a signal obtained through a time constant circuit. CONSTITUTION:Either of the resistance values of resistance R3 for charge and resistance R4 for discharge is 10k to 20kOMEGA, the capacitance value of a capacitor C1 is set approximately to 1000muF, and the charge and discharge is performed with the time constant of a few seconds. Therefore, even when the output from a stereo/monaural decision circuit 21 is switched from 'H' to 'L', the output from a time constant circuit 25 is gradually reduced. The output from this time constant circuit 25 is respectively transmitted to each control signal input terminal CTL of electronic volume 15L and 15R as a mixing ratio variable control signal. Thus, there is no sense of incompatibilitly since the switching between the stereo sound field expansion signal and a monaural sound field expansion signal is gradually performed. |
