| 摘要 |
PURPOSE:To obtain a sufficient muting effect by opening directly a signal path of a muting circuit and using an auxiliary muting circuit provided separately to mute a pop noise generated in this case. CONSTITUTION:When a mute signal having a prescribed level is inputted, the mute signal is fed to a base of a transistor (TR) Q3 via resistors R6, R4. After a delay time by a time constant comprising a capacitor C4 and a resistor RS, however, the TRQ3 is turned on and a point (e) is connected to common. Since the potential at the point (e) is zero by a resistor R3, no pop noise is generated when the auxiliary muting circuit comprising the TRQ3 is turned on. After a prescribed time, the TRQ3 is turned off, since the point (e) is in the steady state, that is, potential 0, no pop noise is generated at the release of the muting circuit.
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