| 摘要 |
PURPOSE:To decrease click noise at muting release by turning off a constant current source during muting and turning on the 1st and 2nd switching means so as to decrease the current consumption during the muting. CONSTITUTION:In turning on a muting switch 24, a transistor (TR) 10 is turned on, TRs 12, 13 are turned off, no current is fed to an output amplifier 1, which is turned off. Since the TR 11 is turned off, a collector current flows to the TR14 by a current mirror comprising of the TR14 and a diode 16 and the electric charge in an output capacitor 2 is discharged by constant current through the current mirror comprising of a TR15 and a diode 18. On the other hand, the capacitor 3 is charged by the current mirror comprising of a TR9 and a diode 16. Thus, no current flows to the amplifier 1 during the muting period and the amplifier 1 rises from zero at the release of muting and no click noise is generated.
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