| 摘要 |
An audio amplifier circuit according to the present invention features an arrangement of a power line with a smoothing capacitor inserted as a power filter and a power line without such a smoothing capacitor. The audio amplifier circuit in which an input stage amplifier of a main amplifier is supplied with power via the former power line has a muting circuit for rapidly charging a negative feedback capacitor for generating negative feedback voltage to be fed back from the following stage of the main amplifier to the input stage amplifier up to a voltage level at which a pop sound is inhibited when the power is supplied and for rapidly discharging the negative feedback capacitor up to a reference operating voltage level when the voltage of the former power line with the smoothing capacitor exceeds a predetermined level, the voltage of the former power line being monitored after the power is supplied from a power supply. In this way, the negative feedback capacitor connected to the input stage amplifier of the main amplifier is caused to perform a muting operation by rapidly charging the capacitor up to a level higher than a pop sound level. A point of time the muting operation terminates is determined by a point of time the negative feedback capacitor is caused to start to discharge itself by rapidly discharging the charge of the negative feedback capacitor.
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