| 摘要 |
PURPOSE:To reduce a transient sound without extending a muting period by supplying a DC voltage to a resistance with its one end connected to a joint between a holding capacitor and the buffer input terminal of a buffer amplifier. CONSTITUTION:A positive DC voltage VCC is supplied to the resistance R1 whose one end is connected to the joint of the holding capacitor C and the input terminal of the buffer amplifier 28 and one fixed terminal of a variable resistance R2 whose sliding body is connected to the other end of the resistance R1 and whose other fixed terminal is grounded. Here, the resistance value of the resistance R1 is set far smaller than that of the resistance R2, and the sliding body of the resistance R2 takes a DC voltage equal to the central current potential of a terminal voltage when the capacitor C is not holding. A time constant equal to the product of values of the resistance R1 and the capacitor C is selected to a value larger by one digit than the sufficient holding time to remove an impulsive noise in a reproduction sound signal at the time of head switching and to a value smaller by one digit than a time constant when the DC potential of the terminal voltage of the capacitor is changed due to the leakage current of the amplifier 28.
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