PURPOSE: To couple directly a line amplifier and a recording amplifier by decreasing a time constant comprising a negative feedback resistor of a negative feedback amplifier and a capacitor between a negative feedback point and a common point less than a time constant viewed from a control circuit to control a transistor (TR) of said capacitor circuit.

CONSTITUTION: The negative feedback resistor R3 is connected between an output point of the negative feedback amplifier 2 and its negative feedback point, and a passive circuit having a series capacitor C5 is connected between the negative feedback point and the common point through a switching TR1. The 1st time constant comprising the negative feedback resistor R3 and the capacitor C5 is decreased less than the 2nd time constant comprising an impedance viewed from the control circuit connected to a base of the TR1 and the capacitor C5. Thus, the effect due to a charge current is almost eliminated and distortion is reduced remarkably.