PURPOSE: To degauss by a signal to be handled and to enhance aging effect after degaussing by reducing a load impedance of a coil while supplying a normally handled signal in a transducer circuit consisting of a coil and a magnetic core material.

CONSTITUTION: A voice coil 2 of a speaker 1 is connected in series with a network coil L1 with a core as a low pass filter between input terminals 3 and 4, a capacitor C1 as a low cut filter and a degaussing switch S1 are connected in parallel with the coil 2 to limit a signal to be supplied to the coil 2 to a predetermined frequency or below. The load side of the coil L1 is short- circuited by the switch S1. When a signal is input to the terminals 3 and 4 in this state, the impedance of the load side of the coil L1 is reduced. Accordingly, a quasi-magnetic saturation is generated in the core of the coil L1 to degauss the core.