a shock sound prevention circuit which provides a btl audio amplifier with stable operation about 100 msec after turning - on of a power supply is required . since the btl audio amplifier is usually integrated in an ic , use of capacitors which takes up a large pattern area on the ic chip needs to be minimized . this invention offers a shock sound prevention circuit which has a capacitance for reference voltage to generate a reference voltage which rises according to turning - on of a power supply , a first operational amplifier to which an audio signal input and the reference voltage are applied , a second operational amplifier to which a reverse signal of the audio signal input and the reference voltage are applied , a first and a second buffers to which the reference voltage is applied and a level comparator which compares a voltage of the power supply with the reference voltage .