PURPOSE: To prevent the generation of a bass to the audio output of a TV picture receiving signal, by setting the DC level of the demodulated noise signal at a low value by means of a dropout wave detection output signal in order to prevent the overmodulation of an RF converter.

CONSTITUTION: The signal obtained by delaying the dropout wave detection output waveform through an LPF7 is supplied to an amplifier 8 in the noise component period of the demodulated output waveform of a video demodulating circuit 5. The DC level is set at a low value in a prescribed period for the noise component of the output waveform of a mixing circuit 10 by the output of the amplifier 8. Thus the noise component is turned into a small signal and supplied to a clamping circuit 11. Thus the signal larger than a synchronizing chip is clipped. As a result, no noise signal larger than the video signal exists any more for the video output signal. Thus no overmodulation is caused to an RF converter 13.