This stereo noise blanker or suppressor attenuate the noise with 45dB when the music signal is low or null, is just a noise limiter. The noise blanker sensitivity can be adjusted with P1: the highest it gets the faster the noise suppression occurs. It has only one IC – 741 and 3 cheap transistors.
The maximum input level is 210mV and the distorsion is less than 0.01%. The delay time for this circuit is 1S and depends of R7 C4 values. The power supply is between 12V and 30V and the current consumption is 2-3mA.