Low distortion audio limiter circuit diagram

The level in the audio limitercan be adjusted using the limit level trimpot. If the potentiometer level is exceeded, the output of the limiting detector from half the op amp (acting as a comparator) causes the LED to light up and the photoresistor's resistance rapidly decreases. At the same time the gain of the limiter of the other half of the op amp increases. When the signal falls below the desired limit level, the LED goes out, the resistance of the photoresistor increases, and the gain of the op amp's limiter is reduced to normal levels. The combination of resistors R1 and R2 determines the normal level of gain.