We got this circuit in a publication of 1987. This is an audio limiter, a circuit that cuts peaks that eventually become unpleasant to the ears or cause distortions. The circuit can be mounted with BC548 and BC558 transistors and requires symmetric source. The other components are common and equivalent operational amplifiers can be used. As the circuit operates with low-intensity and high-gain audio signals, signal cables must be shielded and the power source must have excellent filtration. The input impedance is 45k and limited signal level is around 70 mV. The output signal level is limited to 775 mV.
