A tranistorized d.c. coupled amplifier having very good gain stability, as well as very low drift of the output d.c. level, has been designed. Low frequency input signals with an amplitude of .04 to 2 volts peak-to-peak, approximately, coming from a low impedance source (voice soil of a speaker system) are amplified to an approximate peak-to-peak amplitude of 4 volts. The output is intended to drive a load of the order of 100 kohm.