Balanced stereo preamplifier circuit diagram composed of OPA2111

As shown in the figure is a balanced stereo preamplifier circuit . Figure (a) shows the left channel preamplifier circuit, and Figure (b) shows the right channel preamplifier circuit . This circuit uses dual operational amplifier OPA 2111. The left and right channels respectively use one of the dual operational amplifiers OPA2111. Therefore, there is good matching between the left and right channels (the gain difference is 3dB, the bias current difference is 0.5pA, and the drift difference is ±0.5μV/℃), which is extremely suitable for forming a balanced stereo preamplifier. It can be seen from the figure that the left and right channel circuits are exactly the same. The capacitors 0.01μF, 0.03μF and 1μF in the circuit all play a role in improving the sound quality. The adjustment range of the semi-variable capacitor CT is about 0.01~0.047μF. The IF gain of the circuit shown is approximately 26dB.