This is a preamplifier with 48 V phantom power for professional microphones. Gain can be set in 6 steps from 20 to 70 dB, 20 dB by 1: 10 input transformer. The analog +/-12 V/+48 V power supply is kept separately on a 2nd PCB.
The project consists of 2 PCBs. One for the microphone preamplifier (140426-1 v1.1) and one for the power supply (140426-2 v1.0). All parts are through hole.