Channel strip microphone preamp and equalizer features a volume control circuit with project drawings are quite detailed diagrams and printed circuit board. +/-15dB @ 12Khz shelving (switchable, either 8Khz or 16Khz) +/-15dB from 600hZ to 10Khz peaking/dipping +/-15dB from... Electronics Projects, Microphone Preamp Equalizer Circuit Channelstrip "audio control circuits, " Date 2020/04/27