This is a mono preamp which will sum the channels from a stereo MM cartridge either in phase for lateral records or out of phase for vertical records. It has a selection of bass turnover frequiencies and treble cut frequencies. It provides the switching to connect the turntable to a stereo preamp for stereo records. Both EQ switches have a flat position. Selecting those will give a constant velocity response. By selecting both the 700 Hz bass turn and treble cut a constant amplitude response can be had with no points of inflection. Selecting 500 Hz bass turn and 2121 Hz treble cut gives RIAA EQ.