Pseudo quadro stereo mixer
This audio mixer is a bit special. It has the ability to add and subtract each of the six stereo channels and the resulting (L+R, L-R, 2xL, 2xR) outputs are sent to four amplifiers and loudspeakers. It can be used as normal stereo mixer also. I finished it in 1997.
The knobs are for treble, bass, balance – it is doubled for the sum and subtraction of the stereo channel (each of the six modules can be used as two independent monophonic channels also). The white fader is for sum, the black for subtractions. Volume control and panning can be done with control voltages also. The small black pushbuttons in the middle serve as functions’ selectors.