This is a utility module we found ourselves always needing and using. The three well spaced knobs can act as active attenuators, attenuverters (bipolar) and inverting attenuators depending on the three position switches.
Each input is normaled to a dc voltage but this voltage is selectable for each channel to be 5v or 10v via jumpers. so with nothing plugged into the jacks, each knob controls a voltage amount. so if the rear jumper for channel a was set to 5v then the knob a would control the following ranges on output a: position 1: 0 to -5v, position 2: -5 to +5v, and position 3: 0 to +5v
skiff friendly (single pcb)
3 modes for each channel
5/10v normalling to inputs
with external signals it acts as active/buffered attenuator/attenuverter/inverter