It is a four-channel voltage controlled crossfader. As the scan CV is swept from 0V to 5V, the mix output fades from channel 1, through a mix of channel 1 and 2, to channel 2, then fades to channel 3 and finally channel 4. In addition to the main mix output, there is an individual output for each channel. Front panel knobs provide an offset and attenuversion on the scan CV.
The gain of each channel is also individually controllable, so the module can be used as a four channel VCA as well. A switch allows the scanning control to be disabled so that only the VCA CV affects channel gain. Finally there are attenuator for the gain CV and initial gain knobs on the front panel.
4U format- Loudest Warning panelbuild documentation: https://hollasynth.github.io/scanner4/