Wave folding is when a waveform that exceed a maximum volume is folded back on itself rather than being clipped.
Wave Folding is another concept available in your Mavis to change the harmonic content of the sound, and Mavis is the first Moog instrument to ever feature a wave folder. The wave folder is not part of the Mavis signal chain by default, and must be patched in to use.
Patching any signal to the FOLD IN input jack will connect that signal directly through the wave folder to the VCF and VCA, bypassing the VCO.
In order to try this out, return all of the parameters to their default settings and rotate VCO WAVE fully counterclockwise to the saw wave.
Next, connect a patch cable from the VCO output jack to the FOLD IN input jack. As you hold down any key on the keyboard, slowly rotate the FOLD knob back and forth between the full left (counterclockwise) and full right (clockwise) position to hear how controlling the amount of wave folding affects the timbre of the sound. Generally, rotating the FOLD knob to the right will add a more aggressive sound.