The “Cul-De-Jatte” is a low-cut filter (high-pass). It has 2 control buttons. The first one (Tronc) selects the cutoff frequency with a 6 voice rotary switch selector. The second button (Tête) determines the intensity of the cut.
Depending on the setting, it may cut only very low frequencies, and thus ridding the sound of 60 Hz hum caused, among other things, by single-coil pickups, and, at the other extreme, it can drastically cut the low frequencies to create a low-fi effect.