A sine wave, pitched by the note played. The simplest sound source there is. What is patched into Detune can move the pitch by up to four octaves, which is what a kick drum is: an envelope that drops a sine from a click to a boom in the first moments of the note. The Detune knob sets the pitch up to four octaves either side of the note, so a sub-bass or a whistle is a setting rather than something to patch.
Four notes played on it, from a Keyboard, as a patch plays it.
ATMOSYNTH built-in module