Decaying Feedback
Just noise and feedback.
Tune the filter to C4.
Turn up FM 2 so MIDI pitch can modulate the filter.
Subtle changes in settings and velocity can take this from gentle to aggressive. Sculpt the sound using drive, Q and Mix In-2.
Good for both atmosphere and noisy bass.
I got the idea for patching feedback into the ringmod like this from the TimeWarp2600 patch ‘Singing Feedback’ by Robert Rich.