Trying to break out of mental stereotypes for patching, I’m delving more into feedback.  I discovered this interesting combination.  Teezer VCO Triangle out -> Oakley ADSR/VCA -> MOTM 480 In(1A); MOTM-480 HP(1) -> MOTM-480 In (2A); MOTM-480 BP(1) -> Teezer VCO Linear FM In.  The final output comes from the MOTM-480 LP (2).  Remember, my MOTM-480 is modified into two separate filter sections.  In this patch it’s in “super bandbass” mode with the first HP section in series with the second section in LP.  The feedback here is by taking the bandpass output of the first section and feeding it back to the Teezer through-zero linear FM input (AC mode).  The growly effect seems to come from the combination of the formants of the 480 modulating the VCO through zero.  The VCA in the loop dramatically impacts the sound, because the depth of VCO modulation is proportionate to the signal level.  There is a stepped random voltage generator clocked in sync with gating the ADSR/VCA that produces a new pitch at the start of the slow envelope.  I used the MPX-1 Rich Chorus to create a lively stereo field.