Third Oscillator Droning and FMíng the Filter by Otto van Zanten
Copied from the video by Starsky Carr where he compares the Poly D to the Model D reissue by Moog.
If you dont want the third oscillator to drone but to track set Osc 3 control on, switch it to 4' and set the tuning to slightly under -3
Turn on the second oscillator for more bottom end.