There is currently a 3-module challenge going on over on DivKid’s discord, and this week it is filters only. Copying what I posted there (using Sisters and QPAS):
FWIW I went through the exercise this morning of building up a Sisters/QPAS patch step by step, documenting the additional feedback paths on each additional recording. Track thumbnails also document the state of the patch. Maybe someone will appreciate it. It was a good exercise for me to understand (and I use that term liberally) what is happening in these feedback paths.