Help me with this Tonepad Rebot Delay circuit!

[Agung Kurniawan]

Can anyone please explain to me what does that circuit do?
I know they are both filter, but I have no idea about them

[EBK]

Take a look at this page, particularly Fig. 2 to get a start:
https://www.maximintegrated.com/en/app-notes/index.mvp/id/1762

[duck_arse]

also:
http://sound.whsites.net/articles/active-filters.htm

[EBK]

also:
http://sound.whsites.net/articles/active-filters.htm

+1
Actually, just read everything you can on Rod Elliott's site.  I've learned so much valuable stuff from him.