Posted by induction on Oct 06, 2021; 8:47pm URL: http://guitar-fx-layouts.238.s1.nabble.com/LPF-question-tp50267p50270.html
Looks like Voltage-Controlled Voltage Source (VCVS) low-pass filter (2nd order, non-inverting), which is a variation on a Sallen-Key filter with gain.
In case it's not obvious:
- the top left op-amp is an input buffer
- the bottom left op-amp is a buffer for the 1/2 rail reference voltage
- the op-amp on the right is a makeup gain stage
- the stuff between C2 and C6 is the filter