Op-Amp circuit: Check understanding
Your general description seems to be correct.


  Shouldn't C5 and R6 be reversed to prevent the DC building up at the inverting terminal of the op-amp? Does this influence build-up of charge &amp; thus saturation?


Under normal operation the input terminals of U1 will be equal. The DC bias point is set by the bypassed divider of R4&amp;R5. Any charge or input bias current will be drained through R7.

R8 prevents overloading U1, and isolation from capacitive loads.

The input/output RC elements also serve for EMI/ESD immunity.

From the limited number of effects pedals I have seen, they tend to have the battery switched through the connector sense terminal on the input jack. So, even if the pass-through switch is engaged, the circuitry is still operating on the internal 9V battery. This prevents the click/pop from power up and sudden signal insertion. It is only if you pull out the input phono cable that the battery is disconnected.