Hi, I am thinking of adding a clean blend circuit to a Paia Gator swell pedal and I don't want to run into phase cancellation issues. I'm not great at understanding these type of circuits, beyond being able to recognize an inverting or non inverting opamp......
Here is the schematic (I posted a link because the image seemed to be huge):
http://gaussmarkov.net/layouts/gator/gator-schem.png (http://gaussmarkov.net/layouts/gator/gator-schem.png)
I can see that IC1 inverts, but after that I get confused. The 3 stages on the lower half return to IC2 (the 3080) and I really have no idea whats going on there. ;D ::)
Help is much appreciated!
Here's a link to download the PDF of the original project which includes a pretty good explaination of the circuit.
http://www.paia.com/talk/viewtopic.php?f=6&t=204
IC1 does NOT invert. Simple follower.
(using the gaussmarkov notation)
IC2 is fed at its "-" input. It inverts.
IC4A is connected inverting.
Follow + invert + invert = no-inversion. Output is IN-phase with input.
> The 3 stages on the lower half....
...are NOT in the signal path. This is a "small demon working a gain knob". No effect on signal polarity.
You could instead have just added your Blend and tested for cancellation at center, then (IF cancelled) figure-out what to do.