General Op-Amp question

[EBK]

I need to get an overview of the principles to fit into my poor ADHD addled brain first.

That's why I used the word "magic" in my explanation.   

[PhiloB]

Reddesert, thank you for the in depth explanation.  I have a better understanding but will check the link and reread later tonight.
But what I understand, if I remove the op amp from the socket and probe on the "right side" of r5 I'd hear audio.  This also explains why it sounded like PIN6 was "grounding out" somewhere.


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[reddesert]

A picture, as always, is worth a thousand words written while tired, so here is an example drawing of what goes on in this circuit.  I've drawn it as if the first op-amp is outputting a +/- 1V ac signal wave, and labeled the voltages and the current flow through the resistors. The two drawings are similar but one is for the trough of the wave , and the other is for the crest of the wave, so you can see how the output signal varies and the voltages change, but the voltage at the inverting op-amp does not change. The direction of current flow changes, as the voltage drops across R5 and R6 change. (The "v" and "^" in the current label are just my attempt to show the direction of current flow, because I don't know how to draw an arrow in Eagle.)