Figuring out the AC equivalent circuit(re model) of a Pre-Amplifier and Tone Control Circuit
In this circuit, with numerous AC feedback paths (even the top-right C13 is a feedback element, with the external load affecting the output voltage and thus how much signal comes back thru the VDD node), the only AC model is this actual circuit.

Given the top left capacitor, 100uF tied thru R13 to the VDD node, has no purpose, I doubt this is the real circuit.