I don't understand the connections to the variable R1 in the second attachment.
Normally the top end goes to the driver, the bottom to "ground", and the wiper to the load.
Also, what biases the inputs to the two amplifiers in the second drawing? The amps are connected between +12 and 0 V, so the bias should be around +6 V at the input. If the bias is internal to the amps, then the electrolytic capacitor is connected with reversed polarity since your generator has 0 V DC level.