Ι know how to measure fr, the impedance is that i want to... can you tell me how ? i dont use external soundcard(i have usb mic for the fr. )
As i can see in the drawing i must put a sense resistor the same value that the panel displays first of all, but i dont have separate sound card so how would that be?
Just on series in one channel to the one of the binding posts (+ or - ) and the other where ?