for the DIY audi tester can i use any capacitor or does it need to be a 0.1uF?
thanks
Is this the same as an Audio Probe? I think you can use a .22 if that's all you have handy.
Any cap will work but .1uf is a good choise since it passes most frequencies without cutting bass.
Anything higher will be fine as well.
john
You need it there to block DC while letting the relevant AC signals through relatively unattenuated, If electrolytic, make or use a non-polarized cap.