My project consist in connecting my electric guitar to the arduino and make the led strip blink.
Since the electric guitar signal is weak I have it connected to stomp boxes first to boost the signal a little.
I don't think the connection to the arduino is right even though it works when I strum the guitar,
one of the reasons is because the threshold has to be set really low around 10,
and the other one when I switch to fading mode using PWM a buzzing sound comes out from my amp,
I think I'm creating a ground loop connecting the guitar this way.
So the connection is like this:
The positive side of the jack goes to A0 and the negative side to GND and I have a 1Mohm resistor in parallel (the connection idea was taken from the nocksensor project) http://www.arduino.cc/en/Tutorial/KnockSensor