Any ideas on what I am doing wrong?
On the packaging of the diode I am using it sais: 1N4001
Not without you posting a good picture of your wiring.That is a rectifier diode and while it will work the response is not so fast, so try a small signal diode like a 1N4148.Also with a diode your audio signal needs to be above 0.7V for the diode to conduct.
Does the signal also has to be above 0.7V for the 1N4148?
With very load volumes I am getting a reading, otherwise I get no reading at all.
Can this be due to the fact that the diode only conducts when the voltage is above 0.7V?
Or should I find a way to amplify the signal?