If all you really want is the absolute amplitude, look into using a precision peak detector circuit, otherwise you must sample the signal at a very high rate to catch the peaks accurately.

I looked into the precision peak detector circuit option but I think it wouldn't work since my "peaks" become smaller and smaller after the guitar is string is strung. I need to detect these smaller peaks also.

 

Hi A,
Interesting project, can you say why you need to detect the sound peaks of a guitar string as the vibration decays.?
E

 

I looked into the precision peak detector circuit option but I think it wouldn't work since my "peaks" become smaller and smaller after the guitar is string is strung. I need to detect these smaller peaks also.

You need a peak detector that 'leaks' i.e it has a resistor to bleed off the charge in around 200 mS. so it tracks the decaying signal amplitude.

 

hi A,
Downloaded a Guitar single note for checking wave pattern.
It is very complex, the possibility of detecting individual peaks is very doubtful.

Used the guitar note to simulate a LTSpice circuit, which shows 4 stages of the signal processing, for reference ONLY.

Added the actual Guitar sound file, delete the .txt extension and play the sound.
E

 

Seems like multiple frequencies together, maybe they can filtered out seperately.