First of all, a big thank you for all who made this possible. Especially the community contributors.
I kind of fumbled around trying to find the right way to upgrade this unit to have FFT functionality. I found the following link very helpful: hifiduino.wordpress.com/2011/04/ … art-guide/
I just picked my unit up from a small office in Santa Clara after buying it on ebay. Had it in my hand within 30 minutes of using buy it now. The reason I got it was to look for harmonic distortion using the FFT function. I realize its not a 10k$ spectrum analyzer with 24 bit resolution, but for 175 bucks I’m sure it will find any glaring abnormalities in a signal.