StereoChorus code in JUCE GUI Application (and not VST) make noise with electric guitar

[areFranz]

Hi!
I've converted your Stereo Chours code to a GUI Application for guitar.
But if I connect a mic, i ear clean and effected sound, instead if I connect an electric guitar,
I ear some noise.
Can you tell me why and the way of correct this bug?

Thanks
Francesco