Teensy 4.0 + Audio Shield + Guitar + High Gain = Noise

[beyound]

Hello my friends, I am a newbie.

I'm making a guitar pedal with a teensy 4.0 + Audio Shield Rev D. (Guitar: Gibson Les Paul Std connect to Audio Shield Line In with AUX Line-in Cable)
Everything sounds great, except that the teensy keeps making noise when my left hand touches the guitar strings. (Just touch, the hand has not pressed)
When the left hand leaves the strings, the noise also disappears. After the Gain is increased, the noise is more obvious. （Seems like I can generate electricity, maybe I can be a Marvel hero after a while)

Is there any way to reduce this noise?
Thank you so much.

 

[TomChiron]

The inputs on electrical guitar amplifiers or pedals are high impedance inputs to work best with such a signal. Assuming that there is no builtin preamp in your guitar it would be necessary to use some sort of pre amp / buffer for best results to offer the necessary impedance and gain.

You should find a lot of information regarding this question searching for "Teensy guitar pedal" or something similar, e.g.:
https://learn.sparkfun.com/tutorials/proto-pedal-example-programmable-digital-pedal/all

should also be useful:
https://forum.pjrc.com/threads/65795-Programmable-guitar-microphone-effect-pedal

 

[Frank B]

Blackaddr made an awesome board: http://blackaddr.com/products/
I built one - really good sound quality (better codec and good input circuit)

 

[beyound]

Thanks to TomChiron and Frank B,

I don't have a preamp, but I have an ESP32 LyraT evaluation board (with an es8388 DAC/ADC chip). I compiled the ESP32 into pass-through mode, then connected it to the Teensy and Audio Shield, then output to a TPA3116 power amplifier, and then connected to a computer speaker. That BUZZ noise is gone, it's really amazing. Thanks again for your ideas and help. ESP32 can also be used as a control unit (it also have bluetooth and WIFI module built-in, 240Mhz), the total price is not high, maybe I can use ESP32 for a preamp?

I also bought a few preamp modules, and I will test the effect after they arrive.

 

[beyound]

I just tried a Fender Telecaster and I can barely hear the sound, the ESP32 doesn't seem to be able to do preamp, I'll just wait for the preamp module.