Ok, I have a midi keyboard connected to my arduino, and I'm using the arduino midi library to read the keyboard and generate a certain frequency square wave signal based on the key being pressed. The signal goes into a speaker. The problem is that whenever I press a key or turn any knobs/wheels on the keyboard, I can hear a clicking, popping sound. Pressing a key makes one little pop, turning the knobs makes a bunch of pops as I turn them, it sounds kinda like zipping a zipper.

What's the issue here? Here's the circuit I'm using to connect the midi keyboard to the arduino:

 

Sounds like maybe your MIDI signals are creating some electrical noise.

Post some photos of the setup, both MIDI and speaker wiring.

 

Sounds like maybe your MIDI signals are creating some electrical noise.

Post some photos of the setup, both MIDI and speaker wiring.

Yes clearly thats the problem. The midi connections can be seen in my original post. As for the connection to the speaker, the output of the arduino goes through a 1m resistor with a 5k resistor to ground (voltage divider) and out to my guitar amp. Sorry i can't take pictures at the moment. But its really simple circuit, i just dont understand how to eliminate the noise.

 

the input to guitar amp should be an analog signal by DAC of arduino. RC filter or a differential amp may cancel the noise you hear.