Amp buzzing / shielding question

[Pea Turgh]

I put this little amp module kit together and stuffed it in a wooden box I had lying around.  Made it look nice, and it works, but the buzzing is off-putting.

 

I know not what I’ve done, I have no training or skills, just daft ideas and the occasional 10 minutes spare!

 

What would cause buzzing in an amp like this?  Bad soldering?  Lack of shielding?

 

(powered from a 9v pedal supply).

 

 

[Mottlefeeder]

Lack of shielding is a possibility, but also poor earthing practice.

Wire has a small but significant resistance, and if you daisy-chain the earth connection from the input socket through the amp to the power supply, those small resistances can cause problems. Better practice is to pick one earth point, eg the power input socket, and run a separate wire from the amp, the input socket and the output socket to that point. It's known as star point earthing.

David