LM386N-1 Guitar amp- get feedback/radio hum/crackle when run off AC/DC power converter...? Answered
Last year I built a mini guitar amp using the LM386N-1 IC and I followed these instructions/ schematic and modified it a little with the help of the author.
I integrated a switched DC plug so that I can run it from a 9V wall supply. When I use it with the wall wart I get a radio hum and crackle feedback that I do not get from the batteries. Is this because of the type of transformer? I've read something about audio grade power supplies before but cannot remember the ins and outs.
Does anyone have any insight into the cause of this humming?