I have a query about an amplifier I have just acquired, a second hand Roland Cube X20 . It’s in really good condition and all it’s features work fine but when I plug in the jack, before it’s connected to the guitar, I get a distinct hum. This almost disappears when I hold the the other end of the lead - except if I touch the jack tip – then it really screams.
The hum also almost disappears if I touch any metal part of the amp.
When it’s connected to the guitar the hum is still there but not so obvious when it’s being played.
I don’t know much about amps or electronics but I feel that the amp may have an earthing issue. Then again, it might be quite normal. This is my first experience with an amp so I really wouldn’t know.
Any help/suggestions would be greatly appreciated