I have a Randall RG100SC (100 watts, two 12" Celestions) that has developed an annoying buzz. I turned it on the other day and there it was. It is definately coming from the amp because it does it without a guitar or any cables plugged in. I tried to pinpoint where the buzzing sound is coming from but it is difficult to do. It almost seems like it is not coming from either of the speakers. Now I'm a dummy when it comes to amps so any help or input from someone who knows more about them would be greatly appreciated. Also, there is a small box above the speakers that the speaker wires run from. Is this a transformer or something? It has this written on the outside of it: GA 100 120 60
built-in thermal fuse

It almost seems as though the sound may be coming from the area that this thing is located. Any ideas?
Love is a friendship set to music.