I have a 65 reissue Fender Twin. When I power it up, if I immediately take it off standby, it screams the most awful and loudest static/screech I have ever heard. I almost S**T myself the first time it happened! I quickly learned to power it up, wait a few minutes, then take it off standby...this keeps the aforementioned chaos from happening. What is this? I have not had to do this with other tube amps. It was like this out of the box but I was not familiar with tube amps then and figured it was normal. I'm assuming it has to do with the tubes warming since it does not happen when I wait a few minutes. I know this isn't typically a bass amp, but guitar is my second instrument, and this is the only place I have found concise accurate info. THANKS IN ADVANCE!!!