Ol Boy Rivers

It's been a while since i've been online. ( Work. ) I'm coming into possession of an old Crate mosfet amp, and I don't know the preamp tubes it takes. ( The amp is so old the tube labels arn't even there ) It's a CRATE GT-200H, has four preamp tubes. I KNOW for a fact one is a 12AU7, outside of that the tubes wording are so old and rubbed out I can't make out details. Thanks a bunch, Miles! =D