I have a 1993 Fender Blues Deville. Through much research I have decided to choose JJ-electronics. I understand that my amp has a fixed bias and is not adjustable. It has 3 12Ax7a vacuum tubes and 2 6l6WGC 5881 power tubes. My question is, without having to bias, what perameters do I have to stay in as far as brand, voltage, etc......... does anyone happen to know the plate volatage on these? I want tubes with a breakup/headroom as I am going to be running a couple of pedals. Any help would be much appreciated.