OK, so I bought a trashed Dynaco St-70 from this guy on craigslist and rebuilt it from the ground up. I have added new tube sockets, can cap, bias supply, tubes, choke, power transformer (Tomiko toroid), new output trannies (Tomiko), and a new board I got off the bay (China) that uses the 6GH8 tubes. With no input hooked up there is only a slight hum, but as soon as I hook up an input, there is a very very loud hum that is so loud that I quickly power off the amp out of fear of something bad happening. I have already tried two different new can caps, 3 new rectifier tubes, and checked and double checked all solder connections and made sure everything is wired correctly.With no input connected, if I as much as run my hand next to the input I get a loud hum. I am at my at the end of my rope with this thing and would really love to listen to it!
Update:
Ok so it really is only the right channel that hums, also with both input tubes removed, the amp is dead quiet. I am going to replace all the resistors on the board just in case and maybe the coupling caps.