6505+ 112 combo hum?

[Jimbofilms]

Hey there, I bought a 6505+ 112 combo from ebay recently.

There is a very noticeable hum when I turn on the amp, turning up the volume doesn't affect it.

I have changed the power tubes to Sovteks and tried replacing the Ruby preamp tubes with JJs, one by one. The hum is still there... I have read on some guitar forums that hum is normal on a tube amp, is it normal?

[ScottMarlowe]

All tube amps hum a little, that's' normal. So, is this hum 60hz or 120hz? Here's a GREAT video on hum from Uncle Doug, who really is a great resource.

https://youtu.be/GrVtX0QGNls