Tonight, I had a rather scary experience. I powered up my Crack to listen to some music when my Tung Sol 6AS7G started making audible noise and then released sparks inside the tube. This is the same tube that had made some noise in the past, but it stopped after I let it burn for awhile.
I put my old Russian 6AS7G tube in and the amp seems fine. Music is playing normal too.
Could this be due to an issue with my Crack or a tube gone bad?