I just got a matched quad set of EL84's from TAD, to put into my Peavey Classic 30. The current ones were old, and had tendency to rattle. As far as I knew, and can see in the schematic, there is no adjustable bias on these tubes it is set. I started playing and it sounded LOUD...almost overly so. I checked the tubes at power up and they glowed a light red top and bottom, and blue in the middle of the tubes. After a few minutes playing the second tube was glowing like an ember from inside the middle of the tube...the first tube (after turning down lights in the room) also was glowing slightly red, the 3rd and 4th aren't showing any red. It also had a slight burning smell. I turned the amp off. Looked up the schematic on the blueguitar.org site and don't see bias (in fact one mod he has is for adjustable bias). So what is the next step? I probably can put the old tubes back in and see if there is a difference in glow in the same positions. That might tell me something. Also might be good, because the preamp tube that feeds the power section is not glowing much at all...I could see if it does with the old tubes? Any help appreciated, I may try the old tubes, but will wait for some advice before turning it on with the new ones. Is it just likely I have not got matched tubes, or something else going on? I also have a new set of 6BQ5's I could try, that are matched, but bought also at the same time.