I recentley purchased a used, original 5150 head, It sounds really muddy, Sometimes the volume fades in and out, and at times the notes become So muddy that you can't even hear them well, with almost NO sustain, so I replaced the Power tubes in the head, I can't really tell if it made a difference or not, I used grooves for the power tubes, Then I could really only get a usable tone for the music I play (METAL) with an eq in the loop and a overdrive infront of the amp. So just yesterday I replaced the preamp tubes, thinking that it would make the tone better, I put the tubes in, and apparently musiciansfriend sold me some bad tubes, I bought 1 tung-sol 12ax7 and 4 EH 12ax7eh tubes, I put the tung-sol in V1, I turned the amp on and it started making a weird noise, and it seemed like the tubes blew. I am pretty new to tube amps, Any one have any sugestions? or advice? is my amp bad? Thanks!
Sounds like there is something wrong like a bad connection or solder somewhere. I had a similar experience with my ampeg and I took it to marshall to get checked out about 6 months ago have had a problem since =]