TOV Problems

Yesterday, I turned on my TOV for the first time in 3 weeks. After playing for about 30 minutes, the amp started making a low continuous hum/rumble that would not stop until I put the amp on standby. It did this only on channel 2. When I turned the SB switch back on , the noise was gone, but would reappear shortly. I had the amp serviced at Mesa about 2 years ago. The replaced LDRs and it sounded great. It was retubed then as well. I do not gig. I only play the amp about once a month. I am going to put the old EL34s back in today in place of the newer 6L6s to see if it's the power tubes. Anybody got any other thoughts that might help ?


Thanks, Mike

From your description, it sounds like your amp could be "motorboating". Hopefully just a bad preamp or power tube. Try swapping them out, one by one, (in pairs with the power tubes) with a known good tube.

Did you have the Red channel in Modern? If so, it's probably a bad power tube. The reason it will only show in Red/Modern is because that mode switches off the power amp negative feedback, which acts to regulate the power stage - without it, there is much less damping and anything wrong with the power stage will come through a lot more. It's probably only just on the point of it normally.

If it's this, get it to make the noise then try gently holding each of the power tubes in turn (you may want a cloth!) and see if the noise stops with any particular one. If it is this, you should probably be able to stop and start it at will by either holding or tapping the suspect tube.

I put the EL34s in and let it warm up for 20 minutes, then played it for about 30 minutes. It never made that sound again, so I'm going with the bad tube/s. I will try the 6l6s again and see if moving one of them causes the problem to reappear. Forgot to mention there was also some crackling before as well. Not there now. I really prefer the 6L6 sound, but don't feel like cranking out the dough for new tubes given the fact that I don't play that much.

Thanks for the replies......

Mike