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Hey guys. I have an old Sunn 190L (similiar to the Sceptre) and have been having a bit of a muddiness problem when I turn the volume past 2. Even when I plug into the bright channel it just sounds like a blanket is being placed over my cabinet. Lots of bass and no real definition. I read somewhere that trying out different tubes might be the best solution so I was thinking about trying that. Here's a graphic I made of what tubes are in my amp now:



I'd like this amp to have a TON more clean headroom than it has now. I know nothing about tubes so any information you can pass along to help me fix this problem would be greatly appreciated!

Do you have extra tubes to try?

I don't. I was hoping someone could point me in the direction of which types to try.

I'd start by replacing the preamp tubes (the little ones).
If that doesn't help, then try the power and rectifier tubes (the big ones).

As far as tubes go, I've always had good luck with JJ's
If you call (503-659-7401) or email Bob at http://www.eurotubes.com
He'll probably be able and willing to help you out.
When it comes to old Sunns and tubes not many people have more knowledge then him.

If that doesn't help, I'd take it to a tech.

OK. After some internet reading, it seems like my preamp signal is being boosted into compression/mushy-ness territory too early possibly due to the 12AX7. So I bought a 12AY7 to replace the 12AX7 to see if that will solve the problem. I've read that a 5751 in this position will usually do the job, but I feel like a more drastic change was needed.