I have a Super Reverb Reissue I bought earlier this year. Love it.

The only problem is that even on the clean channel, I get distortion starting at about 5 or 6 on the volume, and by 8 the distortion is very heavy. There's no way I could play a clean song at loud volume with this amp.

I suspect at least one of the power tubes may be going. Would that cause distortion on the clean channel at medium volumes? I'm just wondering if the volume is actually lower because a power tube is going (can they be weak but still function?), and so the distortion is kicking in at what would be a lower volume setting with fresh power tubes.

I've used both 12AX7 and 12AT7 tubes for preamp and it's the same thing.

Thanks for any replies.
You just described every old Marshall.

Power tubes.
Gilchrist custom
Yamaha SBG500
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100

Cathbard Amplification
My band
Thanks for the reply. Now the standard question: which tubes to buy as replacements?

I've been looking here on UG and elsewhere for information on various 6L6 power tubes. The ones in the Super Reverb now are Fender GT's made by SovTek. I don't know what the power rating is, but maybe they were low for early distortion.

I'm looking at JJ's and Fender GT6L6 GE's and GT6L6 S's.

I've been trying to nail the SRV sound and, contrary to what I hear often on YouTube with SRV tutorials, he didn't use a lot of distortion, at least in the songs I like. I figure I can get more distortion if I need it through the Tube Screamer.

So, any recommendations?
That's not what he meant.

You turn the amp up loud you get power tube break up. There's nothing wrong with the amp or the tubes.

If you want less breakup you could always switch to 6V6 tubes, or swap out some of the 12ax7s for 12ay7. That however would also lower the overall volume of the amp.

Correct me if I'm wrong though... Isn't 5 or 6 on a Super Reverb loud enough to destroy the planet, or are the reissues different?
In another thread I asked about some noise (not distortion, but something more) I was getting from the amp, and the answers were that I had a power tube going. I should have mentioned that. I thought maybe the distortion was caused by the tube going bad. As I think back about it, I could swear the distortion didn't start until 7 or so when I got the amp.

On the Fender site, they have the GT tubes in three categories: low, average and high power, with low having early distortion, average having an average dynamic range and onset of distortion, and high having a wider dynamic range and late onset of distortion.

Doug's Tubes has all sorts of 6L6 tubes, with Fender GT6L6G GE remakes, GT6L6S Sylania remakes, GT6L6 SovTek, JJ 6L6, NOS NIB GE's and Sylvania's, and a bunch of others.

I listened to a Youtube video demonstrating different brands of power tubes, and there were some noticeable differences in tone as well as distortion. The GT6L6 sounded too bright compared to the NOS RCA tube and one that was just marked "Fender" (which sounded the best).

If nothing else, I'll just go with a Fender GT in the average range.