Tubes are way off....HELP!

[LivewireBlanco]

I just checked my tubes in my 2266c and I got 44.2 mA on one tube and 52.0 mA on the other! I have had my amp about 14 months now. Should I switch the tubes around and see if it's any better or what? Is it time for new tubes?

[LivewireBlanco]

Swapped the tubes around and same readings. The one tube is hot no matter which socket I put it in.

[Dave W]

I read in one of the more recent posts about biasing where there was the room for error/tolerances. I believe its 8. Like 72-80 on the 2466, it may be less on the 50 watter. If you swapped the tubes to the other sockets and the higer number travels wih the tube then it seems clear its the tube not the electronics. I do not know if it will damage your amp at that difference, but it may not be the best tone possible, my ear probably could not tell the difference. My concern would be that if the tubes were matched at one point then one is now drifting then when will it go bad, a week a year? My thought would be to swap tubes or at least start saving up to. I know they are $36 plus shipping but may be better off in long run. See what those with more knowledge say. You may be fine though, its only 5.8 points. maybe rebias to get that hot one down to the recommended number and check the bias frequently.

[Dave W]

I am a dumbass and cannot add. I said they were off by 5.8 and its 7.8. My bad, sorry. I just checked back with the bias thread for the 2226 and its 43-48 which is 5 points tolerance in the 50 watter as opposed to 8 in the 100 watter. 7.8 is more than 5, I can do that math. See what others say, my guess is one tube is slowly fading and may need to be put to rest.

[lowenzz]

lower it down till the highest one is at 48mv. Yes that spred is a bit much. I've gotten two matched sets now and they were both around
4-5mv spred, even that seems a bit much for being matched to me.

I'll just take a guess that it's probably not wise to go over 50mv.

According to Steve D, max is 48mv.

[LivewireBlanco]

I was checking because our sound guy was saying that he was getting a very thin sound from my amp. Suggestions? I may be interested in trying the Golden Lions. I want a little fuller sound from the amp and my combo has always suffered from the tube rattle.

[Dave W]

I know some guys do not like the idea of using JJ's because of the bases and thus having to use spring style tube retainers, but I have talked with Bob at Eurotubes and I trust him completely, call him, he knows his stuff. I read some reviews/comparisons from several tube stores online and the JJ's seem to be the most rugged made(the tube store the tube depot reviews of KT66's). They would seem to be less of a risk with tube rattle or at least prolong the inevitable.

[SteveD]

The parameters of output valves do indeed drift with age or more specifically use, and eventually will go out of acceptable tolerance, sonically degrade and maybe even blow. I would recommend replacing your output valves (Shuagangs recommended) and holding on to your existing pair for spares just in case.

[surfnorthwest]

I would recommend replacing your output valves (Shuagangs recommended)

When I first got my 2466 I spent some time changing tubes as a experiment to satisfy my curiousity. My amp guy has all kinds of tubes in stock so this was easy to do. IMO the power vales in this amp sound perfect with the Shuagangs (also labeled as Valve Art) and the Pentas sound fantastic also. I thought the Lions and the JJs were not as good, and both were more money. The most expensive tubes are not always the best sounding tubes.

[LivewireBlanco]

Cool! Thanks for all of your help everyone! I was really going to pull the trigger on those Gold Lions but after hearing Steve and Surf recommend the stock tubes I will just go with them. I hope it's the tubes just getting old that made them drift out of bias. I am glad I checked them before anything happened. My band has some down time from recording and gigging and I just thought I would see what they were running since they are about a year old now. Looks like it was a good idea! I think I will be checking my bias on my JTM45 next!

[lowenzz]

I would recommend replacing your output valves (Shuagangs recommended)

When I first got my 2466 I spent some time changing tubes as a experiment to satisfy my curiousity. My amp guy has all kinds of tubes in stock so this was easy to do. IMO the power vales in this amp sound perfect with the Shuagangs (also labeled as Valve Art) and the Pentas sound fantastic also. I thought the Lions and the JJs were not as good, and both were more money. The most expensive tubes are not always the best sounding tubes.

Penta's are also shuagangs, Those are the ones I installed after my fiassco aways back. Very happy, and no drift yet after about 4-5 months in my 2266.