I bought a used mesa 2-90 a while back and it seemed to work fine for a few months but now the sound is gettin kinda weird,like when I turn the volume up it'll start to fade away and kinda sounds like the volume is goin up and down a little and it just plane ol dont sound so good anymore. My question would be , how do you know when tubes need replaceing? What are the symtoms of bad tubes? Thanks

Those are some of the usual symptoms.Shitty,weak tone,lower volumes,ect.

I can turn up the volume to 50% and it might sound ok with just me playin, but when my whole band starts to play and I need to turn up the volume to like 75 or even 100%, it doesnt get any louder, just shitier soundin.

what would it cost me to have it completely retubed? And would I have to send it to mesa or are there usually local people that do that kinda stuff?

heh, you can just buy the tubes and do it yourself. just be carefull you don't fry yourself

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dont they have to be biased? is it possible to get trim pots installed on the 2-90. I saw that video on the randall amp site where they are describing there new amp with the modules and they were showing the back and how the trim pots work, its pretty cool, I want em..

depends which ones you need. turn your amp on and look at the tubes, do they all light up, if not which ones dont ? (bigger ones= power tubes, smaller ones=preamp tubes, should be 4 of each)

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Wait what?

the small ones are the preamp tubes and the big ones are the powertubes.

haha yea oops

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They all light up and look just fine but I can only see the 6l6's. I know it has some 12ax7's as well but they are inside. Could they be bad if they all light up and look fine?

If they are wearing out,they still light up and everything.If they dont they are dead.

hey, I talked to a dude at guitar center and he said cause the amp is class a/b that it DOES need to be biased, is that true? I keep hereing different from people.They also said that the 6l6 tubes are like $40 a peice and the 12ax7's are like $15, are they really that much?

Yes, and why do you have a SN almost like mine?

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wasnt tryin to copy ya, thats just all I could think of.

its not really that close to yours soul

about the amp needing to be biased, i think all tube amps have to be

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According to mesa you do not need to bias the tubes as long as you're replacing mesa 6l6's with mesa 6l6's. This info is in the 2:90 manual or the 2:100 manual(i dont remember which one). mesa released an article talking about how people get jipped into biasing their crap when its not always necessary.

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tis true... mesa amps are typically biased in the same range these days(a bit cold too) and all their tubes are matched and tested to fit that range.

now of course, lets say you don't want to play crummy old mesa tubes... lets say you want to upgrade to some jj's or something... then you need to git er all biased up and whatnot.

on another note... i see alot of lazy techs using this to their advantage... a kid brings an amp in wanting to get it retubed an rebiased. so they just throw a matched quad in and say the amp is go to go. charging full list price for the tubes and like $20 for doing the "retubing"... which consists of them popping the old tubes out and putting the new tubes in.... 4 minutes of work even a child could do.

so watch out for those guys. buy your own tubes, bring them with the amp, and explain what you want done.

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