So I've found an amp that I think I'll buy, but I've only got one reservation. The power tubes are listed as 3 JJ EL84s and 1 Fender EL84 (it's used). Would this be too big of a deal, or should I replace them as soon as I get it?
Well, it's better if they are pre-matched.
One of the tubes may not be working up to par, so another tube has to work that much harder to pull it up.
Often, it ends up dropping the odd watt or two. But if it's an extreme case, such as it sounds muddy, and if you can tell if it's as loud as it should be, then change them to pre-matched tubes.
Quote by leeb rocks
considering you have the money, id get the right tubes. it makes all kinds of difference in the sound
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Quote by primusfan
you shoulda lynched that nigger.

*spits in spittoon and feels up his cousin*
I'd replace them right away with a matched set and a bias.

I don't think it's too bad that it's like that, but I could see it causing major problems as well, so I would be safe and get it taken care of.
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If the current draw is the same on both tubes then you are fine, no need to replace anything.
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