I got a lee jackson gp1000 off of ebay some time ago and I have to say it kicks major ass and im a lot closer to the tone I've always wanted. However, with the gain turned up and all i get a pretty bad hiss and sometimes when i mess around with controls, like have distortion up with pre volume gain thingie half way i get a really loud tone noise that i can control the pitch of by the volume knob. I am also going to replace my emgs with some passives and would probably need more gain out of the preamp. I dont know what kind of tubes are in there now because they are in some kind of metal tube things but im guessin theyre probably rather old and suck. Would switching to JJ tubes or some good brand give me better sound? And if so what brand would be good. And finally if i do get some new tubes do I need to take it to a tech to put em in and bias it, becuase my dad could install them easily enough but would have no clue how to adjust the bias.

best thing you could do is contact the manufacturer and tell them what you said here. failing that, a repair agent or a music shop.
anyways, brand of tubes isnt as much of a concern as the type. 12A7X 6LGC somwthing or rather are usually preamp tubes, and EL34s. the type affects your tone alot, so choose wisely. you can also get 5881 and 6550 tubes.

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my peavy classic 50 has two 6L6 tubes, what exactly are 6L6 tubes?

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So can preamp tubes be changed regardless of type, like i can take out my 12ax7s for el34s or somethin?

I dont think so. Search the web or check out the harmony central amp forums, they know ALOT about tubes and such

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No, unless you have a bias switch, you have to use the same kind.

Changing to JJs or another high quality brand of tubes will improve tone.

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Checkout this site : Watford Valves you can find/learn everything you need to at this site.

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