I've had my Peavey 6505+ head for a couple of years now and I'm obviously going to have to replace the tubes at somepoint. I've never done it before but it seems pretty straight forward from videos and guides I've seen.

As I only use the distortion channel (multi-effects for cleans) will I only need to replace some of the 12ax7's or all of them?
Generally, you won't have to replace the pre-amp tubes through general use unless a tube becomes microphonic (you'll know when this happens). Power tubes will wear out with extended use, especially at good volumes.

You'll usually only want to replace the pre-amp tubes for sonic reasons, to tweak your tone, lower gain/higher gain etc.
I have the 112 combo version of this amp and I replaced the first three tubes with EHX 12ax7's and i noticed a difference in the clarity of the amp, it sounded less muddy to my ears.

if you live in england try watford valves they have lots of pre amp and power amp sets designed for the peavey 6505 and also they have lots and lots of different tubes to choose from. thier customer support is amazing as well just email them what sort of sound your after and they will advise you the best tube to buy.

one thing to remember when changing tubes is that the pre amp tubes you can do yourself but it is always better to get a technician to change your power tubes as they need to be biased properly.
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Ok cool, thanks for the advice.

Am I wrong in thinking the 12ax7a's are the ones that need replacing every now and then? I have 2 6L6GC tubes in it at the moment, are these the ones that I'll need to replace?
Last edited by Afroboy267 at Apr 11, 2013,
Actually, the 112 combo has a fixed bias... you can't adjust it, thus, no need for technicians.