Ok, so I'm a bit of a t00b n00b. I just got a JCM 900 head, and naturally, I wanna re-tube it. Can anyone give some advice about tubes to use? Which ones will work? I think that it's the pre amp tubes that shape tone the most, am I right? I was checking these out http://www.groovetubes.com/product.cfm?Product_ID=1737 and they seem to be up my alley, since they increase the gain. How do power amp tupes affect tone? Also, can someone explain what biasing is? Should it be done with each re-tube? I know it has do be done by a pro, what are the different biasing options? If anyone could answer some or all of those questions I would be much obliged.
Well if you want to get real quick help go to www.tubestore.com.... Just e-mail them with all the things that you want in the tube, example- Higher gain, increased mids, tight bass etc. They will hook you up. Just tell what kinda of amp you got and you can get perfectly biased tubes... They do so you don't have too... That's my suggestion, hope it helps bro.
Oh and they don't have groove tube because the companies that they have on the are the companies that make the tubes for groove tubes. Kind of confusing... Groove Tubes just ups the price because the name gets slapped on there... tubestore.com will tell you all about it.
biasing is adjusting the voltage (i think) going into the power tubes. underbiasing and overbiasing have an effect on tone and life, and generally you want to run the tubes at their optimum, so generally you do rebias with a tube change, maybe with a few exceptions, like if youre using identical tubes or something i dont know the specifics.

you can do it yourself but if you dont Really know what youre doing you really Shouldnt. but you can, if you have a multimeter.