#1
Alright, so I have recently acquired a Laney GC-30V (the model that became the VC-30) It sounds amazing, loud as all hell, (on the clean channel) but amazing. My problem is this; while the clean channel can rattle windows while set to 1, I have to crank the gain and volume of the gain channel to get a semi-usable tone which sometimes jumps in volume if I wail on the guitar with a lot of pressure.

I've already replaced the pre-amp tubes (they weren't matching anyway) and before I dump more money into power tubes (which appear to all glow as they should) what could the most likely culprit be? Tubes? The transformer? I really don't want to shell out money for a tech to tell me it's a tube.
#2
If you crank the clean channel up does it do the same thing?

If yes, it could be anything. If not, I would guess a resistor or cap somewhere around V2 (that's the tube used for the drive channel according to the manual).

You wouldn't be taking a loss if you buy new power tubes. The ones you have are going to die at some point anyway and it's always nice to have a spare set on hand. Then again, it might cost you to have the new tubes biased, and if the same problem is there, then you'd have to bias again to go back to the old tubes.

P.S. The preamp tubes don't need to match. People change preamp tubes in different positions (especially V1 and the phase inverter) to get different tones and drive levels. For example, I like to put a 12AY7 or 12AT7 in place of the 12AX7 in the phase inverter to drop the volume level a bit (depending on the amp). Also, in an amp like this where the clean and drive channels use a separate tube, using a higher or lower gain tube in the clean channel (V1) can shape the sound to be cleaner or grittier.  
"Practice doesn't make perfect. Perfect practice makes perfect." -some dude
#3
If the clean channel does what it should and the gain channel doesn't it probably isn't the power tubes.  It could be caused by a lot of things.  Could be a bad resistor , a bad cap, dirty valve socket, or a bad solder joint.  1st thing I'd do is swap the preamp valve from the clean channel with the one from the gain.  If the clean still runs fine you know it isn't the valves.  2nd thing I'd is open the amp and see if anything looks burnt.  Usually when a resistor blows you can tell by looking. If everything looks OK I'd  replace the electrolytic caps that bias the gain valve.  If that doesn't help I'd turn the amp on and start poking parts with a chopstick and seen if you hear any popping or changes in volume.  Finally I'd clean and resolder the valve sockets.  Remember to only open your amp if you know what you are doing because the inside of a valve amp can kill you even if it's unplugged.
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#4
UPDATE: took the amp back apart and started to mess with stuff. I noticed a HUGE jump in volume when I physically pushed down on the gain channels volume control. Thinking a bad pot, or just a bad solder? Seems like an easy enough fix either way?
#6
Yup, I re-soldered it, same issue. I can't read those schematics to save my life. What resistance of pot do I need? I'm going to replace.the gain pot as well because it's doing the same thing.
#7
I'm not sure off the top of my head but in my experience most amp companies are happy to supply information like this if you send them an email.  Just tell them which pot you need to replace and they will probably give you a value and might even suggest a brand.
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