V1 V2 V3 V4 explanations please?

[snappinnecks]

While I am down to only two useable power tubes right now I decided to mess around with the preamp tubes to try and get the IDEAL tone. I have Tung Sols, Shug 9th gens, Shug 8th gens (no difference to my ear), JJ ECC83, JJ ECC81, EH's, and a couple of Shug 12AT7s. I know that V1 is clean right? V2 and V3 handle the gain channel OD1 and OD2 together right? Or does V2 only handle OD1 and V3 handle OD1 and OD2?
My other question is V4. Phase inverter. What exactly does the phase inverter do and what is the ideal tube to have in that spot. I have put the stock JJ, 9th gen, 8th gen, 12AT7, Tung sol, and another no name tube I had left over from my Randall. The no name and 9th gen sound the best in that spot, but does the V4 tube have to be high gain, balanced (like 105/105 etc). I'm trying to learn all this amp tinkering stuff since the Splawns are pretty easy to service tube wise. Any knowledge you fellers can share is greatly appreciated.
In V2 and V3 I am torn between the 9th or 8th gens and the Tung Sols. The tung sols give the tone more ooomph and you feel it more in your chest while the Shugs sound more raw and have more midrange.

[LooseCannon]

Check out the manual at the Splawn site for description of each preamp tube position. As for the phase inverter, i'm not sure but I think it doesn't really affect the tone?

[SonicExplorer]

There's no point trying to guess the correct tube specs for a phase inverter circuit. The circuit itself is typically not balanced in the conventional sense and varies from amp to amp. So generally speaking getting a balanced tube is not guaranteed to make the circuit balanced. Granted, it's probably not wise to use a tube that is extremely out of balance either. Point being, you can't assume a balanced cuircuit simply because the phase inverter tube is balanced.

Sonic