I got a humbucker guitar and am looking for some clean headroom in the 'ole Brown Deluxe.
I put 12AY7's in v1 & v2 and a 12DW7 in v3.
The DW has a gain factor of 100 on one side and 20 on the other.
Will this hurt anything ?
It sounds good and is a lot cleaner.
The phase inverter takes the signal from V2 and literally "splits" it to feed the output section's dual 6V6's. You are providing normal signal to one output tube and reduced signal to the other. You want them to be the same to get max volume. I'd get a lower gain balanced triode 12ax7 tube personally.
I understand what you're sayin' but why does it SOUND good ?
I have 12ay7,5751,12at7,12au7,12av7,& other computer tubes to sub.
It sounded good with the 12av7 and the 12ay7 in v3 as well.
Maybe my Deluxe has a different kind of preamp topology ? http://www.ampwares.com/schematics/deluxe_6g3.pdf
If you look at the schematic you reference, you'll see a 12ax7 in V3.
Here is what I think, though I have not heard your amp before or after the tube swap. You already reduced gain in V1 and V2 with the 12Ay7 swap and that is what I think you are liking now about the tone.
The 7025 that is called for in V1 for a brown deluxe is probably the most likely place to put a lower gain tube, IMO. That was a very high quality 12ax7 that is hard to find these days.
Why? Because the amp is being run in a very lopsided way. If you are running one side of the PI normal, and starving the other side, it is almost like pulling one of the power tubes and running it single ended. It will sound awesome for a while. Then it might get expensive. Might sound awesome for years, might be days. No one can really say.
A little intentional imbalance in the PI is a good thing if you like that sound - it'll make the amp full of rich harmonics normally cancelled out. But you've gone way beyond a little imbalance, and as the previous poster said, you'll likely piss it off eventually.
I'd try the 12at7 in there. In every amp I've ever put a 12at7 in the PI spot in place of 12ax7, it got louder, cleaner, bolder and tighter. Seriously. Can very much help reduce a harsh sounding overdrive w/ the amp dimed.