[quote author="khstudio"]
Changes to the input (tranny or tube) don't seem to have too much effect on the output gain control, at least not that much.
I found that the 12ay7 changes the character & feel more than gain & I also find that my Gain & Peak Red. controls end up in about the same spots.[/quote]
My assumption is that the lower gain from a 12AY7 is, for all intents and purposes, mostly subtracted from the feedback loops negative gain, and you arrive at a very similar place. The negative feedback amount is lower, as is the positive gain. And that's really secondary to the fact that actual db gain difference between 12AY7 (40) and 12AX7 (100) is fairly small in practice. But, the changes I think exist in total feedback are going to most significantly alter the character of the sound, without altering the actual gain quantity by very much.
Transformer gain, or lack thereof, is the whole game with knob position and stock tube circuit. And even without transformer gain, you have tube gain to compete with if feeding in high level signals. Hot +12 recording in a +18 system will require a knob setting that chucks out almost all of the system gain, so more gain in the input transformer means more to chuck out with the knob. Thus, the sub-9 o'clock settings.
10K:10K Jensen etc = -1 db or less transformer insertion loss
600:10K Sowter = +/- 13 db more gain
600:50K UTC = +/- 21 db more gain
