While I realize things are complicated with multiple gain stages, please tell me what part of this is wrong. If Gain stage B overdrives at a made up number of 100, and gain stage A when wide open can push it to 130, then pretending the pot sweep was simple 1-10, then gain stage A would overdrive gain stage be somewhere around 7 on the knob. Reducing the gain of stage A to 100 would then allow you to turn it to 10 without overdriving stage B. But, it is the same drive thru the circuit at 10 as the original was at 7. You have lowered gain, but haven't increased headroom.
That is very oversimplified on purpose. Please explain to me where it is not applicable. You reduce the P/I you're simply not hitting the power stage as hard. Maybe it doesn't overdrive like it did before, but only because you aren't pushing it as far. I'm not disputing a reduction of clipping. I get that. But there is no increase in clean headroom, which is what is claimed.
I'm no amp designer and I don't claim I'm right and everyone else is wrong. But so far, nobody has ever been able to explain to me how reducing gain through any gain stage INCREASES clean headroom. It simply reduces gain and lowers the output of the next stage... and I'm saying that turning the knob down on the higher gain tube will yield a spot where it doesn't break up and that will be at the same actual output as it happened with a lower gain tube, but with the lower gain tube the knobs will be turned higher to get to that point.
Do you disagree with this?
I could go on and this is interesting. But time consuming. LOL If you have a multiple gain stage preamp section for example, there is NO question you can reduce gain by dropping a lower gain tube in there. But that doesn't make the amps clean tones louder/increase clean headroom, it just reduces the level of gain in that stage. See again, I don't dispute that it makes the amp cleaner. That's a given. But it doesn't make it cleaner-louder.
IMHO And I do not get paid anything for these opinions.
But I have tried for years to find a way that this couldn't be true, and I haven't found one yet that I could understand. I'm not saying it's not possible with multiple gain stages intentionally designed to distort, that you couldn't lower them all to just the right amount that none overdrives the other and the end result is you maybe get more true output... headroom, without overdriving any of the stages. But I don't see that being a norm in any of the amps I've ever analyzed.