NFB vs Presence?

[iknowjohnny]

Here it is

I don't understand this. It just looks like a pre PI master. It's exactly how my amp's master is wired except for the 220k, tho i do have a 100k there. Can you clarify what makes this different?

[M Fowler]

Your right that wasn't what I was looking for I was thinking about pseudo presence control rather then taking the NFB from the OT the tail is connected to the pot but I am not finding it.

The PIG is a phase inverter gain and you are correct no difference from what you have.

[iknowjohnny]

I see. On my amp tho, a presence wouldn't be needed with no NFB. My amp w/o NFB is painfully bright ! I'd be interested to see it tho if only to consider other possibilities it may have with some variation in the circuit. Always interested in new ideas.

[Andy Le Blanc]

A cap shunted with a pot. or a switch in the feed back loop is sometimes called
resonance or a tone expander, simply making the feedback variable can be
a very useful tweak.

[iknowjohnny]

Mine IS variable. 50k pot in series with 47k resistor. It is indeed usefull. I think the amount of NFB is a huge reason some marshalls have reputations as having creamy distortion. I'd love to hear about some other NFB tricks i have yet to try. Tried resonance, but it just never sounded quite natural mto me. One of those things you like at first then eventually find yourself never using it. At least for me.