NFB question

[iknowjohnny]

I know that the 16, 8 and 4 ohm taps are all different as far as voltage to the NFB, and it's always said that a 100k on the 4 ohm tap is the same as a 47k on the 8 ohm or something like that. Can't remember which is which) anyways, i use a 47k on the 8 because it just seems to work fine and other scenarios i tried (different resistors, different taps) never seemed to make much difference aside from amount of NFB. The question is, does anything change besides the amount of feedback? In other words, does anyone find that certain taps, all resistors being equal, (as in whatever values makes each tap put out the same) have a different feel or anything noticeable thats different or in your opinion better?

I ask this because i don't really want to experiment with it ad nausium, and i can't help but wonder why some marshalls use different taps with resistor values to make the gain equal. Why bother? Wh6y not just use the same tap and resistor on every amp if there is not difference?

[dartanion]

Read Randall Aiken's white paper on NFB. Pretty much everything you ask about is discussed in it.

http://aikenamps.com/GlobalNegativeFeedback.htm

[Structo]

Are you using the feedback on a presence pot?

[iknowjohnny]

yes