Simplistic NFB question

[EFK]

Looking at the attached schematic portion, I have a question about the .1uF cap which is bypassing the lower 4.7K tail resistor to ground in the PI: since there is no presence pot utilized, is this effectively acting as presence wide open or presence permanently dialed back? What would be the effect of lowering the value here to, say, .05uf? Thanks!

[Chuck H]

is this effectively acting as presence wide open or presence permanently dialed back?

Presence wide open.

What would be the effect of lowering the value here to, say, .05uf? Thanks!

The bypassed frequencies would shift up. That is, the presence effect would wouldn't cut as deeply into the bandwidth and only higher frequencies would be boosted.

You could also add a pot to the grounded end of that cap and make it a presence control or if you don't want to drill a hole you could set a presence level you like with a pot and then measure the pots resistance and replace it with a fixed resistor. You can experiment with higher and lower cap values and different resistances to see if any combination really talks to you.

Chuck

[EFK]

Thanks for that! Cleared it right up for me.