Hot Rod DeVille Negative Feedback loop

[alga]

I think the NFB (presence) on this amp is designed in order to work for clean & drive mode. Since the clean mode on this amps is what everyone likes, even though I feel that with the Presence on 0 still got that high mids harsh which I think the NFB is responsible for. So I think this amp could be fine tunned for the clean mode even more (I never use the drive or more dive mode). R67 (presence pot) R68 4.7k R69 47k and C29 .1 uF ....... What values should I change if I want the presence potentiometer to go down further than 0?

I attached the NFB schematic of the Hot Rod DeVille.

Thanks in advance from Venezuela.

[pdf64]

I don’t think there’s much that can be done.
Why do you think the presence circuit is the problem?
Have you tried disconnecting the capacitor C29 or the presence pot?
Maybe you don’t like the speaker or something else in the circuit.

[Pedro Vecino]

If you always use the presence at minimum and want to access higher cuts, you can replace the potentiometer with a resistor of the same value and install an AC30-style cut control.
In the drawing you will see a resistor added in series with the potentiometer in order to limit the maximum treble trim setting. The operation of the control is inverse to that of presence, but this makes it easier to have a good curve.

[Helmholtz]

I never tried the cut control with an amp having global NFB, which will try to counteract the treble loss.

Experiences?