variable slope mod

[beinz]

ive been looking at the krankenstein amps with the variable slope control, and thought it would be a cool mod. after reading up on this, the main concern seems to be eliminating dc from hitting the pot/s. i am working from a soldano-like pre, the tonestack is cathode fed. from what i understand, i need to put a cap before the tonestack to eliminate the dc. this all makes sense, but i was a bit confused after looking at a supposed krank schem (not sure if its correct or not) as it is also cathode fed, but has no dc blocking cap...
anyways, i have drawn a simple diagram of how i believe this should look, i was just hoping the experts here could verify the diagram for me.
also, i am not completely sure on a value for this cap. i understand there is a range of exceptable values, my concern is making sure the cap has as little effect on the way the tonestack would otherwise sound. is the 100n in the diagram too small? is 1uf too high?

thanks for your help guys.

[beinz]

i think i found my answer, thanks anyways.

[Enzo]

And that answer WAS???

[JoeM]

Instead of using a pot for the slope resistor, (or part of it), why not just do like a Rivera amp and have a switch for 2 different values?
(I'll post a schem)

[beinz]

joeym - i thought about that, but i like the idea of pinpointing any point along that spectrum instead of being limited to 2 set values.
enzo- 100n cap goes in place of slope resistor, then the slope resistor / pot combo.
i would actually like to increase the range, but i am concerned that if i stay with 1 set value for treble cap, it will be less than ideal across the range.
this would give me from 30k to 55k, still very usable.

[defaced]

I've played with this before in a SLO style circuit. I used a multipole switch, and IMO, going much outside of the 30k to 55k range doesn't get very good results with a 22n mid and bass cap. I tried different treble caps and found that between 470p and 560p tended to be where I like it. For me, the bass frequency was the limiting factor, depending on the slope setting it was not inspiring. For the isolation cap my go-to size would be 220n and then work from there if it interfered with anything.

[beinz]

thanks defaced -this is kind of what i thought regarding range. i just want the ability to finetune, but still have the whole range sound descent.
im mostly a "mids" kind of guy, i also play baritone with 14-66 strings, so i usually end up keeping the bass control down or off, ill have to see how the low end comes out, hopefully wont be much of an issue.

[beinz]

my brain was digging up this thread again, you suggested starting with a 100n cap for a slope mod for guitar frequencies, what cap would you suggest if you were to apply this to a bass circuit? obviously the resistor values would change to something like 75k fixed + 25k-50k variable, but what value of cap? cathode bypass caps in bass amps can be as high as 100u, is it necessary to go that high for a slope cap?