About creating tone mod on delay?

[bufftonz]

Hello everyone. I am currently modding the Repeat aspect of my analog delay pedal to have a tone control, that is to have tonal control strictly over the wet signal or actual echo repeats.

With help from (on a different discussion thread), I was able to locate the resistor and capcitor that were responsible for the output tone of the echo Repeats on my DOD FX90 delay.

As I see it, in route to the output via the Repeat potentiometer(100K), there is a 22k resistor followed by a 0.56uF electrolytic cap. From the previous advise I was given over the thread, I should replace the cap with a 0.47uF one and the resistor with a 20k one to allow for more higher-frequency tones and more echo repeats.

However...I had an additional idea. Why not make this mod to be more versatile? Yes, exactly, I want to take this mod a step further.
I want to turn this mod into a tone control-knob mod. Yes, I know i'll have to do some drilling and in-line measurements, but that's OK...I just want to make the mod an adjustable one. Meaning to say instead of replacing with a fixed resistor and cap, why not replace with a variable trim pot, or even better, a 1/2" control-knob pot. However, here's two concerns I have:

1. Is it OK to replace 22K resistor with a 50K potentiometer? (I can't find a 1/2" diameter 22K or 20K pot)

2. How do I make this mod a variable lo-cut filter type?

I.E. Should it be this way:

                                                        _________
                                                        |             |
                                                        |             V     Echo Tone (50K)
                                                        |______/\/\/\/\________
                                                        |                                  |
<---Output------l                         -----------------||---------------------. . . .etc. . . --------<Input>
                       l                         l                  +     -
                       l                         l                   0.47uF
                       l                        V
                       -----------------/\/\/\/\--------- . . .etc.
                                            Repeat (100K)



Or should it be like this (below):

                                                                     _________
                                                                     |              |
                                Echo Tone (50K)            V               |
                                                        ______/\/\/\/\____ |
                                                        |                           |
<---Output------l                         -----------------||---------------------. . . .etc. . . --------<Input>
                       l                         l                  +     -
                       l                         l                   0.47uF
                       l                        V
                       -----------------/\/\/\/\--------- . . .etc.
                                            Repeat (100K)


All help and suggestions are greatly appreciated. Thank you.


--Chris