Distortion pedal with Fender 5F6-A type EQ

[sffwy]

Is there a guideline value for C? If so, it would be very helpful.

It depends both on LPF cut-off frequency of your taste and EQ variable output impedance..
(so proceed to trial and error process..)

P.S.
May I ask the reason for LPF ..??

Sometimes in my environment I need to input directly through EQ and DI into the mixing console. (This happens only a few times a year, but it's a problem if I can't do it.)
The output from the full range speakers is fine for clean tones and saturation, but distortion is very unpleasant because you hear overtones that should be cut by electric guitar amp speakers.

So I used to carry 4u rack mount EQ and filters that I didn't know if I would ever use.

The cutoff frequency is fixed and 6db/oct is fine. (The filter I used was 18db/oct or higher, but as far as I can tell that seems difficult to do with a simple circuit).
If the recovery stage has a capacitor for the low pass filter, it would be very useful for me if I could switch the value between the original and the low pass filter.

Another reason is that i want to take full advantage of what you have designed for us.

[antonis]

The cutoff frequency is fixed and 6db/oct is fine. (The filter I used was 18db/oct or higher, but as far as I can tell that seems difficult to do with a simple circuit).
If the recovery stage has a capacitor for the low pass filter, it would be very useful for me if I could switch the value between the original and the low pass filter.

Alright but at WHAT frequency..??

[GibsonGM]

cough cough cab sim after the pedal  cough     

[antonis]

cough cough should I be informed about cab sim frequency band cough cough..?? 

[sffwy]

The cutoff frequency is fixed and 6db/oct is fine. (The filter I used was 18db/oct or higher, but as far as I can tell that seems difficult to do with a simple circuit).
If the recovery stage has a capacitor for the low pass filter, it would be very useful for me if I could switch the value between the original and the low pass filter.

Alright but at WHAT frequency..??

I think it would be about 3k Hz, taking into account that it is 6db/oct.
I believe that combining this with Electra Tone controle will give an attenuation close to 12db/oct.