How to adjust 3 stompboxes to use a common volume pot?

[gigimarga]

Hello,

I want to put in a same enclosure 3 stompboxes that i like very much:

1. Krank Distortus Maximus (http://www.aronnelson.com/gallery/main.php/v/Schematics-etc/Krank+Distortus+Maximus.jpg.html)
2. Tube Sound Fuzz (http://www.geocities.com/CollegePark/Library/1355/tsf.gif)
3. Muff Fuzz (transistor version) (http://fuzzcentral.ssguitar.com/schematics/mufffuzztransschem.gif)

I will switch between them  using a rotary 3P4T switch and a LED with 3 colors will indicate which one is active.

Because the enclosure's inner space is limited, i want to have only one pot for all these 3 stompboxes, but i have a big problem: they have 3 different values for the pot volume:

1. KDM - 1M
2. TSF - 10K
3. Muff - 100K

IMHO, if i want to use a 100K pot for volume in the TSF i must to decrease the output cap from 10uF to 1uF (to keep unchanged the corner frequency)...it's right?
But what to do for KDM, because i have no output cap and i don't want to scale the tonestack by 10...

Following the same idea, it's seems unreasonably to me to use a 1M volume pot because i would use a 1000uF output cap for TSF...

Any suggestions?

Thx a lot!

[slacker]

If you make the resistance to ground bigger then the filter frequency gets lower so if you gave the TSF a 1meg pot you could reduce the output cap to 100n and keep the same response. Same with the Muff fuzz if you use a 1 meg pot then reduce the output cap to 10n.
Using a 1meg pot may introduce noise and will mess with the output impedance of the circuits though, like you've said it would be better to use a 100k pot for all of them and scale the Krank's tone stack, I think there's a thread about doing that somewhere.

The other thing you could do is replace the volume pots from all 3 circuits with resistors of the same value. Then build a buffer with a volume pot on the end and put your switch between the outputs of the pedals and the buffer.

[ashcat_lt]

I was going to say you could get some more poles on that switch and switch in resistors in parallel with the 1M pot to get different effective values.  I like the buffer idea much better, though.

This leads to the following question:  Won't each circuit have a different output level anyway?  Unless you do something with the individual fuzzes, you're likely going to want to twist that knob every time you flip the switch.

[gigimarga]

Thx both for your replies!
The buffer ideea seems good to me, but i have only a bit of free space, so i can't include a buffer too.

It seems to me that to scale the tonestack for KDM is the best idea.
For TSF, if i will use a 100K volume pot i must to use a 1uF cap (in my initial post i made a huge mistake...i don't need to use a 1000uF  ...it must to be 0.1uF...but it was 2AM when i wrote it  )?

[gigimarga]

Finnished...and works very well...100K log pot shared by all 3...KDM tonestack scaled by 10...TSF output cap decreased to 1uF...that was all!