Putting a NPN and PNP circuit in the same pedal enclosure

[alexpaz]

Hi, I'm trying to wrap my head around putting 2 different fuzz faces (mangler and violenzz) in the same enclosure. I would really like to have dual pots so I can control the volume and fuzz of each with only 2 knobs while having a switch to change between the Ge and Si circuits. I have an old version of the mangler (2011) so I plan to use a road rage for the -9v. 

Basically my question is, how can I run both circuits in the same enclosure? I've built a lot of pedals, but never a PNP, and for some reason how to run both of these from the same power supply is confusing the crap out of me.
Since I will be switching between circuits anyway (only one will be active at a time), if I just use a 4PDT toggle or something, can I switch the voltage that way?

As far as hooking it up, would I basically wire the power jack as normal, and then use the regular ground as the ground for the PNP circuit and the -9v from the road rage to power it? So basically, the ground would be the same on both circuits, but one would be +9v from the power supply and the other would be -9v from the inverter?

Could I use a sag control with this configuration? Where the ground didn't change, only the voltage polarity?


I've looked around the internet, and haven't found a satisfactory answer to this question which is why I'm asking here.

Thanks in advance

Alex

[Bio77]

There is a project on PPCB that has both PNP and NPN FFs in the same box.  You might look at the schematic for answers to some of you questions. 

https://www.pedalpcb.com/product/twinface/

My two cents: I found it to be kind of a waste since I used expensive trannies for both sides.  With most options on pedals I end up comparing the options and finding the one I like best, which with this configuration meant not using some nice parts. 

[jwin615]

I'd wire both as always on and just use a switch to OR the inputs and outputs.
That way, if you use GEs, you wouldn't have any tone/gain change as they warm.
Sag could probably be done with a dual pot, or maybe mount two mini pots on the side so they could be set differently. Go from sputtering zipper to blitz as desired.
The kicker is, do they use the same pot values? If not, may have to build your own.
IIRC, CTS do have a few premade dual pots with different values.
Good luck!

[alexpaz]

Yeah, I'll have to make my own pots but I've done it before so that's not too bad.

That pedalpcb project is perfect.  Idk why I didn't find it before.  it looks like they are running the voltage the way I thought. I may do the switching similar to their method. Maybe I'll breadboard everything first just to get an idea of what is going on.

Thanks for your help!