Multiple circuits connected to same pots and switched via DPDT?

[jtrezzo]

OK, so this may be a really ridiculous idea, but I had the thought of putting 6 different fuzz circuits all in one 1590DD - "The Master Fuzz". I'll just talk about one section for simplicity. I want to do a Ge and Si Tonebender section, with two different circuit boards, and switch them with a DPDT. They would be an either/or thing, I do not want them on at the same time. I would like to ideally just connect both circuits to the same pot. Is this possible, or will the circuits interact with each other? If so, is there a better way to accomplish this? I think dual gang pots may solve the pot issue, but it would just be something else I have to order. That still makes me wonder if the DPDT switching will work right and not interact with each other. I would also like to do this with a Ge and Si Fuzz Face, and a FZ1 and Fuzzrite, but the FZ1 and FR would have their own separate pots, but still use the DPDT switch.

So, am I crazy? or will this work? I attempted a poor drawing just to kind of show what I am thinking. Any help greatly appreciated.

[jtrezzo]

and a slightly less cluttered version just showing the proposed switching.

[EBK]

I may not be understanding this correctly...
If you want two of the same circuit type with the same pots but only differing in diode type, why not just use one board and use the switch for just the diodes?

[R.G.]

I may not be understanding you correctly either. The circuits *will* interfere with each other if they are simply connected to the same --electrical-- pots. You may be able to use the same pot/knob, but use dual section pots so the electrical part of the pots are separated.

[robthequiet]

My fear would be not getting the levels of each circuit to be equal enough to just switch, so possibly adding mixing pots to set the individual levels, unless of course you have the whole circuit including output volume in t̶h̶e̶  each effect anyway. Dual-gang pots for blending or for setting levels of two different things at the same time?

[robthequiet]

Come to think of it, you essentially would have a loooper switching between the pedals and have to have true bypass anyway. Would impedance differences matter?

[PRR]

As said, they can't be in two circuits at the same time.

And the switch is nearly as big and costly as a pot.

And it is unlikely you want the pot the SAME on effect A and on effect B.

And for some cases, if you switch a pot out, the circuit goes wack, and does not get back to sanity quickly when you put the pot back.

Just buy more pots. Switch whole effects, not the guts of effects.

[jtrezzo]

Thank you for all the responses.

And it is unlikely you want the pot the SAME on effect A and on effect B.

In this case the pot values are the same on both effects. But you and RG are saying that it is not possible to isolate them if they are connected to the same lugs from different circuits it seems. I believe a dual gang could solve that for me then? It wouldn't be that bad to me to have 4 knobs instead of two, worst case, since I will have the space. I just figured if there is a way to simplify it that might be nice.

My fear would be not getting the levels of each circuit to be equal enough to just switch, so possibly adding mixing pots to set the individual levels, unless of course you have the whole circuit including output volume in t̶h̶e̶  each effect anyway. Dual-gang pots for blending or for setting levels of two different things at the same time?

It is more for convenience of having them all in one box, rather than being able to switch them on the fly. Having to change the level a little if on the same pot wouldn't be an issue (if that is possible without causing some interference, but it seems that it will). I don't want to add more footswitches for different things and have no need to do so, hence the DPDTs to switch between the two circuits. I would just want the dual gang pots so that I could change both at the same time (only one would actually be switched on at a time, via DPDT). And really, cranked all the way is usually the best setting for fuzzes anyway 

I may not be understanding this correctly...
If you want two of the same circuit type with the same pots but only differing in diode type, why not just use one board and use the switch for just the diodes?

The diodes aren't an issue here (that would be much simpler), it's that the transistors are different, and are biased differently with different resistors for the Ge vs. Si Tonebenders. It's probably possible, but not without being more complex. They will have to be different circuit boards. It's also simpler because I already have them populated! This is just an idea that came forth after accumulating 6 different fuzz circuits with veros that all sound good to me, but I don't feel like doing 6 different boxes for. 

[EBK]

If you really want to go forward with this idea, you could probably pull it off with a complicated relay switching scheme, including the pot reuse part (but note Paul's warning on instability -- dual-gang pots would be better for switching those). Wouldn't be very cost-efficient though....  Far easier to just build each pedal separately.

The biggest risk of the project as I see it is that, after great expense (time and money), the end result may not be as impressive or useful as you imagine.  I love adding lots of switchable mods to pedals, but I have more than once ended up with a toggle that appears to change nothing but barely audible mojo.

EDIT: After rereading everything, your idea is simpler than I thought because:
1) You aren't looking to switch things on the fly;
2) You don't care if the levels are different or if you want different pot settings for different boards;
3) You already have the boards built; and
4) You don't mind adding extra pots.

Ignore that stuff I said about complicated relay switching!

If your paired-up boards use the same pot values and tapers, go with dual-gang pots if you want a cleaner look.  Otherwise, I think what you've drawn up is more or less fine according to your criteria.

[jtrezzo]

EBK - you are probably right about the "barely audible mojo" lol Thanks for the help - looks like I'll need to order some dual gangs to make it happen.