Two Tone Pots with a Switch for Cap Values

[brak]

Long time lurker - first time poster. Guitar wiring hobbyist would be generous, I am learning, some lessons the hard way.

My Neck pickup is quite dark (humbucking P90) and my Bridge pickup is quite bright (PAF). I find that when switching between the two I need to mess with my tone knob to get desired tone. The obvious solution is 2 tone knobs. I had concentric pots for this reason, didn't like fiddling with 2 volumes and 2 tones. Solution 1v,2t.

The neck P90 is not so dark that I want to try a bass-cut at this time, bypassing tone control makes it bright enough, but it is dark enough that even with my current .022uf cap, it is like throwing a wet blanket on it. The .022uf cap works nicely for the bridge pickup. Simple answer, 2 tones pots each with a .022uf, different sweet spots in each. But I have a DPDT on/on that is currently being used as a master bypass so I want to change it to a dark/bright switch. This way in bright-mode, the neck pot will be bypassed and the bridge pot will use a .011uf cap, and in dark-mode, the neck will use the .011uf cap and the bridge will use .022uf. Sounds intuitive enough to use and suitable for the sound of my pickups. So, will all this work if wiring as shown in my diagram?

Some things I'm unsure of:

1. I'm trying to use each pole of the DPDT on/on "separately", but with a diagonal x-over so the dark-mode of the Neck PU can use series caps of the Bridge PUs bright-mode, will this work?
   
2. If yes to A, I assume it doesn't matter that the caps originally meant for the Bridge PU (and on the Bridge pole of the DPDT) are being used by the Neck PU?
3. If ok so far, am I creating a feedback loop of some kind (not sure if things can run upstream??) - example, when setting switch to dark mode, I hope for the bridge to get the single .022uf cap to ground (bottom-right lug), but that same lug is connected to another .022uf cap and to the the top-right lug so they'll run in series in bright mode. I assume in dark mode, it will try to take both paths off the bottom-right lug, but will hit a dead end at the top-right lug because that part of the switch isn't on (so the second cap won't be in the circuit). Is that right?
4. If correct about C with regards to the second cap, what about the diagonal jumper, I want the Neck Pickup pole to use the caps on the Bridge Pickup side, but not the other way around.
   

OK, on to the illustration:

[newey]

brak-

Hello and Welcome to G-Nutz2!

I'll give you my take on this, but please await the input of others. IOW, my confidence level in this response isn't peaking.

I think the cap combinations and the switch wiring is fine for what you want. You can certainly use the same caps for both B and N, but my question mark is with regard to the center position on the 3-way, where both pickups are active. Might be some bigger issues there that I'm not aware of.

What I do see as the bigger issue is the single volume and dual tone controls setup. With that, both tone pots are connected, in parallel, and thus will interact- turning one down will affect the other. That's why the set-up using concentric pots is preferred- the pots are wired as in an LP. There is still some control interaction in the center position, but not as bad as with the single V pot.

Given that you don't like concentric pots, the solution is to get a dual-gang pot, which is like a concentric pot but with one shaft turning both the elements. Then you wire it the same way as the concentrics, like an LP wiring scheme. You still have your master volume but with less control interaction.

But again, let's let others chime in . . .

[tubejockey]

For the cost of a capacitor, I would do seperate caps and avoid all the interactions.  The OP's diagram will not work as drawn.  Try this.

[Yogi B]

May 1, 2024 19:54:01 GMT -5 newey said:

What I do see as the bigger issue is the single volume and dual tone controls setup. With that, both tone pots are connected, in parallel, and thus will interact- turning one down will affect the other. That's why the set-up using concentric pots is preferred- the pots are wired as in an LP. There is still some control interaction in the center position, but not as bad as with the single V pot.

Well, less interaction assuming you lower at least one of those volume controls, at full volume the tones are still directly in parallel (also assuming modern wiring). (With '50s wiring, the middle position has the tone pots in parallel no matter the position of the volume pots, which is a feature I do sometimes envy.)

A potentially bigger issue is that, with the proposed scheme of using two caps in series for one tone control whilst using one of those caps for the other control, there is a path via those linked capacitors for the output of the deselected pickup to bleed through in both of the outer positions. Note, although this could we worked around by switching the tone pots at the same time as the pickups (like the old shared-cap Strat wiring, but at the cost of requiring greater switching than either typical 3-way switch: Gibson style toggle or Tele style lever), there would still be some weirdness in the centre position.

May 1, 2024 22:42:47 GMT -5 tubejockey said:

For the cost of a capacitor, I would do seperate caps and avoid all the interactions.  The OP's diagram will not work as drawn.

I agree that separate caps is the way to go, but you only need two if you stick to the actual sought values:

[brak]

May 1, 2024 19:54:01 GMT -5 newey said:

brak-

Hello and Welcome to G-Nutz2!

What I do see as the bigger issue is the single volume and dual tone controls setup. With that, both tone pots are connected, in parallel, and thus will interact- turning one down will affect the other. That's why the set-up using concentric pots is preferred- the pots are wired as in an LP. There is still some control interaction in the center position, but not as bad as with the single V pot.

Thx for the Welcome Newey! Interesting. Hadn't considered (and can't pretend to understand) that. I just looked up some 1 vol/2 tone diagrams on Seymour Duncan and GuitarElectronics sites and the diagrams seem consistent, so I assumed this to be a common and acceptable set up. The only difference between mine and theirs is the shenanigans with the caps at the tone pots.

May 2, 2024 3:51:21 GMT -5 Yogi B said:

May 1, 2024 22:42:47 GMT -5 tubejockey said:

For the cost of a capacitor, I would do seperate caps and avoid all the interactions.  The OP's diagram will not work as drawn.

I agree that separate caps is the way to go, but you only need two if you stick to the actual sought values:

OK, you've caught me out! I have two 22n caps and was trying to get crafty without having to buy a new cap! I appreciate the feedback that keeps me from having to learn another lesson the hard way. Some lessons - like "Keep It Simple Stupid" - are timeless and I just need a reminder.  tubejockey's schematic is harder for me to understand, but I do get it and the sentiment is heard, Thanks!

The diagram provided by @yogi B is awesome. I think I'll order the cap today and proceed down this path.
Can you please tell me what program you used to create this diagram? I used PowerPoint for the simple diagram I posted of the switch and tone pot because it is easy to connect dots, but when I do the diagram of how the entire cavity comes together with current wire colors vs new, so I can see what I need to add/take away, I use Adobe Illustrator and it is somewhat cumbersome for this task.