3 volumes plus master tone on JM

[strasurf]

On my Jazzmaster and I want to add a third pickup in middle position and I want to have three volume controls and one master tone control. Since on the pickguard there is room for just two knobs I wonder if it's possible to replace the two original knobs with two stacked knobs:

1) stacked knob 1: neck volume + middle volume
2) stacked knob 2: bridge volume + master tone

Do you think this wiring is possible?

[Steadyriot.]

If you don't use the rhythm circuit I'd use that.
But the way you've laid it out should work.

[strasurf]

Yes I'm referring to the lead circuit only.

[jorri]

It should work and easy to find things like jazz bass wiring diagrams you can adapt.

As long as you realise
a) its hard to find 1meg stacked pots sometimes
b) they 'add' together, well not add, but are parallel resistors. two pots =1000/2= 500k impedance. But 1000/4=250k impedance. and 500/4=125k impedance but that's still about what a guitar with 250k pots has. May lose some top end is what i am saying, unless you did something like use 2.2M pots!

[strasurf]

It should work and easy to find things like jazz bass wiring diagrams you can adapt.

As long as you realise
a) its hard to find 1meg stacked pots sometimes
b) they 'add' together, well not add, but are parallel resistors. two pots =1000/2= 500k impedance. But 1000/4=250k impedance. and 500/4=125k impedance but that's still about what a guitar with 250k pots has. May lose some top end is what i am saying, unless you did something like use 2.2M pots!

So if I opt for two 500k stacked knobs, it's like to have one 250k volume pot?

[jorri]

It should work and easy to find things like jazz bass wiring diagrams you can adapt.

As long as you realise
a) its hard to find 1meg stacked pots sometimes
b) they 'add' together, well not add, but are parallel resistors. two pots =1000/2= 500k impedance. But 1000/4=250k impedance. and 500/4=125k impedance but that's still about what a guitar with 250k pots has. May lose some top end is what i am saying, unless you did something like use 2.2M pots!

So if I opt for two 500k stacked knobs, it's like to have one 250k volume pot?

Yup, if you double the number of 500k pots it would have more of the tone of 250k.

In electrical terms: a resistor to ground is like a leak but the more resistance, the less gets through. If you double the number of leaks its the same situation as halving the resistance.

I think even with one single pickup engaged the output still sees the resistance of the "off" pickup but depends, maybe there are diagrams that take it out, like maybe wiring it before the switch?

[jorri]

I dont really work on gibson guitars but it looks like the les paul setup does that with a switch after.
So 1 pickup = 500k, both pickups =~250K.
I guess it might be a real reason 'humbucker' guitars use higher resistance: because they tend to have more pots, at least back in the day.