Help with pickup selector switch

[OggyOi]

Hi all.

I have been working on a bass with a P pickup in the neck, and a MM in the bridge.

At the moment they are wired volume - volume - tone, with the MM wired in parallel.

I'd like to install 1 volume, 1 tone and a pickup selector switch. I have done this with a pj before.

My question is: would it be possible to install a 4 or 5 way switch (maybe a rotary, tele or strat style switch) with something like:

1. Neck pickup

2. Both pickups with the MM in parallel.

3. Both pickups with the MM in single coil.

4. Neck pickup in parallel.


Or failing that, a 3-way with numbers 1-3 available?

I am not very electrically minded, so any advice or a makeshift wiring diagram would be much appreciated!

Thanks.

 

[XLunacy]

The simplest I can think of to achieve 1/2/3 (actually 1/3/2) is a DPDT on-on-on, with the P hot straight to volume, and all ground wires to ground.
You then wire the switch to go from P only (MM out of the circuit) to P + MM single coil (adding one of the MM coils to the circuit) to P + MM in parallel (adding the second coil). If you see it as 3 individual coils it becomes much simpler.
I'll provide a basic wiring diagram tomorrow

To have the possibility to switch the P in series / parallel, you'd either need to add an additional DPDT on-on, or simply use a larger switch, like a 4P4T at minimum I think.

 

[OggyOi]

That's great, thanks! I'd never have thought of wiring the p straight to the hot.

I appreciate it.

 

[XLunacy]

Hopefully this is correct and clear enough (big fingers, small screen ):

Squared + goes to hot / volume / whatever comes after.
P1 and P2 can be swapped depending on which single coil you want.
Make sure the pickups are in phase.

Something to be mindful of: there will probably be some sort of impedance imbalance and interaction between the pickups, and people much more educated than me on this subject (@ctmullins , @micguy, @fig, @walterw) would explain all of this way better than me, but the result might not be exactly what you imagine; just try and see for yourself!

Let me know if it works

 

[micguy]

When you wire 2 pickups with different impedances in parallel, the one that is lower in impedance “wins” - it will be tend to be louder in the mix. Both pickups shunt each other in that configuration, but the one that is lower in impedance shunts the higher impedance one more. It’s an effect that can be useful, if that’s what you want, but unless you understand this, it’s something that can work against you - that all depends on what you want to hear. Anyway, just know that the settings with both pickups on won’t be a 50/50 blend.

 

[XLunacy]

There you go thanks @micguy

In your case, that means that as you flip the switch from configs 1 => 3 => 2, you get noticeably less and less P, and more and more MM (that is in addition to the comb filtering / mid cut you'll be getting when 2 pickups placed far from each other are in the circuit at the same time)

 

[micguy]

There you go thanks @micguy

In your case, that means that as you flip the switch from configs 1 => 3 => 2, you get noticeably less and less P, and more and more MM (that is in addition to the comb filtering / mid cut you'll be getting when 2 pickups placed far from each other are in the circuit at the same time)

One clarification - comb filtering happens all the time, regardless of pickup spacing. Where it occurs spectrally is where the spacing of things matters. A P (even with just one pickup) definitely has comb filtering going on, because the wave traveling along the string goes back and forth, passing by the pickup each time it's going up or down the string. A single pickup MM has the same thing, but the frequencies where that occurs are different, because the pickup is in a different spot - it's closer to the bridge, so the time between when the wave passes it on the way to the bridge, and on the way back is shorter. That means less low end, and the first dip in the "comb" is higher in frequency. A bass with two pickups has additional comb filtering, which occurs at different frequencies, due to the spacing of the pickups - that is most audible in the lower mids as a "scoop". A dual coil humbucking pickup (like the MM here) has additional comb filtering, which is most audible as a scoop in the upper mids - that due to the spacing between coils.

 

[OggyOi]

This is great information, thank you so much. I appreciate taking the time to draw a diagram.

I have tested the pickup combination in their current spacing with a simple jazz style vvt setup, and they sound great together (with the MM in single coil mode). No idea if it's close to 50/50 or not, but certainly gives a nice alternative to have to the solo p sound.

I'm not sure I quite understand why there would be less p and more mm in positions 2 and 3, but I guess I'll wire it up and see what it sounds like

Just to clarify Xlunacy, the pickup labelled P1 would be the pickup selected as a single coil when the switch is in that position?

Thanks again!

 

[XLunacy]

If you have a switch like the one in the top row of this picture:

Then yes, P1 will be the coil selected for the pickup to act as a single coil. Just reverse P1 and P2 if need be, everything else is symmetrical

 

[OggyOi]

Amazing, thanks so much.