Can I use a single pole to coil-split 2 pickups?

[BrotherJack]

So, I am still at my mad wiring experiments, and wanted to know before I order a switch:  Can I use a single pole to coil split 2 pickups?  In other words, the wires coming out of my pickup are like so:

-> ground wire and black wire we connect to ground
-> green wire to output/hot
-> red+white wires soldered together and we short these to ground (or not) to shut off one coil (or not).

If I have two pickups but only one spare pole on my switch, if I have both red+white pairs connected to that single pole (and thus touching each other), will them touching each other have undesirable results (such as possibly permanently coil split situation),  Or will it be 'pickups work as usual, unless we put switch into position to short the coil split wires to ground?'

One answer is a $15 switch, one is a $4 switch. 

Thanks in advance for your consideration and answers.

 

[line6man]

Firstly, you are talking about wires without specifying what color code you are using.

In any case, it would not be plausible to use a single pole to split two pickups simultaneously. You would end up connecting the series links together, changing the nature of the impedance of the pickups.

 

[BrotherJack]

That's what I was figuring, so the answer is 'nope', which is the important part.  So, $20 switch it is, then.

I'm not sure what the code is either, that's just how the pickups came.

 

[line6man]

That's what I was figuring, so the answer is 'nope', which is the important part.  So, $20 switch it is, then.

I'm not sure what the code is either, that's just how the pickups came.

What kind of switch are you using, that costs $20? Unless you are using a rotary switch, a DPDT On/On should not be expensive.

 

[BrotherJack]

To do what I am contemplating, I would need a 4 pole 3-way mini (1/4 inch shaft).  Only ones I can find in web search are $20 and up, though I did find a pair of them for $30, so $15 each.  That would allow me to:

Pos1: Off (short output to ground)
Pos2: On and 200kohm to ground
Pos3: Coils on both pickups split without 200kohm to ground (though maybe a 500kohm to ground here will be nice - would have to play with some)

It's Pos3 that's the deal breaker.  On a on-on-on 3 way switch with only 2 poles, I only have a single pole being actuated when the switch is moved between any position.  So I don't have any one position I could use to split both pickups.   

The idea of the circuit is just an improvement on the one I have now, which is done with a On/Off/On switch:

Pos1: off (short to ground)
Pos2: on (nothing shorted to nothing - wide open humbuckers direct to output jack)
Pos3: coils on both pickups split - also direct to output jack

I want to introduce varying resistance between split and not split so that the volume drop when switching to split isn't as noticeable, and also just to warm/mellow the tones in general.

Thanks,

 

[line6man]

To do what I am contemplating, I would need a 4 pole 3-way mini (1/4 inch shaft).  Only ones I can find in web search are $20 and up, though I did find a pair of them for $30, so $15 each.  That would allow me to:

Pos1: Off (short output to ground)
Pos2: On and 200kohm to ground
Pos3: Coils on both pickups split without 200kohm to ground (though maybe a 500kohm to ground here will be nice - would have to play with some)

It's Pos3 that's the deal breaker.  On a on-on-on 3 way switch with only 2 poles, I only have a single pole being actuated when the switch is moved between any position.  So I don't have any one position I could use to split both pickups.   

The idea of the circuit is just an improvement on the one I have now, which is done with a On/Off/On switch:

Pos1: off (short to ground)
Pos2: on (nothing shorted to nothing - wide open humbuckers direct to output jack)
Pos3: coils on both pickups split - also direct to output jack

I want to introduce varying resistance between split and not split so that the volume drop when switching to split isn't as noticeable, and also just to warm/mellow the tones in general.

Thanks,

Well, in that case, you will need the pricey switch.

A series resistance would likely serve you better than a parallel resistance, however, in the interest of balancing differences in output between series and single coil operation. Parallel resistance will give you a loading on the coils that will mellow the highs. Series resistance would be a more effective means of altering volume.

 

[BrotherJack]

Ah, I see.  That wouldn't be too hard actually, just wire the 4-pole switch in series on the way to the output jack, and switch between resistors at the same time I'm switching between split and not split.    Any suggestions as to what size (value?) resistors would be a good place to start?      500K on humbucker mode and 250k on single?  (the usual values of pot's for said single vs double coil pickups)

Thanks,

 

[line6man]

Ah, I see.  That wouldn't be too hard actually, just wire the 4-pole switch in series on the way to the output jack, and switch between resistors at the same time I'm switching between split and not split.    Any suggestions as to what size (value?) resistors would be a good place to start?      500K on humbucker mode and 250k on single?  (the usual values of pot's for said single vs double coil pickups)

Thanks,

I personally wouldn't use a fixed resistor. It's too much hassle to determine what resistance is necessary. (Though I would guess something around 100k.) Get yourself a trimmer pot, instead, and mount it inside of the control cavity.

 

[BrotherJack]

Say, my next dumb question (it's actually related project-wise to what I was asking about here, so I didn't make a new thread for it).  If I have


Pickup hot wire -> switch pole -> resistor -> output
                    |                          | 
            other switch pole -----------------| 


When switch is in a position where the two poles are not connected, only way out is through the resistor to output.  However, when I put switch in a position that connects the two poles in that diagram, current will follow the path of least resistance, thus by-passing the resistor (even though it is not truly disconnected, we have just made a path around it).

Yes?

Thanks,

 

[Cagey]

No. It's an over-simplification, but a resistor in series with the output will simply reduce the current from the pickup, rather than change its voltage. Since the amplifier's input is high impedance, it's more voltage sensitive than current sensitive. What you want is a voltage divider, which you can create by tying a resistor of some value from the source (pickup) to ground and taking your signal off the junction point. This effectively puts the signal in series with the source and depending on the division that takes place, changes the amplitude of the signal the amp sees. This is essentially what a volume pot does, being a resistor itself, but when properly wired adds the ability to change the division point, and thus the output level.

 

[BrotherJack]

Nod nod (sponges up info).

I have already done some experiments like this:


Pickup output -> output hot terminal <- resistor to ground


This works relatively well (extremely well if the goal is to mellow the harshness that humbuckers seem to get when wired direct to output jack like I am doing), but my (very crude/amateurish) understanding of the way things work is, that wiring it as above will roll off the treble a good bit (and it does, but not so much that it's a particularly bad thing), where as this:


Pickup output -> resistor -> output hot terminal


Will have similar effects (at possibly differing resistor values) in terms of volume attenuation, but more-so across the whole frequency spectrum (ie: not so much treble roll off). 

If my understanding is wrong, then no big deal, I can just buy a more expensive switch to accomplish what I am after via doing it like the first diagram (if you can call my text a 'diagram') above and using poles to connect/disconnect the resistor->ground line.   

However, If I am right, then I am interested to know if what I am trying to accomplish can be done as I described in my last post before this one.  I gather you said 'no, that wont work', but I am new to all this, and didn't quite understand everything you said.

Thanks

 

[Cagey]

Doing it the way you propose is not going to accomplish what you want, which I'm assuming is to get a preset output drop as if you'd turned down a volume pot.

As for doing it the way I suggested, you're right - you'll lose some high end response as you change the overall impedance of the circuit, the same way regular volume knobs work on guitars/basses. This is why "treble bleeds" or "bypasses" are getting more popular. Sometimes you just want a lower output without a corresponding change in tone.

I think if it were me, I'd get a small collection of resistors, capacitors and and a set of test leads...

so I could experiment with a variety of values in parallel until I found something that worked. Save yourself a helluva lotta soldering time and smoke inhalation. Would also allow you to use a simple SPST switch once you found the RC combination that worked.

 

[fdesalvo]

Get a decent decade box.  A tweaker's delight man!

 

[Cagey]

No doubt. I was going to suggest that, but the things are surprisingly expensive for casual use. It's more of an engineering tech tool, where you're constantly searching for just the right value without doing the math before you head to production.

Back when I was a tech, we used to buy them just for the packaging and switches because we'd burn 'em up in no time. The installed resistors/caps were often way too small in wattage/working voltage, so the things got wrecked in to time flat. You know how the stupid laws of physics fail in engineering labs. But, then you replace the faulty components with something that would take some abuse, and they were good to go. For a while. Maybe. Depending on how destructive you were feeling that day... :icon_biggrin: