Coil Tapping Both Sides Of A Humbucker Pickup

[1Way]

How does one go about being able to selectively coil tap each side of a humbucker pickup? Here is my vague understanding of a four wire pickup. One is for ground, one is hot/signal, the other two are for coil tap and are just connected together if you don’t want to coil tap.

Seems to me that somehow the hot and ground must become involved as I just do not see how one could coil tap two different halves of pickup by opening or closing one set of wires. "One connection" or "disconnection" should only produce one effect which should be to shut off (or turn back on) one half of the pickup. So the question remains, how do you coil tap the other side? Plus I understand that there are primarily two different ways to interrupt a coil tap circuit, one is to break the circuit with a switch or variably brake it with a control pot, the other is to send the signal to ground via a switch or variably with a control pot.

I’m not to worried about variable coil tapping at the moment, but after I learn how the circuit works to coil tap both coils correctly, then I want to place both coil tapping functions onto separate control pots. I’ve been scanning for diagrams for how to tap both sides of a pickup, but so far no luck...

[Mattia]

Re-think it; a humbucker is two coils wired in series (hot from one into ground of the other, other two leads as hot and ground for the entire thing). A 4 wire bucker gives you access to the start and end (lead and ground) for each coil, to mix and match as you see fit. For humbucking operation, yes, you connect the end of one coil to the start of the other, for tapping you generally short out one coil.

Check stewmac's free info on wiring, and Guitarnuts.com, and the electronics section here.

[mikhailgtrski]

Here's a schematic for tapping both coils (color code is for Seymour Duncan): dual coil-tapped humbucker

(fyi - this should be in the electronics forum, and you could probably have found it by searching for coil tap)

Edited March 31, 2006 by mikhailgtrski

[hessodreamy]

It's something I'm working on at the moment. Check my thread:

http://projectguitar.ibforums.com/index.php?showtopic=22578

I've not wired it up yet, but I'm assured it'll work

[lovekraft]

http://guitarelectronics.zoovy.com/categor...ckerwiringmods/

Scroll down to the 4th row of diagrams.

[GnognoFasciani]

http://www.guitarnuts.com/wiring/sw3.php

[1Way]

I'm going to have a separate pot for each coil, so each coil tap adjustment will amount to a volume knob for that side of the humbucker. I don’t see any diagrams or layouts explaining how to tap both or either side of the humbucker, just a side. Some say “either side” but do “not” explain which side you get because they are apparently only concerned with tapping one side or the other, not optionally either (or both).

Lets say I have 4 conductor wires coming out of my pickup and one ground shield.

Can I hook up each coil to it's own volume and tone control, and thus be able to variably coil tap either side or both sides of the pickup? You can variably coil tap both sides, like cut one to 1/3 volume and the other to 2/3 volume it allow virtually any blend of coil tapping possible. I’ll have stacked concentric pots and stacked concentric knobs to allow for the extra control.

So how do you hookup such a humbucker?

Ground > Ground

1+ wire >

1- wire >

2- wire >

2+ wire >

Lets please try to stick to layouts, I’m no good with electronic symbols.

[JoeAArthur]

Since you would be able to get any degree of coil tapping possible with a single pot, is there any particular reason you want to use two pots?

[unclej]

this thread has me very curious..what is the advantage or the tone difference if you will, to being able to make either coil of a humbucker hot? my mind tells me you wouldn't be able to hear anywhere near the difference in tone as you would by tapping the neck pup and tapping the bridge pup. considering the close proximity of both coils on a humbucker would you get much tonal difference unless they were wound differently?

[mikhailgtrski]

I can hear a definite difference between the coils on both pickups... the bridge outside coil is thinner and more "stratty" whereas the inside coil has a little more meat to it, kind of like a hot tele or maybe a P90. The neck outside coil gives me a good strat sound, and the inside coil, well I don't know how to describe it, except it's a lighter single coil sound, nice for clean single-note stuff or light comping.

Same when combining the bridge/neck with the middle (or all three on) - the outside/inside coil taps sound different.

BTW - I'm using Duncan '59s. "Your mileage may vary."

[1Way]

Unclej

By being able to tap either coil exactly how much you want, you can dial in between sounds that one person said can approach a P90 sound, I think he said it was like coil tapping something modest like around 30%, so it was mostly single coil, but with more bite than if it was tapped 100%.

JoeAArthur

Coil tapping is tapping one coil to ground so that only the other coil works. Variable coil tapping allows you to control how much of the tapped coil gets sent to ground, and double variable coil tapping is the same thing but for both sides! I wish to have a volume and tone knob for each coil in my pair of humbuckers. Plus if you are combining single coils from a different pickup, you want to know which one you are matching up if you want it to remain humbucking.

Mikhailgtrski

Of special note, one can get several interesting in between sounds by variably splitting. So far I’m thinking of getting into a Bare Knuckle Mule for the bridge, maybe a Stormy Mondays for the neck later on. What kind of guitar did you match those 59’s up to?

Edited April 12, 2006 by 1Way

[mikhailgtrski]

What kind of guitar to do match those 59’s up to?

They're on my old '91 Warmoth soloist (maple body/neck ala George Lynch ) along with an SSL-2 in the middle. I'm using a similar setup on my new project (Warmoth VIP maple/mahogany body + mahogany neck) so we'll see how it sounds with some warmer-sounding tonewoods.

Mike

[JoeAArthur]

1way - sorry I wasn't clear about my question.

If you wire up a humbucker and a single pot (linear recommended) like the diagram below, you will be able to variably split the pickup - both coils to any degree you wish.

As wired, the control when rotated fully clockwise will give you the coil between the series link and ground. When rotated fully counterclockwise, you'll get the coil between the series link and hot. In the middle will give you both coils series humbucking. Rotate one control to mix both coils.

To me... two controls to accomplish the same result as one won't provide you with any additional flexibility or sound choices. And with two controls, you will get much more fluctuation in volume as you try to dial them in for a correct mix.

It's your guitar and I really don't care how many knobs you have... but I am curious. So... now that you know two controls aren't necessary, what benefit do you see by using two controls?

[1Way]

JoeAArthur

First, I'm not certain about your proposal, please help me understand it. Do you mean to use a blender pot, where it’s like a single knob for treble and bass, you get only treble on full treble and only bass on full bass, but both blended in toward the middle where they are both full on. I believe that is the function you speak of, if so, it requires a “blender” pot, where they both peek at the middle position and may have a center detent position to hold that setting, and the one or the other direction bleeds off as you move away from the middle position. And, just in case, I’m not saying you can’t do that. I’m saying I’d rather have a separate volume and tone control for each coil, that is why I want so many knobs.

See if I play with one volume knob to variably mix either coil in or out of the mix, then I might constantly wonder which tone knob was active or which is semi active or which is not active. With dedicated tone/volume pairs, you always know how much the tone is in effect because of the closely associated volume setting (“closely associated” in settings relationship, and in location). Also, I tend to view variable coil tapping as a one coil event, I most likely would leave it tapped at a general vicinity and make adjustments as needed, although it would be nice to be able to pan the entire variable coil tapping spectrum with one knob.

So even if I had blender pots, I’d still rather have stacked concentric to keep the volume and the tone controls associated and dedicated. Also, your way does not allow mixed blending of the two coils, like 75/40, yours would always be that at least one coil is 100% full volume (or maybe its 50% each in the middle?). Not enough flexability.

Then I’ll have two three way switches, each switch will be a coil selector, one switch for the neck pickup and one switch for the bridge pickup.

Single coil > both coils HB > second single coil

If I want only one HB or only one SC on, I’d have to turn off the other coil(s) with it’s associated volume control(s).

1way - sorry I wasn't clear about my question.

If you wire up a humbucker and a single pot (linear recommended) like the diagram below, you will be able to variably split the pickup - both coils to any degree you wish.

As wired, the control when rotated fully clockwise will give you the coil between the series link and ground. When rotated fully counterclockwise, you'll get the coil between the series link and hot. In the middle will give you both coils series humbucking. Rotate one control to mix both coils.

To me... two controls to accomplish the same result as one won't provide you with any additional flexibility or sound choices. And with two controls, you will get much more fluctuation in volume as you try to dial them in for a correct mix.

It's your guitar and I really don't care how many knobs you have... but I am curious. So... now that you know two controls aren't necessary, what benefit do you see by using two controls?

Whenever I coil tap, you always have the one coil going weaker than the other coil, the goal of my version of variable coil tapping is not to balance out the volume levels between the two coils, the goal to discover a variable coil setting that happens to provide the best amount of mix for the particular music selection/style you are wanting to play. I find that at this stage of my rig’s underachievement (lacks upgraded pickups), that I tend to keep the guitar’s volume set to around 75% to help it remain tight. With variable coil tapping, I can increase the volume while sporting precise control over how clean I want my guitar to sound.

Edited April 12, 2006 by 1Way

[JoeAArthur]

First, I'm not certain about your proposal, please help me understand it.

I'm not sure I can. I don't have any different words... HOLD IT. I think you got it... right here where you said:

... although it would be nice to be able to pan the entire variable coil tapping spectrum with one knob.

Yep, THAT'S IT!!! My diagram shows how to wire it. It doesn't require a "blender pot". (Didn't I mention a recommendation for a linear pot - maybe I should have said a single pot linear pot?)

Also, your way does not allow mixed blending of the two coils, like 75/40, yours would always be that at least one coil is 100% full volume. Not enough flexability.

Whenever I coil tap, you always have the one coil going weaker than the other coil

Those two statements sound contradictory to me. But think about this: (and let's pretend you said 80/40 instead of 75/40 to compensate for my lousy mental math skills)

Let's say you have your guitar set for that 80/40 split. Do you really believe a 40/20 split, or a 100/50 split of two coils are going to sound different from an 80/40 split (besides volume level)? All of these are two parts one coil, one part the other coil - the same ratio.

Whatever you decide... good luck!! And post us a diagram of what you wind up with!

[lovekraft]

...your way does not allow mixed blending of the two coils, like 75/40, yours would always be that at least one coil is 100% full volume (or maybe its 50% each in the middle?). Not enough flexability.

Not a Math major, obviously (remember fractions/ratios?) - 75/40 is the exact same ratio as 100/53, and yields nearly identical results. However, while there are a few little problems that will need to be addressed (and I'm sure you've already thought them all out - for instance, you know what the effect of having two tone pots with two coils in series is gonna be, right?), there's no reason why you can't implement a volume and tone pot for every single coil on your guitar. There's simply no compelling reason to do so.

JoeAArthur's setup does it all, and with a single pot - why would you want to complicate that? What sort of flexability does it lack?

[scott from _actual time_]

If you wire up a humbucker and a single pot (linear recommended) like the diagram below, you will be able to variably split the pickup - both coils to any degree you wish.

that is really slick--nice job. the only tiny problem i can see is that it'd be hard to keep the pot exactly at the center full humbucking position unless the pot had a center detent.

Edited April 13, 2006 by scott from _actual time_

[scott from _actual time_]

I just do not see how one could coil tap two different halves of pickup by opening or closing one set of wires. "

i tried to reply to this last week, but it seems my post didn't come through.

there are two ways to coil cut a humbucker, and each way gives a different coil. you can connect the series link to ground, which gives you the "first" coil [the coil that the humbucker hot wire is coming from]. or you can run the series link to hot, which gives you the "second" coil [the one the colored ground wire is coming from]. so those Duncan and other diagrams that use one SPDT switch to give either coil of a humbucker are just switching the series link to ground or to hot.

unclej:

i hear a big difference between each coil in a humbucker, especially in the neck position. the outer coils sounds sharper and brighter, like a Tele, and the inner coils sound rounder with more "quack," like a Strat. it makes a difference when running the cut coils alone, or when running them with other coils.

most humbuckers contain two coils that are very similar in construction, and they sound different because of how far they are from the bridge. but if you have a humbucker where the two coils are not similar [like the DiMarzio D-Sonic], the sounds from each cut coil are even more different.

[1Way]

Scott,

Would you please explain what “series link” is, and how to identify it?

I understand that every pickup comes with a hot wire and a ground for the enter pickup. When you have 4 conductors and a ground, I assume that you have access to both coils in the pickup. Which somehow basically consists of two coils of spooled up wire, and each coil has two ends, hence the four wires.

Thanks!

Edited April 16, 2006 by 1Way

[lovekraft]

The series ink is exactly what it sounds like - it's the point where the two separate coils in a humbucker are connected in series. That's the two wires on a 4-wire humbucker that you solder together for normal humbucking operation.

[1Way]

Lovekraft

Thanks for the response. I see your point about equivalent ratios and your right in that every possible ratio is available while one (of the two coils) is set to max. Thanks much, I stand corrected. As to

... However, while there are a few little problems that will need to be addressed (and I'm sure you've already thought them all out - for instance, you know what the effect of having two tone pots with two coils in series is gonna be, right?), there's no reason why you can't implement a volume and tone pot for every single coil on your guitar. There's simply no compelling reason to do so.

Oh yes, I forgot about that. I don’t know off the top of my head what the effect would be, but it would likely double or half something and that’s not acceptable. I need to change my plan.

Ok, so if I use just one pot to variably coil split one humbucker pickup, then what is the best design for the volume and tone controls?

At first I thought it would be cool to have a separate tone control for each coil, but maybe that is not such a great benefit, especially if having two tone controls causes a problem.

Would you suggest a dedicated master

• volume
  
• tone
  
• variable dual acting coil tap
  

control for each pickup? Sounds viable to me, what do you think?

Suggestion 1

I just ordered 4 concentric 500k/500k CTS pots. So I’m sorta stuck with using about one hundred dollars worth(!) of pots and knobs... So far, I’d say, hook up 2 pairs of knobs for volume and tone control of each pickup. As to the 4 other pots, 1 pair for each pickup, one pot can be used for dual variable coil tapping, and the other can be used for... ?

Suggestion 2

I might consider having half standard single knob controls, and the other half dual concentric for 6 pot controls total.

Other recommended features besides coil tapping? I'm not sure if there are other things like series/parallel or in phase and out of phase I might be interested in.

Push/push and push/pull

I have a Gibson SG, which is very slim, so I’m told that I can’t use some of the push/pull type pots because they are too long, although I’ve heard of some SG’s with push/push for example, but I don’t know who makes them or if they are quality parts or not.

Thanks much for explaining the coil tap function in relationship to the 4 wires! So you don't need to do anything special individually with those two wires, just leave then connected together as effectively one lead, and as diagramed eariler, either variably tap it to ground or hot to select for the one or the other coil. Pretty cool!

Edited April 16, 2006 by 1Way

[JoeAArthur]

<sigh>

[lovekraft]

Personally, I'd sell the CTS pots on Ebay, get some regular ol' Alphas (linear for the tone, linear center detent for the coil tap(s) and audio for the volume), and use a single master volume and master tone for both pickups (for a total of 4 control pots), but that's just me, and I'm not a "kitchen sink"-style designer - come to think of it, I'm probably the last person you need to be getting advice from. Good luck with it!

<sigh>

[1Way]

JoeAArthur

Thanks for helping with the great layout diagram! Seems it's more handy than I at first realized. Thanks much.

... Wait, ... I have one question about your diagram. In the middle position, since the nature of a linear pot is to be full on at one end, and full off at the other, and (electrically, not volume) midpoint half way thru, so when that pot is set to humbucking (no coil tap, right in the middle position), then am I correct that both pickups are set at something less than full volume?

If so, then maybe I don't like this approach so well after all... I want full volume when not coil tapping.

Edited April 17, 2006 by 1Way

[JoeAArthur]

If you wanted full volume from your pickups you wouldn't use any controls at all, much less an individual volume and tone control for each coil.

Any control resistance placed across the coil will increase the load on the coil. The reduction in signal strength is roughly equal to the control value divided by the sum of your pickup's impedance and the control value. In reality you have to consider all parallel "resistances" including the input impedance of your amp, and you can't actually do simple math with mixed impedances and resistances so this is somewhat simplified.

Let's say you place a 500K volume control across a series wired humbucker and the combination of those coils has a 60K impedance. So 500K / (500K + 60K) = .89 If we assume the humbucker has a max signal of 1 volt unloaded (for easy math), the signal is now down to .89.

Replacing that volume control with this dual coil rotary splitter using a 500K linear pot set to the electrically middle position. For each coil, our pickup impedance is now cut in half (30K) and so is our load across that coil section. So we do the math again with these new values 250K / (250K + 30K) = .89 The same value. Since the series of these coils produced an unloaded 1 volt, one coil must be producing a signal of 1/2 volt. So for one coil, our signal would now be .445 volts. Add those two signal voltages for two coils in series and we are back to .89 volt - the same as our series connections with just a single volume control across it.

Now let's go back to your idea of separate volume controls for each coil. Since you were going to split the coils, it must have been a series connection. What values were you going to use? 500K's for each coil? If so, you would wire this dual coil rotary splitter with a 1 meg linear and you wouldn't notice any volume loss between the different wirings.

Think about it. The wiring of your volume controls for each coil would be the same electrical combination as this control set to the mid electrical position!!