Questions about wiring a coil split.

[MattSA]

Hi guys,

I just got two replacement Seymour Duncan pickups for my Washburn. I'm ready to wire, but after looking through your schematics I have a few questions about the leads. I know each lead by color:

Bare - ground; Green - start of south coil; Red - finish of south coil; Black - start of north coil; and White - finish of north coil.

Can you explain the purpose of start and finish leads? I would think that the finish leads would make good hot leads and the start leads would be for parallel wiring. For instance, if I wanted to coil split the humbucker to get the south coil signal alone would I be interested in the Green lead or the Red lead?

In the case of the Green lead I would think the purpose would be for parallel wiring of the White lead of one humbucker to the Green lead of another.
Can someone give some advice or a link to this information?

Thanks,
Matt Armshaw

[ArtieToo]

Re: Questions about wiring a coil split.

I would think that the finish leads would make good hot leads and the start leads would be for parallel wiring.

Not exactly. Remember, the two coils generate an out-of-phase signal because of the orientation of the magnet. So you want to tie the two "finishes" together. This is why I never speak in terms of "start & finish", but rather in terms of plus & minus. The black and red are the two "+" and the white and green are the two "-". You connect them together like the batteries in a flashlight, so, plus to minus. In other words, black is hot, red and white tie together, and green is ground.

[hermetico]

Re: Questions about wiring a coil split.

Thinking on all this and, probably, just elucubrating...

I guess that because engines traditionally spin clockwise, most coils are being wound in the same way, clockwise (CW).
Start and finish wire are, in fact, the two extremes of a single wire, the one wound around the coil framework.
The start "wire" corresponds to the first turn, while the finish "wire" corresponds to the last turn.

Single coil pickups had some magnet bars that had a TOP South Magnetic Polarity. Maybe, to make the electrical direction the same as the winding direction.I dunno. But, because of this, Start wire was considered the negative (to ground) and Finish wire the positive (to hot).

Then, the humbucker came to the playground.
A humbucker uses two coils wound in the exactly same direction: CW.
Under the two coils of a humbucker lays a magnetic bar that brings a TOP South polarity to the outer coil (screw) and, a North polarity to the inner coil (Slug coil, the one that looks like a typical single coil).
A reverse magnetic polarity reverses the direction (electrical polarity) of the signal.
That North polarity will leave that slug coil out-of-phase (well, with reverse electrical polarity) if you used the start as negative and the finish as positive.
To correct this situation, we reverse the electrical polarity of the coil just reversing which "wire" do we use as negative or positive.
So, for that slug coil, we will use the finish as negative and the start as positive and, that would make both coils working "in-phase", with same electrical polarity, again.

Let say that we have now a CW-S (Clockwise-South) screw coil and a CCW-N (Counter-Clockwise-North) slug coil.
When you have two coils with oposite magnetic polarity and reverse winding (same electrical polarity), you have an in-phase and hum-cancelling combo. If those two coils are arranged in series, as in a train, you have a typical humbucker pickup.
But, even if you arranged those in parallel you will still have a hum-cancelling combination.

So, CW-S / CCW-N and CCW-S / CW-N are hum-cancelling combinations.

What happens with traditional Strato Coils?.
In a traditional Strato, the three coils are CW-S.
They have same electrical polarity but, also same magnetic polarity so, they are in-phase but, they aren't hum-cancelling.
So, any combination of the same electric polarity and same magnetic field will give us in-phase sounds but not hum-cancelling ones.
i.e., CW-S / CW-S, CW-N / CW-N, CCW-S / CCW-S and CCW-N / CCW-N will give us in-phase not hum-cancelling combinations.

How Stratos achieved hum-cancelling notch positions?.
By swapping the magnet polarity and reversing the wound of coil in middle pickup.
So, the typical middle RWRP (Reverse wound Reverse Polarity) is a CCW-N (counter-clockwise wound with top north mag polarity).
When you combine that middle with neck or bridge, we have a combination CW-S + CCW-N, that is an in-phase and hum-cancelling position.

To wind a pickup reverse has the same effect as to swap start and finish wires (it can be a discussion about if it's noisy to have the positive on the start instead of the finish wire, but in fact, this is what it's traditionally done with the North coil of a humbucker).

Please, just take into account that some pickups have reverse magnetic polarity, as the Texas Hot, that are CW-N (Clockwise wound with North polarity) instead of CW-S. So, a RWRP middle for that set should be of type CCW-S (Counterclockwise wound with South Polarity or, just swap black and white wires to any regular middle pickup).

So, let's go to Seymour Duncan humbuckers.
Usually (there are some exceptions, as in the case of the P-Rails):
Slug coil is North, start is black (coil positive, because we reversed it and, overall pickup hot), finish is white (coil negative, because we reversed it).
Screw coil is South, start is green (coil negative and, overall pickup ground), finish is red (coil positive).
In fact, it doesn't matter which coil goes first or after, as soon as you preserve the polarity of those wires.
So, if you have:
Screw into slug
(ground) green -> red -> white -> black (hot)
or slug into screw
(ground) white -> black -> green -> red (hot)

you have the same electrical polarity and both ways are hum-cancelling but, traditionally first arrangement is the standard one.

You will see on most of diagrams that to split to North (outter, screw coil), red & white are being soldered together to ground.
Since the green was already to ground and now the red also is, you have the screw coil shunt to ground and, since the white is now to ground and, the black is still on hot, you have just the slug coil working.
Since it's a CCW-N coil, it will create in-phase and hum-cancelling positions if paired with a traditional strato pickup (CW-S) and, in-phase but not hum-cancelling if paired with a traditional RWRP middle coil (CCW-N).

But you will see on most of diagrams that a way to achieve split to South (screw) can be achieved by soldering white & red wires to hot path.
Now, black was on hot and white also is so, you have a slug coil shunt to hot and, since the green was to ground and the red is now on hot, you have working just the screw coil (which is a CW-S).
This will give you in-phase but not hum-cancelling combos (typical strato) when combined with any regular strato pickup but, hum-cancelling combos when combined with a RWRP middle pickup.
This is a tricky way to do it but, the drawback is that you have a ton of wire hunging on the hot patch, which potentially can catch unwanted noises and have some bleed. But, it comes handy when you just have a SPDT on/off/on switch to have both splits.

A better way to achieve that split is just to change the order of those coils (as explained as slug into screw) and then, to ground black and green.
Since the white was on ground and, now black also is you have the slug coil shut to ground and, since the green is on ground now and the red already was on the hot, you get that screw coil alone, without potential side effects.

Finally, if you swap the two wires on each coil, you are reversing everything and you will get:

Slug: CW-N (black=negative, white=positive)
Screw: CCW-S (green=positive, red=negative)

This would be handy in certain cases, always thinking on what do you want to achieve.
in-phase not-hum cancelling combinations (typical strato, more quacky and chimmey but noisy).
in-phase hum-cancelling combinations (typical notch positions of stratos with RWRP middle pickup, less quacky, bolder but quiet).

Just my 2 cts.

[State of Epicicity]

Re: Questions about wiring a coil split.

Thinking on all this and, probably, just elucubrating...

I guess that because engines traditionally spin clockwise, most coils are being wound in the same way, clockwise (CW).
Start and finish wire are, in fact, the two extremes of a single wire, the one wound around the coil framework.
The start "wire" corresponds to the first turn, while the finish "wire" corresponds to the last turn.

Single coil pickups had some magnet bars that had a TOP South Magnetic Polarity. Maybe, to make the electrical direction the same as the winding direction.I dunno. But, because of this, Start wire was considered the negative (to ground) and Finish wire the positive (to hot).

Then, the humbucker came to the playground.
A humbucker uses two coils wound in the exactly same direction: CW.
Under the two coils of a humbucker lays a magnetic bar that brings a TOP South polarity to the outer coil (screw) and, a North polarity to the inner coil (Slug coil, the one that looks like a typical single coil).
A reverse magnetic polarity reverses the direction (electrical polarity) of the signal.
That North polarity will leave that slug coil out-of-phase (well, with reverse electrical polarity) if you used the start as negative and the finish as positive.
To correct this situation, we reverse the electrical polarity of the coil just reversing which "wire" do we use as negative or positive.
So, for that slug coil, we will use the finish as negative and the start as positive and, that would make both coils working "in-phase", with same electrical polarity, again.

Let say that we have now a CW-S (Clockwise-South) screw coil and a CCW-N (Counter-Clockwise-North) slug coil.
When you have two coils with oposite magnetic polarity and reverse winding (same electrical polarity), you have an in-phase and hum-cancelling combo. If those two coils are arranged in series, as in a train, you have a typical humbucker pickup.
But, even if you arranged those in parallel you will still have a hum-cancelling combination.

So, CW-S / CCW-N and CCW-S / CW-N are hum-cancelling combinations.

What happens with traditional Strato Coils?.
In a traditional Strato, the three coils are CW-S.
They have same electrical polarity but, also same magnetic polarity so, they are in-phase but, they aren't hum-cancelling.
So, any combination of the same electric polarity and same magnetic field will give us in-phase sounds but not hum-cancelling ones.
i.e., CW-S / CW-S, CW-N / CW-N, CCW-S / CCW-S and CCW-N / CCW-N will give us in-phase not hum-cancelling combinations.

How Stratos achieved hum-cancelling notch positions?.
By swapping the magnet polarity and reversing the wound of coil in middle pickup.
So, the typical middle RWRP (Reverse wound Reverse Polarity) is a CCW-N (counter-clockwise wound with top north mag polarity).
When you combine that middle with neck or bridge, we have a combination CW-S + CCW-N, that is an in-phase and hum-cancelling position.

To wind a pickup reverse has the same effect as to swap start and finish wires (it can be a discussion about if it's noisy to have the positive on the start instead of the finish wire, but in fact, this is what it's traditionally done with the North coil of a humbucker).

Please, just take into account that some pickups have reverse magnetic polarity, as the Texas Hot, that are CW-N (Clockwise wound with North polarity) instead of CW-S. So, a RWRP middle for that set should be of type CCW-S (Counterclockwise wound with South Polarity or, just swap black and white wires to any regular middle pickup).

So, let's go to Seymour Duncan humbuckers.
Usually (there are some exceptions, as in the case of the P-Rails):
Slug coil is North, start is black (coil positive, because we reversed it and, overall pickup hot), finish is white (coil negative, because we reversed it).
Screw coil is South, start is green (coil negative and, overall pickup ground), finish is red (coil positive).
In fact, it doesn't matter which coil goes first or after, as soon as you preserve the polarity of those wires.
So, if you have:
Screw into slug
(ground) green -> red -> white -> black (hot)
or slug into screw
(ground) white -> black -> green -> red (hot)

you have the same electrical polarity and both ways are hum-cancelling but, traditionally first arrangement is the standard one.

You will see on most of diagrams that to split to North (outter, screw coil), red & white are being soldered together to ground.
Since the green was already to ground and now the red also is, you have the screw coil shunt to ground and, since the white is now to ground and, the black is still on hot, you have just the slug coil working.
Since it's a CCW-N coil, it will create in-phase and hum-cancelling positions if paired with a traditional strato pickup (CW-S) and, in-phase but not hum-cancelling if paired with a traditional RWRP middle coil (CCW-N).

But you will see on most of diagrams that a way to achieve split to South (screw) can be achieved by soldering white & red wires to hot path.
Now, black was on hot and white also is so, you have a slug coil shunt to hot and, since the green was to ground and the red is now on hot, you have working just the screw coil (which is a CW-S).
This will give you in-phase but not hum-cancelling combos (typical strato) when combined with any regular strato pickup but, hum-cancelling combos when combined with a RWRP middle pickup.
This is a tricky way to do it but, the drawback is that you have a ton of wire hunging on the hot patch, which potentially can catch unwanted noises and have some bleed. But, it comes handy when you just have a SPDT on/off/on switch to have both splits.

A better way to achieve that split is just to change the order of those coils (as explained as slug into screw) and then, to ground black and green.
Since the white was on ground and, now black also is you have the slug coil shut to ground and, since the green is on ground now and the red already was on the hot, you get that screw coil alone, without potential side effects.

Finally, if you swap the two wires on each coil, you are reversing everything and you will get:

Slug: CW-N (black=negative, white=positive)
Screw: CCW-S (green=positive, red=negative)

This would be handy in certain cases, always thinking on what do you want to achieve.
in-phase not-hum cancelling combinations (typical strato, more quacky and chimmey but noisy).
in-phase hum-cancelling combinations (typical notch positions of stratos with RWRP middle pickup, less quacky, bolder but quiet).

Just my 2 cts.

This is the best explanation I’ve found of two topics:

The relationship between Start / Finish and Positive /Negative

and

Reverse wiring

This is an incredibly helpful post that will help make more efficient any wiring diagram I create in the future. Thanks so much for this.

[GuitarDoc]

Hey, Hermetico. Long time no see. Welcome back.

I've missed reading your informative contributions. I think I've learned just about everything I know about guitar electronics from reading your extensive series on the topic several years ago. I even printed out each article and put them all in a "book" for any future reference.

[Mincer]

Yes, a very easy to understand post that I was happy to read this morning. If I am not doing a lot of wiring, I totally forget most of this stuff. If someone wants to add some pics demonstrating the concepts, I will clean this thread up and sticky it.

[eclecticsynergy]

Hey, Hermetico. Long time no see. Welcome back.

I've missed reading your informative contributions. I think I've learned just about everything I know about guitar electronics from reading your extensive series on the topic several years ago. I even printed out each article and put them all in a "book" for any future reference.

Those articles sound like a valuable resource.
Would you please post links to them?

[beaubrummels]

Hermetico hasn't posted since 2015, but their blog is still up:

http://hermeticoguitar.blogspot.com/