Humbuckers 102 or How I (Hope to) Split My Coils..

[ozboomer]

I've been working with single coil pickups in my Stratocaster guitars quite alright for the last few years and I'm now delving into the humbucker side of things... but I have a few questions... which is weird, 'coz it's almost like I don't know what I want to ask(!)

I could say I'm looking for a "Humbuckers 102" -type thing (the 2nd lot of "what one needs to know"), I guess, 'coz I've had a look at the web sites for Seymour Duncan, DiMarzio, and others... and all I managed to do was get more confused. So, back to GuitarNutz^TM to set me straight

Now, I've had a bit of a look through this section of the forum... but didn't find something obvious that would address my questions... I think I understand the basic concepts, like a humbucker is made up of two single coil pickups, frequently joined in series... and I'm guessing that they somehow have to be wound in different directions and/or the magnets are set-up differently, so within the humbucker itself, we get the out-of-phase thing happening, giving us hum cancelling.

What happens, though, when you combine such a pickup with a single coil pickup? One of the "halves" of the humbucker will, no doubt, be "in phase" with the single coil, whilst the other "half" will be out-of-phase, so does that mean the sound produced by the combination of the HB+SC will be (totally) hum cancelling? If I do something with the humbucker so I can select a "coil split", I'll be able to work out exactly which of the two "pickup halves" is in- or out- of phase with a given single coil pickup... but can it be determined with something like "the old screwdriver trick"?

...and what of the "matching" of the HB+SC? I read someplace that if the resistances (impedance, really, I guess) of both pickups are similar, then you'll get some decent mixing of sounds happening... but if one pup is a much higher impedance, the lower impedance sound will dominate the output (unless I have that backwards)...

Speaking of backwards.. what's the deal with having a neck pup one way and the bridge pup the other way around (for same-model HB pups)? Again, I'm guessing it's so that individual coils, when split-out to run as single-coil pups will be hum-cancelling with each other? Maybe I'm thinking too much (again!)...

Y'see, the next few projects I'll be working on under the SimpleMod + ToneMod = ... thread will involve some mods using humbuckers, so I think I need to know a bit more about what I'll be working with before I start designing, let alone soldering...!

Many thanks for any pointers...


John

[newey]

a humbucker is made up of two single coil pickups, frequently joined in series..

So far, so good!

and I'm guessing that they somehow have to be wound in different directions and/or the magnets are set-up differently

Yes and Yes. One coil is Reverse Wound (RW) with respect to the other, and also has its magnetic polarity reversed (RP).

so within the humbucker itself, we get the out-of-phase thing happening, giving us hum cancelling.

Half right. Noise is generated through the coil wires, acting as antennae. Because one coil is RW, the noise signal is out of phase, and the peaks and valleys of the wave cancel each other out. The magnets don't have a role in the noise equation, just the coil wires.

But the signal, which depends on both the coils and the magnets, is not out of phase. If the magnets were the same polarity, and we swapped one pair of coil wires (i.e., same as one coil being RW), the 2 coils would be out of phase 180°. But because the magnetic polarity of that coil is also reversed (RP), it brings that signal a full 360°, and it's back in phase.

So, when both coils are operating, the 2 coils are in phase with each other. Assuming you add a SC wired in the correct orientation, it will be in phase with the HB. And if you split the coils, each individual HB coil will likewise be in phase with the SC.

The SC and HB together will have some degree of hum cancellation, but imperfectly, since only one of the 2 coils is RWRP with respect to the SC. Personally, I've never noticed a noise issue with that type of set-up.

Speaking of backwards.. what's the deal with having a neck pup one way and the bridge pup the other way around (for same-model HB pups)? Again, I'm guessing it's so that individual coils, when split-out to run as single-coil pups will be hum-cancelling with each other?

Yep. It's easier to rotate a pickup than it is to dismember it to change the magnets around. Just depends on what coils one wants to split.

[JohnH]

All agreed, as newey says, and a good explanation

One thing which is of interest, is that the two coils are not actually wound in opposite directions, they come off the same machine. All that is required to achieve the reversal is to connect one the other way round. Hence, on sites that describe guitar wiring colour codes, you will see that the start and finish of each coil are identified, and it is normal that the two starts go to hot and ground, and the two finishes are joined together.

This page by wolf is insightful:
www.1728.com/guitar1a.htm

John

[ozboomer]

Hi again, all...

[...newey's post...]

Ahhh, 'tis good to see I remembered some of your earlier teachings, newey ...and I more-or-less understand your explanation about the hum cancellation (I'll have to read and think awhile for it to really sink-in); ...and so, I'll keep wearing my "engineer" hat for the moment and I'll wear my "physicist" hat later

Also, it seems one of the "halves" being RW/RP means the two "halves" are in-phase; however...

Aug 1, 2010 0:48:40 GMT -5 newey said:

...Assuming you add a SC wired in the correct orientation, it will be in phase with the HB. And if you split the coils, each individual HB coil will likewise be in phase with the SC.

What is the "correct orientation"?

*thinks* ... The penny dropped as I was writing the rest of my question here. For example, if the "clockwise winding" half of the HB has a "north-upward" magnet, then the SC to be combined with the HB should be built with a ( "clockwise winding" + "north-upward" ) configuration... or a ( "anti-clockwise winding" + "south-upward" ) SC would work Ok as well in terms of getting hum cancellation to work.

The SC and HB together will have some degree of hum cancellation, but imperfectly, since only one of the 2 coils is RWRP with respect to the SC. Personally, I've never noticed a noise issue with that type of set-up.

So, does this mean to include a "coil split" switch (to select "A"*"B", "A" only or "B" only) on the HB to select only ONE half of the HB when combining it with a SC pickup would be overkill? It's unnecessary? ...even though it would probably be "required" to get "perfect" hum cancelling (in theory)?

*more thinks* ... and to check the direction of winding, I can use "the old screwdriver trick", and check the direction of current flow, right? ...and a magnetic compass will tell me about the orientation of the magnet... I think(!)

As an example, the following layout would illustrate what I've just written, I think:

[...about wolf's diagram...]

Now, THAT's a good diagram... and it shows how the two pickup "halves" could be wound in the same direction on the same machine (JohnH)... and it's simply the "starting point" of the coil with respect to the magnetism of a single magnet that determines that the magnet is reversed AND the winding is reversed for one of the two "halves". Good job, Mr wolf

Anyway, I think I have some better idea of what's going on now... providing my thinking as outlined above is Ok -- I'm sure you'll let me know otherwise

Fanx again, folks..

[newey]

*more thinks* ... and to check the direction of winding, I can use "the old screwdriver trick", and check the direction of current flow, right? ...and a magnetic compass will tell me about the orientation of the magnet... I think(!)

Not needed, really. To check which coil of the HB is RWRP with respect to your SC, just hold the SC face-to-face with one coil of the HB, then the other. Opposites attract, so the side that attracts the SC is the one that's opposite polarity- and if it's opposite polarity, it will be opposite wound as well, since that's the way HBs are built.

It's a little trickier to suss out which coil of the HB is which if all you have is the HB itself, or if all the pups are mounted in a guitar. Yes, you can use the old screwdriver trick if you have an analog multimeter.

A compass will also work- the needle will point North with the South coil, remember.

[ozboomer]

Aug 1, 2010 5:00:43 GMT -5 ozboomer said:

...to include a "coil split" switch (to select "A"*"B", "A" only or "B" only) on the HB to select only ONE half of the HB when combining it with an appropriately configured SC pickup would be overkill? It's unnecessary? ...even though it would probably be "required" to get "perfect" hum cancelling (in theory)?

Just to check this, please..

...and so, the only reason you'd include a "coil split" switch is to get the (not so flash, I understand) "single coil" sound when combining the HB with a SC?

[newey]

The ability to choose coil A vs. coil B from a HB can be useful where the HB is being combined with multiple other coils- this allows one to find the hum-canceling combos.

If you've only got one other SC, it's pretty much redundant, as only one of the 2 HB coils will hum-cancel with the SC- figure out which way is hum-cancelling, and just use that coil for the split.

[ashcatlt]

Yeah, I'm not so sure about the "partially hum-cancelling" thing.

| 1 + (-1) + 1 | = | 1 + (-1) + (-1) | = 1

When combining any 3 coils, one of which is RWP with respect to the others (and only one, at most, can be) you are expected to get the same noise as exactly on coil. Of course, in practice even the HB doesn't reject all the noise, so it'll be a bit more.

I have a number of ways to get this kind of combination on my guitar and there is always a noticeable increase in noise when bringing in the odd numbered coil.

[ozboomer]

Aug 2, 2010 16:22:03 GMT -5 newey said:

If you've only got one other SC, it's pretty much redundant, as only one of the 2 HB coils will hum-cancel with the SC- figure out which way is hum-cancelling, and just use that coil for the split.

Ya, I think so. ...At this stage, though, I'll be keeping the HSS arrangement for a good bit of the experimenting, so the switch will probably be handy, methinks...

Aug 2, 2010 17:19:53 GMT -5 ashcatlt said:

Yeah, I'm not so sure about the "partially hum-cancelling" thing.

...and I was thinkin' it probably wouldn't hurt to have the switch in there, as in theory, one of the coils will always give a "better"(?) degree of hum cancelling than the other (when you have a choice).

Fanx! for the confirmation... Now I can get started on cobbling together some of the details of my designs...

[wolf]

I was thinking of adding another humbucker page to my website and I went looking for information and came across this discussion.
(By the way, thank you for the good remarks about my website).

As newey explained, hum gets canceled because it only enters through the coils and not the magnets and the reverse wiring reverse magnetic polarity (RWRP) of the humbucker's coils cancels out the hum but not the guitar signal.

If we look at the different ways coils can be wired to be hum canceling (see large diagram):

we can see that the RWRP of the coils in the first two examples explains the hum canceling.
I was just wondering how the coils can be humbucking when the coils are wired in parallel (example 3). The magnetic polarities are opposite but the windings are the same.
Also, examples 4 and 5 are two more examples of humbucking being in effect but both coils are not RWRP. (Incidentally, examples 4 & 5 are based on 2 identical single coils).
*************************************************

Another question - are the coils in a standard humbucker series wiring really out of phase? I'm sure we've seen that term used a lot in books and the Internet but is out of phase the correct term?

[newey]

Another question - are the coils in a standard humbucker series wiring really out of phase? I'm sure we've seen that term used a lot in books and the Internet but is out of phase the correct term?

No, they are not OOP, again, phase is dependant on more than just the direction of the wiring.

If you swap the wires round on a HB (Both "starts" to hot, both finishes to ground), then the windings will be identical, but the magnets are still opposite, so the 2 coils will be OOP with each other even though the windings are now the same- and because the windings are the same, you won't get hum-canceling.

I was just wondering how the coils can be humbucking when the coils are wired in parallel (example 3). The magnetic polarities are opposite but the windings are the same.

Look again. Your example shows the windings to be opposite; one coil is still RWRP with respect to the other, and you'll get humcanceling the same as with the standard series wiring.

[wolf]

Wow, in example 3 (parallel wiring) the coils do have different "windings". (I mistakenly thought of the coils as just being one on top of the other but the direction is different).
Well a +1 for that!

Now (if I can keep those windings straight), time to discuss examples 4 and 5. As I stated in the large diagram, the pickups are identical, such as the neck and bridge in a Stratocaster™. As we know, when the neck and bridge pickups are used together, they are not hum canceling. (Windings and magnetic polarities are identical). However, when they are wired out of phase, hum canceling does take effect. Why is this? The windings are different but the magnetic polarities are the same.
*****************************************************
EDITED TO ADD
Because the coils are reverse wired the hum gets canceled and since the magnets have the same polarity, the guitar signal gets canceled too.
Okay, the guitar signal doesn't get 100% canceled but it is sufficiently altered that it has that thin, squawcky "out of phase sound"?

[newey]

Because the coils are reverse wired the hum gets canceled and since the magnets have the same polarity, the guitar signal gets canceled too.

Exactly. If the 2 coils were in phase to begin with, we can alter the phase by either swapping the wires on one coil or by flipping the magnet on one coil around to swap pole positions.

If we switch the wires on both coils, we're back in phase.
If we switch the magnets on both coils, we're back in phase. If we switch the magnet and the wiring on one of the coils, we're back in phase (and humcanceling, as the coils are now RWRP).

And if we swap both sets of wires and magnets, we're back in phase.

Okay, the guitar signal doesn't get 100% canceled but it is sufficiently altered that it has that thin, squawcky "out of phase sound"?

If the signals from both pickups were identical, the signals would theoretically perfectly cancel each other out, and you would hear no sound. Real world, each pickup produces a different signal, due to its unique windings, etc., but primarily because of differing positions along the string. Frequencies not replicated by one pickup will remain.

The same is true of the noise cancellation- "hum" is not perfectly "bucked" because the noise signal picked up through each individual pup varies a bit.

And thanks for the +1, but I don't deserve it. I didn't understand any of this until ChrisK explained it, and I'm just repeating what he (and others) have already said on the subject.

[sumgai]

Aug 11, 2010 19:33:25 GMT -5 newey said:

I'm just repeating what he (and others) have already said on the subject.

Yeah, but you're repeating it correctly, so you just keep that there +1, young feller!

;D

[newey]

young feller!

Now that I really don't deserve!

[wolf]

newey
Yes, I'd say that was a well-earned +1 for that explanation.

Anyway, I should have another "humbucking" web page ready in a few days.

[peterrabbit]

Well, yes you do - and that's another plus one from me.

[wolf]

Okay, I finally created a web page about humbuckers and it is located here: www.1728.com/guitar1b.htm

I'm surprised at the amount of time it has consumed and I don't know how many times I double-checked and reread it. (English translation - it still probably has LOTS of mistakes . And it is still a bit unfinished.

But be that as it may (and I doubt if it ever was), let me know what you think.

[newey]

Very good, Wolf!

My only quibble is that, although you later indicate that wiring the coils in parallel is also hum-canceling, in the first part where you explain the hum-canceling effect, you speak of the signal going from one coil through the other (i.e., series connection), giving the impression that this arrangement has something to do with the hum-canceling effect, which it does not.

[wolf]

Thanks for looking that over newey.

I think what you are saying is that I describe series wired humbuckers as going through one coil then the other, whereas with parallel wiring I describe the current as going through at the same time?

Sorry to be a pest about this, but Guitar Nuts do take this kind of thing seriously.

[newey]

Wolf-

I was bothered by the following statement:

"when the hum travels from one coil to the other, it gets cancelled due to the opposite coil windings."

Not as I understand it. Each coil is generating its own guitar signal, and each generates its own noise signal. This is true whether the coils are wired in series or parallel.

The 2 noise signals cancel because they are out of phase. Here's my somewhat shabby-looking graphic representation:



The 2 noise signals, "A" and "B", are represented as black lines, and are out of phase. Coil "B" is RWRP, meaning its guitar signal (red line) is in phase with coil "A" (orange line). Thus, only the noise signals cancel.

[chuck]

that is how i understand it also Newey .

[wolf]

Okay, I have posted a seriously re-written guitar page about humbuckers right here:
www.1728.com/guitar1b.htm

Yes, I have spent a lot of time on this, but I wanted to make sure I could present the entire story ... and I name names. ;D