Pickup Theory!

[big_teee]

You can configure the humbucker anyway you like.
I've made a lot of double screw humbuckers.
I have a set in my left hand LP type guitar.
They work similar, but with all adjustable screws, instead half rod slugs.

[J M Fahey]

It still seems like magic, really.

Arthur C Clarke was a brilliant futurist and writer, but he is probably most widely known for the third of his famous three laws, "Any sufficiently advanced technology is indistinguishable from magic."

Meaning: if you donīt understand it (yet) , it will certainly look like magic.

But when explained or even reading on your own, the full book or at least the relevant chapter, at a certain point it "clicks" in your mind and you go: "why ... OF COURSE, NOW I get it"

As a parallel example: you look at some amorphous shape, such as a cloud, a damp/dirty spot on a wall, or an inkblot and you "see nothing".
But a friend says: "look at the horse head/flower/whatever" ... it "clicks" ... and now you "see" nothing else

[frus]

it "clicks" ... and now you "see" nothing else

Like all those "satanic" messages in certain songs of reverse polarity

[Dolmetscher007]

Like all those "satanic" messages in certain songs of reverse polarity

Number 9, Number 9, Number 9, Num...

[nosaj]

Number 9, Number 9, Number 9, Num...

But if 6 was 9 .....

[Dolmetscher007]

But if 6 was 9 .....

69 Dude!!!

-Bill & Ted (1989)

[Chuck H]

Michael,

I'm going to predict some of your follow up questions and (try to) explain the basics of humbucker operation. I may fail to use some proper physics terminology and may the brain trust here go easy on me if corrections are required

As explained, the basic design humbucker magnet has the N-S polarity aligned at it's width ends. This way the magnetic charge to all strings on one coil is south and the magnetic charge to all strings on the other coil is north.

The coils are wired in series, out of phase. That is, in reverse of each other.

Sooo... What happens is that any EMF/EMP noise in the general environment from things like fluorescent ballasts, light dimmers, electric motors, transformer coils, etc. is picked up by both coils. Because the atmospheric noise is the same on both coils, but the coils are wound inverse to each other, the noise signal from the coils is phase cancelled.

Now, because the string magnetization on each coil is in opposite polarity the inverse wind on the coils corrects it so that the string signal leaving the pickup is IN phase. ergo, no cancellation (or very little).

I've seen this explained before and none of the explanations seemed very clear. I can only hope I did a little better. Once you get your head around it the N-S orientation of the magnet is forehead slapping obvious.

[Dolmetscher007]

I've seen this explained before and none of the explanations seemed very clear. I can only hope I did a little better. Once you get your head around it the N-S orientation of the magnet is forehead slapping obvious.

Yeah, I have read a lot of different "takes" on how a humbucker works. I do get it, for the most part. I worked for Texas Instruments in Germany (Freising) for many years, and I worked a lot with Digital Signal Processors, so I understand phase cancelation. I worked on several noise-cancelation headphone projects for Bose, and the C5000 DSPs by TI were going into tons of cell phones at the time, so phase cancelation of background noise was a hot topic.

But with such a basic analog device like a pickup, I still do not see how the reverse-wind and reverse-polarity doesn't phase-cancel the wanted-signal i.e. the guitar tone, and not just the antenna-like properties of environmental distortions like 60 cycle hum, radio, and florescent lights.

Also... one of the main problems I had with understanding polarity came from this video with Jason Lollar. Right at 14:17 in that video, he starts explaining how his take on a Teisco Gold Foil pickup is built. You'd have to go watch the video for a minute or two to really get what I'm saying, but he talks about the coil being off to the side of the pole pieces, and that some "little piece of the North polarity" comes up from below and... yeah, I just didn't get what he was saying. So it kind of threw my whole brain off on how pickups work.

I still do not understand how the Teisco gold foil pickup works, but I do think I get a standard humbucker (even though a Teisco GF is a single coil).

[Helmholtz]

But with such a basic analog device like a pickup, I still do not see how the reverse-wind and reverse-polarity doesn't phase-cancel the wanted-signal i.e. the guitar tone, and not just the antenna-like properties of environmental distortions like 60 cycle hum, radio, and florescent lights.

Maybe this further explanation helps to understand the HB -PU principle:

The external AC magnetic interference fields are not sensitive to/influenced by the static magnetic polarity of the PU cores. Thus the phase of the induced interference signal only depends on the electrical phase of the coils.

The string signal, however, is produced by an amplitude variation of the static flux through the coils caused by the moving string. As the static flux flows in opposite directions in the 2 coils, increasing flux magnitude (caused by the string approaching the PU) means more positive flux through one coil and more negative flux through the other and 2 identical coils will produce inverse signal polarities at their respectice ends. To get a net output voltage with the series wired coils, one of the coils needs to be wound or connected out of phase.

[big_teee]

A passive humbucker is a real simple design, and importantly, it works.
However humbucker guitars can still be a bit noisy.
Grounding is important.
One other thing I heard mentiioned, was reverse wound coils?
In a typical humbucker the two coils are wound the same direction. (CCW)
When they are wired in series, the signal in the second coil is traveling in reverse direction, even though they are wound the same.

We try to keep this section down to pickup basics.
If theory gets to complex, we like to keep that in the main pickup area.

T

[Chuck H]

A passive humbucker is a real simple design, and importantly, they work.
However humbucker guitars can still be a bit noisy.
Grounding is important.
We try to keep this section down to pickup basics.
If theory gets to complex, we like to keep that in the main pickup area.
One other thing I heard mentiioned, was reverse wound coils?
In a typical humbucker the two coils are wound the same direction.
When they are wired in series, the signal in the second coil is traveling in reverse direction, even though they are wound the same.
T

Thanks T. Of course actually winding the coils in opposite directions would make building them harder than it already is. I should have tried harder not to infer that the actual, physical winding was inverse.

Of course it doesn't help that for decades the typical Strat middle pickup has been called RWRP (for reverse wound reverse polarity)

[big_teee]

I've experimented with winding one of the humbucker coils in reverse to see if there's any improvement in noise.
To keep the signal further from ground, but most of the results seem to be a placebo!

In fender single coils, it is IMO important to keep the start lead near the magnet and grounded.
So typically with 3 strat coils, the middle pickup ends up RWRP.

[J M Fahey]

You donīt need to actually reverse wind it, at all, just to reverse wire it. (in this case wire meaning "connect".)

[Chuck H]

You donīt need to actually reverse wind it, at all, just to reverse wire it. (in this case wire meaning "connect".)

Yes, that's what we were delineating In contrast T mentioned that (at least for single coils) it's best to have the grounded lead as the start around the poles. He didn't mention why, but I'll leave that to the pickup guys.

[Helmholtz]

Yes, that's what we were delineating In contrast T mentioned that (at least for single coils) it's best to have the grounded lead as the start around the poles. He didn't mention why, but I'll leave that to the pickup guys.

In my most simple words: Having the grounded part of the coil inside makes the PU insensitive to inference injection by touching the poles. This makes sense especially for strat type PUs. Not necessary for HB coils as their poles are typically grounded anyway.