Humbucker and Phase Relationships

[hermetico]

Re: Humbucker and Phase Relationships

Sorry guys, but these statements are all somewhat incorrect.
Magnetic polarity has nothing to do with hum-cancelling.
Both coils on a Duncan pickup are wound the same direction. They can be wound the same, or opposite, without regard for magnet polarity, and still be hum-cancelling. For example, both coils of a Duncan humbucker are wound the same direction, while the middle pickup in singles is wound reverse. When used with a neck or bridge pickup, its hum-cancelling.

Here's how it works: for hum-cancelling, we need two coils. If I wind them the same direction, I connect them start-finish-finish-start. If I wind the two coils opposite directions, I connect them start-finish-start-finish. Notice that both of those configurations are out-of-phase, internally, and hum-cancelling and I haven't brought magnets into the picture yet. (The start-finish-start-finish coils are out-of-phase because one is reverse wound.)

Now, for the signal to be in phase, I need the magnetic polarity of each coil to be opposite. In the first case, we get the typical humbucker, and in the second case we get the neck/middle or middle/bridge of single coils. (Or neck/bridge of a Tele.)

Does that make sense?

I'd post a diagram that might help, but I'm not at home.

Thanks again, wizard!
Memory fails or are there two kind of cancellations? (somewhat about what the "coils sense" and what the "magnets sense")?
I am forgeting this every time.

 

[uOpt]

Re: Humbucker and Phase Relationships

Thanks again, wizard!
Memory fails or are there two kind of cancellations? (somewhat about what the "coils sense" and what the "magnets sense")?
I am forgeting this every time.

The opposite oriented magnets don't cancel anything. They just flip the signal (as opposed to the hum) back to where it should be after you reverse one coil.

 

[hermetico]

Re: Humbucker and Phase Relationships

The opposite oriented magnets don't cancel anything. They just flip the signal (as opposed to the hum) back to where it should be after you reverse one coil.

Yup, thanks, uOpt. I've got that but, I rememer to read something about two kind of cancellations related to noise generated inside coils and outside coils. I need to dive in my spread notes, I guess. Once I have a working rule, I usually forgot how did I came to that. I need to update my brain's Operating System. LOL.

 

[G0lden]

Re: Humbucker and Phase Relationships

A coil acts as an antenna. It typically picks up the lovely 60 Hz hum. Humbuckers are designed so that the 2 coils are wrapped in opposite directions. Note that they may look like they are wound in the same direction, but one is probably wired up "backwards". Now you have 2 antennas that will cancel each other out. Seth Lover patented this design back in the late 50's. Now we just need our magnets. If we use one with south up and another with north up, we make 2 coils that produce the "phase" electrically. That ends up making double the output of a single coil (though they are typically wrapped less than a single).

Make sense?

Here are two links to an explanation. It probably explains it better than I can.
http://www.seymourduncan.com/blog/the-tone-garage/how-hum-cancelling-works-part-1/
http://www.seymourduncan.com/blog/the-tone-garage/how-hum-cancelling-works-part-2/

 

[hermetico]

Re: Humbucker and Phase Relationships

A coil acts as an antenna. It typically picks up the lovely 60 Hz hum. Humbuckers are designed so that the 2 coils are wrapped in opposite directions. Note that they may look like they are wound in the same direction, but one is probably wired up "backwards". Now you have 2 antennas that will cancel each other out. Seth Lover patented this design back in the late 50's. Now we just need our magnets. If we use one with south up and another with north up, we make 2 coils that produce the "phase" electrically. That ends up making double the output of a single coil (though they are typically wrapped less than a single).

Make sense?

Here are two links to an explanation. It probably explains it better than I can.
http://www.seymourduncan.com/blog/the-tone-garage/how-hum-cancelling-works-part-1/
http://www.seymourduncan.com/blog/the-tone-garage/how-hum-cancelling-works-part-2/

Great links!. I missed those.
Very graphically explained.

 

[Cyberleader]

Re: Humbucker and Phase Relationships

This is getting more technical then I think I require. I think at this point I'm just confused about having two humbuckers active at the same time. If both are wired correctly for in-phase relationship, and both are active via the middle position of a three way switch, your saying I should be fine. You also said I can rotate the bridge or neck pickup 180 degrees without causing problems. Are these statements correct?

Next, Im now concerned about electrical polarity. I understand this means knowing which interior lead is used as the ground and the hot lead. Switching the leads will also cause phase issues? Can you explain the science behind this? How does the electrical current affect polarity, scientifically? Also, what is the best way to test electrical polarity without opening the pickup? I have heard it can be determined with an ohmmeter but Im not sure how.

Thanks for all the help!
MattSA

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Here Dude, if you've not already encountered it for yourself, an excellent YouTube upload detailing and answering everything in your queries...

https://www.youtube.com/watch?v=7UfxQBhqen8

 

[Cyberleader]

Re: Humbucker and Phase Relationships

Feeding the same signal but with phase reverted cancels the signal. In the case of two pickups being active it means that all the signal that is left is the part that was previously canceled out (when pickups were in phase).

There is no way to test wind direction without trying. Obviously if it's the same vendor then using the same colors will ensure that things are in phase.

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What would that entail? Using a weather vane? Is it an easterly or nor'westerly air stream? And without trying what exactly? I'm all ears (eyes). .