Reverse wound versus out of phase

[sploorp]

I've been looking at pick ups for a couple of project guitars I have in the works.

I know what in phase and out of phase are and I know the difference between series and parallel wiring. I've read that reverse winding one pick up turns two single coil pick ups into a humbucker when played together.

My problem is I learned way back in the day that the coils of a humbucker were wired out of phase and the phasing canceled out the hum. That has created a bit of confusion for me when confronted with reverse wound pickups. I'm getting the impression they aren't the same thing and that there is some fundamental nuance between the two that I'm not quite grasping.

Sooooooo ...

What's the difference between reverse wound and out of phase? Are they the same thing? If they aren't, can reverse wound pick ups be wired out of phase like regular single coils? Will they lose their humbucking qualities if reverse wounds are wired out of phase?

Thanks in advance,

--sploorp

[ArtieToo]

Re: Reverse wound versus out of phase

It's simply two different ways to accomplish the same thing. You can wind two coils the same, and connect them out-of-phase, or you can wind one reverse, and connect them in-phase. I imagine singles and humbuckers are done the two different ways because of tradition.

[Myaccount876]

Re: Reverse wound versus out of phase

There are two ways to get out of phase.

Electrically and magnetically (both generally sound the exact same).

Reversing lead wires in one pickup is going to give you "electrical out of phase".

Reversing magnet polarity in one pickup is going to give you "magnetic out of phase".

Reverse magnet polarity AND lead wires (reversing current direction in coils) causes the sound to be in phase (with normal phase being "+" and reversed phase being "-", two negatives make a positive). The reversed polarity and reversed current is where 60 hz hum is cancelled.

A standard humbucker works having two coils, each with metal rods magnetized by a bar magnet underneath the coils. This bar magnet has a north polarity and south polarity, with an imaginary horizontal line straight across the middle of the magnet separating the two. So one coil's rods are magnetized with a "+" polarity and the other coil's rods are magnetized with a "-", resulting in the two coils being magnetically out of phase ("-").

The windings of each coil have their "start" and "finish". Reversing the "start" and "finish" on one coil makes it "-" while the other coil has a normal start and finish "+", resulting in the coils being electrically out of phase "-".

The combination of being magnetically out of phase ("-") and electrically out of phase ("-") returns the combination of coils to be of the same phase/in phase ("+") minus the 60 hz hum, which just got cancelled ("bucked").

[sploorp]

Re: Reverse wound versus out of phase

Thank you for the info!

[uOpt]

Re: Reverse wound versus out of phase

My problem is I learned way back in the day that the coils of a humbucker were wired out of phase and the phasing canceled out the hum. That has created a bit of confusion for me when confronted with reverse wound pickups. I'm getting the impression they aren't the same thing and that there is some fundamental nuance between the two that I'm not quite grasping.

They key bit to understand here is that the magnetic and electric interference that makes noise and hum is inserted into the pickup only via the coil. It doesn't care about the magnet in the pickup.

The signal you want, the strings, only works through the pickup magnet.

So by having out of phase coils (regardless of whether they are reverse wound or just reverse connected) you cancel the unwanted signal and you get your desired signal back by double inverting it.

[uOpt]

Re: Reverse wound versus out of phase

So here is what I always wondered about:

does reverse wind do anything other than cosmetics (looking cleaner and making it more obvious how it's to be wired)?

Obviously most or all of the noise cancellation works if you just reverse the leads on a normal coil. However, I wonder whether the cancellation is just a bit more complete with a rw coil. The way that I understand electric (as opposed to magnetic) interference a coil only picks it up in the outer windings, the inner windings being shielded by the outer ones.

Maybe I need to make a drawing to see whether I might have a point.

[Myaccount876]

Re: Reverse wound versus out of phase

On the MLP forum I think it was Zhangbucker who said something along the lines of what I'm about to say:

Reverse wound actually isn't the best term. The coils can be physically wound the exact same direction, just the current flows in the opposite direction in a RWRP set. So in reality, a better term would be Reverse Current Reverse Polarity, as the reversed current is all you need to get the electronically out of phase half done.

[uOpt]

Re: Reverse wound versus out of phase

On the MLP forum I think it was Zhangbucker who said something along the lines of what I'm about to say:

Reverse wound actually isn't the best term. The coils can be physically wound the exact same direction, just the current flows in the opposite direction in a RWRP set. So in reality, a better term would be Reverse Current Reverse Polarity, as the reversed current is all you need to get the electronically out of phase half done.

As said above, I am not convinced that are necessarily the same things.

[Myaccount876]

Re: Reverse wound versus out of phase

Sure thing. I don't have all the answers; we're all still learning to some extent.

I'd contact Zhangbucker at this point.

[Zhangliqun]

Re: Reverse wound versus out of phase

As said above, I am not convinced that are necessarily the same things.

They are the same thing effectively. The only difference is whether you end up grounding the start lead or the finish.

[uOpt]

Re: Reverse wound versus out of phase

They are the same thing effectively. The only difference is whether you end up grounding the start lead or the finish.

Right, but I think in theory it can make a small difference in picking up electric field noise. If the outer windings are the ones that are grounded, shouldn't that have a couple layers of wire less picking up noise than if the ground is connected to the inside of the coil?

Of course that's a very small difference either way and there would be no way to notice in a single coil. However, if you want to have almost complete hum canceling with evenly matched coils, I think it is possible that there would be a difference between grounding the same winds in both coils or having one coil grounding the inner windings and the other coil grounding the outer windings.

[Zhangliqun]

Re: Reverse wound versus out of phase

It's not the case that the outer turns are somewhat more grounded than inner turns. And besides, you have both in a humbucker (one coil start lead grounded the other finish lead grounded) but is one coil by itself more noisy than the other by itself? Rig up a 4-con bucker so that you can test each coil by itself and see if you hear a difference in the noise level. I can't -- unless maybe one coil happens to be slightly closer to the noise source than the other.

[uOpt]

Re: Reverse wound versus out of phase

It's not the case that the outer turns are somewhat more grounded than inner turns. And besides, you have both in a humbucker (one coil start lead grounded the other finish lead grounded) but is one coil by itself more noisy than the other by itself? Rig up a 4-con bucker so that you can test each coil by itself and see if you hear a difference in the noise level. I can't -- unless maybe one coil happens to be slightly closer to the noise source than the other.

Well, the tricky part is that if you test coils individually then you get a majority of noise from electromagnetic fields, which the shielding is ineffective against either way. Once you connect two coils you kill those fields completely (given exact even winds), then you might be able to hear a difference in the electric field noise which might or might not be impressed by connecting the outer windings to ground, which might give less noise than connecting them to hot.

[Zhangliqun]

Re: Reverse wound versus out of phase

Well, the tricky part is that if you test coils individually then you get a majority of noise from electromagnetic fields, which the shielding is ineffective against either way.

If you have to be in an electrically pristine environment to hear a difference, then we are talking about angels cutting the rug on the head of a pin. But even so, metal covers do reduce noise even from electromagnetic fields. The Phat Cats are definitely quieter than standard plastic cover P90's, so I don't understand your point.

Once you connect two coils you kill those fields completely (given exact even winds), then you might be able to hear a difference in the electric field noise which might or might not be impressed by connecting the outer windings to ground, which might give less noise than connecting them to hot.

I'm not sure I understand your point here either. When both coils are on you would by definition be hearing both coils and not know which one was the greater source of noise. It's like putting two toddlers in a wading pool and they both turn the water yellow and claiming to be able to figure out which one urinated an ounce more than the other one.

[uOpt]

Re: Reverse wound versus out of phase

Allright, reboot.

Interference from oscillating magnetic fields. Interference from oscillating electric fields. Before all the exceptions apply, you can use a regular shield (a conductor around hot) to shield against the latter, but not the former.

The former (magnetic) would be wiped out in a humbucker. The field penetrates the whole coil.

The latter (electric) reacts to shields. A shield is a grounded conductor around hot. So if you wire it up so that the grounded side of the coil is the outside windings, wouldn't that shield? I think it surely does, because a single coil would really buzz like a mofo from electric fields if it wasn't.

Anyway, if that is the case, wouldn't it make a difference whether you wire up the coil so that the outer windings are facing ground versus facing hot? And wouldn't a humbucker with one coil each way have uneven cancellation?