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Thread: Effect of higher wound screw vs slug coil in offset humbucker?

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    Senior Member elipsey's Avatar
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    Effect of higher wound screw vs slug coil in offset humbucker?

    It seems like most asymmetric humbuckers are wound with more turns on the slug coil. One might naively expect that putting more turns on the screw coil would tend to make the pickup brighter because that coil has lower inductance, but I recognize that it could be more complicated. For example, con/destructive interference at might occur at various frequencies, the pickup might sense different parts of the string more strongly and with suprising results, and so on, so I don't expect to be able to guess what should happen.

    Gibson apparently does this with the '61 zebra pickups*, for example, which I played in an SG Special at GC a couple of months ago. I expected this pickup to be brighter than I would normally enjoy (and not just because of the dominant screw coil, see other specs), but I thought that guitar sounded great.

    Any thoughts about the effect of putting more turns on the screw coil instead of slug coil?

    Cheers


    *Gibson.com: SG Special 2015

    Pickups: Rhythm Lead
    Style: 61 Zebra 61 Zebra
    Winds/Coil:
    Screw side/Slug side: 5261/5000 5261/5000
    Material of Wire (gauge):42E 42E
    Qfactor: 5.39 5.39
    ResistanceDC: 7.74k ohms 7.74k ohms
    Resonant Frequency: 2806 Hz 2806 Hz
    [...]
    Control Pocket Assembly
    Lead Volume Rhythm Volume
    Type: 500K Non–Linear 500K Non–Linear
    Lead Tone Rhythm Tone
    Type: 500K Non–Linear 500K Non–Linear

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    How did you come to understand that the slug coil is more often the higher wound pickup in a mismatched humbucker?

    I'd think that the biggest factor in deciding which coil to wind higher would be to pick which coil contributes more to the final sound. I can think of reasons why you might want to favor the slug coil, though. A case for the slug coil in the bridge position is that it's slightly further from the bridge, where the sound produced will be louder and fuller, and in the neck position, the slug coil might be less bassy and boomy than the screw coil, since it's nearer to the bridge. The end result in either case could result in a more balanced humbucker, rather than one that is more bassy in the neck and more trebly in the bridge.

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    Senior Member LtKojak's Avatar
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    Quote Originally Posted by elipsey View Post
    *Gibson.com: SG Special 2015

    Pickups: Rhythm Lead
    Style: 61 Zebra 61 Zebra
    Winds/Coil:
    Screw side/Slug side: 5261/5000 5261/5000
    Material of Wire (gauge):42E 42E
    Qfactor: 5.39 5.39
    ResistanceDC: 7.74k ohms 7.74k ohms
    Resonant Frequency: 2806 Hz 2806 Hz
    [...]
    Control Pocket Assembly
    Lead Volume Rhythm Volume
    Type: 500K Non–Linear 500K Non–Linear
    Lead Tone Rhythm Tone
    Type: 500K Non–Linear 500K Non–Linear
    Ellipsey, do you really think Gibson would publish actual detailed data of their p'ups, so anybody and their dog could reproduce'em?

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    Pepe aka Lt. Kojak
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    Senior Member elipsey's Avatar
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    Quote Originally Posted by John Kolbeck View Post
    How did you come to understand that the slug coil is more often the higher wound pickup in a mismatched humbucker?
    Small sample size, rumors, and stuff I read on the internet.

    Gibson states turn counts for all burstbucker models, which are slug-coil dominant, except the '61 zebra model. The offset pickups at my house all have higher DCR on slug coil (n=3). I have been advised to use higher turn count on slug coil by MEF members.

    Quote Originally Posted by John Kolbeck View Post
    I'd think that the biggest factor in deciding which coil to wind higher would be to pick which coil contributes more to the final sound. I can think of reasons why you might want to favor the slug coil, though. A case for the slug coil in the bridge position is that it's slightly further from the bridge, where the sound produced will be louder and fuller, and in the neck position, the slug coil might be less bassy and boomy than the screw coil, since it's nearer to the bridge. The end result in either case could result in a more balanced humbucker, rather than one that is more bassy in the neck and more trebly in the bridge.
    Thanks for your input.

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    ToneOholic! big_teee's Avatar
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    I've looked over the 2015 gibson pickup data.
    Some of it looks highly suspicious to me, as being wrong.
    Use at your own risk, would be my advice.
    I do very little offset, but on the bridge I put the most on the slug, because it is further from the bridge.
    T

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    Last edited by big_teee; 02-10-2016 at 03:57 PM.
    “When you find yourself in a hole, quit digging.” WILL ROGERS

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    Senior Member elipsey's Avatar
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    Quote Originally Posted by kayakerca View Post
    To be fair to elipsey, Gibson actually is publishing those specs on their website. As to whether or they are 100% legit. . . Who knows.
    Perhaps kojak jests.

    Edit: I'm starting to think I shouldn't have posted those specs. I hope it's not too late to return to the original question, before this turns into another thread about whether Gibson dyes their wire brown.

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    Last edited by elipsey; 02-10-2016 at 04:24 PM.

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    Pickup Maker David Schwab's Avatar
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    The offset makes the pickup brighter. If the original PAFs had an offset it was by accident. There was an article in Guitar Player magazine in the 70s where Jeff Baxter said he would unwind the coil with more windings until they matched. He felt it sounded better. He did this on all his Gibson humbuckers.

    So, why are you offsetting the winds? Because you read that somewhere, or because you are trying to get a certain tone? Also, do we know that the slug bobbin has higher inductance? The screws on the screw bobbin are often much longer. So there's more steel there. I find they sound better with the screws cut shorter.

    Bartolini has been offsetting winds by 1,000 turns on some of their pickups since the mid 70s. It makes them brighter like a single coil.

    I'd start off winding both bobbins the same. Then decide if you need something different. Then try it out. It takes time to come up with new recipes.

    I I agree with the others here that who ever writes those pages for Gibson either doesn't know the specs or they are intentionally putting in mistakes. I think it's all just marketing crap.

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    Senior Member elipsey's Avatar
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    Quote Originally Posted by David Schwab View Post
    So, why are you offsetting the winds?
    In general, I'm experimenting with brighter pickups to mate with single coils and low value pots, as in an HSS strat, for example. Also, I enjoy trying different sounds. At the moment, I'm particularly curious about what the effect will be of winding the screw coil hotter vs the slug coil.

    Thanks for your repsone.

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    I'd bet that the overall permeability of the slugs is higher than the screws. The portion of the screw that sticks out of the top and bottom contribute slightly less to the inductance than the permeable material immediately inside the code, and the screws put more "air" between the metal and the windings than the slugs do.

    Note that the total inductance of the pickup in series is the sum of the two coils, so it doesn't matter so much which coil provides how much inductance, so long as you arrive at a desired grand total. For a given wire gauge, the coil with more winds and which exposed greater flux density, coming down from the guitar strings, will generate more voltage than the coil with less of either. If the winds are equal, I'd imagine the screw coil can only potentially overtake the slug coil in terms of EMF productivity if the screws are raised up close to the strings. So the real issue is not so much about the electrical properties of the pickup, so much as the physical properties, as in which portion of the guitar string is picked up the more than the other. It's the "wide window" of a typical PAF that characterizes it's sound. When you have a narrower "window", such as with a single coil, you get more of the Strat / Tele tone, so the more you mismatch the coils, the closer you get to that "narrow window" tone.

    If the goal is to achieve a brighter pickup, use fewer winds overall. Making the coils match as close in wind count as possible will provide the best humbucking operation, and make for a quieter pickup than one with mismatched coils.

    Another thing to note is that Gibson only added the screws to one of the two coils for aesthetic reasons, to make it look a little bit more like a P-90. Seth Lover was going to make both coils slugs coils, so the issue at hand is more like a bug than a feature, but we're lived with it for so long that we think of it as a feature anyway.

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    Last edited by John Kolbeck; 02-10-2016 at 06:04 PM.

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    The exact permeability is not the issue; it simply does not matter as long as it is significantly greater than unity (as it is with any steel) because the magnetic circuit has such a long way to go through free space to complete. (Obviously it matters in something like a transformer where the core is closed, a continuous loop.) (A similar situation is with the guitar string: its exact permeability also does not matter as long as it is significantly greater than one.) Be careful about how much the part of the screw that sticks out contributes; that is a complicated question, but remember, it does shorten the path of some flux lines, and so you would expect it to make some difference, especially in reducing the divergence of flux lines near the bottom and top of the coil. I think the slugs and screws are close to the same in magnetic affect, and thus the humbugger does pretty good job of reducing hum.



    Quote Originally Posted by John Kolbeck View Post
    I'd bet that the overall permeability of the slugs is higher than the screws. The portion of the screw that sticks out of the top and bottom contribute slightly less to the inductance than the permeable material immediately inside the code, and the screws put more "air" between the metal and the windings than the slugs do.

    Note that the total inductance of the pickup in series is the sum of the two coils, so it doesn't matter so much which coil provides how much inductance, so long as you arrive at a desired grand total. For a given wire gauge, the coil with more winds and which exposed greater flux density, coming down from the guitar strings, will generate more voltage than the coil with less of either. If the winds are equal, I'd imagine the screw coil can only potentially overtake the slug coil in terms of EMF productivity if the screws are raised up close to the strings. So the real issue is not so much about the electrical properties of the pickup, so much as the physical properties, as in which portion of the guitar string is picked up the more than the other. It's the "wide window" of a typical PAF that characterizes it's sound. When you have a narrower "window", such as with a single coil, you get more of the Strat / Tele tone, so the more you mismatch the coils, the closer you get to that "narrow window" tone.

    If the goal is to achieve a brighter pickup, use fewer winds overall. Making the coils match as close in wind count as possible will provide the best humbucking operation, and make for a quieter pickup than one with mismatched coils.

    Another thing to note is that Gibson only added the screws to one of the two coils for aesthetic reasons, to make it look a little bit more like a P-90. Seth Lover was going to make both coils slugs coils, so the issue at hand is more like a bug than a feature, but we're lived with it for so long that we think of it as a feature anyway.

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    Senior Member Jim Shine's Avatar
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    I prefer the sound of asymmetrical coils, but I don't always wind the slug side hotter. For neck positions I usually wind the screw side hotter. Especially if those screws lay on the harmonic node. It is one of those things that is better to tinker with than theorize.

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    it all depends on what you want to achieve. I wind humbuckers, matched and mismatched, some with higher turns on the slug bobbin, some with more on the screw. Ultimately, you will have to experiment and decide what YOU like and the subtleties of each.

    its very hard to give an definitive response to your question, and I do suggest you to experiment and find the sound you like and don't forget that different magnet types also influence the tone

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    ToneOholic! big_teee's Avatar
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    What Jim Shine said!
    For the most part you can't theorize Sound.
    Bottom line, guitar players want pickups that sound good.
    Don't know how you do that with theories.
    You can get close with basic pickup winding rules.
    Beyond that you have to wind pickups, to prove your theories.
    T

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    Theory and experimentation are not mutually exclusive. Once answers the "what?", the other answers the "why?"

    OP asked "Any thoughts about the effect of putting more turns on the screw coil instead of slug coil?" some have given theory based opinions, so what is your experiment based opinion on this matter?

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  15. #15
    ToneOholic! big_teee's Avatar
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    On neck pickups I usually wind equal coils, I like full hum cancellation.
    On Bridge Pickups I do equal , or more to the slug bobbin.

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    Last edited by big_teee; 02-11-2016 at 08:22 PM.
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    Quote Originally Posted by John Kolbeck View Post
    I'd bet that the overall permeability of the slugs is higher than the screws. The portion of the screw that sticks out of the top and bottom contribute slightly less to the inductance than the permeable material immediately inside the code, and the screws put more "air" between the metal and the windings than the slugs do.
    Ive found that the inductance is extremely close with both screw and slug coils wound to the same number of turns and loaded with the screws, keeper bar and slugs.
    From my experience the difference between the two is negligible.

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