Vacuum Potting Guitar Pickups Explained Video

Discussion in 'Pickups' started by cooljuk, May 20, 2017.

  1. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    There's lots of talk and questions around here lately regarding potting pickups, specifically vacuum potting pickups. I promised a few members that the next time I did a batch I would make a video to show the process. Here it is:



    A couple recommendations:

    1) Don't pot your pickups unless you must. It's not a front line solution, it's a last line of defense that can't be undone without cutting the coils off and rewinding the pickups.

    2) If you attempt a thing like this, don't do it in your kitchen. I just needed the lighting for the video so I moved my setup into the kitchen for this one run. ...then spent a half hour cleaning atomized pump oil off of everything.
     
  2. Guitar Rod

    Guitar Rod Senior Member

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    I'm sure some of the bubbles are from air being removed from the coils, but wouldn't most of the bubbling be the hot wax boiling because of the lower/zero atmospheric pressure? Like how your blood would boil in space?
     
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  3. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    Sure, but you can also see that the majority of it originates at the pickups, themselves. The cloth wire, forbon, and twine on the Tele bridges also have a great deal of air in them. You can play into it that I'm at about 6000' feet above sea level to begin with, as well.
     
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  4. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    Ironically, I got some of this gear from "the other potting industry" around here. The seller definitely assumed I was manufacturing some marijuana products until I corrected her. Then, she was further confused whenever I said the word "potting" about what I was actually doing with it. She seemed to just be confused in general, actually. :hippie:

    The previous crucible I used for vacuum potting was a large steel and aluminum heated tank that I bought from a chocolate factory. They were using it to dip various baked goods in chocolate with. It worked extremely well but ran on 220v at about 10A and took a very long time to melt all the wax, as it was so large. I ditched that when I moved out here for the more efficient and controllable system above.
     
  5. MasterEvan07

    MasterEvan07 Senior Member

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    Just watched the video, cool!
     
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  6. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    Anyone else want to share their methods or experiences with potting? Vacuum or otherwise. It's a cool topic ...with lots of misinformation out there about it.
     
  7. MooCheng

    MooCheng Senior Member

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    interesting vid' thanks for posting,

    I've never wound a pickup in my life and are unlikely to but often think about alternative ways of doing things.
    Has anyone ever wound a pickup where the wire is treated in some way with an adhesive so it bonds during winding. Just thinking out loud of ways of pinning the winds together while still keeping intact some of the air voids.

    Interesting things, pickups
     
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  8. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    Moo - that's actually common in industry. There is wire coated in an alcohol soluble adhesive. The wire passes through an alcohol bath on its path to the rotating bobbin/core/form, then cures. I have a colleague who works in medical device manufacture that uses this method.

    I can't see any reason why this would sound any different from a wax, lacquer, epoxy, or otherwise potted pickup, however. If the wires don't move, they don't move, regardless of how you pot them. The only reason lacquer potted Fender pickups from the 1970s can sound different than their wax potted brothers is because the lacquer generally didn't penetrate the surface. With heat, vacuum and more time it would have but there can be other problems with lacquer potting, like damaging the insulation so it's not common. So, many of the lacquer potted Fender pickup were effectively not potted at all and often squeal and feedback, accordingly. That may have helped mislead some people to think that different potting materials will significantly change the sound of a potted pickup. Dunno. :dunno:
     
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  9. B5Erik

    B5Erik Senior Member

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    Now that's an educational video! Interesting stuff. Thanks for posting it!
     
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  10. zoork_1

    zoork_1 Senior Member

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    Thanks for posting...
     
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  11. BigM

    BigM Senior Member

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    My only question is if this is the last resort what are other things you can try to alleviate micro-phonics?

    I've got a humbucker mounted to a dog ear P90 base plate (Custom made for me) that's unpotted. It's squealing at gig level volume/gain settings (More so when i have the plastic cover on). I've got several of the same humbucker with normal humbucker base plates (and some with nickel covers) that don't suffer from these issues.
    I'm not sure if it's because the P90 base plate is screwed to the body as appose to the floating humbucker mounting arrangement , or if this is just the pickup itself.

    What could I try other than wax potting?

    Thanks
    M
     
  12. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    Sounds like you've isolated the problem to the custom mounting of the humbucker to the baseplate (or maybe to the guitar) and the cover. I've made full size humbuckers that look like dog ear P-90s from outside and it's definitely possible but also not easy to do so here are some ideas....

    My first suspect would be that something is not mechanically tight. Make sure that nothing under the coils is able to vibrate. It may not be totally obvious, as in loose/falling apart, but high SPL will find any little thing that can oscillate and make it do so. How are the pole screws designed? Do they pass though the P-90 baseplate or have they been cut short? Double slug design? A few photos could be helpful but, overall, make sure everything is all firmed up and tight. You can always have just the lower portion of the pickup, below the actual coils, potted. ....but it also sounds like you may be getting some oscillation from your plastic cover. Address the situation to satisfaction without the cover, first. You then will want to look at how firmly the cover contacts your guitar top. For instance, I've had P-90s from arch tops installed into Juniors and the covers like to pivot on the two little contact points at the ends of the "ears" with the rest of the cover just floating. That's likely to feedback so I've had to sand them flat on the bottom and perhaps use a shim.
     
  13. BigM

    BigM Senior Member

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    Thanks James.

    The adjustable pole pieces go through the base plate. Standard slugs are on the other side.
    It's a standard humbucker mount (four brass screws securing the base plate to the pickup) with the P90 wings extending from the ends (Don't have a photo as i'm at work).
    I was thinking of removing the bass plate and adding a thin layer of silicon gel before re-screwing it. I was also thinking of applying it to where the pole pieces exit the base plate and between the cover and the top of the pickup.

    Thanks
    M
     
  14. CCK

    CCK Senior Member

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    Very, very interesting! I had a conversation with Jim Wagner once after installing a set of his pickups in my SG. I asked him if they were potted, and he was pretty emphatic that, in his opinion, potting a humbucker was a "tone killer". I can't confirm or deny that opinion, but these humbuckers sound very good to my ear, and yes, I can get the high pitched squeal from them, but it takes really obscene amounts of gain, and a very close proximity to the speaker cabinet. Again, very interesting video, very informative. Thanks!
     
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  15. Brutus

    Brutus Senior Member

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    I doubt I'll ever need to pot any pickups much less wind any but I do enjoy learning something new.

    Thank you!
     
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  16. DarrellV

    DarrellV Likes > Posts Silver Supporter Premium Member

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    Great video! Thanks James... I'm one of the one's who's been waiting..

    BTW, I see what you did there.....Purple font even! :cheers:
    rewind.jpg
     
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  17. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    I hadn't even thought about the font being purple there, honestly. I just thought it contrasted well with the orange and other stuff on the screen. Worked out, though! :cheers2:
     
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  18. DarrellV

    DarrellV Likes > Posts Silver Supporter Premium Member

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    To me it showed your priorities as a PAF winder. Wax potting is verboten! So the first 'benefit' you list is this.....:lol:

    Then, almost as an aside you mention it also reduces feedback squealing! Class act! :cheers:
     
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  19. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    :D

    You'll notice all those pickups in the video are Fender single coils. It takes some real convincing to get me to wax pot a PAF-style pickup. Sometimes, it can be what's needed but only RARELY is it the right solution to have a lower output style humbucker like a PAF potted. Generally, guys playing humbuckers who need potting are not playing PAF-types.
     
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  20. DarrellV

    DarrellV Likes > Posts Silver Supporter Premium Member

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    THAT is what really torqued me about my Shaws!:mad:

    As you say, there are plenty of potted pups out there for high gain stuff. Why ruin one purposely designed to be un-potted?
    Lazy, ignorant, cheap, or any other of the 7 deadly sins are most likely the culprit.... :(
     

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