Does a dummy coil need to be potted?

Discussion in 'Pickups' started by BigM, Jul 23, 2017.

  1. BigM

    BigM Senior Member

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    Hi

    As per the title does a dummy coil need to be wax potted?
    Specifically for high volume playing.
    I'm making a DIY illich (wide area low resistance/impedance) systems. I've completed the proof of concept coil which tests OK (hum is reduced).
    I don't have the equipment required to pot coils and don't particularly want to buy it if i don't need to.

    Thanks
    M
     
  2. ARandall

    ARandall Senior Member

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    You don't own a saucepan then???

    If the coil is not part of a pickup, then mechanical vibration can not make squeals. As I see it the dummy coil sits in the ground circuit......negating a signal created on the hot side.
     
    Last edited: Jul 23, 2017
  3. ARandall

    ARandall Senior Member

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    You could do double boiler......pan of water on stove and maybe can or mug inside. That way the wax volume needed is small.
     
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  4. Brutus

    Brutus Senior Member

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    pressure cooker?
     
  5. Antigua

    Antigua Senior Member

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    It possibly could be microphonic, or susceptibe to noise when it gets knocked around. If the wires jiggle around, the capacitance between them changes, a voltage is produced and you get noise. The noise is "microphonic" if it happens to be sound that induced the movement and the voltage change, but you can sometimes tap on a coil, or step on a guitar cable, and cause noise with physical shock. If the coil wire is wound tightly, it's less likely to move, and therefore be less microphonic. You might be able to preview how microphonic/noisy it is or isn't being lightly tapping on the coil and seeing how much noise you get from the physical shock. In lieu of wax potting, you can try securing the coil really well, so that it's windings are less able to move around.
     
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  6. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    Please do NOT put combustibles in a pressure cooker!

    I'll walk you through a safe way or pot your pickups for free, if you really have NO other option. Just please do not make a bomb full of molten combustibles on your stovetop.
     
  7. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    ...to answer the OP, try it without potting, first. You can't go back but you can always go forward.
     
  8. BigM

    BigM Senior Member

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    Thank you all.

    I'll wire up the test coil and test it a gig volumes.

    If there is any issue i'll look at potting.
    I would buy dedicated equipment as i know how dangerous the process can be.

    M
     
  9. chasenblues

    chasenblues Senior Member

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    What could possibly go wrong..?

    [​IMG]
     
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  10. ARandall

    ARandall Senior Member

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    You are only heating wax so it melts, not doing a chemical experiment with volatile substances.
    I do the same thing with hideglue all the time, it goes to something like 70 deg C sitting in a jar in a heated bowl of water.
     
  11. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    It's the pressure cooker I worry about.

    A double boiler like suggested above (pan of wax in a pan of water) or even a non-pressure electrical typical crock pot is much safer.
     
  12. freefrog

    freefrog Senior Member

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    FWIW, I've wound a handful of "Ilitch coils" and never had to pot them.

    The only noise that I've noticed with these things happened when I manipulated the dummy coil while the guitar was plugged and the gain cranked up (while I was testing the effectiveness of noise cancellation). Once the thing mounted in the axe without any risk to move, no problem.

    Anyway, wax potting might make the dummy coil less "transparent" when wired between the pickup and ground, because of an increased stray capacitance (at least the most capacitive dummy coil that I've built was altering the resonant peak in a noticeable way). For the same reason, I wouldn't recommend to wind the coil too tightly nor to wrap it too firmly in any protective tape. YMMV.

    Good luck in your experiments....
     
    Last edited: Jul 24, 2017

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