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Why do jazz pups hum if both pickups aren't fully on?

Discussion in 'Pickups & Electronics [BG]' started by MistaMarko, Feb 27, 2008.

  1. MistaMarko


    Feb 3, 2006
    I just notice that the pickups hum if the both aren't both turned all the way up
  2. because they only hum-cancel when they are both outputting at the same level. lots of read on this physics subject everywhere
  3. Turock

    Turock Supporting Member

    Apr 30, 2000
    They don't have to be "all the way up"; they just have to be at the same volume to eliminate hum.
  4. They are reverse wound, so when they are both turned up they basically act as a humbucker.
  5. Turock

    Turock Supporting Member

    Apr 30, 2000
    They don't have to be "turned up"; they just have to be at the same volume.
  6. Fair enough. But you do agree that the coil winding direction is the point, right?
  7. yeah. they are in anti phase perhaps and the poles are also opposite
    so one creates "hum" and the other u can call "anti-hum"; when you give both the pickups the same current ie volume the "hum" and "anti-hum" canncel each other equally and hence no noise. the more the difference in the amount of current flowing through both the pickups the more is your noise
    you can reduce the noise by shielding and using quality cables but can eliminate it as long as you are using single coil picups as they are susepitble to the 60cycle hum

    the hum and anti hum concept is sort of an analogy i just thought off to explain whats happening in simple terms hope i was not wrong
  8. ggunn


    Aug 30, 2006
    Austin, TX
    That's half of it; one pickup is wound the opposite way from the other and its magnets are reversed as well. One pickup is standard and the other is RWRP (reverse wound and reverse polarity). This makes the signal that each picks up from the string in phase but the noise each picks up from the environment 180 degrees out of phase, hence signal reinforces but noise cancels.
  9. MistaMarko


    Feb 3, 2006
    Well I also have the whole problem where when I'm not touching the strings it buzzes..and when I touch a string it stops. (this isn't the pickup problem..its another buzzing problem..)
  10. Bad bridge ground is the most likely culprit.
  11. MistaMarko


    Feb 3, 2006
    Well there is a copper strip going from my bridge p-up to the bridge (i guess thats how they grounded the MIJ '88 basses). when the neck pickup is turned completely OFF, this problem does not happen.
  12. awall


    Oct 30, 2006
    Mine does a strange thing, if both are up full and I turn one down it hums. If both are off and I turn one up, no hum. Am I the only one with this?
  13. Jim Carr

    Jim Carr Dr. Jim Gold Supporting Member

    Jan 21, 2006
    Denton, TX or Kailua, HI
    fEARful Kool-Aid dispensing liberal academic card-carrying union member Musicians Local 72-147
    Probably someone else has pointed this out, but IME, if you have disrupted the bridge
    ground, touching the strings has limtied effect on hum.

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