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Are jazz pickups out of phase by design?

Discussion in 'Pickups & Electronics [BG]' started by blipndub, Mar 6, 2008.


  1. Is that what makes them hum-canceling?
     
  2. eeyorebass

    eeyorebass

    Jan 2, 2008
    That's how I understand it.

    With both pickups on full, it's like having a humbucker with space between the coils.
     
  3. Let's get the difference clear between 'out of phase' and 'reverse wound'.

    It's a common fallacy that the pickups on a Jazz (AND the centre pickup on a Strat) are 'out of phase'.

    They are, in fact, reverse wound.

    It was Seth Lover working for Gibson who patented the construction of two coils in series (or parallel!) where one coil is wound in the reverse direction to the other, but the magnet is in the same polarity - this cancels out induced interference.

    When you wire a pickup 'out of phase' you take two coils wound the same way and of the same polarity and reverse the wiring of one of them. This configuration cancels out most of the lows & mids present in the signal and gives an immediately identifiable weak and middy/trebley signal. It's possible to wire a reverse wound pickup out of phase.

    The pups on the Jazz are wired in 'reverse wound' configuration so that when both are on *full* the combination is hum cancelling in a parallel configuration.

    The P Bass pickup is actually two smaller pickups wired in hum cancelling series configuration - the series config is what gives the P its meatier tone - it boosts the lows & mids and cuts some of the upper frequencies - also gives more gain - exactly the opposite of 'out of phase'. If you use a push/pull switch to put the Jazz's pups into series (many diagrams on this forum) you'll get a much chunkier tone - not the same as a P as the configuration of the pickups is obviously different, but somewhere toward it. Putting a P pickup into parallel mode is, IMHO, not worth it.
     
  4. DavidRavenMoon

    DavidRavenMoon Banned

    Oct 20, 2004
    The way a humbucker works is that the two coils are opposite polarity. Saying out-of-phase is actually incorrect, because phase is a time domain thing.. the initial condition of a cyclic phenomenon.

    But since we say electrical connections are in or out of phase, we use that term.

    So the two coils are either wound the same direction and wired up in reverse, this is the way it's done on a Gibson Humbucker, or wound in opposite directions and wired up the same. It really makes no difference which way you do it. Reverse wound and reverse electrical connection is the same as far as the signal is concerned... getting back to the time domain thing, it's the direction the current is flowing in the wire over time.

    Ordinarily two pickups out-of-phase would sound very thin, because they are canceling out frequencies common to both. So the trick is that the magnets on each coil are also reversed. One is north facing the strings, and one is south. Reversing the magnets will make two in-phase wound coils out-of-phase, so since they are already out-of-phase, the reverse magnets brings them back in phase.

    So why does this cancel noise? Because the noise doesn't rely on the magnets to get induced into the coils the way the strings do. So the noise is induced into both coils with the same polarity, and is canceled out when the two out-of-phase signals are summed. The string's signal on the other hand has been picked up in reverse in each coil, because of the magnets, so it's summed in phase.
     
  5. So, there you go and I (possibly) sit corrected!!!

    :D
     
  6. DavidRavenMoon

    DavidRavenMoon Banned

    Oct 20, 2004
    it's a common misconception, even amongst some pickup makers. There may be some subtle reasons why one might want to reverse wind as opposed to reversing the polarity, but that only has to do with noise from the magnets.

    The funny thing is even before Strat middle pickups were reverse wound, people still called that tone "out-of-phase", even though it's not. There is some phase cancelation going on anytime you have two pickups on at the same time though.

    So you had the right idea though. :D
     

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