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Phase problems with a P+J bass layout

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  • Phase problems with a P+J bass layout

    I was wondering..

    many basses have the very useful P+J layout: a precision style dual coil in the middle, and a jazz style single coil at the bridge.

    But..
    The p-style is a coil in series with a RW/RP coil, for hum cancelling.
    The J-style is a single coil, let's say north oriented.

    When the two P and J pickups are both activated, and in parallel (of course), aren't we going in phase trouble?
    Wont' the single J coil cancel the signal from one of the P coil?
    Biarnel Liuteria
    Italian handmade guitars and basses
    http://www.biarnel.com/liuteria/
    http://www.myspace.com/biarnel

  • #2
    I've had this happen in the past... I'm trying to remember the details.

    First off, the P bass pickups are not RW/RP. The magnets are opposite though. Both coils are wound in the same direction.

    Wire it like this:

    http://www.seymourduncan.com/support.../p-j_bass.html

    If you do reverse wind one coil, wire it up like this:

    http://www.riograndepickups.com/images/wiring/PJSet.PDF

    I'm not sure how to work it with two Jazz pickups that are RW/RP. But with a regular P/J setup, it will cancel out one way, and not the other.

    The way it works out is one coil is the same polarity and magnet polarity as the Jazz, while the other is opposite magnetic polarity, but wired out of phase, which puts it back in phase with the Jazz.

    If the P was able to pickup one string with both coils, it would be out of phase with itself.

    I'm pretty sure that's how it works... but it's been a while....
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


    http://coneyislandguitars.com
    www.soundcloud.com/davidravenmoon

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    • #3
      Originally posted by David Schwab View Post
      First off, the P bass pickups are not RW/RP. The magnets are opposite though. Both coils are wound in the same direction.
      I'm sorry. I said RW/RP to be quickier, but that will be:
      The finish wire of the NORTH coil is the HOT, its start wire is soldered with the start wire of the SOUTH coil, and the finish wire of the SOUTH is the GROUND.
      This, in parallel with a typical jazz bass single coil, will be prone to problems? Sound cancelling?
      Maybe if the jazz coil is NORTH, and its finish wire is the HOT, I will cancel the sound and not only the hum.
      Is it right?
      And what if the jazz coil is NORTH, and its finish wire is the GROUND?

      Originally posted by David Schwab View Post
      The way it works out is one coil is the same polarity and magnet polarity as the Jazz, while the other is opposite magnetic polarity, but wired out of phase, which puts it back in phase with the Jazz.
      I think it's the way I'm doing it
      By saying "wired out of phase" you mean that in the coil with opposite magnetic polarity the GROUND is the finish wire, right?
      Biarnel Liuteria
      Italian handmade guitars and basses
      http://www.biarnel.com/liuteria/
      http://www.myspace.com/biarnel

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      • #4
        You know I just don't remember!

        But you will find out when you wire it up.

        I had this happen once. I just reversed one coil on the P bass pickups and it was fine.

        I guess out of phase would either be same magnet polarity, and opposite coil wiring, or opposite magnets and same coil polarity.

        I might be wrong.. as I said I can't recall.

        But I have a Pedulla bass in for repair (cracked neck/headstock!) and it has Bartolini P/J pickups. I checked it and the P has two opposite magnets.
        It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


        http://coneyislandguitars.com
        www.soundcloud.com/davidravenmoon

        Comment


        • #5
          Originally posted by David Schwab View Post
          First off, the P bass pickups are not RW/RP. The magnets are opposite though. Both coils are wound in the same direction.
          It took me a minute to consider this, as I'd always assumed they were RW.
          Then I realised; they're not seeing the same strings... so no need to worry about "mechanical" cancellations.

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          • #6
            Originally posted by Plectrum View Post
            It took me a minute to consider this, as I'd always assumed they were RW.
            Then I realised; they're not seeing the same strings... so no need to worry about "mechanical" cancellations.
            Exactly. But even then, you don't need to wind one coil in reverse. Just wire it up in reverse.

            I'm seen P bass pickups done both ways.
            It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein


            http://coneyislandguitars.com
            www.soundcloud.com/davidravenmoon

            Comment

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