Out of Phase question on LP mid position

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by alanfc, Jan 6, 2008.


  1. alanfc

    alanfc Member

    Messages:
    975
    Joined:
    Feb 4, 2004
    hi- I use position 2 on the LP for quiet clean-ish parts.
    On this LP copy I had, I use to run the neck volume on 3-4 and used the bridge at about 2 or 3.

    Now on this used Gibson LP I just got, I find that when the neck volume is anything under '7', I get a small transistor radio sound when using the mid position. This may have been the previous owners intent.
    So does this mean it was wired out of phase?
    Thanks
     
  2. MikeMcK

    MikeMcK Member

    Messages:
    2,495
    Joined:
    Oct 7, 2007
    Location:
    Jersey shore
    It could be intentional. Google "Peter Green mod" to get more information.
     
  3. alanfc

    alanfc Member

    Messages:
    975
    Joined:
    Feb 4, 2004
    aha thank you
     
  4. Bill Brasky

    Bill Brasky Senior Member

    Messages:
    1,422
    Joined:
    Jun 23, 2007
    Location:
    Michigan, USA
    "Peter Green mod" has NOTHING to do with out of phase wiring. If it was electronically out of phase you would get a thinner, quieter sound. Not if it was magnetically out of phase, ie. "the Peter Green mod".
     
  5. alanfc

    alanfc Member

    Messages:
    975
    Joined:
    Feb 4, 2004
    ok good thanks
     
  6. MikeMcK

    MikeMcK Member

    Messages:
    2,495
    Joined:
    Oct 7, 2007
    Location:
    Jersey shore
    Point taken... I missed the word "wiring" in the OP's original question.
     
  7. JLee

    JLee Supporting Member

    Messages:
    2,145
    Joined:
    Nov 23, 2004
    Actually, you'll get that thin, transistor radio tone with both out of phase wiring or magnetically out of phase magnets. As you decrease the volume pots on magnetically out of phase pickups, the effect increases/gets thinner and more hollow. Volume drop in the middle position is going to depend on the balance between the two pickups with magnetically out of phase pickups. I have the WCR Peter Green Set and WB Pickups Peter Green Burst set and both react the same with pickup heights and volume knob adjustments. I've also done the magnet flip on several sets of pickups over the years and the results have always been consistent.
     
  8. Bill Brasky

    Bill Brasky Senior Member

    Messages:
    1,422
    Joined:
    Jun 23, 2007
    Location:
    Michigan, USA
    Yeah, you can get a thin sound depending on how your volumes are set. With the volumes on full, I get a volume jump in the middle position with sort of a wah stuck in the middle sound. Not thin at all.
     
  9. alanfc

    alanfc Member

    Messages:
    975
    Joined:
    Feb 4, 2004
  10. John Phillips

    John Phillips Member

    Messages:
    13,080
    Joined:
    Mar 17, 2002
    Location:
    Scotland
    Actually it makes no difference which it is. Either reversing the coils or reversing the magnet puts the pickup out of phase with the other one. A pickup is either one phase or the other, there isn't more than one kind of 'out of phase'. (Technically it's 'polarity', not phase, but it's become the usual way of describing it.)

    Peter Green's Les Paul neck pickup did have the magnet reversed, but you can get exactly the same sound by reversing the wiring too. Turning the pickup round (poles towards the bridge) also makes a small difference to the tone, but it's not the reason the pickup was out of phase.

    The out-of-phase sound is most noticeable when the pickups are equal volumes. If you have the neck pickup at 7, does the sound start fairly strong with the bridge pickup volume at closer to zero (say about 4), then go through a thin tone as the volumes equalize, then get strong again as the bridge pickup goes up to 10? If so, they are out of phase. If not, there's some other problem, possibly a faulty pot.
     
  11. ojo1138

    ojo1138 Member

    Messages:
    13
    Joined:
    Oct 16, 2007
    I have a Les Paul copy with this same problem. Kind of cool in a way, but also kind of irritating, mostly because of the volume loss. The problem started when I replaced on pickup with an old Duncan PAF. Is there an easy way to fix this other than replacing one of the pickups?
     
  12. JLee

    JLee Supporting Member

    Messages:
    2,145
    Joined:
    Nov 23, 2004
    Flip the magnet around in one of the pickups. Doesn't matter which. I find the easiest way is to completely unscrew the bottom plate and flip the bobbins up and away from the base plate. BE VERY CAREFUL not to break the connections. Pull the magnet out and roll it over like a log and place back in the pickup. You can also just loosen the bottom plate screws enough to push the magnet out from one end of the pickup between the bottom of the bobbins and the plate. If the pickup is wax potted, this method may need a bit more effort, since the magnet will probably stuck to the plate with wax.
     
  13. alanfc

    alanfc Member

    Messages:
    975
    Joined:
    Feb 4, 2004
    aha thats it ! Thats when its happening. I will try switching the hot/ground wires first. Magnet flipping, not so thrilled about that.
    Thanks
     
  14. John Phillips

    John Phillips Member

    Messages:
    13,080
    Joined:
    Mar 17, 2002
    Location:
    Scotland
    You can only switch the hot and ground wires if the pickup has 2-conductor plus ground cable (or 3- or 4-conductor, but there must be a separate ground). If it has single-core cable where the shield is used as the ground, and you swap the wires, you will get a huge amount of hum and buzz, and even worse if you touch the pickup cover or polepieces.
     
  15. alanfc

    alanfc Member

    Messages:
    975
    Joined:
    Feb 4, 2004
    OK thanks alot John I'll check carefully first
     
  16. Bill Brasky

    Bill Brasky Senior Member

    Messages:
    1,422
    Joined:
    Jun 23, 2007
    Location:
    Michigan, USA
    That's debatable if it's exactly the same sound. There are similarities, yes. In the November 2000 issue of Guitar Player there's a story on Peter Green. It quotes Jol Dantzig of Hamer Guitars who actually inspected and played Peter Green's LP when Gary Moore took it to the Hamer factory. They mention both methods and say re:magnetically out of phase "the resulting sound is sweeter and more musical than what you get from wiring humbuckers out of phase. Magnetically generated phase shift seems to respond to pitch changes - the higher the note, the more pronounced the effect. Chords and bass notes don't have the thin, shrill sound of out of phase wiring, yet high notes played on the top strings have a pronounced hollow cry."
     
  17. John Phillips

    John Phillips Member

    Messages:
    13,080
    Joined:
    Mar 17, 2002
    Location:
    Scotland
    Sorry, but that isn't supported by physics.

    There are more than 'similarites'. There may be tiny differences depending on which coil (and which end of it) is closer to electrical ground - because obviously that changes if you rewire the pickup, but not if you flip the magnet - but otherwise the result is identical. Out of phase is out of phase.

    If you directly compared the two sounds (which is actually difficult, since it takes some time to swap a magnet, and can't be done without potentially disturbing other adjustments as well including the pickup height) it is possible that you could detect a small difference, but I will guarantee you that if you listen to a guitar that has the two pickups out of phase, you cannot tell just from the sound whether it's magnetically or electrically so.
     
  18. Bill Brasky

    Bill Brasky Senior Member

    Messages:
    1,422
    Joined:
    Jun 23, 2007
    Location:
    Michigan, USA
    So for all those years and years that people sought after that elusive Peter Green sound, all they had to do was wire their guitar out of phase, which everyone knows about and had already been doing anyway? That non-mystery was the answer to the mystery?
     
  19. John Phillips

    John Phillips Member

    Messages:
    13,080
    Joined:
    Mar 17, 2002
    Location:
    Scotland
    Many people thought that it was the turning round of the pickup that did it - it doesn't, although it does alter the tone slightly because the two coils don't have identical responses.

    Later, people who realised that the turning of the pickup wasn't the cause may have reversed the phase without turning the pickup - for a long time it was said that the orientation of the pickup didn't make any difference. That doesn't get you quite there either.

    But if you turn the pickup round and reverse the phase - either by flipping the magnet or rewiring it - and of course if you can play like Peter Green ;) and use the right amp (notice that Gary Moore didn't get the same tone even with the actual guitar) - then you do get the sound.

    Really :).
     
  20. JLee

    JLee Supporting Member

    Messages:
    2,145
    Joined:
    Nov 23, 2004
    The mystery was how Peter achieved the sound without the aid of 4 conductor wiring. According to a few boutique pickup winders, Peter's neck pickup was accidentally rewound in reverse, reversing the polarity of the neck pickup as opposed to the magnet simply being flipped. The work was done by a tech named Sam Lee. Shed Pickups, Bareknuckle Pickups and WB Pickups all offer sets wound to the original rewind recipe.
    Jim Wagner of WCR Pickups also has stated that the effect is the same whether you wire out of phase or flip a magnet.
    The height balance between the two pickups affects the degree of effect more than anything else. The effect can go from extremely hollow and thin with a considerable volume drop, almost unusable IMO, to seemingly no out of phase effect at all.
     

Share This Page