I must be nuts - unRWRPing a strat pickup

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by LReese, Jan 19, 2008.


  1. LReese

    LReese Member

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    Ok - I definitely prefer non RWRP pickups in my Strats. I even prefer a bridge pickup that is the same as the neck and middle. I must be going insane on this one.

    I've got some RWRP pickup sets - is there a good and easy method for a DIY'er to reverse polarity on RWRP middle pickups? I'll have to swap wires on the pickup, no way around that without rewinding. I know there will be slight noise differences, but I've heard of a shielding method that would allow pickup shielding without losing highs.
     
  2. David Collins

    David Collins Member

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    If you wanted to revert to non-rwrp, you would have to remagnetize the poles with the opposite polarity, then swap the leads. Of course the outer windings will then be on the hot end rather than ground, which won't make too much of a difference, but to truly convert it you would need it rewound. When you're done, it will sound exactly like it does right now, but with more noise.

    Whatever it is you don't like, I doubt it has anything at all to do with the fact that the middle is RWRP. The whole purpose of that is to cancel hum in positions 2 and 4, without changing the sound. It's probably just the pickups themselves that you don't like, irrelevant to the RWRP configuration.
     
  3. John Phillips

    John Phillips Member

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    I have to disagree with David on the last part. I do think there is a tone difference (in the 2 and 4 positions) between normal and RW/RP middle pickups. (I posted some more about it in the 'single coil hum' thread.) I prefer the tone of non-RWRP too.

    Actually swapping the winding is the easy part, and certainly does not require a rewind. Just swap the two wires to the coil. On some guitars without enough wire left at the pot/switch end, it's necessary to do it at the pickup eyelets, but this is possible with a little care.

    The magnetic polarity can be fixed easily if (and only if) the pickup is a Fender USA Standard type with a molded plastic bobbin such that the magnets are in 'tubes' inside the bobbin and not in direct contact with the coil. You can literally push them out and reinsert them the other way round - it's actually quite easy.

    Do NOT even think about doing this with a vintage-style fiberboard bobbin pickup - the coil is wound directly onto the magnets and you will almost certainly break it. The only way with these is to have the pickup re-magnetised the other way round.
     
  4. David Collins

    David Collins Member

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    The magnets can actually be reversed in polarity without removing them at all if you have the right gear. I've degaussed and remagnetized poles on a number of magnets this way, and it can be done either with a strong enough electromagnet setup or even some large permanent magnets. The trick is often getting the field even though. If you just take a few small neodymium magnets and remagnetize starting at one point and moving to the other, you will in effect pull the field orientation off at an angle on some of the poles as you move beyond them. To do it well, you really need to set up a system of a long magnets, or ones held together in a way that will create a straight field from top to bottom across the entire length of the pickup. Of course if it's a plastic bobbin, simply turning the poles around is the easiest way, which as John said would certainly not be a good idea on a conventional bobbin.

    As to rewinding, I think there are different schools of though on this. Traditionally the hot lead goes to the inside of the coil, ending with the ground on the outside. Just switching the leads will reverse this, but the end effect is what's debatable. I don't know how much tonal difference there is here, but I do feel that one with the hot connected to the outside of the coil is slightly more susceptible to noise.
     
  5. LReese

    LReese Member

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    These are vintage style pickups - so no pole swap.

    People are going to disagree on the sound difference - I hear more low end and less high end. Also more "character" to the sound. To me you lose more than the hum. A BPSSC takes away the hum and leaves the sound to my ears intact.

    I could see the discussion on the sound difference going in a bad direction. Anyway, it has been discussed in previous threads many times...

    I'm really interested in the method of flipping the poles and what I would need in order to do so. Any links to the best method would be appreciated.
     
  6. David Collins

    David Collins Member

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    I have no ambition to get in a discussion about tone differences, but the reason I suggested that the RWRP layout may not be your problem was from this -

    "I even prefer a bridge pickup that is the same as the neck and middle."

    RWRP of course means only that the middle pickup is reversed (my apologies if I'm saying something you probably already know), and the only two positions that I feel you could arguably or remotely hear any tone difference would be in 2 and 4. From what you said I thought you may have been dissatisfied with tone from the neck or bridge positions alone, but I may have totally misread your meaning. Changing to a non-RWRP would certainly do nothing to change these positions.

    If your complaints are with positions 2 and 4, than by all means try switching over. I just posted because I hate to see someone going on a completely wild goose chase, barking up the wrong tree, etc., if it were positions 1, 3, or 5 that were the issue.
     
  7. David Collins

    David Collins Member

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    As to actually reversing the polarity, I don't have any pictures around, but it's not too difficult. Seymour showed me how to do it years back with a huge horseshoe magnet that he has. I set up a pair of blocks to fit ten 1/2" by 1/2" neodymium magnets in - five side by side in each block. They need to be held in place by some mechanical means, because they have to be arranged in a way where they would repel each other.

    The two blocks can then be attached to opposite faces of a vice, with opposite poles facing. I place the pickup directly against one magnet block, then close the vice in on it, creating a good straight field from the top to the bottom of the pickup. Then rather than pulling the pickup out sideways through the field, I prefer to spread the vise back out so that I can pull the bobbin straight away from the magnet block it remains resting on. These magnets are powerful, and even if you charge them in a straight field, it can be thrown off if pulled out at an odd angle. I also keep a few sheets of magnetic viewing film around to double check the shape of the field.
     
  8. Rosewood

    Rosewood Member

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    David, that sounds like a good way to charge. I was charging some bar magnets one day and got the center line off to one side, (the white line in the viewing film) it's easy to do. Probably had to do with removing the magnet in a uneven way.
     

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