Mixing P90s and single coils, misc other wiring questions

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by rh, Jan 6, 2005.

  1. rh

    rh Robo Sapien Noise Maker Gold Supporting Member

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    I want to put a HD Z90 into the bridge position of a Strat. I'm thinking about using Fralin steel-poled 43 in the neck and middle positions.

    I can rig it vol (500K bridge) vol (250K neck/mid) and tone. I'm trying to figure out what the best pot and cap value would be for the tone position, though.

    I normally dial down the tone to about 6-7, regardless of pickup type, and almost never dime it.

    I'm thinking maybe 300K with a .02uf cap...

    Since the Z90 bridge is RW, as is the Fralin middle pup, I'm thinking I can reverse hot and ground to reclaim a quiet quack in pos 2, without affecting the sound of position 1.
     
  2. Jim Collins

    Jim Collins Member

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    250K or 300K would be fine as a tone control. Try either a .047uF or a .022uF tone cap. These days, I prefer .022uF, but those are my ears (vintage ears -- and getting more vintage every year).

    Regarding the RWRP issue... There is no standard for a pickup's magnetic polarity. A pickup is only RWRP with respect to some other pickup. A given Strat middle pickup may be RWRP with respect to the neck and bridge pickup from the same manufacturer, but that is no guarantee that it will be RWRP with respect to pickups from another manufacturer. You may, or may not, be able to accomplish what you want, as far as hum cancelling sounds go.

    As far as reversing hot and ground on the Z90 goes... This can only be done if the ground wire for the coil is seperate from the ground wire for the metal base of the pickup. If this pickup has only a single conductor with a braided shield, you cannot reverse the hot and ground leads. (Sorry, I don't know what leads come with this particular pickup.)
     
  3. rh

    rh Robo Sapien Noise Maker Gold Supporting Member

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    I've got vintage ears myself. Can't tolerate highs. (Back when I was a kid, I used to play with the wah pedal clicked on and down for an extreme treble boost. I can't frigging even imagine doing that now).

    The leads on the pickup are white black and a separate plain metal. The pup is taped up pretty well, and I don't want to mess with it, but I'd guess that the plain metal goes to the pickup base.

    Thanks for the very helpful reply. :AOK
     
  4. Jim Collins

    Jim Collins Member

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    Yep, the bare wire should be the one going to the base.

    That turns out to be a good thing. If you wire the pickup in phase with the other pickups, and discover that the parallel position involving this pickup is noisy, you can easily flip the magnets and swap the white and black leads, and it is suddenly RWRP with respect to the other pickup.

    If this critter is manufactured similarly to a P90, you'll find two magnets underneath the coil, straddling the row of pole pieces. Each of these magnets gets flipped.
     
  5. rh

    rh Robo Sapien Noise Maker Gold Supporting Member

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    Beauty. Thanks very much.
     
  6. Mark Robinson

    Mark Robinson Member

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    How are you planning to wire the two volume controls? I have a Strat with Z-90 neck and bridge pickups, and Strat pickup in the middle. The way it's wired, I can't seem to run the middle pickup alone. The neck and bridge are on a three position switch, like a Telecaster. I have a separate switch to kill or run the the middle pickup, and it's on it's own volume pot. It hollows out ok for funk rhythm, when blended with one or both of the Z-90's, even though the middle is a Kinman. Its a bit out of phase, like half out, but usable. When I turn down the vol. for the neck and bridge. I lose the middle pickup too.. I'd love to be able to turn the neck and bridge off, and run just the middle pickup. But I don't wan't to lose the neck+bridge only sound, it's great, and noise free. Sorry to jump your thread Richard.
     
  7. rh

    rh Robo Sapien Noise Maker Gold Supporting Member

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    Let me sketch my planned wiring out and I'll scan it and post the URL.

    Can you sketch and scan your wiring schem? Although it sounds like what you might want is a 4way switch instead of the three way. If you've got the circuit shut in the middle position (by turning down the Z90 volumes) I think you're probably SOL with a 3-way.
     

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