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reverse polarity on single coil to eliminate hum?

Discussion in 'Pickups & Electronics [BG]' started by lovethegrowl, Dec 13, 2015.


  1. lovethegrowl

    lovethegrowl Banned

    Oct 30, 2013
    I will be using just my neck pickup on my jazz bass (using Roto 88s to get a pseudo fretless sound) & I am wondering if I should reverse the polarity of the bridge pup (before soldering in the new Alnico neck pickup) in order to have both in parallel (like my old Rickenbacker) to "buck the hum" while using the front pickup only.
     
  2. bassbenj

    bassbenj

    Aug 11, 2009
    This makes no sense. Slow down and say EXACTLY what you are trying to do. If you are using just the neck pickup on a jazz bass then the bridge pickup will be doing nothing.
     
    bholder likes this.
  3. lovethegrowl

    lovethegrowl Banned

    Oct 30, 2013
    According to tech support at Carvin, Rickenbacker basses have their single coils in parallel & hum when equally balanced & don't hum when only one pickup is used. The exact opposite of a standard Jazz bass. I know reverse wound isn't exactly the same as reverse wired, but shouldn't the effect be similar when reversing the polarity of the wires? If not, then having both the existing neck pickup put where the bridge pickup is & the new neck pickup put in the neck cavity should minimize the hum using just a neck pickup (shouldn't it?). Both pickups will not be "reverse wound in relation to one another
     
    Last edited: Dec 13, 2015
  4. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    central NY state
    Received a gift from Sire* (see sig)
    Rickenbacker basses hum whenever there is a source of hum that isn't well shielded. Nature of the beast, whether pickups are balanced or not matters nil.
     
  5. lovethegrowl

    lovethegrowl Banned

    Oct 30, 2013

    So Albert @ Carvin was yanking my chain by telling me the parallel polalarity of both the Rick 4001, 4003 pickups have the converse effect of a jazz bass' "humbucking" properties. I had a 4001 & don't remember a hum at all, either way.
     
  6. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    central NY state
    Received a gift from Sire* (see sig)
    I'm no expert, but Rickenbacker's approach has always been shielded non-humbucking single coils, that's key to their unique sound. I don't see how taking a pair of coils with identical magnetic and winding directions and setting their blend even or one completely solo or anywhere in between can make a non-humbucking arrangement humbucking.

    So, yeah, I guess I'm accusing Albert of talking out his @$$. His job is not to help you with your Rickenbacker, his job is to sell you a Carvin instead.
     
  7. lovethegrowl

    lovethegrowl Banned

    Oct 30, 2013

    He did that in the context of explaining the wiring of the j99a Carvins I bought. It actually might of been Kieth or Brian in sales who alluded to the difference between Carvins & Ricks. Ricks are not reverse wound. But I have no recollection of any hum
     
  8. bholder

    bholder Affable Sociopath Supporting Member

    Sep 2, 2001
    central NY state
    Received a gift from Sire* (see sig)
    ...because yours was well shielded.
     
  9. One pickup cannot humcancel with nothing. That defies physics. If you want humcancellation, you need an even number of coils.
     
  10. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    This,

    If a single coil is soloed it is going to hum, the other coil has to be RWRP and also in the circuit for it to cancel hum, series or parallel makes no difference.
     
  11. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    alpha-music.com
    it's already reversed on a jazz bass
    it's already in parallel on a jazz bass
    won't happen, captain. gotta have both pickups on at equal volume.
     
  12. rufus.K

    rufus.K

    Oct 18, 2015
    SoCal
    I have two northwound pickups in a jazz, with one reverse wired. It bucks hum when both are on, but you don't wanna touch the pole of the reverse wired one.
     
  13. Use nail polish on the pole pieces.
     
  14. rufus.K

    rufus.K

    Oct 18, 2015
    SoCal
    Oooh that's a good idea
     
  15. TheBass

    TheBass

    Jul 2, 2004
    Germany
    The best way to eliminate hum and still keep that single coil sound is using a phantom coil. Take another PU, take out the magnets and mount it upside down (important !) next to the "active" PU. Hum is picked up equal with both PUs (hum signal polarity reversed at the phantom coil). The strings are picked up by the active PU only. Wire both PUs parallel and you get a quiet single coil sound.
     
  16. lovethegrowl

    lovethegrowl Banned

    Oct 30, 2013

    Ironically my pickup cavity might be large enough to facilitate that, as it was over routed with the intent of covering up the soap bar sized hole with a pick guard with a single coil cut out. I don't want to use that pick guard on my SX. Thanx!
     
  17. mikezimmerman

    mikezimmerman Supporting Member

    Apr 29, 2001
    Omaha, Nebraska
    That is basically what the Audere hum-cancelling preamp does:
    Audere Audio Jazz Hum - Noise Cancelling Preamps

     
  18. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    It will remove hum, but it will leach tone and output.

    It works because it is active and the signal is boosted, this isn't an elegant solution on a passive insturment
     
  19. TheBass

    TheBass

    Jul 2, 2004
    Germany
    Didn't knew the Audere preamp. Interesting.

    I had in mind the way the phantom coils are implemented by Alembic Series I/II or EBMM Sterling. I don't know whether those are electronically gain compensated too but at least they provide a very authentic and completely hum free single coil sound.
     
  20. It's true that certain Rics don't have a RWRP pickup and so even if you run them at equal volumes it'll hum. Not sure why they did that. Jazz bass has one pickup RWRP in order to solve it. But both have to be ON for it to work. So if you intend to use only the neck pickup but want hum cancelling, you'd need to remove the magnets from the bridge pickup and leave it turned on. OR simply use a neck pickup that cancels hum already-there are many available. While they don't sound exactly like a real single-coil most folks think they're close enough.
     

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