Bartolini MK1 phase problem on Ibanez SR900

Discussion in 'Pickups & Electronics [BG]' started by llukuma, Apr 10, 2021.


  1. llukuma

    llukuma

    Apr 10, 2021
    So, I got an Ibanez SR900 in my repair shop, where somebody swapped volume pot and installed Bartolini MK1 pickups (not sure if they are stock, neck and bridge has been soldered vice versa). I soldered them intuitive "right" places, according to directions of ballance pot, and stumbled upon a problem I've never dealt with before. Neck and bridge pups sound full and balanced when played separately, but if I roll the Balance pot in a middle position, turning both of them on, E and A strngs sound thin and "wah"-y, but D and G strings sound okay. Reversing Ground and Hot wires on one of the pickups made D and G sound hollow, and E and A are fine.
    I also see that balance pot has marks that it also was soldered non-factory. And before I dive deeper into this nighmare of a controls forest soldering, I want to ask if anybody had this problem before, and how did you manage it? Also, original wiring diagram for SR900 with no switches would be appreciated.
    Feel free to ask question if anything written above is unclear, as I'm not a native speaker.
    Here's a photo of a control cavity:
     

    Attached Files:

  2. llukuma

    llukuma

    Apr 10, 2021
    Pickups and preamp, which has MK1 written on it, seem to be stock.
     
  3. mmbongo

    mmbongo I have too many basses. Supporting Member

    FYI Ibanez installs these backwards on purpose....Bridge in the neck and neck at the bridge.
     
  4. Any ideas why they do this?
    And what is the difference in the pickups anyway?
    Curious as I have recently acquired one of these basses, which for the OP doesn’t exhibit the same oddness.
     
  5. llukuma

    llukuma

    Apr 10, 2021
    Seems legit. They were reversed for sure. Bridge was cliiping, neck was very quiet. Now at least the volume is ok. Looks like they organize the preamp to compensate resistance difference.
    Still wondering, why on earth would half the pickup sound fine, and other half - out of phase. Any ideas?
     
  6. llukuma

    llukuma

    Apr 10, 2021
  7. dwizum

    dwizum

    Dec 21, 2018
    Are these two or four wire pickups?

    Do you own a multimeter? What do they both show for resistance, measured across whichever leads you have them wired with?
     
  8. llukuma

    llukuma

    Apr 10, 2021
    One hot, one ground for each pickup. Neck is 6,1 kOhm, bridge is 7 kOhm. I tried to wire them directly to output, and have had same problem, so It's not a preamp.
    I'm a noobie with electronics, and have got into phase problems recently, when I tried to hum-cancel my S-S guitar. For what i suspect, Bartolini has 2 coils for each pickup, situated end to end, one for upper and one for lower strings. And one of the coils is out of phase with the same positioned coil in another pickup.
    So, it begs the question: why the hell are they out of phase, when it's obviosly a Neck-Bridge couple (speaking from resistance measuring), and how can I shift the phase of a coil if only two wires are availible?
    Does anybody know how Bartolinis are assembled?
     
    Last edited: Apr 12, 2021
  9. dwizum

    dwizum

    Dec 21, 2018
    Have you tried reaching out to Bartolini? They're usually very good with support via email.

    Many of their pickups are constructed as you guessed (two coils inline end to end, almost like a P pickup without the stagger) but I don't know about that particular set off the top of my head. Some of their older pickups have exposed coil wiring on the back of the pickup, which allows you to swap phase and series/parallel even with only two leads going to the controls, I'm assuming these don't or else you would have mentioned it.

    How about a photo of the backs of the pickups?

    Also, stupid question, but has this bass ever been "ok" with this set of pickups? Was it brought to you because of this problem or did it just sort of show up as you were working? Just trying to backtrack mentally to understand if we can figure out if a specific change caused the issue.

    Can you flip one of the pickups around end to end? That would essentially switch which coil is underneath which set of strings. Would at least be an interesting experiment.
     
  10. dwizum

    dwizum

    Dec 21, 2018
    Have you tried reaching out to Bartolini? They're usually very good with support via email.

    Many of their pickups are constructed as you guessed (two coils inline end to end, almost like a P pickup without the stagger) but I don't know about that particular set off the top of my head. Some of their older pickups have exposed coil wiring on the back of the pickup, which allows you to swap phase and series/parallel even with only two leads going to the controls, I'm assuming these don't or else you would have mentioned it.

    How about a photo of the backs of the pickups?

    Also, stupid question, but has this bass ever been "ok" with this set of pickups? Was it brought to you because of this problem or did it just sort of show up as you were working? Just trying to backtrack mentally to understand if we can figure out if a specific change caused the issue.

    Can you flip one of the pickups around end to end? That would essentially switch which coil is underneath which set of strings. Would at least be an interesting experiment. I'm wondering if you have a mismatched set or something. Most bartolinis have obvious visual clues as to orientation, so it's hard to mess up, but you never know...
     
  11. llukuma

    llukuma

    Apr 10, 2021
    Neither I or owner, of previous one do know when it started. I tried flipping them around every single way, but the issue is present on some side. So, I suppose, one of the coils was wired the wrong way on the factory, or maybe orientation of the magnet was twisted 180 in some way...
    How do i spot which one of pups is faulty?
     

    Attached Files:

  12. llukuma

    llukuma

    Apr 10, 2021
    I also got a reply from Bartolini. Dude says that it's Ibanez problems, as MK1 isn't actually a Bartolini, and he has no clue how to fix it
     
  13. ex-tension

    ex-tension

    Jun 11, 2009
    There is a similar case @JoePP has had with other kind of pickup set:
    Geezer Butler signature pick ups
    You can check out his post to have some idea. The case starts at post#3503.
    It's a PJ pickup set but still both of them are split coils like MK1 pickups.

    Another case: Volume loss when blending Jazz Bass pickups
     
    Last edited: Apr 13, 2021
  14. dwizum

    dwizum

    Dec 21, 2018
    Do you have a compass handy? An actual magnetic one? You can check magnetic polarity that way to see if there's an obvious issue (i.e. one pickup has N up under two strings and S up under the other two, but the second pickup has N up under all 4 strings - that one has a backwards magnet!)
     
  15. llukuma

    llukuma

    Apr 10, 2021
    I
    Checked with another magnet, pups are NS SN, so maybe it's the coil.
    I still don't exactly understand how does hum cancelling work. I get that reversing coil direction reverses one sine and makes it out of phase with another, cancelling ALL the sound, but why reversing the polarity of the magnet amplifies output, still letting the hum to be cancelled?
    Can anyone please send me a comprehensive lesson about how the electricity in a guitar works, please? I've watched a dozen of videos relating subject, but can't grasp the whole picture how two humbuckers get along together.
     
    Last edited: Apr 13, 2021
  16. dwizum

    dwizum

    Dec 21, 2018
    Hum cancelling works because "noise" doesn't care about the magnet (or it's polarity) but the signal generated by the strings does.

    Reversing the wind and the magnet mean that the signals for the strings are in phase (both reverses flip the phase of the string signal - flip phase twice and you end up back in phase) but because background hum only gets it's phase flipped by the coil direction (not the magnet), the signal from the hum is only flipped once, so it's out of phase with itself, and cancels out.

    the magnets seem fine, and your DC resistance readings seem to confirm that the pickups are in the right positions and no coils are shorted or open. This is a bit of a mind bender. It's not really possible that one pickup has one of it's coils reversed in terms of wind direction, or else that pickup would be out of phase with itself (since both pickups have the correct scenario of their two magnets being reverse polarity).
     
  17. Joseph basses

    Joseph basses

    Apr 30, 2021

    Hello my friend i new in here. But i have same problem buy 2 mk1 for 5 string bass and u can repair it. Its not 100% repair but it will work. Pickup is 2 wires not 4 and put in epoxy. Rewire not works. One pickup take it out, and you now its split coil, so one coil is south other is north so you put under one coil that is out pahse under pickup thin plate strong neodimium magnet that is same polarity like other in that same pickup. So you will have split coil pickup same polarity not true humbucker but it will work. I do the same. T

    Barts are cermaics so you cant demagnetized easy.. you will need to cook pickup remove epoxy and do it from beginning. Rewind it and all stuff..

    So this is easy fix.
     
  18. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    May 25, 2022

Share This Page