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Weird issue: pitch varies, sounds like two notes played together

Discussion in 'Hardware, Setup & Repair [BG]' started by Mickets, Feb 21, 2018.

  1. Mickets


    Feb 18, 2018

    I couldn't find a similar issue here in the forums, so here's my post.

    I have a fretless Ibanez BTB series bass, and over the last few months a problem developed: when I place a finger on the fretboard and play a note, on a single string, I hear two notes. It sounds as if the pitch of the note is varying up and down, or as if I were tuning the bass by playing harmonics on two different strings.

    I make sure I press the string with my left hand finger and don't vibrate it (tremolo) and the other strings are all muted with the help of the remainder of my left hand and also the right hand (I.e.: there is definitely only one string vibrating).

    The problem is more evident the further up the neck (higher notes).

    I made some minor adjustments of the truss rod, pickup heights, intonation, but no change.

    I changed the strings, and the problem just became more evident.

    Last week I took the bass to a Luthier, which also adjusted the neck (was too lose, neck curved). It improved a bit but the issue is still evident.

    It doesn't seem to be related to the neck.

    I changed pickup settings (two humbuckers, switchable), and no difference.

    I don't see how it could be the bridge.

    I also don't see how it could be to do with the tuning gears.

    Anyway, I recorded a small video, in the hope that anyone could give an idea. It's driving me nuts.

    Thanks in advance!


    Video link:
  2. lz4005


    Oct 22, 2013
    Try lowering your pickups, particularly the front one. Having the magnets too close to the string can cause that issue.
    walterw, wvbass, 96tbird and 3 others like this.
  3. Lofreck


    Apr 25, 2013
    It looks like the second half of the string is vibrating (from finger to nut). Try to mute that part of a string to confirm the idea.
  4. I'd agree with Lofrek. Hard to tell in the video but it seems like you're not muting the string behind where you're playing. Try that first, it's free.
  5. walterw

    walterw Supportive Fender Gold Supporting Member Commercial User

    Feb 20, 2009
    what @lz4005 said, lower the pickups, especially the neck pickup and especially the bass side of the neck pickup.

    those big magnets can pull on the string, causing it to actually vibrate out of tune with itself.

    also, how old are those strings? old worn-out strings will also vibrate out of tune like that.
    Lbsterner likes this.
  6. Wasnex


    Dec 25, 2011
    Sounds almost like chorus. What are you playing through? I had a preamp tube going out on one my amps once and it would sometimes oscillate slighly out of tune with instrument. Other times it would track the notes an octave down. Very weird.

    Have you tried playing through a different amp and does the problem occur when you are playing without an amp (unplugged)?
  7. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    All of the above plus a twisted string(s). "Chorus" is the best description. Here's a @walterw trick which may help: loosen each string to the point where can pull the "coil wrap" off the tuner post. If the string is twisted, the coil will spin one way or another. Re-align with the coil in its relaxed state and slide back over top the tuner post, re-tune to pitch. Just as effective as removing the entire string.

  8. Mickets


    Feb 18, 2018
    Thought of that as well, but:

    1. The problem started without me ever changing pickup heights;
    2. I did lower them and didn't notice any change.
    I will check again, though.

  9. Mickets


    Feb 18, 2018
    I thought the same, and tried that already. No change...

  10. Mickets


    Feb 18, 2018
    I did that, but not in the video. No change...

  11. Mickets


    Feb 18, 2018
    Forgot to mention: issue started while it had older strings, and persists after changing to brand new strings...
  12. Mickets


    Feb 18, 2018
    Yes, I tried through different settings. First through neutral effects on a Boss eBand JS10, and then directly on a Hartke A100 with no effects.

    Besides, my other bass, plugged in to the same amp or effects, doesn't show the weird sound.
  13. Mickets


    Feb 18, 2018
    Interesting trick. I will try that timely, but I have a feeling it's not the cause, because I replaced old strings with new ones, and the issue occured/occurs with both old and new set.

    The issue started without me removing or rewinding strings.

    But I will try over the weekend..

  14. SoCal80s


    Oct 1, 2015
    Do you have the volume up on both pickups? Try it with just one at a time and see what happens.
  15. Lofreck


    Apr 25, 2013
    These 'beats' are heard mostly at 8, 12, 16 frets? Maybe also at 6, 18? Or even 4, 20?
  16. HeavyDuty

    HeavyDuty Supporting Curmudgeon Staff Member Gold Supporting Member

    Jun 26, 2000
    Suburban Chicago, IL
    Active or passive? If active, try replacing the battery.
  17. Are the nut slots too low? That can cause a “back buzz.” There has been a couple of threads recently on that here. For a quick and dirty test you could shim one of the slots with a slip of paper and see if that helps.
  18. Wasnex


    Dec 25, 2011
    What about unplugged. You need to eliminate the basses active electronics as a source of the problem.
  19. Mickets


    Feb 18, 2018
    I have tested with all combinations of pickups and humbucker on/off. No change.

    If I lean my ear on the neck, I can hear/feel it clearly so I don't think it's a pickup/electronic problem, but more of a bass body/hardware problem.

  20. Mickets


    Feb 18, 2018
    Yes, same issue unplugged. It must be something with the body/hardware...


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