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Yamaha TRB-6II--Question About Electronics

Discussion in 'Pickups & Electronics [BG]' started by bbjonz, Jul 29, 2007.

  1. bbjonz

    bbjonz Supporting Member

    Aug 6, 2004
    Tucson, AZ
    Hi Everyone,

    I initially posted this as a dead battery question but now I think it has something to do with the bass. I have a Yamaha TRB-6II (bolt-on, 35", 2 humbuckers) that sounds very strange when the pan pot is even between the two pups. It sounds out of phase there, but sounds just fine when panned all the way to the neck or bridge pup. I put in a new battery but the problem persists. I opened the control cavity and noticed two yellow adjustment screws which I think allows one to micro-adjust the volume of each of the pups. I played with it and noticed some difference but the problem still persists. Does anyone know what these screws do? Has anyone had this problem with at TRB from that era? Any advice is appreciated.

  2. Liko


    Mar 30, 2007
    Any bass with two pickups is going to have certain frequencies of certain notes where the two pickups' signals cancel out part of the wave. This is most noticeable in the mids; with both pickups on the mids are usually less present and the bass and treble are boosted. This is technically "out of phase", but the term generally describes a far larger change in the sound.

    Some dumb troubleshooting questions, just to make sure:

    1. Is the sound more scooped, or does it sound thin and shimmery without a lot of bass?
    2. Are you sure you're adjusting the pickup blend knob (which pans between the two magnetic pickups and not the piezo blend (which blends the two magnetic pickups with the piezo)?
    3. How are the pickup heights adjusted? Too close and they will affect the vibration of the string.
    4. Have you made any customizations to this bass, such as swapping pickups?
  3. bbjonz

    bbjonz Supporting Member

    Aug 6, 2004
    Tucson, AZ
    Thanks for your reply. No, those questions are not dumb. Responses are below:

    1. Thin and shimmery with little bass
    2. Yes.
    3. Way down. I always err on the side of less pull.
    4. I don't know--just bought it. A previous owner might have, but everything looks original in the control cavity.


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