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Distorsion From Active Bass

Discussion in 'Bass Pickups & Electronics' started by Jns223, Oct 24, 2017.

  1. Jns223

    Jns223

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    Hi
    I have an issue with distorted signal in active mode. It is a thumb nt4 -90 with bartolini soapbar and j-mic, mec two-way electronics and preamp. Could this possible be generated by to high position of the microphones, they have been adjusted lately or could it be the preamp? Any known issues? Optimal mic hight on bartolinis? And yes i have checked the battery. Any suggestions on this matter?
     
  2. RIP

    RIP California U.S.A. Good Vibe Sponsor

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    By microphones do you mean Pick Up's? If so lower them and see what happens.
     
  3. jester

    jester ocdemon Moderator

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    Is the noise there all the time? Or just when you play notes, they sound distorted?
    Not that I can tell much with your answer though. It may well be a semi-fried preamp.
     
  4. Jns223

    Jns223

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    When i play it sounds distorted, no hum or anything when not played.
     
  5. jester

    jester ocdemon Moderator

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    The preamp could still be damaged. Did you mention you changed the pickup heights lately? If you
    raised them, you can try lowering them. Also what is the "j-mic"? Am I missing something here?
     
  6. DiMarco

    DiMarco nutcase Good Vibe Sponsor

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    The old two band pre-amp has a white trim pot on top of it.
    This regulates the input signal for the pre-amp coming from the pickups

    If you raised the pickups they probably now have a higher output, which can cause distortion in the pre-amp.
    Lowering the signal going into the pre-amp by turning the trim pot counter clockwise will most probably solve your problem.
    Best practice is setting the trim pot so that in active and passive modes your output level is about the same, the trim pot only changes your active volume.
     
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  7. Jns223

    Jns223

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    Yay! Super reply! I Will try that. The bass has always had pretty huge difference in volymen between active and passive mode so this info. may sort that problem to!
     
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  8. jester

    jester ocdemon Moderator

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    I was sure Dr. DiMarco had the cure.
     
  9. Marcoelwray

    Marcoelwray Commercial User

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    I had that same problem once, it was on a brand new Glockenklang preamp. It was born dead.
    'hope it's not your case.
     
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