Treble pot acting as volume

Discussion in 'Pickups & Electronics [BG]' started by Sabudum, Feb 3, 2014.


  1. Sabudum

    Sabudum

    Joined:
    Feb 3, 2014
    Hello, i live in Brazil, and i have an active bass, a Strinberg CLB-14A, it uses a bartolini ntbt, here is the wiring i found in bartolini's site, the bass came exactly like this:
    http://www.bartolini.net/1_wirngs/ntbt_2.gif

    Although it has a problem, the treble pot acts as volume, when the treble is raised, the volume lowers, when the treble is lowered, the volume raises.
    The volume pot works fine, all other pots work just as fine.

    Any ideas on what could be causing that?
  2. RobbieK

    RobbieK

    Joined:
    Jun 14, 2003
    My first thought is a faulty treble pot. I'd also check for dry solder joints at the treble pot.
  3. Ric5

    Ric5 Supporting Member

    Joined:
    Jan 29, 2008
    Location:
    Colorado
    A volume and tone pot are the same until you add a capacitor. A volume pot will bleed all frequencies to ground and a tone pot will bleed just treble to ground because of the capacitor.

    So there is a wiring problem.
  4. ddnidd1

    ddnidd1 Supporting Member

    Joined:
    Mar 31, 2003
    Location:
    Southern California
    Except this an active preamp circuit - not a passive circuit.

    Double check your wiring and the pot values.
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  6. pfox14

    pfox14

    Joined:
    Dec 22, 2013
    That wiring diagram is very confusing. Can't tell what wires are coming from the pups and there's no capacitor. No wonder it's not working right.
  7. ddnidd1

    ddnidd1 Supporting Member

    Joined:
    Mar 31, 2003
    Location:
    Southern California
    Exactly - no capacitor -its an active preamp. It doesn't use one.

    Here's a different diagram -

    http://www.bestbassgear.com/wiring-diagrams/Ntbt_918.pdf
  8. sfxster

    sfxster

    Joined:
    Apr 12, 2011
    Location:
    Chile
    This.

    I had a similar issue when I changed the preamp for my Ibanez and there was a tiny bit of solder between two of the terminals


    Also, check if the pot is making contact with the paint, since it's a conductive paint it could have the same effect
  9. Sabudum

    Sabudum

    Joined:
    Feb 3, 2014
    Wow, thanks for the help guys, i've checked for cold solder joints, in fact i remade all solder joints, and the problem persists, i guess a capacitor is not needed, since it uses a preamp, and it came from factory like this, the pot is not touching the paint either, the problem persists when i unscrew it from the bass body. Could it be a faulty preamp?
  10. sfxster

    sfxster

    Joined:
    Apr 12, 2011
    Location:
    Chile
    Maybe is a faulty pot. Try with another pot and if the problem persists I'd contact Bartolini
  11. Sabudum

    Sabudum

    Joined:
    Feb 3, 2014
    Yes, that's the only explanation i could come up with as well, and now, another issue has presented itself, the bass pot makes a strange whistle sound in a certain position, and also produces crackles when moved, i guess these pots are too old, and maybe they overheated when i remade the connections, even though i made it quick.
  12. sfxster

    sfxster

    Joined:
    Apr 12, 2011
    Location:
    Chile
    That sounds like a dirty pot. Try using some contact cleaner
    If not then is a bad pot definitely
  13. rumblinbass

    rumblinbass

    Joined:
    Aug 22, 2003
    Location:
    Wimberley, TX
    I am going to guess the preamp is faulty.
    Assuming it is a Baxandall circuit circuit, if the cap is shorted it will not act as Treble control but as overall Gain control.
    I would contact Bartolini and arrange for return or exchange.

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