Hum and crackle: Need help fixing an unconventional custom bass

Discussion in 'Pickups & Electronics [BG]' started by Josh G, Dec 1, 2021.


  1. Josh G

    Josh G

    Dec 1, 2021
    Hi there, all. I need a bit of help with my bass. I built this thing custom using Warmoth parts a few years ago. It's got a J neck pickup and an MM bridge pickup, and active electronics. I sounds great, but obviously I don't have a whole lot of support when it comes to fixing it! Hopefully someone on here can help me out.

    For a few months now I've noticed a few things that never seemed to be problems before. 1) When I turn the volume knob on the bass up and down, I hear a crackling sound coming from the amp. 2) The bass emits a buzz that it didn't used to emit. The buzz is worse when I'm on the neck pickup, but still present with both pickups.

    These problems both happen with multiple cables and out of different amps, so I'm pretty sure the issue is in the bass itself. The pickups are a Seymour Duncan Apollo jazz in the neck position, and a Seymour Duncan Music Man pickup in the bridge position. Rather than wire all the pots myself, I used an Audere jazz bass preamp (this one: Jazz 4B Chrome), whose inner workings are a little mystifying to me.

    I emailed Audere for assistance and they told me that I probably have a grounding problem, but I opened up the plate and it doesn't look like anything has come lose; all the soldering still looks fine. I went in with a multimeter and poked around, but I couldn't find an obvious disconnect anywhere. This is my first time messing around with that kind of diagnosing, so I might have missed something, but I'm not sure what it could be.

    Does anyone have any advice, or anything I could try to troubleshoot a bit more and figure out what the problem is? Or maybe a link to some kind of resource that I might be able to get more information out of? Thanks for your time!
     
  2. dwizum

    dwizum

    Dec 21, 2018
    Crackling is almost certainly a dirty or failing pot. Sometimes you can clean them with a squirt of contact cleaner in the vent hole on the back of the pot. Or just replace it.

    In terms of the hum - make sure your grounds and shielding is are correct. Audere preamps need the pickup negative lead separate from any shielding ground. Read here:

    Audere Audio Classic FAQ
     
    LoveThatBass likes this.
  3. Josh G

    Josh G

    Dec 1, 2021
    Thanks for your help! I'll check that out. The crackle seems to happen on all of the pots, not just volume. Does that tell us anything?
     
  4. dwizum

    dwizum

    Dec 21, 2018
    Could be all pots dirty. Could also be a loose solder or screw terminal connection somewhere - a weak signal through a bad joint can sound crackly. I'd clean the pots and check any joints over carefully.
     
    LoveThatBass likes this.
  5. Josh G

    Josh G

    Dec 1, 2021
    Thanks for the advice, I'll give this all a go.
     
    dwizum likes this.
  6. Try spraying the pots with Deoxit5 and rotating them a few times. If no help then pot may need replacing.
     
  7. Primary

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    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.

     
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