Help confirming buzz diagnosis

Discussion in 'Amps and Cabs [BG]' started by BboopNnb, Jul 12, 2020.


  1. BboopNnb

    BboopNnb

    Jul 12, 2020
    Hi all. I have a buzz issue that I think I've narrowed down to my amp, but I wanted to check whether I'm missing anything. Please let me know.

    Amp: Fender Rumble 15 (10+ years old, from a starter pack)
    Bass: Fender MIM P Bass (1 year old)

    When everything is set up and being played, there is a minor buzz that gets worse when I move my hand closer to the pickups and goes away when I touch the strings. Things I have tried:
    • Same amp, same bass, same cable, different location - Still buzzes
    • Same amp, different bass, same cable, same location - Still buzzes
    • Same amp, same bass, different cable, same location - Still buzzes
    • Different amp (Vox amPlug), same bass, same cable, different location - NO buzz
    All of this seems to add up to an amp issue, which wouldn't surprise me given the age and price/quality of the amp. The only thing that gives me pause is that most of the time when I see this type of issue described by others, the cause it not usually the amp. Also, the only other amp I have on hand to try (thanks to COVID) is a Vox amPlug, which isn't quite the same as trying another real amp.

    Any thoughts or recommendations for other things to try? Thanks!
     
  2. Can you try a different instrument? Even if it's a guitar?
     
    DiabolusInMusic likes this.
  3. MynameisMe

    MynameisMe What will you be remembered for? Supporting Member

    Dec 31, 2018
    Jax, Florida
    House electrical issues? Grounding issues?
     
    DiabolusInMusic likes this.
  4. DiabolusInMusic

    DiabolusInMusic Functionless Art is Merely Tolerated Vandalism

    Is the different location in your house still? If so, try the amp somewhere else and see if the issue persists. It could be the house wiring. Your AmPlug is going off batteries so it wouldn't be affected by a poor power source. Your bass may require shielding (fixing the buzz that stops when you touch the strings) but I wouldn't look into that if the issue doesn't persist elsewhere.
     
    MynameisMe likes this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    Does the power cord have the ground pin present?
     
  6. BboopNnb

    BboopNnb

    Jul 12, 2020
    Here's some additional info:

    - Ground pin is present
    - The "different location" is another floor in the same house. Not sure when I'll be able to try it elsewhere. Don't know of any grounding issues in the house, but we've only been here a couple years so it's possible
    - Probably the most useful: I realized I hadn't tried it with my uke bass in a while. There is NO buzz with the uke bass (piezo pickups, of course)

    So to recap, the buzz only happens with my amp + my J or P bass. Any other configuration involving the AmPlug or the uke has no buzz.

    So maybe it's a shielding issue with the passive basses? It seems odd that the AmPlug would remove/mask that.

    Thanks for all of your input so far!
     
  7. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
    It's sounding like either shielding, or possibly that the bridge is not bonded to the signal ground (sleeve of jack). It's almost certainly not the amp at this point.
     
    Downunderwonder likes this.
  8. Yerp. Monkeying with bass causes ebb and flow of noise = bass not amp.
     
  9. BboopNnb

    BboopNnb

    Jul 12, 2020
    Update: I went ahead and shielded my ancient Squier Affinity J bass. I hadn't done it before, but I figured that even if I completely screwed it up, I wouldn't be out much. That bass is worth basically nothing and I rarely use it anymore.

    It turned out to be pretty easy and it definitely reduced the buzz. I imagine it would also help my other bass, and I feel pretty confident in doing it now, especially since the P ought to be less complicated than the J was.

    Thanks for all of your input!
     
    agedhorse likes this.
  10. Primary

    Primary TB Assistant

    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.

     
    Oct 16, 2021

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