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Feedback noise playing active bass thru amped PA

Discussion in 'Amps and Cabs [BG]' started by vilago, Nov 25, 2017.

  1. vilago


    Dec 5, 2016
    has anyone ever played through a self powered pa speaker like a stand-alone bass cab? I’m getting some weird “buzzing” feedback when playing notes that is distracting but otherwise the bass sounds pretty good. Is there a pedal or something I can use to clean up this problem? Using Yama 504 and EV self powered speaker.
  2. There's an awful lot of things that could go wrong, which makes it hard to diagnose given the limited information.
    You usually can't plug a bass directly into a PA system, so for starters I will ask. What interface (DI?) are you using?
    Do you have an unbalanced, 1/4" tip/sleeve) signal going to a balanced, 3-pin XLR PA input?
  3. Steve


    Aug 10, 2001
    I've done it a bunch without issue. You have to pay a little more attention to your gain structure with that kind of rig. Line distortion can sound pretty ugly.

    I've used a self powered JBL a bunch, sometime with a sansamp just to get controls closer, it's a great keyboard rig and maybe on of the great acoustic guitar set ups of all time
  4. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    Are you remembering to mute (dampen) all of the unplayed strings?
    Al Kraft likes this.
  5. vilago


    Dec 5, 2016
    “PA system, so for starters I will ask. What interface (DI?) are you using?
    Do you have an unbalanced, 1/4" tip/sleeve) signal going to a balanced, 3-pin XLR PA input?”

    This is correct. The XLR Input is a hybrid 1/4” of sorts and I’m just plugging directly into that.

    This being said, what is line distortion? The buzzing isn’t the other strings ringing out or a technique issue or anything like that. It’s a humming/buzzzzz feedback sound I can hear clearly while playing sustained notes. When playing on an actual dedicated bass amp I can’t hear it so it is something related to the PA.
  6. vilago


    Dec 5, 2016
    Reading about this it sounds like I’ll need a direct box. Does this sound right? If so can anyone recommend one?
  7. You normally cannot go directly from unbalanced 1/4" TS to balanced XLR audio. You need to have a balancing circuit, like the transformer or active balancing found in a proper D.I. Without balancing you risk getting hum into your system.
    It also may cut the level between the two significantly, which forces you to turn the amp up more than normal and bring up the inherent system noise even more.
    I'd suggest you find a proper D.I. box to put between your bass and the PA system.
  8. vilago


    Dec 5, 2016

    YES! This is exactly the problem I have been having. I really gotta crank it to even get it to normal levels. Glad there’s a simple solution to this. I appreciate the advice.
  9. vilago


    Dec 5, 2016
    I wanted to chime back into this thread as I still have the sound and have not been able to figure out where it's coming from. Tried a radial DI box and different cable so its not related to ground. I carted the whole rig, bass, cable and speaker to the music store I got it from and couldn't hear it, most likely due to the ambient noise. I am posting an audio clip of the sound recorded by my phone. You can hear the sound start on 0:07 on the 2nd note. Anyone got any ideas? Dropbox - Bass Sound.m4a
    setup is Yamaha TRBX504 and EV ZLX12P powered PA.
  10. vilago


    Dec 5, 2016
    Am I the only one who has heard this sound before?

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