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Gig Nightmare: Markbass Amp Feedback

Discussion in 'Amps and Cabs [BG]' started by selowitch, Sep 10, 2019.

  1. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    I am endeavoring to learn some lessons from an awful performance the other night. My longtime originals band performed a twenty-minute set as part of a multi-band show so setup was rushed and there was no real chance to troubleshoot. Anyway, for whatever reason my Markbass amp started feeding back something awful and I had to turn it down so low that I could no longer hear myself or be heard. Things pretty much crashed and burned from there.

    Is it possible the Fender Downtown Multieffects pedal that I had place on top of the amp is what caused the amp to feed back so badly? I am really chagrined.
    Last edited: Sep 10, 2019
  2. Mingo Sanders

    Mingo Sanders

    Mar 11, 2008
    Austin, TX
    Is this the first time you've ever played with your gear situated that way? First time in that performance space? Any bandmates experience issues that might point to a problem with the power in the performance space?
    BrentSimons, Ductapeman and gorneyg like this.
  3. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    Not sure.
    BrentSimons likes this.
  4. To find the cause first you must know for sure where the loop is occurring. The bass instrument itself back feeding the stage amp is unlikely unless it's an acoustic, which you didn't mention.
    BrentSimons, murphy and Acoop like this.
  5. DWBass

    DWBass The Funkfather Supporting Member

    Were you on a hollow stage?
    BrentSimons and Robert B like this.
  6. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    It was my usual gigging bass, an Ernie Ball Music Man StingRay 5H.
  7. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    I don’t know. Since I have since gone home, the post-facto troubleshooting is something of a challenge.
  8. Normally you would have to make an actual effort to get that to feed back through your stage amp. Are you sure it wasn't something in the drum kit got excited by you then feeding back through its mic and the PA? The other doozy is an acoustic guitar feeding back at your lower mid bass frequency and you cop the blame.
    DJ Bebop, Helix, HolmeBass and 3 others like this.
  9. Stumbo

    Stumbo Wherever you go, there you are. Supporting Member Commercial User

    Feb 11, 2008
    Song Surgeon slow downer. https://tinyurl.com/y5dcuqjg
    Good time for an HPF/LPF in your signal chain.:thumbsup: And a parametric eq.
    Last edited: Sep 11, 2019
    dbsfgyd1, BOOG, Wavebird and 6 others like this.
  10. JimChjones


    Aug 6, 2017
    SE England
    As others have said, sees an unlikely setup for uncontrollable feedback. What were general voume levels like, and did any of the other bands experience problems? Was it a particular frequency? Could you feel it in the strings getting excited?
  11. Are you sure it was feedback? It sounds like it may have been resonance in the stage or the room.

    What other instruments were on stage and what was the PA system like?
  12. Different gear but I learned that an Ampeg SCR-DI that’s running on low voltage (e.g. rundown battery or the wrong output on a brick) will squeal, feedback-like. Be prepared to look for oddball stuff.
  13. Acoop


    Feb 21, 2012
    If it's not doing it once you got home, I'd bet it was a input into a loop mistake. ... Too bad they didn't just have a backline everyone plugged into. ... The 'ghost in the machine' strikes again.
    ObsessiveArcher and Stumbo like this.
  14. BobDeRosa

    BobDeRosa Commercial User

    May 16, 2012
    Penfield, NY
    Owner, Tritone Jazz Fantasy Camps
    Bottom line: Never, ever agree to "a twenty-minute set as part of a multi-band show so setup was rushed and there was no real chance to troubleshoot."
  15. Robert B

    Robert B Supporting Member

    Jan 21, 2000
    Hampton, Va USA
    That's what I'm thinking - resonance.
  16. I had a Markbass 121CMD, which I remember fondly. Seemed too bassy for my needs so I sold it later. With that combo, there was no real chance to plug something badly. My thoughts:
    - try to emulate the same situation at home. Look for a volume level when the feedback starts. Things might be different when the bass is closer to the amp, also the angle between the bass and the amp might matter.
    - if you use overdrive and/or compressor on the effect pedal, the feedback treshold goes lower. The more compression/distortion, the easier feedback
    - if you can recreate feedback this way, it would be the feedback rock guitarists sometimes use for achieving neverending tone. I was able to get this kind off feedback intentionally on by passive Fender jazz with a volume quite high; not on my P or active P-J Pedulla. Solutions: reduce comp/dist; step further from the amp; put the amp higher from the floor (so you can hear it better with lower volume); find the frequency that is 'feeding back' and reduce it on EQ.
    - otherwise, it would probably mean a trouble in the PA setup. Likely suspects: feedback through some mic forgotten on, miking the bass unintentionally, or singer's mic too close to the bass amp or to the wall that's reflecting bass amp sound etc.
    ObsessiveArcher likes this.
  17. TNCreature

    TNCreature Jinkies! Supporting Member

    Jan 25, 2010
    Philadelphia Burbs
    Can you confirm that is was the bass feeding back? I have a hard time imagining that. Was it more of a squeal? My guess is the effects pedal/loop being plugged in incorrectly or a low battery, or a defective pedal,cable, amp... Something like that would be more likely
    seamonkey likes this.
  18. Lammchop93

    Lammchop93 Supporting Member

    Feb 4, 2007
    Louisville, KY
    could it have been a grounding issue at the venue? a bad cable? try the same setup at home/practice space and see if it happens again.
  19. selowitch

    selowitch Supporting Member

    Aug 6, 2005
    Rockville MD
    I’m inclined to think it was a grounding issue at the venue but there is no way to test it after the fact.
    ObsessiveArcher likes this.
  20. tpaul

    tpaul Supporting Member

    Mar 19, 2011
    You said it was a multi-band show. If other bands were not experiencing the same problem using the same stage and power supply, it's likely something in your setup or gear.
    Downunderwonder and redwingxix like this.

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