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Need PA help/ bass buzz through tweeter on PA

Discussion in 'Live Sound [BG]' started by mcapote, Aug 8, 2012.


  1. mcapote

    mcapote

    Sep 9, 2009
    Miami Florida
    Ok so i got a little problem, my new band got in a new PA system last night. When i plug my GK MB210 into the system i notice my G and A off my E string cause a buzz out of the tweeter of the mains(does not buzz on my amp itself though). I tried turning off the highs on my system but it still does it. Any ideas on what I need to do to eliminate that buzz? only happens from my bass, not if i plug and ipod with heavy bass into the system.

    PA system
    ___________
    Mixer
    Carvin C1648 16 Channel Mixer

    Amps
    Carvin HD2000 - subs
    Carvin HD1500 - mains

    Speakers
    2 x Carvin LS2153 mains
    2 x Carvin LS1801 Subwoofers

    Crossover
    Peavey PV-23XO
     
  2. Hactar

    Hactar

    Sep 25, 2011
    Boulder, CO
    Only the G & A on the E string?

    Sounds like wolf-tone/resonance type of thing.
     
  3. MrCincinnati

    MrCincinnati

    Mar 6, 2011
    I'm getting the same kind of thing from one specific bass - high buzz in tweets of house system...and to add to the confusion - it happens whether or not I have D.I. from amp to house...and only when I turn volume up.
     
  4. mcapote

    mcapote

    Sep 9, 2009
    Miami Florida
    well i noticed it on the G and A of the e string to be honest i dont remember if it did it on the g and a of other strings. I may bring one of my better basses tomorrow to see if it is a bass issue
     
  5. mcapote

    mcapote

    Sep 9, 2009
    Miami Florida
    its any G or A not just the e string.
     
  6. mcapote

    mcapote

    Sep 9, 2009
    Miami Florida
    ehh got a sound guy coming to practice monday to check it out. I cant figure it out. I dont see why my bass would be coming out the tweeter of the mains.
     
  7. testing1two

    testing1two Gold Supporting Member

    Feb 25, 2009
    Southern California
    you may need to lift the ground on your DI signal going to the PA.
     
  8. Floyd Eye

    Floyd Eye Banned

    Feb 21, 2010
    St. Louis
    If your bass is coming through the mains something isn't set up correctly. Aux feed your subs and set your crossover properly.
     
  9. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Good idea provided the SG has some diagnostic skills and willing to take the time to track down and isolate the culprit. As it stands, we just don't have enough info but it's probably one of two things: equipment compromise or operator error. I have my suspicions as you're dealing with new & untried gear but to flatly assume such is foolhardy. That being said, the first thing I would do is to plug my bass into a decent DI box, run a mic cable to the mixer, and see if the anomoly (buzz) is still present. No bass amp, cab, effects...nuthin'. The results will dictate as to how to proceed.

    Riis
     
  10. Hactar

    Hactar

    Sep 25, 2011
    Boulder, CO
    This. This will remove a good chunk of your signal chain and help isolate the problem. It will allow you determine whether your amp is the source of noise.

    Also, when you say you "turned off the highs", what exactly did you do?
     
  11. mcapote

    mcapote

    Sep 9, 2009
    Miami Florida
    on my amp and bass i turn the treble all the way off, and i cut the highs to my channel on the mixer. I got to see if i cna borrow a DI from someone I been using the DI on the MB210
     
  12. testing1two

    testing1two Gold Supporting Member

    Feb 25, 2009
    Southern California
    Looks like the DI on the MB series amps does not have a ground lift switch (epic fail btw) so you will need a separate DI box with a ground lift switch as mentioned above.
     
  13. mcapote

    mcapote

    Sep 9, 2009
    Miami Florida
    yeah, a little off topic but what are some good DIs? not too expensive. I didnt notice any threads on it.
     
  14. mcapote

    mcapote

    Sep 9, 2009
    Miami Florida
    well it was the built in DI, I tried two other ways, direct from my bass preamp to the mixer and miced my amp instead and no buzz with either. Thanks for the link, DI is too short to do a search on and direct box didnt bring anything up.
     
  15. uhdinator

    uhdinator

    Apr 20, 2010
    Maine
    Radial ProDI

    Or make your own ground lift.

    Get a 3' mic cable and disconnect pin 1 on one end and mark the cable so you know which one it is later.

    Connect it to the amp DI first then connect another mic cable to it to send to snake/FOH mixer. Now your ground loop is broken.
     
  16. mcapote

    mcapote

    Sep 9, 2009
    Miami Florida
    interesting idea. might try it
     
  17. Zooberwerx

    Zooberwerx Gold Supporting Member

    Dec 21, 2002
    Virginia Beach, VA
    Pretty flippin' simple, eh? Doesn't fix the source problem but you've at least isolated it.

    Riis
     
  18. Barisaxman

    Barisaxman Gold Supporting Member

    Aug 17, 2005
    Omaha, NE
    OP solved the problem, but if anybody else reads this thread, this is bad/misinformation. There's LOTS of bass guitar content in the frequencies serviced by main speakers. Usually the fundamental and one or two harmonics at best would end up coming from the subs, but the character of the bass (mids/mid highs) are goiing to be largely serviced by your main speakers, not the subs. If you aux feed subs and only put bass through the subs, that's a fast track to muddy/cr@ppy, unintelligible bass guitar in the mix.
     
  19. Floyd Eye

    Floyd Eye Banned

    Feb 21, 2010
    St. Louis
    I suppose it depends on your subs. Personally, I find having bass, drums, guitars and vocals all coming out of your mains sounds a little muddy.

    Then again, I am not really a sound guy so I am guessing you probably are right.
     

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