Live Sound Questions

Discussion in 'Amps and Cabs' started by smitty2point0, Sep 3, 2008.

  1. smitty2point0

    smitty2point0 Member

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    Hello,

    I'm having some problems setting up our sound right. We are a four peice band, with a lead guitar, acoustic, bass and drums.

    We use Mackie SRM450v2's for mains, and Mackie SRM350v2's for floor monitors. We are running vocals only through these, going through a Yamaha MG166C mixer.

    The Mackie speakers have a "gain" level on the backs of them. Our problem is using the floor monitors without getting feedback. The level is nice when your just talking and not playing, but we start getting with it, I can't hear anything through the monitors.

    It seems I can't adjust the volume of the monitor on the board without getting feedback, and I can't adust the gain's on the back of the 350's without getting it either. Am I doing something wrong? I know there is ton's of ways to set this up, but our gain setting on our mics are normal, the volume to the main speakers are fine. It's amazingly clear, it's just the monitors I'm having trouble with. Any thoughts?

    Our Board....[​IMG]
     
  2. dk123123dk

    dk123123dk Member

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    Get yourself a 31 band EQ for each monitor channel. You should be able to dial out the offending frequency. Some of the EQ's have a built in Feed Back Destroyer. The eq slider lights up to tell you which slider to move down.

    dk
     
  3. angelo

    angelo Member

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    Sounds like that would certainly help.

    Feedback in the monitors is a "since the beginning of time" thing. From what you describe, I would guess the mic'ing of the acoustic as the first to blame.

    Is it plugged in? Have you talked to player about keeping the mic closer to the neck than the soundhole? Don't know if either applies, just throwing out suggestions....

    You say only vocals through the monitors .... what mics are you using? Are they unidirectional like 58's or 57's?
     
  4. Belmont

    Belmont Member

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    :agreeringing out those monitors with a 31 band is a must.:drink
     
  5. epluribus

    epluribus Member

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    +1 on this, mics would be my prime suspect as well. Have you pulled up the skull diagrams to see where they're deaf so your monitors/mains aren't getting into the hot spots?

    Piggybackin' on the flattop issues...it's really hard to do a mic rig just right for an acoustic, ditto internal mic systems--because the body resonates with the monitors, they can be feedback magnets. Trouble is, so can those surface-mount transducers--they pick up the vibration from the monitors as it resonates in the deck and can feed back worse than a mic. Piezoes seem the least problematic IME, though only the best ones seem to really project the acoustic sound with authenticity. Some guys use combinations of pickup systems to fill out the guitar sound and (hopefully) reduce feedback.

    Anyhoo, ya might try muting one channel strip at a time and see if you can isolate the problem to one piece of gear. Might be able to track down an errant mic or clear the good name of your flattop that way. :)

    --Ray

    Btw, gain settings...as long as none of 'em are clipping, they shouldn't be a player. With those the goal is a good hot signal with max
    S/N, and that means generally keeping your peak levels tweaked just below clipping--plus a few db for enthusiasm in the heat of battle. If you do have to pull the whole channel down to battle feedback, do it with the fader/monitor send, not the gain levels. The latter plays hob with your comps and other PA rack gear, your aux busses, and your monitors--besides sounding bad.
     
    Last edited: Sep 4, 2008
  6. SatelliteAmps

    SatelliteAmps Member

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    Just out of curiousity, have you tried moving the monitors about 18 inches to either side and changing the angle? Most people aim monitors directly at the back of a microphone, thinking for some reason that the mic won't pick that up. It does, and is the single most common reason for monitor feedback. Chances are it is one mic creating a feedback loop.

    A nice stereo EQ is helpful for ringing out rooms, but this doesn't seem to me to be the issue.
     
  7. smitty2point0

    smitty2point0 Member

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    I've tried different angles with the monitors. All instruments are going through their respective amps, even the acoustic, with the exception of the drums of course, which are not mic'd. We don't play venues big enough to mic the drums, or any of the amps for that matter.

    We are using SM58 mics. I think I will try the stereo EQ to try and fix the problem.

    Thank you so much for all the replies. Hopefully we can get this straightened out!
     
  8. Deuce007

    Deuce007 Member

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    EQ should fix your problem.
     
  9. GCDEF

    GCDEF Supporting Member

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    Do you have the mic preamp gain properly dialed in on the mixer?
     
  10. buddaman71

    buddaman71 Student of Life Silver Supporting Member

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    31 band graphics are good for overall room equalization, but sweepable parametric EQ is the most effective way to kill feedback. Actually, those feedback busters do just that. They analyze what frequencies have too much energy and then attempt to notch (surgically cut) the gain on the offending frequency.

    You can do this to a certain extent using the sweepable mid range knob on your board.

    Here's the quick dirty trick for reducing midrange feedback:

    1) Get the feedback to happen
    2) Isolate the offending channel (mute through all channels until you find it)
    3) Cut the Mid GAIN knob
    4) Slowly sweep the Mid FREQUENCY until you hear the feedback lessen
    5) Bring the gain back up as high as possible before you hear the feedback.

    This is very useful for reducing tom/acoustic ring/howl.

    (The best purchase I ever made for my band was a Yamaha 01v96 digital mixer. EVERY frequency band on the EQ of every channel is parametric. I literally need zero outboard gear. I have that mixer and a couple sets of QSC active 15" 3-ways and 118 subs. Just killer club-size PA.)

    If you are getting very high-pitch microphonic feedback, try, as suggested earlier, repositioning the monitor slightly to the sides. If you have the polar pattern chart of the mic you are using, look at it and position the monitor in the areas with the least amount of pickup.

    http://www.sweetwater.com/shop/studio/studio-microphones/buying-guide.php#3

    This is a very easy to understand mic guide from Sweetwater.

    Keep in mind that no matter what, eventually you will reach the max gain-before-feedback level in any system. At that point, you just have to turn down. Positioning makes all the difference in the world to help you get the most you can from your system.
     
  11. epluribus

    epluribus Member

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    Nice summary, nice post Buddaman. Bet you gotta be lovin' that mixer, eh? :BEER

    --Ray
     
  12. Dexter.Sinister

    Dexter.Sinister Still breathing Gold Supporting Member

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    +1

    ds
     
  13. dosmun

    dosmun Member

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    Find out which vocal mic(s) are causing the feedback first. Monitor position is crucial with vocals. I have run monitors with no EQ several times with no problems and plenty of volume. A 31 band is great to have but you also need to have a good starting point before applying the EQ.
     

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