Boomy Stage

Discussion in 'Live Sound [BG]' started by Bassquest, Dec 5, 2014.

  1. How do you reduce the amount of boom from a stage that's made from risers? There's no carpet on the risers. I've been asked to turn my amp down (TC Electronic BG250 115) to the point where I can hardly hear it. I'm also DI'd out to the mains. Possibly raise the amp off the floor or bring my own carpet? Ideas?
  2. DWBass

    DWBass The Funkfather

    You have to raise it off the stage. If you have a moving quilt or some type of foam you can put under the cab to keep it from coupling with the stage, or if you can afford a Aurelex Gramma, that'll work.
    squidtastic, mdjuszyn and Winfred like this.
  3. Yes they are expensive. Thanks I'll look for something that may work.
  4. Winfred


    Oct 21, 2011
    As stated, put your amp on a stand, point it at your head. Roll the lowest frequencies off, a little.

    That should help. YMMV.
    sharkbait130 likes this.
  5. I was gonna say pretty much what Winfred said but since he already said it , I'm just going to shut up and go make a drink. :woot:
  6. "Isolation" pads only stop the direct mechanical shaking of stage and cab from being transfered.

    Mind your distance to the wall behind your cab. Pulling it out a little generates a cancellation from the reflection vs the front. Which note takes off?

    Tilting or raising your cab lets you hear it. Raising it a lot, like over 2.5ft. gets you into same anti-bass reflection zone as pulling out from wall.

    "We got boom, turn down the bass" is not how it's supposed to happen.

    The boom could be coming from open mics picking you up and resonating via the subs. Highpass all mics that aren't gated. Sound check without the PA on for starters, add drums and then PA. You might find it's an acoustic guitar resonating off you. Highpass that thing.
    squidtastic likes this.
  7. zac2944


    Dec 28, 2004
    Rochester, NY
    My $0.02.

    I'm convinced that on some stages you just can't get rid of the boom. At normal stage volume the stage design and house sound in these places are a perfect storm for boom. No bass/cab/eq setting/etc. can save you.

    Anyone else feel this way?

    I've been gigging for 20+ years, have tried all sorts of gear and solutions, and sometimes nothing works.

    Played a casino gig last night, big stage with nice JBL house system, great clear monitors, but bass was all boom on stage. I been playing this venue every other month for the last 3 years, and nothing I do reduces the boom. The stage is like a 30'Widex15'DeepX15'Tall box cut into a wall. My rig is always pressed into the back corner since we have to fit 7 on stage. I've tried different basses, different amps/cabs, drastic eq adjustments, elevating my cab, but nothing works on this stage. I'm convinced it has to do with the stage itself; it just resonates down in the 200hz-100hz range. IEM are the only solution I think would work and I don't have that set up.

    So now rather than wasting my time trying to get a good sound on stage at this venue, I just settle for the boom and play through it. Sucks, but I'm convinced that some stages are just impossible.
  8. derrico1

    derrico1 Supporting Member

    Apr 12, 2005
    Charlottesville, VA
    Putting your cab against a boundary emphasizes the omni-directional low frequencies by 6 dB for each boundary. From's discussion of their MAPP software:

    As mentioned in the "Acoustical Information," MAPP Online Pro currently models only the first reflection from boundary surfaces. This accurately models their "comb filtering" effects. However, it underestimates the effect of "corner loading" subwoofers. For one boundary, it is accurate. i.e. a subwoofer placed on the ground gives 6dB more SPL then a subwoofer in free space. However, for two boundaries (a wall-floor intersection, for example) this first-reflection model shows an increase of 10dB, which is less than what is expected from a two-dimensional " theoretical corner loading", i.e. 12dB. In three dimensions, (which MAPP Online Pro does not currently model), the SPL of a corner-loaded subwoofer increases 18dB. Note that this ONLY works for low-frequency sources placed very close to corners. It does NOT work for higher frequencies, when sound starts to become directional. (source: Acoustical Engineering, H.F. Olson, 1954).​

    That is, in the back corner your bass amp's low frequencies are being boosted by the floor and two walls. If you play by the drummer's hi-hat side, it would be much better to treat your amp as a stage monitor: raise a cabinet on an amp stand and point it back at you. If that's not possible, raise it against a side wall. Even raised against the back corner would be better than on the floor in the back corner.

    There used to be a club (now closed) in my regular circuit that boomed on stage. (Way too much PA, multiple subs on the corners of the stage, and the PA run at dance club levels.) I ended up pole-mounting a Carvin LS1503 at ear-level. I could run it at low volume and just stand back next to it to hear my bass defined against the stage murk. Short of IEMs, nothing else worked there.
    Last edited: Jan 10, 2015
  9. ggunn


    Aug 30, 2006
    Austin, TX
    One thing that might help is to provide some isolation for the mic stands, especially the short ones on the drums, from direct contact with the stage.
  10. derrico1

    derrico1 Supporting Member

    Apr 12, 2005
    Charlottesville, VA
    And high-passing all the stage mics that don't need to carry low-end frequencies.
  11. iceonaboy


    Jan 8, 2013
    Can you give me some examples of how to high pass the mic's? I am trying to get a better understanding about sound. We sometimes suffer from boom coming from our backline through the mics, which is ok as long as we stand in front of them, but as soon as we move....boom
  12. derrico1

    derrico1 Supporting Member

    Apr 12, 2005
    Charlottesville, VA

    For example, let's say you have a bass/drums/guitar trio, and all three musicians sing harmonies and trade lead vocals. On a small stage, you'll have three vocal mics set pretty loud. All three mics will be fairly close to the drum kit, and the bassist's vocal mic will be close to the drums and the bass amp. All three mics will pick up a fair bit of low-frequency stage noise. That low-end spill will be amplified along with everything else in the mic signal, and sent to the front-of-house PA mix, as well as sent back to the stage via the monitors (where it creates more low-end rumble on stage for the vocal mics to pick up).

    Obviously, that muddies up the band's sound for no good reason. Since low frequencies also take more of your PA's power to reproduce, low-end slop in your FOH and monitors also eats up your headroom. The simple solution is to apply high-pass filtering to the vocal mics. (The high-pass filter allows frequencies above the set point through, while attenuating frequencies below the set point.)

    Set each filter to reduce frequencies below the musically-relevant range for that channel's voice. How you set the high-pass for each channel depends on the tone you're after, the overall band mix, and the kind of PA you're running. As a starting point, in a band mix I usually look for the HPF point for male vocals and electric guitars around 120 Hz (or higher). In contrast, hi-hats might be high-passed much higher (even up above 1kHz, if I'm just using the hat mic in the mix for that sandy-shake sound rather than click). Most digital boards allow you to set a high-pass filter point for each channel. On an older analog PA with rack-processing, you might want to save resources, with a subgroup of channels sharing one HPF. For example, if your trio's three male singers have similar tenor range and tone, you might high-pass them all at ~ 120 Hz (or higher, on a boomy stage).

    I usually like to high-pass almost every channel to leave room in the mix below 100-120 Hz for kick and bass. (Actually, I usually high-pass kick, floor tom, and bass, too, but on those channels I'm looking just to keep really low rumble from eating the PA's headroom.) You have to be flexible, though, depending on the band's sound. For example, keys sometimes get invited to the kick&bass low-end party if they bring important deep synth or filter-sweep sounds to the mix. OTOH, give me a half-domesticated piano banger whose busy left hand messes with the bass player, and I'll want an aggressive and corrective HPF setting on that channel.

    If you have an analog budget bar band PA, getting HPF on almost every channel will be expensive and bloat your PA rack. (In terms of budget, performance, and compact load-in, it makes more sense to go to a digital board than buy a bunch of outboard analog parametrics w/ high- and low-pass filtering.) But in that case, many analog boards have a low-cut switch on each channel. While that won't let you get as surgical as proper high-pass filtering, it's a lot better than no low-cut at all.
  13. ggunn


    Aug 30, 2006
    Austin, TX
    I used to take with me to gigs several squares of carpet the right size to put under mic stands. That helped a lot in some situations where the stage was ringing like a bell.
  14. I own a bg250 and it can be boomy on its own, so with a boomy stage...
    Did you try to reduce the bass on your amp EQ ? I often do that and my tone is still full.
    Try to put your amp on a small stand too. It really helps.
  15. Lots of bar band mixers have a low cut button on each mic input. Works wonders on guitars too, just don't tell the guitarist it's on.