Microphones Need Help... Impossible venue to mix in

[natedogg08]

Hey guys, first post Ive made on Control Booth...

I am a high school student in charge of setting up the sound system for our improv comedy group. Heres the setup:

Location: HS Commons (i.e. tiled floors, cement walls, no sound absorbtion whatsoever)
Audio: 3 Self Powered JBL speakers (1 left of stage, 1 right of stage, and 1 in back), 9 wireless Shure bodypacks (for improv performers- each wears a thin headworn style microphone), also we use 1 wireless handheld mic for the podium where we explain the games/skits. We mix on a Soundcraft Series 2 board.

Our problem is because of the floors/venue in general we struggle when it comes to making the performers audible. What is loud in front by the speakers gets muddied and incomprehensible to those who sit in the back. We have tried EQing the space, cutting out bass and mids and boosting treble, but then the performers sound awful and unnatural. How would you recommend making the room sound better so every one can hear the performers and they sound natural as well?

 

[DuckJordan]

Using the boards eq is an okay for a little while. You need an actual eq to take specific frequencies and you shouldn't need to remove them completely. Another thing that could help is the way you aim your speakers. How tall is the ceiling how wide and long is the space. And where are you setting the stage?

Sent from my ADR6300 using Tapatalk

 

[pmolsonmus]

1st off a general rule about EQ. With cheap EQ (and even with expensive EQ) it is usually a better idea to cut than to add. Not always the case but EQ is a phase cancellation technique and can create many additional problems if you don't know what you're doing. With your speaker set up, you sound like you've created a standing wave/ phase cancellation nightmare.

2nd - You say you have 3 speakers - 1 left of stage, 1 right of stage, and one in back?
Is it floor level? mic level, way above stage level? To me, the layout sound unnatural and given a reflective room, you are creating multiple clashing waves with your speakers as well as potential feedback issues with your mics and phase issues with sound from the "back" speaker hitting the mics cancelling stuff in the 2 other speakers and its signal hitting the back of the house at a different time than the front.

I would start by unplugging the center speaker (making sure your amp load is still ok) run a strictly mono set up with the other 2 speakers (assuming your amp can handle the load) and leave your eq and any effects out of the mix. If you need to have both speakers plugged into Channel A and B, then make sure your panning is at Center or engage a mono switch if available.
Start by soloing the hand held mic and adjust your pre-gain level to reach somewhere close to 0 on your meters. Bring up your fader for that channel up to somewhere near 0 then bring up the master fader to a comfortable level. Do the same for each wireless (muting the others while doing so).
You may need to back off a bit on some of the mics when all 3 or 4 are on, but you should be able to be understood with this simple of a set up.

If the mics are decent unless your speakers are trashed, you should be able to be understood. If EQ still becomes necessary start by cutting lows and mid-lows before you add any highs.

The Yamaha "Sound Reinforcement Handbook" is your friend.

Phil

 

[howlingwolf487]

There's always the D60 method, but most people are opposed to that level of "tweaking".

There is a metric in sound reinforcement called the "critical distance". Basically, it's the point at which the direct sound (from the source) and the reflected sound (bouncing off the walls, ceiling, etc.) combine to make localization of the original sound impossible. See this PSW article and also this article by Pat Brown of Synergetic Audio Concepts - both are good reads, and are easy to grok once you put their contents into practice.

Your main goal should be to minimize reflections, etc. that mix with the original sound and make it unintelligible. One of the best ways to accomplish this is to determine at what point the sound source (in this case, your actors) need to be reinforced. Cue "critical distance".

An easy way to estimate the "critical distance" for your space is to have your actors rehearse while you move away from them, towards the audience. At some point, their voices will become garbled and much less intelligible. Repeat this a couple of times and you have found the approximate location of your loudspeaker(s). Use your 2nd and/or 3rd speaker can be used as a fill to get a little more distance from the main set (I'm assuming you'll use two speakers up front). Technically, the second speaker or set of speakers SHOULD be on a delay to time align them with the other speaker(s), but with a room that reflective, I doubt anyone would notice repeats, especially if the system is kept at a low SPL.

Happy Experimenting!

 

[museav]

To add to Wolf's comments, one of the critical concepts behind intelligibility, or being able to comprehend what is said rather than just to hear it, is the direct/reverberant energy ratio. In simple terms the idea is to maximize the amount of sound a listener gets directly from the primary source, usually the speaker covering them, while minimizing the amount of indirect sound they receive from other sources, reflections off room surfaces and general reverberant energy that tends to make it more difficult to understand what was said.

One typical component of this is to look at the room. Is any acoustical treatment possible, even if simply heavy drapes on pipe?

Another is that since stereo or multi-channel sound is not relevant, it is best that listeners are covered by just one source. Having two speaker up front is fine if each is covering a different area of the audience, but intelligibility will tend to be lower in areas where listeners hear more than one source of the same signal. Another common factor is the speaker itself and its pattern. You want the sound to go to all of the listeners, but not at the walls, ceiling, etc. where there are no listeners. So think about where the sound from the speakers is going and try select, locate and aim the speakers as much as possible to a) have each listener properly covered, b) minimize the people hearing the same sound from more than one speaker and c) minimize the sound going anywhere other than to the audience such as that hitting the walls, ceiling, stage, etc. (and especially surfaces it not possible to acoustically address).

One common way to do this in large, reverberant spaces is to use multiple speakers with each covering a portion of the audience, a distributed speaker system. But that may not be practical in this case.

Another factor is that all you can do for the speaker system and acoustical path is minimize the negative effect on what it receives. They can't make things better, so what you do for the microphones and mixing is critical. Watch having more mics on than needed and especially situations such as having multiple microphones picking up the same sounds.

 

[natedogg08]

Thanks for the quick responses guys, I'm still wading through the wealth of information you provided! Based on what I read about separating the crowd into areas/etc, would it help if I setup 4 speakers (2 up in front on both sides of the stage, and 2 more near the back of the crowd), and divide the crowd (essentially) into 4 parts? Then I could try running all 4 speakers at a slightly lower volume so there is less overlap between areas.

Also, could I reduce the amount of sound that gets "lost" over the heads of the crowd by lowering the speaker heights? That way they shoot their sound right into the bodies of the crowd, where sound will get absorbed, rather than shooting sound higher over bodies where it will hit the walls/ceiling? Is this theorizing correct? I'm still trying to understand the elusive characteristics of sound waves!

 

[JohnD]

From reading a lot at some other forums, mostly aimed at weekend warriors, when dealing with sound in very reverberant spaces, the advice was to get the speakers up above the audience and aimed down. If the JBL's you have are the EONs or something similar and light weight you might be able to use something like this.
Accessories
Or this more expensive one from K & M.
K&M Stands 19672 35mm Speaker Tilt Adapter, Black | Full Compass
Adding a second set of speakers further into the space would I think make the problem even worse, unless you ran them on a delay.

 

[howlingwolf487]

Nate,

It would help us greatly if you could supply us with a picture of the space (the more, the better) or even a crude Paint or Google Docs drawing. If the space is known in the area, chances are that others on this forum have worked there and can comment.

We're painting with very broad brush strokes without knowing dimensions and spatial features of the space. Our advice will be more focused and practical if/when we can find out what specifics we're dealing with. Sound is all about physics, and energy-distance relationships ("sound volume" vs. "reflective/absorptive surfaces") are a key factor in deciding what is the most appropriate course of action, time-wise and budget-wise.

I

 

[bishopthomas]

Thanks for the quick responses guys, I'm still wading through the wealth of information you provided! Based on what I read about separating the crowd into areas/etc, would it help if I setup 4 speakers (2 up in front on both sides of the stage, and 2 more near the back of the crowd), and divide the crowd (essentially) into 4 parts? Then I could try running all 4 speakers at a slightly lower volume so there is less overlap between areas.

Also, could I reduce the amount of sound that gets "lost" over the heads of the crowd by lowering the speaker heights? That way they shoot their sound right into the bodies of the crowd, where sound will get absorbed, rather than shooting sound higher over bodies where it will hit the walls/ceiling? Is this theorizing correct? I'm still trying to understand the elusive characteristics of sound waves!

The reason your second idea won't work is within your own text. The "sound will get absorbed" immediately by the first couple of rows and no one behind them will hear anything. The vertical dispersion characteristic of the speakers is what determines how high and at what angle the speakers need to be placed. As a general rule, though, if you can't see the speaker (or at least the horn) then you won't be able to hear it's direct sound either.

Your first thought, however, is very reasonable and can definitely help your situation. I would avoid placing the "other" two speakers directly behind the audience, however, as that tends to "de-localize" the audio source, meaning that the audience will see the sound happening on stage but hear it coming from behind them. Half way (or so) into the auditorium would be a good place to start. Place them as out of the way as possible on the far sides of the room, aiming in and back, with the horns over the audience's heads.

 

[Williams]

Another problem with multiple speakers can be the delay factor. If your audience is hearing the material at two different times, this can further cause issues. Not knowing all of your specifics, you might consider flying your mains as high as possible for far coverage and using your second set as center fills at reduced volume for the front rows.