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Author Topic: I need assistance with our church acoustics  (Read 8033 times)

Ivan Beaver

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Re: I need assistance with our church acoustics
« Reply #20 on: February 11, 2007, 10:46:40 AM »

Is this echo heard while on stage or in the congregation? Is it full freq resopnse or dull sounding? Is it with the sound system on or off or both?

If it is only on stage with the sound system, then you might try raising your speakers up as high as you can go (where they should be anyway-why nobody has told you that I have no idea-eq will NOT fix that) and aim them slightly down.  Aim the center of the horn towards the listening ear height of the people on the rear pew.  When moving the loudspeakers up MAKE SURE YOU DO IT SAFELY!!!!! or have somebody do it.  If they are not equipped with rated fly points (most "custom" cabinets are not) then you will have to build a stand to put them on.


This will take the sound hitting the rear wall (angle of reflection equal angle of incident) and drive it into the back of the pews and the floor, and break it up-so to speak.  This will not be a problem for the people in the rear as the time arrival between the direct and reflected sound will be so close you will not be able to hear the difference.  

You do not have much height to work with, so this will probably be only a partial fix, but will also result in a more even coverage of the congregation.  Not quite as loud in the front and more highs to the back.  That is if I am seeing your photos correctly-I really can't make out the loudspeakers at all.

Of course when you do this you will probably pick up an additional reflection off of the ceiling, but it looks like you have "acoustical tile" so that should help reduce it a bit.  If the ceiling is reflective tile, you have a new different type of problem with the combfiltering you are likely going to create.
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Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.

stanleydeitz

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Re: I need assistance with our church acoustics
« Reply #21 on: February 11, 2007, 03:44:37 PM »

Ceiling height is 149". The  Speakers are 24"W X 21"D X 48"H. Center of Horn is 39 1/2".Stage height is 33". Sofit height is 122"
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stanleydeitz

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Re: I need assistance with our church acoustics
« Reply #22 on: February 11, 2007, 03:55:39 PM »

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Brad Weber

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Re: I need assistance with our church acoustics
« Reply #23 on: February 11, 2007, 04:18:11 PM »

Let's see if I can summarize where we're at.  We started with the fact that you have a perceived acoustical problem.    Your description of the problem sounds like excessive reverberance, but you also keep mixing echo and reveberance in the descriptions.  You also mentioned an echo off the rear wall with no sound system on but described it as specifically a 30ms echo.  Apparently, none of the "sound techs" that came out to EQ the system helped you gain any real understanding of what the problem(s) are but they did suggested adding some home built wall panels of R-19 fiberglass.

Now we have the added information that shows that the room is rectangular, has a relatively low (or at least not high compared to the floor plan) acoustical tile ceiling, has carpeted floors and padded pews and apparently has nothing breaking up the walls or any acoustical treatments on the wall surfaces. We do not yet have any idea of the overall room dimensions, but from the pictures the room looks to be about 44'-45' wide with maybe a 12'-13' ceiling and a 3' to 3'-6" high platform (I just noted your post indicating that the actual dimensions are 12'-5" for the ceiling height and 33" for the stage height, so I will guess that my other dimension assumptions are also close).  We still have no idea of the length of the room.  We also still don't know the style of music involved or what levels you run or if there are any other issues such as intelligibility or coverage problems.

We also now know that the main speakers are sitting directly on the platform at the very outside corners of the room and pointed straight out (they do appear angled in towards the center of the room, but don't appear to be tilted or aimed down).  We also now know that the speakers are apparently "custom made" (and appear to be home built rather than a custom box from a manufacturer) with (2) 12" drivers and a Peavey 22XT high frequency compression driver, but we do not know what horn was used or have any idea of the speaker pattern or pattern control.

Some personal observations from all this ar that with the ACT ceiling, carpeted floors, padded pews and the fact that the pews fill most of the room, I have to doubt that the room is excessively reverberant.  In fact, I would be worried that anything you do to add any significant amount of additional absorption may actually make the room too dead.  However, the flat, parallel side walls and untreated rear wall may be causing some problems.  FWIW, if you do actually have a 30ms echo on the platform, it is probably off the side walls that are 22' or so away and not off the rear wall as that would appear to be much further away.  At this point, it sounds like it might simply be very difficult to get a good handle on the real problems without actually having someone qualified survey the room and system.

The existing speakers and speaker locations are quite likely exacerbating any room problems as well as creating some of their own.  I see all sorts of potential issues with combfiltering, slap back and other undesired room interactions.  Ivan's suggestions to get the speakers located higher and aimed down at the audience rather than aimed directly at the rear wall is very well founded, especially as it appears that more of the speakers' energy is currently directed at the walls and ceiling rather than at the audience.  However, this relocation may be difficult to accommodate with the apparent size and construction of the existing speakers, so new speakers with known pattern control and that can be flown may be in order to better work with the room.

Without anything else to go on, I'm thinking maybe simply expecting too much from the room and a sound system that doesn't seem to really have much consideration for the specific room and acoustical environment in which it is being used.  You might fix some of the problems by randomly adding acoustical absorption on the walls, but that doesn't look like a good path to pursue without first addressing some other factors and potential implications.  Rather than spending your money on guesses and suggestions that are based on limited information and/or knowledge, you might want to consider hiring a qualified professional to come and look at the room, make some on-site measurements and observations, and then present specific recommendations in writing.
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Brad Weber
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Ivan Beaver

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Re: I need assistance with our church acoustics
« Reply #24 on: February 11, 2007, 04:18:57 PM »

Do you have an electronic crossover, I didn't see it listed?  How are you crossing over between the subs and the 12's and the horn?

I am guessing that there is some sort of passive crossover inside the cabinet, but judging by the build of the cabinet, the crossover would be highly suspect as to quality.

I would suggest that before you start to swap out driver to "better" units, you get certain things fixed for what you have.

Putting better tires on a car is not going to do much if the engine is misfiring.  You need to spend the money where it will do the most good.
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Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.

stanleydeitz

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Re: I need assistance with our church acoustics
« Reply #25 on: February 11, 2007, 07:45:07 PM »

First of all i would like to think everybody for the time you have spent on this. Ok lets start over we have an acustic problem. I'm going to call it an echo. I guess it was two seconds or 30 mili-seconds or i don't really know. I do not know if it is reverb, delay, or fluter. The room is 68'9"L x 46'6"W. The height is 149". Stage height is 33". The main house speakers are on the left and right side of the stage and i am not going to upgrade the speakers or driver in them. The main house speakers has a crossover for the horn but i do not have an electrical crossover for the sub. Our monitors are blown and im putting new speakers in them. The echo occurs without the sound system on but when the sound system is on it magnifies it. Look at the other information for the sound system gear we have. As you can tell i am just a button pusher but i am wanting to take this seriously. I would like to take courses to improve my knowledge of sound technition.
Thank You,
Stanley Deitz  Very Happy
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stanleydeitz

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Re: I need assistance with our church acoustics
« Reply #26 on: February 11, 2007, 08:07:36 PM »

As you can tell we have tried to hire a qualified proffesional, spending around $800.00 with no luck. Our Church is in York, SC 29745. Do you know of someone who is qualified in my area? The biggest city closest to us is charlotte NC, Gastonia NC, Rock Hill SC, and Gaffeny SC. Thanks for your help.
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stanleydeitz

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Re: I need assistance with our church acoustics
« Reply #27 on: February 11, 2007, 08:30:16 PM »

What is speaker pattern or pattern control. Our music is praise and worship on cds. The music and the vocalists sound good but the echo occurs when someone is speaking. Our style of music is contemporary.
Thanks. Rolling Eyes
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Ivan Beaver

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Re: I need assistance with our church acoustics-What to do
« Reply #28 on: February 11, 2007, 08:36:39 PM »

I would suggest you start saving for the following items.  You have 2 different problems here.  

The first is your echo problem.  You need to hire somone who knows what they are doing to come in and determine where it is coming from/what is causing it.  Tell them ahead of time what you expect them to do.  I suspect the rear wall, but it could be other issues as well.  Be sure to ask for a written report about the problem AND the proposed solution.  I would expect some sort of meaningful measurements.  These would include RT60 at various freq bands and an ETC at various listening positions to help determine the exact cause.  A polar ETC would be much better, but that is a specialized measurement that can only be done with a TEF and with the addon software.  It is not part of the normal package.

The second part of the first of your problems is to implement what is proposed.  If you don't follow what is suggested, because you think it is to  expensive, then don't expect good results.

The second issue is the alignment of your current system.  This includes the crossover between all of your system components.  The correct thing to do would be to replace your current eq and install a DSP to perform all eq/delay/crossover/limiter functions.  This would also have to be setup by a properly trained person who does system alignment, not some guy who brings out an RTA.  Ask what they are going to use to align the system and if it includes the term RTA, then look elsewhere.  Ask how they are going to measure time offsets.

This will require removing your current crossover in your full rnage cabinets and running another wire to each of the cabinets.  This will also require you to purchase another amp so you can go biamped on your current full range boxes.  During this, they should also take a look at your amp rack wiring to make sure it is correct and rewire as needed.

I would also HIGHLY suggest flying your current loudspeakers.  The biggest problem is that they are not rated for flying, so that would involve building a cage around them that could be flown.  This of course may cost more than buying new loudspeakers that would outperform your current ones.

With a ceiling as low as yours, it is going to be impossible to get even coverage from front to back SPL wise.  But with proper design, it can get better than what you have now.

All of this is going to cost some real money.  You have seen what free or little money has gotten you so far.  

It is time to call in the professionals.  Guessing only gets you so far.
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Can I have some more talent in the monitors--PLEASE?

Ivan Beaver
dB Audio & Video Inc.

Tom Young

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Re: I need assistance with our church acoustics
« Reply #29 on: February 11, 2007, 08:42:38 PM »

"What is speaker pattern or pattern control."

Speaker pattern is its coverage pattern, usually stated in so many degrees horizontal by so many degrees vertical. This indicates how wide and how high the coverage pattern of the loudspeaker is.  Based on this, a sound system designer can then determine how many loudspeakers are needed, how they should be arrayed (relative to one another) and how to aim them.

You clearly seem to have a discrete echo that occurs with the sound system and without it.

Do not expect to find a qualified consultant in acoustics or electroacoustics in the next, or nearby, city or town. These are very specialized fields.

Frankly, I would suggest you contact Brad Weber who is in (or near) Atlanta. Maybe you can work out something with him.
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Tom Young, Church Sound section moderator
Electroacoustic Design Services
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Re: I need assistance with our church acoustics
« Reply #29 on: February 11, 2007, 08:42:38 PM »


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