BISERICA SPERANTA ACOUSTIC Assistance

[mifantrax]

As I have described in another topic but for sure off topic. Our church has a new building, it is still in construction but the main sanctuary is done and ready for use. For a period of time we were sharing our sanctuary with a Russian church and sharing their sound equipment however now they left and we have nothing only things that we rent.

We decided to start buying new equipment however after the advices of so many people speakers are not good to buy as we have a really serious acoustic problem.
http://www.flickr.com/photos/30777552@N05/?saved=1 These are the pictures of our church.

www.bisericasperanta.md is our homepage

So we decided to do some acoustic correction, but how, I went to a few music equipment stores and they said they do not do something like that. I found a few companies but in Ukraine and Romania, that is going to be way too expensive.

So some technical details. The church looks as in the pictures from flickr the sanctuary is 15m x 15m the height is 10 to 15 m where the cupola is, the balcony is 3 meters above the floor and is 3 m deep.
The floor is concrete covered with carpet The walls are made of concrete and limestone bricks and the internal finish is plaster.

If you have any ideas on how to correct our acoustics and you are ready to share them helping our church way in Moldova. We will be very grateful.

I myself was thinking about making some of this http://www.johnlsayers.com/phpBB2/vi...ight=bass+trap however will they make any difference ?

Ideas are welcome.

[Gracetech]

Alright lets get started. I can see how if you are firing your speakers from stage into the audience on poles you are going to have a night mare of an issue with reflected sound off of your parabolic wall in the back of the house. You would come out cheaper if you simply rigged your main speakers so that they are up higher pointing down into the audience. This will only clean up your mid-range and high frequencies which are directionally controlled when they leave the box. Your lower end will splash everywhere but besides having no definition on the low end the intelligibility will improve greatly since most of what we listen to is in the midrange and upper frequencies. Only issue when you do this would be getting sound to the balcony which will have to be done with separate speakers in a delay ring to reduce overly exciting the room.

Absorber panels like the one you linked to will help to get rid of some unneeded sound but it will take alot of panels to cover a room your size. You might start by deadening the stage which is generally the biggest hot spot and then reevaluate after that.

A better way to make much more attractive panels is to use 1X3 lumber on their edges so that they protect the edges of the fiber board. Also for a cheap way of getting fiber board you may want to go to your local HVAC supply store and see if they have Duct Board which is the same material just in 4'X10' sheets with keyed edges. You can use burlap to cover the pannels but i prefer using some thing with a bit more eye appeal though budgets often restrict the choices.

Here are a few links you may be able to get some ideas from or even order from.
http://www.atsacoustics.com/
http://www.acoustimac.com/index.php?...FQoMDQod-ktccQ

Just an idea but you might want to check into the cost of having your back wall scalloped. By creating an ununiform wall you will diffuse the sound returning back into the room. Their are of course treatments you can put on your wall to create the same effect but eventually you are going to want to have some amount of absorption in the room to get rid of wandering waves.

crt

[mifantrax]

So Covering the entire stage back is my first priority ?
What about the balcony edge?

[Brad Weber]

Not to put you off, but that is the type of space that I would really want to hear in person, look at the plans and ideally even make some measurements and perform some analyses before making any recommendations. There are simply too many things that might or might not be happening in that space that I would want to physically verify the conditions before suggesting anything.

The curved back wall is likely one aspect that will need to be addressed but it may also not be an easy or inexpensive one to effectively address since it already exists. And from experience, trying to treat rooms like that with only absorption can easily lead to a room that many consider too dead, some diffusive surfaces may also be required.

[Gracetech]

Stage back, side walls, and ceiling then you will worry about the room. You're balcony edge is pretty small so it's not going to be the bigger issue. Because of the concave shape of your rooms back wall you will have a hard reflection and even worse yet because of it's shape it will focus all the sound back to the stage. So after you treat your stage and move your speakers i would start working on the back wall. If you can't aim your speakers as i suggested you will need to do alot more work to your back wall.

crt

[Brad Weber]

Originally Posted by mifantrax

So Covering the entire stage back is my first priority ?
What about the balcony edge?

Tell us about your services, especially how the contemporary/band portion relates to any more traditional/spoken word content. Because this is a media and tech forum, people seem to sometimes jump to the assumption that the room should be acoustically focused on the music performance aspect when that may not be the reality for every church. So knowing more about your services and your goals and expectations is always a good starting point.

[mifantrax]

Regarding the music played in our church.

We have a modern worship band in devlopement. They progress quite fast. Everything in the band from voices to violin, celo guitars is through the speakers. The drums are not amplified. We also have a choir for which a little reverb is ok. Our sevices last about 2 hours and music is a major part in worship, we also have a lot of people that perform Sunday evenings. Spoken word is usually about 45 minutes not more.

I hope I clarified the fog a little.

Is there anything else that I may do to help you understand the situation?

(like recording something in the sanctuary)

Or what should I do to understand it better ?

[mifantrax]

If we hung the speakers that we have now will that make any difference ? Given the position that they have now they indeed sound horrible.

[cmchamp]

Chad & Brad
I had worked on some of this for him, and were his ceiling at 24', a pair of Electro-Voice EVI12's would have worked great with some under balcony fill, however, his ceiling height is equal to his L&W measurements.
In this space, empty anyway, it doesn't seem that it's the supposed RT60 time (remember, a reverberant field is required for an RT calculation), however, there is great opportunity for first reflections and flutter echo.
I guess, before I make any recommendations on the work I've done, I would like to know how "dead" he'd like the room.
My initial reactions were this. 2" tectum mounted 4" off the wall for more efficient 250Hz to 500Hz absorption. There doesn't seem to be any massive LF build up anywhere in the room due to it's dimensions and the mezzanine.

[mifantrax]

Originally Posted by cmchamp

Chad & Brad
before I make any recommendations on the work I've done, I would like to know how "dead" he'd like the room.

If you can help me understand this please.
I think I sound as the dumbest forum member

[prochlea]

A "dead" room is a room that does not have any reverberation. A "live" room has alot of reverberation.

A quick test for you to help us out a bit - Go into the room with a friend and a stopwatch when it's really quiet. Have your friend clap once (a good loud clap) and start the stopwatch at the same time. Stop the stopwatch when you don't really hear the reverberation of the clap anymore.

you could also hit a hammer on something to make a loud sound.

Obviously this is not a true acoustical test, but given that you're in a location that doesn't lend itself to bringing in someone to do the testing, this is a good start.

[Brad Weber]

Originally Posted by cmchamp

In this space, empty anyway, it doesn't seem that it's the supposed RT60 time (remember, a reverberant field is required for an RT calculation), however, there is great opportunity for first reflections and flutter echo.

You apparently have more information but I'm not surprised that with the ACT ceiling, carpet and upholstered chairs on the floor, perhaps some sheetrock walls providing LF absorption, etc. a Sabine RT calculation would look okay. However, the distribution of the absorption and the shape of the room also probably make it less valid.

However, at least based solely on the photos I did not see anything that jumped out as suggesting flutter echo concerns. The only large parallel surfaces appear to be the ceiling and floor and the ceiling looks to be lay-in ACT (although the acoustical properties of lay-in tile can very greatly) with the floor being upholstered chairs on commercial carpet. Maybe there could be flutter from the ceiling over the rear of the stage, but in a couple of photos it looked like that may be angled, although that could just be the camera angle. It does look like the rear wall is curved and would focus within the room, which would certainly be a potential problem. The entries in the side walls and 'balcony' with openings above them as well as the 'shelf' and recessed ceiling area over the stage could cause some interesting local or coupled space effects.

The use of violins, cellos, etc. also goes to the issue of both how 'dead' the room should be and how to treat the stage. Since they all go through the sound system you are not counting on the room to naturally support them, thus the room could be more 'dead' than if spoken word or unreinforced music were priorities. However, unless you have a good monitor system you may be counting on the stage acoustics to provide some ensemble and reinforcement among the performers. Thus you may not want to make the stage too 'dead' and introduce some diffusion there instead.

The test Pat noted might help define whether the space is generally live or dead, but since you would have no reference to the change in level it represents or any other details it would be rather limited beyond that.