ATS Acoustics

[matthewah]

Has anyone bought panels from ATS Acoustics? My church is looking at purchasing panels for our gym. We got their samples, but would like to hear from anyone who has bought panels from them.

[cmchamp]

The only questions I have when it comes to a gymnasium situation are:
1) is the gymnasium used for worship service or other music services?
2) has ATS or anyone else determined what is required for LF correction?

C.

After perusing ATS's site, they do have corner span instructions to use their 4" product as corner traps, however, I did not find any testing data results indicating how efficient and effective they are.

[pdc]

I last worked for a church with four gyms, two of which doubled as youth and children's ministry rooms. For the youth room I installed a Meyer 5.1 surround system, 16:9 projection, etc. It sounds good, as good as it can. I did it with industrial materials. I needed treatment that will hold up to the abuse. You will likely never make your rooms sound incerdible with after market acoustics. Sound should have been dealt with in the design/construction phase. As long as you know what to expect.

You really need an acoustical engineer to do this right. If you just buy aftermarket panels and put them up, you could make the low-end problems seem worse. You could do lots of other things that I won't get into. That said, if you have the time and volunteer help, you can buy products from companies that are not marketing their products to the sound community, and the SAME (if not better) products will be a fraction of the price. For instance. If you purchase one pack of 3" miniseral fiber boards from Auralex, it will set you back $99 plus $25 shipping. If you purchase the SAME material from a company like SPI, it can be as low as $35. And SPI in my town delivers for free.

You should look at "spaghetti board" for the side walls. It is pretty darn durable. It is pretty darn expensive. You are not going to solve your problems with a little 2", 3" or 4" foam. Compressed fiber panels will discolor, will rip, will crumble. You need to look beyond the pages of what the general public finds on Google and get with an engineer with access to industrial materials.

[Brad Weber]

I have not used them but have heard from others that seemed happy. As Cory alluded to, it is which specific products and how they are being applied that can really matter and even the best products can be misapplied.

The low frequency absorption coefficients of 0.12 at 125Hz and 0.67 at 500Hz for the 2" thick ATS panel do seem unusually low. For comparison, a 2" thick Perdue Acoustics panel is rated at 0.31-0.51 at 125Hz and 1.01-1.05 at 250Hz (you can ignore any values greater than 1, they are an anomaly of the test procedure). Absorption coefficients for typical 2" thick fiberglass panels range from 0.25 to 0.4 at 125Hz and 0.7 to 0.95 at 250Hz. So the ATS panels for some reason seem to provide significantly less low frequency absorption compared to most other wall panels. Depending on the problems you are trying to address and the other room finishes this may not be a concern, but it could be in some situations.

You might also consider whether impact resistant panels might be appropriate for any of your space. These typically use a denser layer of material immediately behind the fabric that helps resist tears, dents, etc. This construction also often increases the low frequency absorption at the expense of some of the high frequency absorption, a characteristic that may or may not be desirable depedning on the application.

I did find ATS's "Free Online Room Acoustics Analysis" of limited benefit. Not only is it very limited in the materials available, including having no options available for seating or people, but I believe it is simply applying Sabine formula which is only accurate under certain conditions, conditions that are not usually met in many worship spaces. And while they do subsequently go into more detail that procides some good information, the comment in the FAQs that "In general, where you place the panels in the room is not critical. A visually pleasant appearance is often the guiding factor in placement. The most important thing is simply to get the total square footage of panels into the room somewhere. No matter where you place them, the panels will soak up the extra sound that is bouncing off every surface in the room." is also very questionable. Put simply, there is a lot more to room acoustics than the total absortion in a room and reverb time.

[Brad Weber]

Originally Posted by pdc

You should look at "spaghetti board" for the side walls.

Are you referring to Tectum, http://www.tectum.com/products/Acoustical%20Walls.pdf? Tectum can be very durable but to have acoustical peformance equal to the same thickness fiberglass or mineral wool wall panel you typically have to install Tectum on sleepers with fiberglass in the cavity space, making the overall assembly deeper and more expensive to install.

In some gyms type spaces I have used more industrial products such as http://www.kineticsnoise.com/interiors/elite.html or http://www.kineticsnoise.com/interiors/knp.html. I have also used panels hung from hooks or mounted with z-clips so that they can be more easily moved or replaced. Also consider that in many large spaces where you are looking simply to add absorption the ceiling may be a more effective option than the walls, not only is it a large surface but due to typically being closer to, and the same distance to, all listeners it can also perhaps benefit the entire audience more.

[pdc]

Yep. That's it.

I too have used Kinetics, especially their HVAC system products.

[matthewah]

I will have a look at some of the other companies you guys recommended. I have worked with Auralex and they told me the ideal RT for the space is 1.5 seconds at 500Hz. The untreated predicted RT at 500Hz is slightly over 3.1 seconds.

Our hope is to be able to have a full band for youth events play in the gym occasionally. I have attached some pictures of the gym for your viewing pleasure.

[cmchamp]

Matthew
Unfortunately, without dimensions, those photos don't help much.
Additionally, 1.5s at 500Hz really means nothing with regard to the overall acoustics of the room.
Before any further assumptions are made, can you describe the surfaces in the room, floor, walls, ceiling and give us dimensions?
After that, I'll give you my 2 cents.
C.

[cmchamp]

Ok, while I'm sitting here awaiting for my 2 year old to finish his dinner, and my 6 year old waits for his Disney™ movie to come on, I'll ramble a bit for understanding.
RT measurements, be they RT60, RT40, RT30 etc. indicate that the room is reverberant indicating a diffuse field. Rooms, such as gymnatoria, with large, flat, reflective surfaces are not diffuse at all. All too often solutions for these rooms are just absorption and no diffusion, creating an unnaturally sounding room. The PA "may" sound great, but the room is uncomfortable to be in mostly because the mids and highs have been sucked out with no correction on the low end.
Without knowing more details of your room, I would suggest a combination of diffusion (reflection at all angles in the horizontal, or vertical, or both) and absorption through out the room, with some good quality bass traps in the corners.
Modeling is great, but when the room is complete, the actual acoustical tests don't always match the model.
Diffusion recommended would probably be a modified slat-abosrber, which is a device that would be designed to reflect diffusely specific frequencies while absorb low and low mid frequencies at a mathematically pre-determined frequency and efficiency.
Bass traps for the corners might be slat absorbers or membrane absorbers depending again on the actual acoustical results of the room, not necessarily a model.
When I model a room with software, I use three different approaches.
1: Ulysses acoustical and speaker simulation software
2: an Excel™ spreadsheet I created myself after the old Bose™ modeler software
3: Excel™ spreadsheets I received during my apprenticeship with Dennis Fleisher, PhD, of MuSonics with whom I've had a working and learning relationship for almost 10 years.

In order to properly "model" the room, the dimensions of both the gymnasium and the room in the upper "balcony" would be required as well as finish surfaces, furnishings etc.

[pdc]

If you jump on over to StudioTips.com, you will find all kinds of RT calcs on Excel spreadsheets. You input the dimensions, finishes, etc and they will tell you what you are likely to see band by band RT wise. I just Googled and found a simple on-line app here:

http://www.csgnetwork.com/acousticreverbdelaycalc.html

Auralex is what it is. Those guys don't design rooms. They do not model. They have nothing that will do the job with guaranteed results. Like I said, you need commercial treatment products (with certified performance data) that will hold up over time.

Call Russ Berger Design Group and Russ (a Christian) will tell you what you can expect for your budget. He loves to work with churches.

http://www.rbdg.com/

[cmchamp]

There are a lot of misconceptions on those sites, especially when being targeted and used by novice users who don't understand that Sabine, Eyring and Fitzroy formulas for RT times work assuming uniform absorption on all surfaces and a sealed room. Uniform absorption results in a more diffuse room. Any calculation or model that doesn't take non-uniform absorption into consideration can be misleading.
To see how a method of acoustical testing and treatment recommendations happens, check out this thread: Diffusion - possible to have too much?

[Brad Weber]

I'm always amazed at how many people try to apply small room acoustics to large rooms and vice versa. There are many online resources for studio acoustics, especially for home studios, just keep in mind that these are addressing small room acoustics and while there are many common areas, not everything presented is necessarily directly applicable to a gym or Sanctuary.

Many of the online or free acoustical analysis programs use the basic Sabine equation which assumes a diffuse sound field and generally lower absorption coefficients. In effect, it assumes that the sound is the same everywhere in the room and that the sound anywhere is equally affected by all surfaces. When spaces have limited diffusion (e.g. all flat, parallel surfaces like this gym) and some non-uniformly distributed, highly absorptive surfaces (such as if you only put acoustical panels on some of the walls of the gym), then the Sabine formula gets increasingly inaccurate. Most of the online programs also tend to look at the reverberation time at one frequency and to ignore that you often want the RT to vary with frequency, especially in spaces intended for music.

When looking at recommended or predicted Reverberation Times times consider whether they are referencing occupied or unoccupied space, a gym with 10 people in it playing basketball is likely much different acoustically than it is with the floor filled with people for an event. This is one place where modeling can be useful especially if you can 'tune' the model to match measurements and recordings made in the existing space and then assess any changes, including addressing the effect of adding people into the space.

If that is a suspended sheetrock ceiling it may be a factor as that typically could be sucking up a lot of low frequency energy but causing undesired reflections at higher frequencies and treating the walls won't change that. Also look at whether you are limited to placing any treatments above the existing band of wall finish, another example of where the absorption or even diffusion might be added that affects the overall reverberation time but might not be located where it can be most effective for the listeners in terms of flutter echo, reflections related to speakers, etc. In addition, the upper balcony that Cory noted probably needs to be heavily treated as it appears to potentially act as a coupled space.

Cory, I thought that the Fitzroy equation, and later Kuttruff and Neubauer, were specifically intended to try to address the non-uniform distribution of absorption.