[rockdrummer]

Hi everybody.  I am a band director and just moved into a new room.  40' x 32' cinder block and concrete walls, with 28' ceilings. However, there was no money budgeted for sound treatments.  A concert band makes the room sound like a bleeping cannon.

I am going to make/buy material for panels.  I may use a cotton batting made by a company here in Minnesota.  It can just be glued to the wall.  That way I'm not drilling anchors so high up.  Comes out to about $400 for 112 square feet.

For the rest, within reason, I can build them cheaper.  These I feel more comfortable installing at 15 ft or less.
I moved from Roxul to Owens Corning and now to Denim (Ultratouch).  The first two products had too many review of strong smells and the formaldehyde binding agents sometimes not being fully cured....Anyway, being that I'm in a school, I would really like to stay as safe as possible. 

Ultra touch is supposed to be formaldehyde free, but on the Lowes website, it states it isn't. 

I assume the manufacturers website is correct.  Anyone build sound absorbing panels with 2" ultra touch batts?

Thanks for any advice you have,
Ben Young

[richidoo]

Ultratouch has borax in it for insect and fungus prevention, but it does not contain any formaldehyde.
http://bondedlogic.com/pdf/denim-insulation/ut-denim-insulation-brochure.pdf

I have used both Ultratouch and normal OC 703 treated with formaldehyde. The FG board requires airing out for a few days before the smell is reduced enough to bring indoors, but it does fade out. They use formaldehyde to prevent microbe growth in the main application of industrial insulation, boilers, HVAC plenums, etc where moisture is common.

Owens Corning also makes bloack color, rigid FG boards for use as sound absorbers. I don't know how easy it would be to get in small quantity. It says it resists rot and mildew, so it might still contain formaldehyde, but worth inquiring if you want rigid FG. http://commercial.owenscorning.com/products/oem/selectsound-black-acoustic-board/

IME, the cotton batt is just as good if not better acoustic absorber than FG, but it's not rigid.

[JLM]

Could you be more specific about the sound you're hearing? 

What's the floor/ceiling covered in?

Your cotton batting idea would cost $8000 to cover the lower 15 feet of walls.  Don't know what the acoustic absorbency characteristics would be.

Not familiar with Ultratouch.

Which Owens Corning product (there are many)?  Owen s Corning 703 (rigid fiberglass) is one of the best wide spectrum absorbing materials (you'd want to cover it in cloth).

Try doing two adjoining walls (it takes two opposite walls to echo, but you don't have to cover entire wall surfaces to get the best effect).

[rockdrummer]

Thanks.

I can't be very specific other than lots of echo/reverb.  Which, I don't know if they are different or not.  We get no articulation, after the initial attack, out of the room.  No accuracy and separation when there really should be.  Not to mention it is really loud. The floor is carpet on concrete, and the ceiling above 6 8 by 8 light clouds is metal.  The wall behind where I direct is a wall door.  When open, that is where the audience will sit.  So i have 2 cinder block side walls, and one flat concrete back wall.

At home, I have a small 2 channel system for which I am building amp and speaker kits.  I have done research about the first steps of acoustic treatments.  But I have no experience or knowledge to describe in detail what I am hearing from my current set up.  Which is frustrating to me because I want to know how you guys are so good at pinpointing problems to make treatment design decisions.   Anyway, I digress.

I can probably get funding for, and build about 250 to 300 square feet of panels. I really should have 400 or more.

I am avoiding rock wool, and the fiberboard products for health reasons.  Even if they are just rumored possible health concerns.

Ben 

[jk@home]

Can you get a hold of (borrow or rent) some moving blankets to hang on the wall? If that helps, then check out this product:

https://www.vocalboothtogo.com/acoustic-and-soundproofing-products-vocal-booths/acoustic-sound-blankets-for-sound-absorption---producers-choice/8#ja-pathway

Obviously not as efficient as thicker insulation, but will cover much more wall area for less cost. I use a couple of them, folded up, on top of my subs, for sound absorption.

[richidoo]

It's such a large room, the bass fundamental modes are all below 20Hz. None of your instruments play that low so those won't be excited. Of course, the upper harmonics of the room will be excited by your bass instruments, but they will not be the crux of the problem compared to the midrange. Midrange echo is extremely distracting and annoying when it over powers the music.

To reduce it you need to apply 1" thick absorbtion to as much hard surface as possible. 1" thickness is enough to cut down the midrange noise very effectively. It is not gorgeous, but it looks reasonable as a finished surface and it's very tough, so you could just hang it and be done.

You could also hang donated or borrowed quilts and blankets on the walls until you can replace them with the cotton panels. It is not hard to attenuate midrange echo, but the hard part is covering enough of the surface to make a meaningful difference. Aim to cover all of the walls, if possible, probably with 2'x4'x1" cotton panels maybe with 6-12" gaps between panels for better visual.  Covering the walls only up to 8-12 feet might help a lot to eliminate slap echo which is the worst of it, but it will still ring a long time with the upper walls bare.

$400 for 112 sq feet seems high. I purchased only two 2'x4'x1" panels for about $20 each a few years ago, but your price is $28 each for the same size panels.

[JLM]

You chasing phantoms in the dark if you can't define the problem.  How does the sound compare with the door/wall open?  It probably was not designed with sound in mind, but wonder if the concept was to create a sound shell to project the sound towards the audience.  If that is the case and it sounds better to the audience (door/wall open) than to you closed, I'd recommend treating the door/wall (if possible) with as much absorption as possible.  This would somewhat simulate the door/wall open condition (absorption simulates pushing the boundaries away).

But this is a different scenario than 2 speakers in a smaller room and if I'd try to contact some of our Audio Circle acoustic product sponsors who have a wider range of experience (like Glenn Kuras from GIK).

[Rob Babcock]

Regardless of the rating I have found that UltraTouch isn't as effective as 'glass or rock wool at low frequencies.  The problem with is seems to be internal reflectivity when you pack it thicker than about 5-6".  It's better than nothing but not really a panacea.  Apparently if you breath the dust of the stuff it's bad for your lungs, worse than 'glass.  It's pretty messy to "cut" to; you kind of have to tear it and you get a crapload of 'denim dust' when you do.