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Acoustical Treatments Master Thread - Page 23

post #661 of 10188
Quote:
Originally Posted by Tweakophyte View Post

Bpape gave me this info from another area:

Quote:


The cotton is a great product. It's class A fire retardant, non-shedding, non-itching, totally natural, etc. No gloves or long sleeves required to work with it. Cutting it is a bit of a trick but if you take your time and use a VERY sharp razor knife at a shallow angle and with multiple light strokes it's not too bad. This is for the thicker stuff. For the thinner 3lb and 6lb material, you can actually use a good sharp pair of scissors (big ones) or can also use the knife as described above. I have people who cut it into triangles to stack up solid all the time.

I did exactly what Bpape suggested (Thank-U Bpape) "cut it into triangles to stack up solid" I did this in all four corners (BAC stacked floor to ceiling covered with GOM)

I don't have fancy gear to test everything for showing graphs, just the Excel & Rat Shack type of things...

But my ears tell me that my room is a lot better with BAC in corners and 103 panels on the walls and it looks OK to the WAF part.

HH
post #662 of 10188
Terry,

> let's go to the videotape, and see if this matches our recent experiment! <<br />
Ha ha.

Seriously, I'd say that's more a function of trying to use "mean" to tell what's going on audibly. Perhaps I should have phrased it the way I usually do: Adding bass traps generally increases the perceived level of bass in a room. Whether you have to turn up the volume knob an extra dB or whatever to get the same volume measured on an SPL meter is less of an issue to me. Even at the same volume setting I'd say that the nulls coming up will more than counter the peaks going down. Audibly, of course!

--Ethan
post #663 of 10188
I am a bit confused....I read on manufacturer sites that sound absorbing cloth and other insulation types can be installed behind the drywall between the studs....I am assuming that you would only do that in the case that you want to stop noise from passing through....A set-up like that would not actually help within the room at all right? I mean the drywall would be reflecting the sounds back and forth correct? I am may be way off, but from what I've read I was under the impression that the absorbing material must be directly exposed to the sound....

In any case, I am about at budget's end but I need to do some accoustic treatments for the walls/ceiling (absorbtion). I do not want to use fiberglass because I worry about my childrens exposure to material that will be "exposed" behind GOM. Can someone give me a reasonably priced alternative that is not in any way toxic? Also, please post where they may be ordered from... Reminder: I am seriously low on funds after renovating the entire basement and all the new equipment, so I am looking for effective but inexpensive treatments (I don't mind if it requires a lot of labor.)

Thanks,
Rudedoggy
post #664 of 10188
Quote:
Originally Posted by HuskerHarley View Post

I did exactly what Bpape suggested (Thank-U Bpape) "cut it into triangles to stack up solid" I did this in all four corners (BAC stacked floor to ceiling covered with GOM)

I don't have fancy gear to test everything for showing graphs, just the Excel & Rat Shack type of things...

But my ears tell me that my room is a lot better with BAC in corners and 103 panels on the walls and it looks OK to the WAF part.

HH

Did you worry about the color of the BAC? Did you make any panels with this for you front wall? It looke like the cotton has a little more acoustic absorbtion than the 703 down low, and is pretty close to the Linacoustic I grabbed from bob's site.

Product thickness mounting density 125hz 250hz 500hz 1000hz 2000hz 4000hz NRC
703, plain 2" (51mm) on wall 3.0 pcf (48 kg/m3) 0.17 0.86 1.14 1.07 1.02 0.98 1.00
Echo Eliminator (Cotton) 2" 3pcf A 0.35 0.94 1.32 1.22 1.06 1.03 1.15
Permacote® Linacoustic® R-300 2" (51mm) 3.0 pcf (48 kg/m3) 0.26 0.73 1.10 1.10 1.04 1.03 1.00

Harley, did you check out the price of other options? Why cotton?

Does anyone have pics of this stuff?

Thanks,
post #665 of 10188
Quote:
Originally Posted by Tweakophyte View Post

Harley, did you check out the price of other options? Why cotton?

Does anyone have pics of this stuff?

Thanks,

bpape (Bryan) has a few pics of the cotton on his website. Here are a few -- left is the 2", right is 4" material:



Steve
post #666 of 10188
Quote:
Originally Posted by Tweakophyte View Post

Did you worry about the color of the BAC? Did you make any panels with this for you front wall?

Harley, did you check out the price of other options? Why cotton?

No worry GOM covered it up.

Corner panels are BAC covered with GOM.

Yes on price options....BAC at the time seemed the way to go and it was so easy.

I took a few Pics of the room but I don't know how to get them to display?

PM me with your email and I'll send them to you if you want to see what a amateur can do to mess up good intentions

HH
post #667 of 10188
Here is a thought...What do you anticipate the problems would be if I did NOT drywall the inside of the theatre room, and instead. filled the space between the studs with accoustic cloth insulation, walled it with duct liner, and used gom attached to 1 X 2" firring strips which I will attach to the door stud. Then stretch the fabric to the inside of a stud roughly 50 inches horizontally and the take a second piece of gommed firring strip and attach it likewise to the same stud and continue on down the wall.... (I probably didn't explain it right) It should appear boxed that way (I can use molding over top and bottom) but there would be no drywall used (two side are concrete with 2 X 4 's used as furring strips to give a little width for the duct liner - duct liner only on the concrete sides - maybe double sheeted). I could then 2 layer the drywall on the outside of the theatre walls for sound deadening... Would this be a dysfunctional setup? I am concerned about how the wall sound would play out and if there are any drawbacks for not using the drywall on the interior of the walls... Any comments/concerns would be appreciated...

It would seem to me that the 4" of cloth between the studs and the duct liner covering it would be a pretty absorbent combo, but then again I know very little about anything audio...


Thanks,
Rudedoggy
post #668 of 10188
I'm no expert, but I'm guessing much too absorbent.

Also, I'm not sure that construction would pass code.
post #669 of 10188
Is drywall required under code in a basement? The accoustic cotton I am talking about is actually used to replace R13 and R19 fiberglass and in and of itself would meet code...I don't know about the replacing of drywall will duct liner as a violation of code. Both have some fire resistance ( I am pretty sure that was listed under the liner..)...maybe someone can answer that? Also, how much is too absorbent? Anyone else have any suggestions on my earlier post?

Thanks,
Rudedoggy
post #670 of 10188
Looks like I'll be constructing some floor to ceiling corner bass absorbers the next couple weeks and have a few questions.

I can not source Owens corning 703 or 705 locally so will be using Ottawa Fibre OFI-48 3lb 2x4 foot 2" thick material doubled up, maybe tripled, the acoustic properties of the FRP faced material look excellent

First question.....when doubling up faced material should only the first outside layer be faced or is there any bass advantage to using faced material for both layers? I'm not too concerned about mid to high frequency absorption at this point.

Secondly, should doubled layers be glued together or would a slight space between them absorb bass better.

Third, I was planning on making enough absorbers for four corners of the primary HT area but due to the room(s) configuration might it be better if one or two were situated elsewhere. I don't have any analyzing programs at this point except for the usual meter and test cd's so am looking for general/probable positioning advice for the room(s).

Attached is the room layout which is a basement, doubled up 1/2 inch drywall over 3" styrofoam board over concretre /fiberglass insulated 5/8 drywall ceiling. Flooring is (soon to be again) carpet over pad. The viewing area is about 19' long and 12' wide at the front and back, obviously wider in central area. Entire speaker/screen area and back wall lined with black velvet.

I'm am not using subwoofers and my general bass response shows a belled hump from 80 to 200 hz will lulls on either side and an 10db gain between 25 and 30hz. While the FR doesn't really look that bad the bass definitely is a little indistinct and needs improvement.

Thank-you
LL
post #671 of 10188
When using faced product, you should remove the facing from everything except the face that is toward the room. The other pieces should be unfaced.

You don't need to glue multiple layers together. If you want to add air space, that can only help by getting the front one further into the room.

Looking at your sketch, I'd do the front corners and the wall/ceiling corners in the front and rear of the theater area. It's such an odd shaped room that you'll still need some more but that will be a start.

Some of your FR issues are likely due to SBIR from the mains being close to boundaries andnot absorbed. You might also want some bass absorbtion beside the speakers to help smooth things out. If you got a sub, you could tune the bass response without having to move the mains.

Also, the seating appears IIRC to be pretty close to the back wall. I'd move it out - that will help smooth things also.
post #672 of 10188
Quote:
Originally Posted by bpape View Post

When using faced product, you should remove the facing from everything except the face that is toward the room. The other pieces should be unfaced.

You don't need to glue multiple layers together. If you want to add air space, that can only help by getting the front one further into the room.


Ok great, this will reduce the cost and simplify the construction.


Quote:
Originally Posted by bpape View Post

Some of your FR issues are likely due to SBIR from the mains being close to boundaries andnot absorbed. You might also want some bass absorbtion beside the speakers to help smooth things out. If you got a sub, you could tune the bass response without having to move the mains.

My room is still packed away due to a water leak but IIRC the speakers average about 10" from the side walls and the rear of the 18" deep speakers are about 35" from the rear wall. I just downloaded Ethan Winers Boundary Frequency/Distance calculator and this would indicate the side wall distance shouldn't really come into play at the frequencies I'm having problems with but the rear wall distance very well could be contributing to the problem. Regardles, my side walls are covered with velvet attached to a frame which I can easily fit some absorption panels behind to experiment.

Quote:
Originally Posted by bpape View Post

Also, the seating appears IIRC to be pretty close to the back wall. I'd move it out - that will help smooth things also.

The seating puts the listeners head in the 40-44" range from the rear wall. Moving out definitely helps the bass response but then puts me too close to the video screen plus it encroaches on the path to the door beside the bar. I can only hope the traps will help somewhat.

Thank-you for spending time answering my questions.
post #673 of 10188
Great answers as usual, Bryan!

Regards,
Terry
post #674 of 10188
Still want to get some expert accoustical advice on the following:

Here is a thought...What do you anticipate the problems would be if I did NOT drywall the inside of the theatre room, and instead. filled the space between the studs with accoustic cloth insulation, walled it with duct liner, and used gom attached to 1 X 2" firring strips which I will attach to the door stud. Then stretch the fabric to the inside of a stud roughly 50 inches horizontally and the take a second piece of gommed firring strip and attach it likewise to the same stud and continue on down the wall.... (I probably didn't explain it right) It should appear boxed that way (I can use molding over top and bottom) but there would be no drywall used (two side are concrete with 2 X 4 's used as furring strips to give a little width for the duct liner - duct liner only on the concrete sides - maybe double sheeted). I could then 2 layer the drywall on the outside of the theatre walls for sound deadening...

Would this be a dysfunctional setup?

I am concerned about how the wall sound would play out and if there are any drawbacks for not using the drywall on the interior of the walls... Any comments/concerns would be appreciated...

It would seem to me that the 4" of cloth between the studs and the duct liner covering it would be a pretty absorbent combo, but then again I know very little about anything audio...


Thanks,
Rudedoggy
post #675 of 10188
Quote:
Originally Posted by rudedoggy View Post

Still want to get some expert accoustical advice on the following:

Here is a thought...What do you anticipate the problems would be if I did NOT drywall the inside of the theatre room, and instead. filled the space between the studs with accoustic cloth insulation, walled it with duct liner, and used gom attached to 1 X 2" firring strips which I will attach to the door stud. Then stretch the fabric to the inside of a stud roughly 50 inches horizontally and the take a second piece of gommed firring strip and attach it likewise to the same stud and continue on down the wall.... (I probably didn't explain it right) It should appear boxed that way (I can use molding over top and bottom) but there would be no drywall used (two side are concrete with 2 X 4 's used as furring strips to give a little width for the duct liner - duct liner only on the concrete sides - maybe double sheeted). I could then 2 layer the drywall on the outside of the theatre walls for sound deadening...

Would this be a dysfunctional setup?

I am concerned about how the wall sound would play out and if there are any drawbacks for not using the drywall on the interior of the walls... Any comments/concerns would be appreciated...

Hi Rudedoggy,

It would be dysfunctional for sound isolation. Sound would travel easily to adjacent rooms, and vice-versa. I don't know about your local building code requirements, but this could be a show-stopper.

For sound quality otherwise, it might be good. I say might because one would have to calculate the absorption of what you propose, and see if it is well balanced for all frequencies. You might have to use some drywall or better, diffusive treatment to reduce absorption. You might also have to use different thicknesses and densities of absorber than just duct liner.

Regards,
Terry
post #676 of 10188
Anyone ever hear of a product called sound board by Weyerhauser. I saw some at Home Depot when I was looking for a solution for some accoustic paneling. It is a very fibrous soft wood product 1/2" thick and they are 4'X8' sheets and they are only $8 each. I was going to double them up for 1" and than wrap with a nice cloth and than hang on walls about 1' off the walls. They also had some JM 2" thick foam stuff also in 4'X8' sheets for about $20 each. I was also thinking I could manufacture some bass traps out of those by cutting into 12" squares and stacking them or 12" strips and attaching them all together to make a sort of 12" sq pillar 8' high. Would this work as a bass trap as well.
post #677 of 10188
Quote:
Originally Posted by jandawil View Post

Anyone ever hear of a product called sound board by Weyerhauser. I saw some at Home Depot when I was looking for a solution for some accoustic paneling. It is a very fibrous soft wood product 1/2" thick and they are 4'X8' sheets and they are only $8 each. I was going to double them up for 1" and than wrap with a nice cloth and than hang on walls about 1' off the walls. They also had some JM 2" thick foam stuff also in 4'X8' sheets for about $20 each. I was also thinking I could manufacture some bass traps out of those by cutting into 12" squares and stacking them or 12" strips and attaching them all together to make a sort of 12" sq pillar 8' high. Would this work as a bass trap as well.

Forget about them both.

What you need is fibrous, open material with moderate air flow resistance (fiberglass, mineral fiber, cotton, polyester). Neither of these materials will work.

Regards,
Terry
post #678 of 10188
I'm not sure if this question goes in this forum or in the construction forum . . .

My speakers are built into my screen wall, to be flush with the screen. They sit about 4 inches above the stage area. The stage area is poured concrete and extends about 24-30 inches in front of the speakers. My concern is about early reflections from the stage. My questions are:

(1) should this be a concern?

(2) if it should be a concern, what should I cover the stage with? Carpet? GOM over linacoustic / sound board? Other? Rarely will anyone stand on the stage, but I'm sure it will happen from time to time.

Thanks
post #679 of 10188
I'd cover in carpet generally. Whether it's a reflection point or not depends on where your seats are.
post #680 of 10188
I am sorry if this has been answered before, There is soo much in here now it is hard to read it all, im trying.

I just called SPI, and they said they carry 703! (Victory) in single sheets of "non-faced" that I can buy at 1.30 a sqare foot. Or Faced in bundles of 192 square feet at .73 a sqare foot. Could someone please exaplain the difference between faced and non-faced? And what should I do if I get the non-faced?
post #681 of 10188
Terry,

I have a 19.5 X 11.5 ft room 7.5 tall. Two basement walls. 6.1 sound system. I am thinking about taking the carpet up the first 3 or so feet of the wall and doing a chair rail and some framed "boxes" with GOM covering holding cotton duct liner (.60NRC I believe) along all back and side walls. Will this be sufficient you think? I have no understanding of the underlying science of all this - which I might add you all have me in awe of.

Thanks,
Rudedoggy
post #682 of 10188
I need to sound proof my dorm room a little so that I don't get complaints from the people living upstairs and downstairs anymore. They've mostly been about the bass coming through. What are some cheap solutions I can get for this? I was thinking placing a dynmat mat under the sub and acoustic panels like these http://www.envisiononline.net/acousticpanel.html on the ceiling. Would this do the job or do I need some sort of sound proofing material?

I already have carpet on the floor, but the sub isn't on carpet. The floor is made of cermaic tiles and the ceiling looks like some stone or something.

I really don't know about this stuff and I don't need anything fancy.
post #683 of 10188
DarkSyde - 1.30 for 1" 703 unfaced is pretty steep but they'll sell it to you a piece at a time. Conversely, 1" FACED 703 for .73 sq foot is pretty reasonable. If you can use all of the material, you can easily peel the facing off.

For reflection points you want unfaced. The faced has a kraft paper and foil scrim on one side. This can be very useful when place on top of thicker material for bass absorbtion without overdeadening the highs.

Doggy, that will be VERY overly dead IMO. I wouldn't do the carpet up the wall thing.


Sorry Borky. Hate to break it to you but you're not going to soundproof a dorm room no matter what. Even if you could, cheap and soundproofing don't go together. It's all in how the structure is built which you can't control. Nothing you do inside the room (other than may be a LITTLE but by putting the sub on something like an Auralex SubDude) is going to do much of anything in the way of soundproofing - sorry.

Oh, and thanks Terry.
post #684 of 10188
What would putting a few acoustic panels like maybe this kit http://www.sweetwater.com/store/detail/RoomDST36B/ do? Wouldn't they "absorb" some of the sound?
post #685 of 10188
Bork,

That is a kit that is used to control the acoustics in the room.. It has nothing to do with soundproofing at all.. Soundproofing is totally differant thing, as Bryan is trying to point out to you..

Glenn
post #686 of 10188
Quote:
Originally Posted by rudedoggy View Post

Terry,

I have a 19.5 X 11.5 ft room 7.5 tall. Two basement walls. 6.1 sound system. I am thinking about taking the carpet up the first 3 or so feet of the wall and doing a chair rail and some framed "boxes" with GOM covering holding cotton duct liner (.60NRC I believe) along all back and side walls. Will this be sufficient you think? I have no understanding of the underlying science of all this - which I might add you all have me in awe of.

Thanks,
Rudedoggy

Is it really bad to do partial carpeting on the walls? I could have sworn I read someone saying to do it....Also, this is going to be used almost entirely for movies/home theatre, so shouldn't I want it to be "dead" as possible? It is all very confusing. Please help a newbie out with some advice guys...

Does anyone know if carpet padding has any absorbtion (NRC). I don't know what to look for for absorbant materials but it would seem to be a low cost alternative if ti does have any NRC value... Is there any common materials you can think of that have a respectable NRC other than fiberglass? Certain cloth types, batting you get form a fabric store etc etc etc

thanks,
Rudedoggy
post #687 of 10188
bpape, yea, I know 1.30 is kinda high, but I figured that is the price I pay for not buying a whole bundle. I think 2 sheets to play with is worth the price hike.

Simpler question for the non-faced vs faced. What should I do for corner bass traps? Faced or non- and if faced, facing which way?

This is what I am gonna start with and go from there, see how I like it and then think about buying a bundle or 2. Thanks.
post #688 of 10188
Well I am getting ready to put my acoustic pannels together, I have mineral wool, speaker grill cloth, trying to figure out what I want to attach the stuff too. Maybe some lighter wood, foam board, who knows. I hope to put them together tomorrow. I hope everything works as planned.
post #689 of 10188
Dog,

> Is it really bad to do partial carpeting on the walls? I could have sworn I read someone saying to do it <<br />
Just because you read it somewhere doesn't make it true! The Internet is a great democracy, and anyone can say anything. Unfortunately, that's what they usually do.

Seriously, the real issue is how well a given material absorbs and, just as important, over what frequency range. Carpet absorbs only the highest frequencies, so the risk is that you'll end up with a room that's too dead sounding yet too boomy at the same time.

--Ethan
post #690 of 10188
Ok thanks, carpet should be out...Now, lets say instead I do ceiling to midway to floor with boxes (covered with GOM) with batting in them and use some silence FR fabric at the bottom instead of carpet.... Would that be a better solution?

Also, I was still wondering if anyone know if carpet padding has any absorbtion (NRC). I don't know what to look for for absorbant materials but it would seem to be a low cost alternative if ti does have any NRC value... Is there any common materials you can think of that have a respectable NRC other than fiberglass? Certain cloth types, batting you get form a fabric store etc etc etc.


thanks,
Rudedoggy

P.S. If anyone is interested in splitting a bolt of black silence fabric contact me. It is like $3 less per yard that way.... I plan on ordering some in the next week or so.
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