[rader]

I am interested in installing some sound panels in my listening room to absorb wall reflections and later on building a few bass traps to absorb lower frequencies. I am in the process of selecting which materials would be best and I have not seen much discussion on the properties of melamine foam ceiling tiles such as is seen at the bottom of the page here: http://www.mcmaster.com/asp/enter.asp?pagenum=3237

I am wonderring if anyone has any experience with Melamine foam and how it compares to something like 705 Owens Corning fiberglass or auralex foam. McMaster-Carr lists an absorbtion coefficient of 0.95 but I assume that is only for high frequencies. I assume applying this material 2, 3, 4 or more layers think and spacing it from the wall would help with low frequency sound absorbtion. Would the fiberglass sound absorbing sheet on the same page at mcmaster carr be a better option? Am I better off hunting for Owens-Corning 703/705 for this project?

I have heard of several people using the Melamine foam to silence HTPC's with good results, but nothing from people using it for home or pro audio applications.

 

[Ethan Winer]

Rader,


How well any foam absorbs depends on how it's made. You'll have to look at the data for all the various products to see how they compare. Any data that's given as a single number is useless, and should not be considered when choosing absorbing material for audio use. You need at least octave band data down to 125 Hz, and 1/3 octave data is even better. Otherwise you're just guessing how good it really is.


I'll also offer this: For a given thickness, foam is typically half as absorbent at low frequencies as 703 rigid fiberglass, and even less effective than 705. Foam is also flammable. Even the "fire proof" types are not Class A rated, and they all smoke and smolder. The only advantage is they can be made to look okay out of the box, so you don't have to wrap them with fabric as you would fiberglass.


--Ethan

 

[Terry Montlick]

Quote:

Foam is also flammable. Even the "fire proof" types are not Class A rated

Much of the Sonex line of acoustical foam is their "willtec" material, which is Class A rated.


I strongly advise people to buy only Class A (Class 1) fire rated acoustical treatments.


- Terry

 

[rader]

Thanks guys - I guess I will try and find a local supplier for 705 fiberglass. I still need to take some measurements in my listenning room to find out what my problem frequencies are.


-Shawn

 

[petermwilson]

Hi.

Often the answer to reflective surfaces has been solved by small wall-hung area rugs placed at the reflective spots, which can also be decorative. Invest in a HAA certified calibrator.


you can save yourself alot of money in the long run if you bring in an expert from the getgo.


Peter m.

 

[rader]

Previously I had a large heavy cloth tapestry hanging from my rear wall behind the seating position and found that it made the sound too dead. The tapestry covered almost the entire rear wall and I really did not like the look of it so I ended up taking it down. Area rugs are a good idea, the problem is I am picky about decor. I have just never found any area rugs I thought would look good on the wall. Fiberglass panels covered with neutral gray cloth are cheap and non-descript, and I may hang some Asian scrolls I have laying around over them made of pourous rice paper (I am not sure how this will affect sound absorbsion). I am thinking the problem with the tapestry may have been that it covered almost the entire rear wall rather than just the area behind the listenners heads. I plan to try smaller panels behind the front speakers, a corner bass trap/coffee table using the principles Ethan has in his acoustics FAQ, panels on the side wall reflection points, and a small panel behind the listening position covering the rear reflection point. I am doing this mostly for fun and my own education on the subject. If I get some sonic improvement out of it then that's all the better. How much does bringing in a pro calibrator cost? It may be something I will consider a few years down the road after my next system upgrade and room upgrade. Generally speaking, I am one of those people where if I can do it myself I will do it myself (my car never sees a mechanic).

The next step I plan to take is to get some measurements with the trusty radio shack meter and plot them in excel. Does anyone have any suggestions on PC based software to produce tones and record relative SPL levels? I know I saw a mention of a few programs around here but have not been able to find the thread.


-Shawn

 

[Ethan Winer]

Terry,


> Much of the Sonex line of acoustical foam is their "willtec" material, which is Class A rated.

 

[petermwilson]

Hi Shawn,

Your tapestry thing makes me think about my former thoughts of the medicinal use of alcohol. I figuered if a little bit was good for you alot should be fantastic.


Others here may be able to point you to an exercise using a mirror reflection on a space on the wall that you could see between a speaker and your seated position. If someone could mention exactly how that is done, then you could take (even some thick welcome mats as test pieces) some readings or at least see how it sounds before spending money on a permanent solution. The RC spl meter should be used with any tones that your prepro has as a start I think. Why re-invent the wheel if its not necessary.


I'm in the office environments business (which could very easily be homes) and back in the early 80's some designers created environments where the stc's (sound transmission coheficients) and nrc ratings (noise reduction cohe) were so stone dead that White Noise had to be invented and implemented to keep people from going crezy from the absolute silence.


Anyway, with a little work and alot of patience you will get this to work. BTW if the floors not carpeted the tapestry might help their if its that type of cloth.


Peter m.

 

[Woochifer]

Great thread! I use a homemade suspension system to hang acoustic ceiling panels off of picture moldings. It works great because I can move the panels around without drilling holes in the wall. Along with a thick rug and a cushy sofa, the panels have significantly reduced the "slap echo" I was getting in my room.


But, I've thought about swapping out the ceiling panels for some of the Owens Corning rigid fiberglas panels, but it seems that the NRC rating is not that much higher with the rigid fiberglas so I'm not it's worth the trouble. And I'm not sure if those fiberglas boards are good for the air just dangling out in the open. I'm also pondering the use of corner foam blocks like the LENRD line to even out the bass.


Anyway, here's a pic of how the paneling setup is. That baker's rack in the corner has since been replaced by an enclosed audio rack that's tucked away in the corner and goes almost all the way up to the ceiling (which is why I want to put some absorbing material behind the audio rack).

http://members.aol.com/sfwooch/images/theater1.jpg

http://members.aol.com/sfwooch/images/theater3.jpg

 

[petermwilson]

Hi,

And as usual a picture tells a thousand world. What your showing on the wall is exactly what I was talking about from a shape and size perspective.


Now if you can find a an effective way of locating the offending reflective spots, I think you're looking at a relatively lowcost and possibly decorative solution.


Peter m.

 

[rader]

Nice looking absorber panels Woochifer! I feel inspired! It looks like the area behind your audio rack would be a perfect place for a corner bass trap.


-Shawn

 

[Woochifer]

Quote:

Originally posted by petermwilson Hi, And as usual a picture tells a thousand world. What your showing on the wall is exactly what I was talking about from a shape and size perspective. Now if you can find a an effective way of locating the offending reflective spots, I think you're looking at a relatively lowcost and possibly decorative solution.

I've thought about making another panel for the sidewall. The suggestions I've read say that the way you position an absorbing panel is to just sit at the listening position and have someone move a mirror around. When you can see the tweeter, that's the reflection point and where you should position an absorbing panel.


The cost of that whole paneling setup is dirt cheap. The picture moldings for the entire room cost less than $40, a box of eight acoustic ceiling panels costs $16, the 2" C-clamps cost about $2 each, the precut strips of wood for each panel cost $1.50, and the fabric to wrap the panels cost a total of less than $20. The hooks cost $2 for a box of five. And some nylon fishing line cost about $5. Altogether, the cost came out to around $100.

Quote:

Originally posted by rader Nice looking absorber panels Woochifer! I feel inspired! It looks like the area behind your audio rack would be a perfect place for a corner bass trap. -Shawn

Thanx. I actually started on this with just a box of acoustic ceiling panels and I lined them up in a row along the front wall, and the difference in the imaging clarity was startling. Once we moved the system to a different room, my wife insisted on something more attractive, so that's when I just whipped out a hot glue gun and wrapped those panels in fabric.


I want something for the corner definitely because right now there's a triangular gap between the audio rack and the wall. It goes almost all the way up to the ceiling, so the rack does capture some reverberation. I had to recalibrate my subwoofer EQ settings after moving the rack into the room. The gap is too narrow for rigid fiberglas panels, so I thought that the Auralex LENRD corner foam traps would be a good option for the corner.

 

[porcupine]

Hi Woochifer,


Can you buy those acoustic panels at Home Depot or do you have to special order them? If I understand exactly, you put the acoustic panels between the pieces of wood and then clamp them? Then you install the picture molding around the ceiling and hung the acoustic panels? Great idea. This will help a lot with my plan. All I have now are foam that I velcro to the walls and blankets hanging. My Ht room looks pretty ghetto-ee.


thanks,

porc

 

[Woochifer]

Quote:

Originally posted by porcupine Hi Woochifer, Can you buy those acoustic panels at Home Depot or do you have to special order them? If I understand exactly, you put the acoustic panels between the pieces of wood and then clamp them? Then you install the picture molding around the ceiling and hung the acoustic panels? Great idea. This will help a lot with my plan. All I have now are foam that I velcro to the walls and blankets hanging. My Ht room looks pretty ghetto-ee. thanks, porc

Some Home Depot locations carry acoustic ceiling panels, but most don't. I know that more Lowes stores carry them, so you could try there. Otherwise, just look for some building materials stores that cater to contractors, basically anyplace that sells parts for suspended ceiling systems.


You got it right, I just used two strips of wood and two C-clamps on each panel and suspended them off the picture molding using fishing line. The ceiling panels aren't durable enough to screw hooks into the back or just drill holes and loop the wiring through, so clamping wood strips was a good solution (plus, it just looks cool!).


The picture molding was actually my wife's idea because she wanted a way to hang pictures and artwork without having to put holes in the wall. And she got tired of looking at those acoustic panels just tilted up along the floor. It works out great because the panels can be moved around very easily.

 

[porcupine]

Hello Again Woochifer,


I went and check out the link that somebody posted about the Melamine Foam Sound Absorbing Ceiling Tiles and will probably get them through the catalog. They also have the Sound Absorbing Wedge Tiles and will try to hot glue these guys on some solid materials. I checked out the foam tubes they have also and will probably get a few and try them out in the corners instead of tightly rolled towels.


Thanks,

Porc