DIY Room Accoustics for Home-Theatre

[sdurani]

Foam Pyramid 50 mm is available for Rs.100/- sq: ft...(can act as diffusers)..

Keep in mind that 50mm depth will only diffuse 1,000Hz (1kHz) and higher.

To address the vocal range (100Hz and up), the diffusers need to be 50cm (20 inches) deep.

That might be OK for professional studios, but impractical for residential homes.

 

[shelley]

In my opinion foam pyramids are not necessary for home theatre setup. The furniture, AV rack and any irregular surface can act as diffusers. I am planning not to overdo acoustics. Do only what is necessary to reduce the echo and bass boominess and I hope we will get a good sounding home theatre setup. Studio acoustics is entirely different and most experts wrongly suggest studio setups for home theatres which in my opinion is absolutely wrong. The result will a dead sounding room..

 

[shelley]

Yet Another Acoustic absorption panel:

High Density PUF slabs

BEARDSELL LIMITED

 

[rdksrk2013]

During the course of my search I had come across this advt in newspaper on decorative acoustic - Rhebin, Bangalore selling its brand of acoustic fibre inthe trade name of 'Niber'.

I had visited this place and collected a sample alongwith some demo work done for a HT.

Specs are provided below alongwith some snaps of the sample. I do not know if this will be helpful but can someone suggest if this is usefull:

Material: Polyester fibre

Density: 160 kg/m3

Thickness: 12,15,20,25 mm



Have different colours.

 

[shelley]

Any idea regarding the pricing?? Please provide Telephone number and address so that I can contact them, if required..
A search on Rhebin, Bangalore and Niber did not yield any results....

Polyfibre NRC value is approximately 0.7
The above product seems like PUF Slabs to me..No idea about NRC value...

 

[rdksrk2013]

Any idea regarding the pricing?? Please provide Telephone number and address so that I can contact them, if required..
A search on Rhebin, Bangalore and Niber did not yield any results....

Polyfibre NRC value is approximately 0.7
The above product seems like PUF Slabs to me..No idea about NRC value...

sent pm on contacts. PM me your mail I have collected a soft copy of the brochure

 

[sdurani]

I do not know if this will be helpful but can someone suggest if this is usefull:

Material: Polyester fibre

Density: 160 kg/m3

Thickness: 12,15,20,25 mm

That density works out to about 10 pounds per cubic foot, which is good for broadband absorption but not so much for bass traps.

25mm (1 inch) thick will be good for absorbing higher frequencies (500Hz and up). To get into the human vocal range, 50mm (2 inches) will absorb down to about 250Hz. 100mm (4 inches) will absorb down to 125Hz).

Low frequency absorption will probably start decreasing if you go any thicker, because of its high density. If you're going to make bass traps that are 10-12 inches thick, then something much less dense (like pink fluffy fiberglass) would absorb more of the bass.

 

[shelley]

@Sanjay
Fiberglass is a strict no due to its health related issues. I am planning to use Polyfibre for bass traps. I plan to use only Eco friendly materials..

 

[sdurani]

Understood Shelley. I'm just used to fiberglass because everybody I know here uses it, but they wrap it in speaker grill cloth (acoustically transparent) to keep the fibers from getting loose. Most companies I know that sell absorbers use fiberglass.

 

[rameshbitra]

Shelley - you could check this website Noise Control,Sound Proof Products,Manufacturers Acoustic Doors,Sound Proof Glass Windows India,Acoustic Barriers,Wall Panels,Ceiling Tiles,Acoustic Baffles and enquire. They have office in Chennai as well.

I havent contacted them yet. I used to bookmark all dealers collecting info for my future hometheatre. Thought of passing it on to you..btw, your inputs are really helpful and I have subscribed to your thread. Incase if you do speak to these guys, please post more info on availability and pricing.

 

[shelley]

@sanjay,
Just b'cause everybody uses it does not mean that it is good ...Now most companies like Anutone, Himalaya etc are turning to wood wool based products..

Ofcourse Glass wool is used in most of the studios, and NRC values are excellent and it is cheaper too..But concerned about health aspects

We should be alive to watch our favourite movies

Today I visited a recording studio and a sound engineer who was dubbing a sound track also shared the same concern regarding glass wool...

Saint Gobain manufactures "Ecophon" Glass Wool based tiles:
Acoustic Ceiling Tiles | Wall Panel | Ecophon Advantage | Saint-Gobain Gyproc Products

I sae Ecophon today and it was very light and there was tissue covering on one side of the panel. For more safety it can be covered using RP tissue/Glass wool tissue and can be used along with Gyptone Big Boards:
Gypsum Board | Gyptone Boards | Gyptone Quattro | Saint-Gobain Gyproc Products

Using Gyptone Big Boards means lesser joints when comapred with Gyptone which is 2' x2':
http://www.saint-gobaingyproc.in/gypsum-ceiling-panel-gyptone.html

Alternative idea:
==========
Gyptone Big Boards can also be used for both ceilings and wall panels with wood wool or glass wool backing as needed. We can paint or paste burlap/wool fabric on it, if required.

We can avoid using perforated mdf/plywood boards on walls...and NRC values of Gypsum is better than plywood or MDF. (Gyptone Big Board: Noise Reduction Coefficient (NRC) : 0.6 to 0.75)
Prices of Gyptone Big Boards will be posted after meeting a Gyptone Dealer tommorrow...

 

[shelley]

Perforated Hardwood Plywood for wall panels:

Another supplier at Bangalore:
Perforated Board - Perforated Hardwood Plywood and Block Board Plywood Exporter & Supplier from Bengaluru, India

Our member rameshbitra has provided details of another supplier of acoustic products, including perforated boards:
http://www.envirotech-acoustics.com/perforatedwooden-acoustictiles.html

Need to check whether perforated hardwood is available locally...Will visit few dealers today and post the details..

 

[sdurani]

Ofcourse Glass wool is used in most of the studios, and NRC values are excellent and it is cheaper too..But concerned about health aspects

Which is why I mentioned wrapping it in cloth. Fiberglass doesn't have magical properties. If the fibers cannot get to your lungs, then health is not a concern.

I'm not suggesting that you should use fiberglass, especially if you are uncomfortable with it, I'm just pointing out why other people use it without the health concerns you have.

 

[raj]

Shelley
Thanks for all the great information. What is the NRC of MDF boards? I remember seeing the wooden boards Anutone a couple of years ago. They looked beautiful but expensive (close Rs 600/sq.ft). Compared to that MDF seems to be a much better value.
Among the other tiles you have listed, Gypsum boards at Rs 40/sqft seems to be the best value.
Raj

 

[sap2nirvana]

@Shelley- loads of info.. thanks for sharing it. since i am from B'lore, can visit these places to check the material upfront.
@John, I suppose you were working on your HT room last week. haven't heard anything since then...

 

[john_k_antony]

@Shelley- loads of info.. thanks for sharing it. since i am from B'lore, can visit these places to check the material upfront.
@John, I suppose you were working on your HT room last week. haven't heard anything since then...

Oh sorry to mention the new thread I started on the build. Please take a look at this - http://www.hifivision.com/home-theater/46258-yet-another-dedicated-home-theater-build.html

-John.

 

[sash]

@Sanjay, i'm also using Fiberglass panels at home and have securely wrapped it in thin foam and covered that again in fabric. When i spoke to few "professional" HT installers they were unanimous in their opinion that fiberglass is ok and secure initially but after some use (with the sub pounding it), they tend to powder and that fine dust can get out even from the most secure of wraps. I don't know if this is true or not but certainly something worth keeping in mind during decision making.
Do you think there could be some truth to this? I have seen your informative posts on the subject of acoustics and value them a lot - pls keep em coming.

 

[Premblr]

This thread is a boon for people looking at a DIY solution for acoustics, thank you and let us know what you finally made. I am glued to this thread.

 

[sdurani]

When i spoke to few "professional" HT installers they were unanimous in their opinion that fiberglass is ok and secure initially but after some use (with the sub pounding it), they tend to powder and that fine dust can get out even from the most secure of wraps.

Not sure how you get a subwoofer to pound fiberglass, but in my experience it hasn't been a problem when properly wrapped. After years of use, my panels (and those of others I know) haven't shown any fine dust on the outside of the cloth.

As I mentioned before, not telling anyone to use fiberglass, just pointing out why it is so commonly used despite health concerns.

 

[sash]

Not sure how you get a subwoofer to pound fiberglass, but in my experience it hasn't been a problem when properly wrapped. After years of use, my panels (and those of others I know) haven't shown any fine dust on the outside of the cloth.

As I mentioned before, not telling anyone to use fiberglass, just pointing out why it is so commonly used despite health concerns.

Low frequencies by their very nature can unsettle loose objects. Think glass shaking during action scenes. But it is reassuring to note that nothing like this has happened after years of use - at least i know i can use my panels for few years.