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Discussion Starter · #21 ·
Leaving the masonite off would improve bottom end absorbtion, provided the panel is away from the wall.
 

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Nice work ... :T

Have we heard about the sub? I'd like to see a thread in DIY on that thing... looks interesting. Actually it's a pair of Shiva's... and would be a good thread I'm sure. :whistling:
 

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Well I finally found the insulation material for the acoustic panels...

They don't call it "Duct board" over here ( which is a generic name ) it's called "Supertel"..and is available through Bradford Insulation...They won't sell it to you, but can be purchased through general Insulation suppliers..
It comes in 25mm.and 50mm. thick, 1200x2400 sheets..
You can get it with or without the foil backing, so since I don't really need the backing I bought a 50mm, plain sheet...Cost $60.00 a sheet..

I'm going to try this as bass traps first, placing two layers 1200x600 in the front corners...
I pick it up next week..

Hakka...How are your panels coming along?
 

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Discussion Starter · #25 ·
I haven't had a chance to finish them, been too busy enjoying the sound quality they bring to the HT. I might grab a sheet of 50mm this weekend and try some bass traps.
 

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Yeah...I know what you mean..
Since I finished setting up my 7.1 system and calibrated the projector, I seem to spend more time watching movies, instead of finishing the theatre..
 

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Nice job. Looking good.

Bryan
 

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Hakka. I have been looking for the stuff every where but have told "must be sold only overseas".thanks for the article as you have also solved a big problem that I had in constructing my home theatre . also thank you Prof. for telling us where to get it. kind regards alan
 

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CSR Bradford makes lots of Glasswool and Rockwool insulation products. Glasswools:

Multitel, Flexitel, Supertel, Ultratel.
18kg/m3, 24, 32, 48.
1.1pcf, 1.5, 2, 3 pounds per cubic foot.

Bradford don't sell direct but possible sources include Gyprock Plaster Lining Centres (I think these may have been re-branded) and possibly air-conditioning ductwork suppliers. You could just ring Bradford 02-9765-7100 and ask where the public can buy the stuff. The web site includes "where to buy" info but this is mainly for home thermal insulation - still could ring and ask your nearest listed supplier about the denser stuff.
"Duct board" is an ACI brand name (I think ACI is now called Insulation Solutions) and is approximately equivalent to Bradford's Quietel product, 130kg/m3 (8.1pcf). Costs a motsa!
There's some good info on www.bradfordinsulation.com.au including a Design Guide with absorption test data for many of the products.

edit: materials are available as "board" and "blanket" except Multitel (roll only). Board is more rigid (2400x1200), blanket is a roll up to 18m long depending on thickness. List price for 50mm plain unfaced Supertel should be around $22/m2. Black matt finish (BMF) adds about $7/m2.
 

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The material I used was Bradfords Supertel... It looks exactly like the photo of the 703 material in the thread above..
It comes in 1200x2400 sheets and is a semi-rigid fibreglass.
I bought the 2" thick, and covered the front wall corners with 2 layers...
This stuff is very effective as a bass trap..
 
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The material I used was Bradfords Supertel... It looks exactly like the photo of the 703 material in the thread above..
It comes in 1200x2400 sheets and is a semi-rigid fibreglass.
I bought the 2" thick, and covered the front wall corners with 2 layers...
This stuff is very effective as a bass trap..
How much did it cost per pack?

If it's cheaper it looks like it could be the go.

Using Bob Golds Coefficient site:

Glasswool Supertel 50mm kg/m3 0.27 0.75 1.12 1.12 1.07 1.04 1.03 1.01

Insulco Semi Rigid IB (nil) 50mm 0.41 0.84 1.02 1.25 1.22 1.16 1.10

Insulco seems to do slightly better down low.
 

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While I'm sure the Insulco will be fine, I wouldn't make the determination based solely on that 125Hz number. Something looks odd in that chart. If you go out and physically look at the data sheet, the 25mm looks significantly worse compared to 703. Then the 50 and 75mm look almost identical at 125Hz. I'm wondering if it's a misprint or just an abberation of the particular test.

Normally, there's a somewhat reasonable progression as you move from 25 to 50 to 75 to 100mm. Also, just from personal experience, even the best unfaced materials would have a really hard time doing .41 at 125Hz. Best I've ever used/seen is the 3lb acoustical cotton. It's only .35 at 125Hz.

The Supertel numbers quoted are much more consistent with 50mm fiberglass/mineral glass board of that density.

Bryan
 

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How much did it cost per pack?

If it's cheaper it looks like it could be the go.

Using Bob Golds Coefficient site:

Glasswool Supertel 50mm kg/m3 0.27 0.75 1.12 1.12 1.07 1.04 1.03 1.01

Insulco Semi Rigid IB (nil) 50mm 0.41 0.84 1.02 1.25 1.22 1.16 1.10

Insulco seems to do slightly better down low.
It came as an individually wrapped sheet, direct from Bradfords.. I don't think it comes in packs.
It cost $65.00 (inc.GST)..
The 50mm. Supertel is a very efficient bass absorber and I had to use it sparingly..
 

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I haven't at this point..I'm working on a design for the panels that will be a wall feature, as opposed to individual panels mounted to the wall.
My theatre is already pretty dead acoustically so most of my panels will be just Polyfill..

I finished up the bass traps last night and played Terminator 3..The whole room virtually vibrated through most of the movie..
 

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Discussion Starter · #37 ·
I finally got around to covering my panels, it only took me 10 months. I used speaker grill cloth from jaycar, they cost 17 bucks for a 1m x 1.5m sheet.

Picture 003.jpg

Picture 004.jpg
 
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