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svenr

Polyester insulation 30 to 45kg/m3 in Melbourne area

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Hi Guys. Yes the 168kg/m3 is in the form of a partition. And yes it is 13mm. could be good though for some applications. Perhaps in a DIY bass absorber maybe?

The product I happed to see Peter the Greek was 96kg/m3 ductboard from fletcher insulation in Dandenong. Not sure if its what your after but its a very dense glasswool product for air con ducts. Could be good maybe.

 

Cheers. Yeah, fibreglass ones are easy to find.....just not polyester, which I prefer

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@ Peter - give Autex in West Heidelberg a call and ask for Rob Jones (market & development manager).

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I had someone asking about a certain brand of polyester batts and whether they could be used for an absorber / diffuser.  Put it that way:

 

Any polyester batt with R2.5 rating and a given thickness and bulk density will pretty much behave the same way acoustically.  The flow resistivity of such a polyester batt will range somewhere between 5,000 and 7,000 Pa.s.m-2.  There are some minor differences due to the way they manufacture these batts which positively affects the absorption at low frequencies.  But both the thermal and the acoustic properties are dominated by the tortuosity of the open flow path and the bulk density of the fibre skeleton.  So if the batt is R2.5 rated, its flow resistivity will fall in the above range and its acoustic behaviour is set.

 

To put it another way - if the above flow resistivity is acceptable for your purpose, there is no need to buy anything else other than the cheapest product you can find.

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old thread, but just revisiting this page based on other threads....

only talking about polyester...

 

If you're handy enough to build a frame, and cover it (for aesthetics only - poly doesn't leak fibres), then R2.5 Greenstuf is the cheapest by far - I paid $24 for a pack of 10 (approx. 1150x430x120mm).

Also works great as speaker stuffing.

You could use this product for all absorption treatment if it doesn't need to be free standing, but WAF factor will mean covering

 

If you need something that will stand up on its own to ceiling height I recommend Tontine Acoustisorb 3 which comes in sheets 2400 x 1200 in various thicknesses - I paid $163 for a pack of 3 x 75mm thick.

Again the WAF will determine if it needs to be covered - mine is OK leaving it uncovered in the dedicated stereo room - the lounge room has very different rules.

 

The other poly products may be better but way more expensive - better to go thicker on the cheaper products if bang for buck is the primary goal.

 

The best thing I've found for cutting the stuff is the thin multi purpose discs for angle grinders from Bunnings. Need to clamp it (both sides) to get a neat cut with strips of wood (or other straight edge).

 

If looks are critical (ie you're not going to cover it), best not to cut it at all, and make the factory sizes fit, or get the supplier to cut it on their tables with the proper tools.

 

If using the Greenstuff batts, don't cut it at all just manage your trap size to fit multiples of the batt sizes.

 

Well done to Svenr for the research on gas flow resistivity - I think you've found the sweet spot in bang for buck with the greenstuff batts.

 

cheers

Mike

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I have tried to purchase polymax 48/100 and martini will not produce any unless you order a min of 12 full sheets.

So I'm looking at autex aab 48/100, their $63 per 2400x1200x100mm sheet which isn't too bad for 48kg.

http://www.autex.com.au/files/files/669_Autex_Absorption_Blanket_-_AAB.pdf

I'm building ikea ivar bass traps which are 500mmx420mmx2.26m tall. It's another project taken from gearslutz forum.

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I've used tontine, just keep jamming it in there to increase the density and flow resistivity :).

Or go to bunnings buy a big tube to use as an impedance tube and measure the absorption properties of different samples.

Completely agree that anything with acoustic in the name is hugely inflated in price!

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Sorry for resurrecting old thread... and a bit off topic too

Came across this thread while goggling to decide which wall batt to use.  Far out.... this bass trap stuff can get confusing and is far too much for my needs. :) Nonetheless, thought someone might be able to answer my question:

 

Greestuf and Earthwool 2.7SHD wall batts are similar price and they will be in a wall - not a bass trap.  Is there going to be any discernible difference for general sound minimisation between walls.  

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9 hours ago, bennygsr said:

Greestuf and Earthwool 2.7SHD wall batts are similar price and they will be in a wall - not a bass trap.  Is there going to be any discernible difference for general sound minimisation between walls.  

 

No - anything fluffy will do. The idea is to stop the wall cavity behaving like a drum. You need isolation and mass to achieve any decent level of soundproofing

 

Read here

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