almikel Posted October 17, 2010 Share Posted October 17, 2010 Guys, about to commence a DIY bass trapping project and want to use the equivalent of 703 semi rigid fiberglass (45Kg/cubic m) or 703 FRK, the same with the foil attached. Andrew from fonic posted a link but I can't find it. What is the equivalent known as in Australia? Mike Link to comment Share on other sites More sharing options...
aechmea Posted October 17, 2010 Share Posted October 17, 2010 http://www.insulation.com.au/content/upload/FI_DS_FI32%20SemiRigid%282%29.pdf Link to comment Share on other sites More sharing options...
aechmea Posted October 17, 2010 Share Posted October 17, 2010 http://www.insulation.com.au/product.aspx?product_id=76 is the 'Industrial Products' manual including pricing 32Kg/m3 on p5 48Kg/m3 on p6 Link to comment Share on other sites More sharing options...
Guest Peter the Greek Posted October 17, 2010 Share Posted October 17, 2010 I'd suggest polyester - www.acoustica.com.au sell is in 48kg (white HD batts) Or John Manville can get it too - they can get it in black which is good if its going behind an AT screen? Link to comment Share on other sites More sharing options...
Kevin Posted October 17, 2010 Share Posted October 17, 2010 Tell us how you get on Mike - sounds as if you have a challenging smaller room. Kevin Link to comment Share on other sites More sharing options...
aechmea Posted October 17, 2010 Share Posted October 17, 2010 Elill beat me to it http://www.acoustica.com.au/hdbatts.html These are poly rather than glass so that makes them more tempting; at least for me. Link to comment Share on other sites More sharing options...
almikel Posted October 18, 2010 Author Share Posted October 18, 2010 Thanks guys, I did some phoning around - polyester is about twice the price, but probably worth it if it's as good as semi rigid fiberglass. Apparently the polyester is difficult to cut, but supposedly tears in one direction OK, but the sample I've got here neither tears easily in either direction or cuts well - although I don't have a sample of semi rigid fiberglass to compare. It seems I'll need to cut either product as all I've found is 1200x2400 sheets, which I'd cut into 1200x600 slabs for each trap - I'm going simple 1200x600x100 traps to either straddle corners or mount on a flat wall 100-150mm spaced of the wall. The extra cutting is another reason I'm not going for superchunks. Also did a quick search on Bob Gold's site: http://www.bobgolds.com/AbsorptionCoefficients.htm absorption coefficient of 0.5 @ 125Hz for polyester at 100mm thick 48 Kg/m (not the brand I'll get) absorption coefficient of 0.84 @ 125Hz for semi rigid fiberglass 102mm thick 48 Kg/m (not the brand I'll get) Even though it's nastier to work with the fiberglass appears significantly better I suspect the difference is due to fiberglass having a higher flow resistivity than polyester (neither are quoted) even though they have the same density (48Kg per cubic metre). Density is a good indicater of the flow resistivity between different thicknesses of the same material, but not between different materials. Unforunately before the bass traps get built I will probably re-sheet the room first, as it's sheeted with asbestos (walls and ceiling), and SWMBO and I have been discussing getting rid of all the asbestos (professionally) downstairs. That may mean I get to play with some green glue first (depending on cost) to enable some soundproofing plus "letting the boundaries move" quoting Toole. Mike Link to comment Share on other sites More sharing options...
Primare Knob Posted January 12, 2018 Share Posted January 12, 2018 A rather old topic, but I like to revive it as I am also researching materials for bass traps. It is rather hard to find a material with 48kg/m3 or even higher, but I did came across this Knauf Mineral Wool Earthwool Building Slab RS60 60kg/m3 or RS100 100kg/m3 My search with other alternatives comes up rather empty. Link to comment Share on other sites More sharing options...
Gav67 Posted January 12, 2018 Share Posted January 12, 2018 A rather old topic, but I like to revive it as I am also researching materials for bass traps. It is rather hard to find a material with 48kg/m3 or even higher, but I did came across this Knauf Mineral Wool Earthwool Building Slab RS60 60kg/m3 or RS100 100kg/m3 My search with other alternatives comes up rather empty. Hi, I used Bradford Ultratel[emoji769] which has a density of 48kg/m3 for my Rives Acoustic Treatments designed room back in 2011. It has a similar specification to the USA Corning 703 and was confirmed as suitable by Richard Rives. Available in 1" and 2". Picture of rear bass trap before the front fibreglass sheet was installed and cloth cover. I used Ultratel for corner bass traps, wall absorption panels, ceiling diffuser and ceiling absorber. Hope this helps. 1 1 Link to comment Share on other sites More sharing options...
almikel Posted January 12, 2018 Author Share Posted January 12, 2018 1 hour ago, Primare Knob said: A rather old topic, but I like to revive it as I am also researching materials for bass traps. It is rather hard to find a material with 48kg/m3 or even higher, but I did came across this Knauf Mineral Wool Earthwool Building Slab RS60 60kg/m3 or RS100 100kg/m3 My search with other alternatives comes up rather empty. Lol - I did a double take when I saw I started this thread the key metric to find is the Gas Flow Resistivity, and use the Porous Absorber calculator to see how it models at low frequencies (given you want to trap low frequencies) http://www.acousticmodelling.com/porous.php Denser isn't necessarily better, and around the 48kg-60kg/m3 is about as dense as you want to go, with thicker "fluffy" being just as effective. Ultratel works fine if you're happy to work with fibreglass - and it's much easier to cut than Poly Polymax XHD is the usual "go to" product for similar density poly. I purchased Tontine Acoustisorb 3, which was a fair bit cheaper than XHD, but it's not available anymore. Ordinary fluffy batts like Greenstuf poly batts work very well with enough of it, and doesn't carry the cost premium of an "acoustic" product like Polymax XHD cheers Mike Link to comment Share on other sites More sharing options...
almikel Posted January 12, 2018 Author Share Posted January 12, 2018 this thread On 5/13/2014 at 12:40 PM, svenr said: 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. In summary: a key benefit from denser products in the 48kg/m3 range (fibreglass or poly) is that they'll free stand - although I've never tried mineral wool like you found, regarding its free standing ability fibreglass needs to be covered to keep fibres in (as does mineral wool), but is significantly cheaper (say Ultratel 'glass vs Polymax XHD) if you're happy to make frames and go large/deep, then any fluffy (poly or 'glass) will work very well ('glass fluffy still needs to be covered) - if you shop around you can get good deals on either fluffy 'glass or poly ('glass and poly appear similarly priced for ordinary batts, as opposed to Ultratel vs Polmax XHD) you'll need to trawl, but good info here regarding Gas Flow Resistivity specs: https://www.gearslutz.com/board/studio-building-acoustics/625978-common-gas-flow-resistivity-numbers.html cheers Mike 1 Link to comment Share on other sites More sharing options...
Primare Knob Posted January 20, 2018 Share Posted January 20, 2018 The biggest problem I am running into at the moment is: 1- CSR owns the Market, Bradford,m Martini and the Acoustic Orb manufacturer are all theirs. So prices for acoustic products seem really high to me. 2- All the products have been re-branded and matching the old data with the new product seems impossible. I am looking for a product to reduce LF energy for two applications. 1- Whole ceiling treatment. 180 - 200mm 2- Corner bass trap. 180 - 200mm Thicker is usually better, but as I understand it, the thicker you go you also want low gas flow resistance. Reading GearSlutz it more of less seems that you want a value around 10.000 mks Rayls /m with 200mm thick absorbents. But I could have it all wrong. Curaso IsoBond WLG35 has a very good LF absorption when used in 200mm thickness, and has a value of 10.000 mks Rayls /m Link to comment Share on other sites More sharing options...
Primare Knob Posted January 20, 2018 Share Posted January 20, 2018 (edited) On 1/12/2018 at 6:55 PM, Gav67 said: Hi, I used Bradford Ultratel which has a density of 48kg/m3 for my Rives Acoustic Treatments designed room back in 2011. It has a similar specification to the USA Corning 703 and was confirmed as suitable by Richard Rives. Available in 1" and 2". Picture of rear bass trap before the front fibreglass sheet was installed and cloth cover. I used Ultratel for corner bass traps, wall absorption panels, ceiling diffuser and ceiling absorber. Hope this helps. Do you know what the gas flow resistance value is of the product? Looking in the brochure, you can order these panels with an applied facing straight from the factory. One seems to be with a perforated front. Might be helpful for me to create some scattering of the di-pole wave of my speaker instead of killing it. https://www.bradfordinsulation.com.au/-/media/bradford/files/supertel-datasheet.pdf Take a look the 125Hz data for the one applied with the Acoustituff facing. That is looking very promising. The HD perf facing ins't bad either. https://www.bradfordinsulation.com.au/-/media/bradford/files/ultratel-datasheet.pdf Or the difference between the perforated face and unfaced finnish. Edited January 20, 2018 by Primare Knob Link to comment Share on other sites More sharing options...
Gav67 Posted January 21, 2018 Share Posted January 21, 2018 No, I don't know what the gas flow resistance values are. The data sheets do include acoustic test results to Aust Standards if that helps. I only used the unfaced 25mm and 50mm versions as per the Rives design. Where high frequency reflection was required (eg front corner bass traps), builders plastic lining was used to coat the front facing Ultratel sheet before the final fabric cover. I would assume mid and high frequency reflection on the front wall area would be essential for dipole speakers. Construction photos of the front corner bass traps: Front Face Plastic Lining and trim Finished with cloth cover FYI, the ceiling joist area (two storey with floor above) between the speakers and listening chair are also treated with layers of Ultratel and sheets of 13mm acoustic Gyprock with green glue in-between the joists. Finally, baffle boards at 30 degrees act as a diffusor. 1 Link to comment Share on other sites More sharing options...
Guest Peter the Greek Posted January 21, 2018 Share Posted January 21, 2018 FWIW, ultratel is SO much easier to work with/cut. @Primare Knob I recall a conversation I had with Andrew Steel once about increasing the density if you have 200mm+. So start fluffy, end up denser in say 50mm layers. I've never bothered to model it, but might be something to look at....but as I say, if me, dense as all get out and slats Link to comment Share on other sites More sharing options...
Primare Knob Posted January 21, 2018 Share Posted January 21, 2018 14 hours ago, Peter the Greek said: FWIW, ultratel is SO much easier to work with/cut. @Primare Knob I recall a conversation I had with Andrew Steel once about increasing the density if you have 200mm+. So start fluffy, end up denser in say 50mm layers. I've never bothered to model it, but might be something to look at....but as I say, if me, dense as all get out and slats Could you please explain this a bit more as I find this very confusing. Is this a 200mm trap straddling a corner and talking about fluffy at the front and increase density moving into the corner? Like density of 50mm layers; front = 1, second =2, third =3, fourth =4 ? What about gass flow resistance? Link to comment Share on other sites More sharing options...
Guest Peter the Greek Posted January 22, 2018 Share Posted January 22, 2018 1 hour ago, Primare Knob said: Could you please explain this a bit more as I find this very confusing. Is this a 200mm trap straddling a corner and talking about fluffy at the front and increase density moving into the corner? Like density of 50mm layers; front = 1, second =2, third =3, fourth =4 ? What about gass flow resistance? That's what he said, yes. Not in the corners though (he didn't recommend that either), for panels/large flat areas e.g your ceiling Link to comment Share on other sites More sharing options...
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