has a density of around 45-50 kg/m3. As far as I understand from reading this forum it should be the best one for broadband absorption, correct? I base that on the OC specifications provided in their website.
Do you have a link to that? I'd like to see it...
Also, density is not really the issue. What matters is something called "Gas Flow Resistivity", which is measured in the unlikely units of "MKS rayls". There's an
approximate relationship between density and GFR, but it is different for each type of insulation. For fiberglass products, if the density is around 28 g/m3 then it should have decent GFR that is suitable for wall cavities and bass traps. But if the material is mineral wool, then you'd need a density of around 48 kg/m3 to get similar GFR.
However, the relationship isn't perfect, and there's still the issue of binders, additives, and the manufacturing process itself.
There's also the issue of what you want to use it for: If you need it to absorb only high frequencies without doing much for lows, then you need a much higher density, probably around 60-80 kg/m3 for fiberglass, and maybe 90-120 kg/m3 for mineral wool. But if you want something that is better at absorbing down to very low frequencies, then you need a lower density. Maybe 20 kg/m3 (fiberglass) or 30 kg/m3 (mineral wool).
And as Frank mentioned, there's also the difference between non-rigid ("fluffy"), semi-rigid, and rigid products, as well as faced and un-faced, and in the case of faced, if it is kraft paper, foil, or something else.
Take care when you compare products: Make sure they really do perform the same, by comparing published independent specs! There are other products that perform as well as 703, or even better, but usually they are not cheaper. There's a certain cost to making high quality insulation products that absorb down to low frequencies, and cutting corners makes the product cheaper, but not better.
- Stuart -
