I was wondering what is the main benefit of using fiberglass aganisnt high density foam 5lb pcf or 8,75lb pcf (80 kg/m3 or 140 kg/m3). Since my room is for mixing but I do sleep there too, I was concern about the health issues involved with Fiber glass or rockwool.
If the density is about the same, would their behavour on bass frequencies be aboud the same?

(I'm in Spain and wished I could get acoustic cotton, for I heard it has great properties on low frequecies.)

My room is 4,12 m * 2,88 m * 3 meters high.
I have my monitors againts the longest wall because the other one a non centered glass window.

I measured a big peak at 117 Hz, then a second one at 141 Hz. There's also a small one at 54Hz.

I was planning on building 33 cm wide (about 1 foot) triangular corner bass traps made from 5 lb pcf foam and cover all 4 meters of the corner between my front wall and the ceiling, and maybe 2 more meters wide on the side wall to the ceilling. I probably would need more. How much more bass traps and where to place them would you recommend me?

Thanks a lot in advance !!

Guido.

Guido,

There's more to absorption than just density. The material must also be the "right type" to function as an absorber. Some foams are very good and some are not, regardless of their density. The best way to know if a proposed material is useful acoustically is to look at the manufacturer's absorption data. If a company sells a material but has no absorption data, it's probably not good acoustically.

Also, fiberglass and mineral wool are not particularly dangerous. As long as they're covered with an appropriate fabric they are perfectly safe.

--Ethan

Hi Ethan, Thanks a lot for your quick response!

What would be an appropriate fabric to cover the fiberglass or mineral wool panels?

Thanks in advance.

Guido.

Put some thin batting (cotton or poly - like the stuff you fill a pillow with) over the fiberglass/wool and then wrap in something like burlap or muslin.

As for how other things perform, one of the main things is its gas flow properties. From this standpoint, even fiberglass and mineral wool are pretty different.

Also, you need to consider the material itself. For instance fiberglass is made from? Glass - reflective. Rockwool/mineral wool is made from? Metal/rock slag - reflective. Acoustical cotton is made from? Cotton - absorbtive.

Bryan

Thanks for your answer!

I'm still thinking about whether to go with the mineral wool or with the heavy density foam made from mixed polyurethane types "in a controlled way".
All the data they give is this (sorry it is in spanish):





The three graphs are from top to bottom for the ceiling, wall, and floor installations. Always with plywood covering it. The white line shows the results without the foam and the black one with it. They relate to noise isolation I guess, so it’s difficult to calculate how would they work at low frequencies when a corner bass trap of a about a foot wide is built with them.
Would you think that with these graphs we can predict anything about this material?
The main benefit is that it's a lot easier to handle (cut, put into place, etc.) than Fiberglas or mineral wool.
Thanks again for your help.

Guido.

No problem - except all they're showing is noise reduction as part of a strructure - nothing with regard to absorbtion coefficients.

Bryan