Material for bass traps and a little idea I have had

Hey, so I am just building my studio now after a few slight delays. My room dimensions : 13ft x 9ft x 8ft (l x w x h). I have 4 x GIK 244 bass panels, and a ceiling cloud absorber (1200 x 1200mm). I am just building my bass traps now which are floor to ceiling, 18'' x 18'', Does anybody know what material will be good for this? I have read that cara Camira is good, it is quite pricey at £50 for my 2 traps.. Is there ny cheaper alternatives in the UK that work just as good? Also my little idea, as you can see from my attached photo my studio is an old bedroom, so at the back (the opposite end to what I'm facing and where my traps are) there are 2 wardrobes, these wardrobes are hollow ( they have a mirror on the front and nothing on the back.) and are about an inch thick. I was thinking it could make sense to flip these round, put inside 25mm rocksil rs45 (the stuff I'm using for my bass traps) and cover them with a layer of fabric ( if I have to go with Camira for my traps I will definitely choose something cheaper for these). I have tried to attach a picture to show what i mean I should also mention my wardrobes that I want to convert are floor to ceiling and cover about 7ft in width I am curios as to whether this idea is any good or could be a bad idea acoustically? I only produce / mix electronic music in my studio, no recording etc.. Any ideas on this would be greatly appreciated! Thanks!!

as you can see from my attached photo

??? :shock: :!: Not seeing the photo! Maybe you forgot to attach it? But anyway, the basic idea of filling an old wardrobe full of insulation should work fine. Just take the doors off!

Does anybody know what material will be good for this? I have read that cara Camira is good,

Not sure what that is, or if you are asking about the insulation fill, the framing, or the fabric cover. If it's the insulation you are asking about, then go with either fiberglass that has a density of around 30 kg/m3, or mineral wool with a density of around 50kg/m3. Either will work. OR if you can afford it, get 4" panels of Owens Corning 703. - Stuart -

Sorry! I sent that last post from my iphone and in the end it wouldn't let me upload the pics in the end, anyway here they are, but i think you know what i mean anyway and thanks for the info! In regards to the 2nd bit, i meant the fabric to put over my traps, i am already filing them with Rocksil RS45 (knauf insulation slab stuff), however i was just curious to the best fabric to put over the front of the frames Thanks!!

Stuart - Thanks for your replies so far.. Just one last thing, i went to the insulation place earlier and the only 25mm stuff they had in was this isowool stuff, ive taken a picture so you can see, the place also builds studio's and the guy said this stuff should be ok but he said it could be anywhere from 60kg - 140kg m3, As you can see the wardrobes will be flipped around and 1 layer of 25mm will go on there with fabric over.. I can take this stuff back if need be and it wont be a hassle but have i bought good stuff for the job or is it a load of crap that he managed to sell to me? Just want to make sure im putting the right stuff up Cheers mate

Take a look at Ebay for good prices on Camira Cara fabric - I bought two lots from a trader on there and they both arrived direct from the factory the next day. I thought the Isowool stuff was only 22kg/m3 but it would be best to check the specs online. James.

Just one last thing, i went to the insulation place earlier and the only 25mm stuff they had in was this isowool stuff, ive taken a picture so you can see, the place also builds studio's and the guy said this stuff should be ok but he said it could be anywhere from 60kg - 140kg m3,

Like James said, best to call the manufacturer and find out for sure what density you are dealing with. That does say "rigid" and "floor slab", so I'm not so sure it will work for a bass trap! And especially if it really is as dense as the salesman said: That's way too dense for bass traps. The other thing you could do is to figure out the volume of that package (it says "1200 x 625" on the label= 0.75 m3), weigh it on your bathroom scales, then calculate the density. But even then, I'm not too convinced that rigid floor slab insulation is what you need for bass traps! Call Owens Corning, and ask them where you can buy their OC-703 product in your area. That's the best stuff. - Stuart -

Thanks very much stuart and James, i have done a few google searches on calculating the density however nothing has jumped out at me, Do you know the best way to work this out? The guy basically said to me because it isnt in a bass trap and accross the lining of a wardrobe it shouldnt be detremental, especially at 25mm, but hey im very new to this so i can only go off what people tell me! Thanks a lot!!

Actually, it isn't really the density as such that matters. What matters for acoustic purposes is a property called "gas flow resistivity", which basically refers to how the material reacts to air moving through it. That's the important characteristic, and that varies according to the type of insulation. The problem is, most manufacturers of insulation never bother measuring that, since it doesn't matter if you just want thermal insulation, so it's next to impossible to find that number for most ordinary materials. You only normally find it for things designed specifically for acoustic applications. Fortunately, there's a very rough relationship between the density of some materials, an their gas flow resistivity, so if you know the type of material and the density, then you can estimate the gas flow resistivity. For fiberglass insulation, the optimum range is about 30 kg/m3 density. For mineral wool, it's around 50 kg/m3. So any insulation you can find in roughly those ranges will work. You don't need to be anal about it, so if you find mineral wool at 45 or 55 kg/m3, that's great. Same if you find fiberglass at 25 or 35. But if you find fiberglass at 120 kg/m3, well, that's waaaaay too dense. That won't work well. The gas flow resistivity is just too high. Also, contrary to popular belief, higher density is NOT better for bass trapping: lower density is! That's not intuitive, but then again many things about acoustics are not intuitive, until you understand the science behind them. Bass = Low frequencies = long wavelengths. Means you need more space around the fibers for them to move and thus convert sound energy into low-grade heat energy. If the fibers are packed too tightly together, then they sort of "shield" each other and get in each other's way. So higher density insulation is better for high frequencies, but not for lows. It's actually a bit more complex than that, of course, but that helps you to get a mental picture of what is going on, and why certain densities are good for certain things. - Stuart -