What material is best for thick bass Traps?

[rimmi2002]

Hi, I am trying to build corner bass traps. I am thinking about doing 24" on each side with ~34" diagonal in some areas and 17" on each side x 24" diagonal in others. While researching, I read in one post that for traps thicker than 8"—which these will be—Owens Corning or Roxul Safe'n'Sound (which I was planning on using) is not as effective for bass as lower-density material. Is that true? If so, what would be the best material to fill these with to maximize absorption of the lower frequencies?


Is there perhaps an online calculator where I can select the material and thickness of the panel and see absorption profiles at different frequencies?

Thanks in advance for your help!

 

[DVDdoug]

I don't know but Ethan Winer has an article about building you own thin (membrane) bass traps. He's got more on his website. (His company RealTraps sells acoustic treatment.)

 

[Flaesh]

lower-density material

See somewhere at avs forum about mikela's home theater. Or simply acousticmodelling .com
For the same reasons, wedges are used in anechoic chambers.

 

[kemmler3D]

Welcome to ASR! Any reason you are going for super thick porous traps instead of membrane? If you have the space and budget for that much absorption, I'd assume you could get better results with membranes. And, you will have an easier time not over-damping the treble and mids.

 

[rimmi2002]

Welcome to ASR! Any reason you are going for super thick porous traps instead of membrane? If you have the space and budget for that much absorption, I'd assume you could get better results with membranes. And, you will have an easier time not over-damping the treble and mids.

Thanks for the welcome. This seems like a great community. I’m going with the super thick porous traps mainly for budgetary reasons. I can build them at home. Membranes are way too expensive. My RT60M time for frequencies from 20 to 80 Hz is close to 1.8 seconds. Just dropping 9 bats of Rouxel, safe and sound loaded on top of each other in one corner dropped that time from an average of 1.8 seconds to 1.5. Not only that but the bass it’s already way punchier than before. It was all muddy before ar the lower frequencies.

I'll update with some REW curves in the next 1-2 days.

I don't know but Ethan Winer has an article about building you own thin (membrane) bass traps. He's got more on his website. (His company RealTraps sells acoustic treatment.)

Thanks this was a great resource. I read through the whole FAQ. A lot of great info.

See somewhere at avs forum about mikela's home theater. Or simply acousticmodelling .com
For the same reasons, wedges are used in anechoic chambers.

Thanks will look into this.

 

[Audio Science Pal]

9 bats of Rouxel, safe and sound loaded on top of each other in one corner

I use the 24 x 24 x 48" bundles still wrapped in the original plastic, then cover them with decorative fabric.

 

[Holmz]

I don't know but Ethan Winer has an article about building you own thin (membrane) bass traps. He's got more on his website. (His company RealTraps sells acoustic treatment.)

^That^ is a pressure trap…
Which might be an idea.

Hi, I am trying to build corner bass traps. I am thinking about doing 24" on each side with ~34" diagonal in some areas and 17" on each side x 24" diagonal in others. While researching, I read in one post that for traps thicker than 8"—which these will be—Owens Corning or Roxul Safe'n'Sound (which I was planning on using) is not as effective for bass as lower-density material. Is that true? If so, what would be the best material to fill these with to maximize absorption of the lower frequencies?


Is there perhaps an online calculator where I can select the material and thickness of the panel and see absorption profiles at different frequencies?

Thanks in advance for your help!

Do you know the frequencies that you have in the room?
Ie. a microphone and measurements?

 

[kemmler3D]

I’m going with the super thick porous traps mainly for budgetary reasons. I can build them at home. Membranes are way too expensive.

Makes sense and that would be one of my key motivations also.

Membrane traps can be built at home with not-too-exotic materials... VPRs might be cost competitive and more effective for the bottom two octaves. Here is a thread on building VPRs and there is a link to limp mass traps also. Winer's designs are also worth looking at.

You may be able to get better performance on a similar budget if you go this route... absorption (velocity) traps can work but they're much less efficient for bass.

 

[rimmi2002]

Thanks for your help guys. Your input is really helping. Wish I found this forum sooner. For some reason I couldn't access this forum from my home computer before and now I got it fixed. I start a new post with all detailed info and REW curves so that way you have all the info related to the room / setup.

 

[rimmi2002]

I use the 24 x 24 x 48" bundles still wrapped in the original plastic, then cover them with decorative fabric.

Are they effective wrapped in plastics?? I though plastic would reflect the sound and not let it get through to the insulation inside?

 

[Flaesh]

Are they

Yes, they are. You may try acousticmodelling.com.

 

[Audio Science Pal]

Are they effective wrapped in plastics?? I though plastic would reflect the sound and not let it get through to the insulation inside?

Yes. The plastic wrapping keeps the mineral wool fibers more densely packed together for an efficient bass trap and the plastic outer surface will reflect the higher frequencies to allow a more natural sounding room.

 

[rimmi2002]

Yes. The plastic wrapping keeps the mineral wool fibers more densely packed together for an efficient bass trap and the plastic outer surface will reflect the higher frequencies to allow a more natural sounding room.

Wow this might be the best quick fix of them to test things out before building the final panels. Curious what type of mineral wool do you use for your bass traps...from what I modeled on www.acousticmodelling.com is that 3000-5000 flow resistivity is the sweet spot as you start getting > 16" thick.

 

[Audio Science Pal]

Curious what type of mineral wool do you use for your bass traps

Roxul Safe'n'Sound. Whatever similar material and size is locally available to you from an insulation supply should work just as well. The bundles are bulky, heavy and won't fit inside a compact car. Keeping them in the original wrapping also allows you to return them if they don't fit your plans.