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Density for big triangular corner traps Studio Monitors
Old 1st April 2010
  #1
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Density for big triangular corner traps

Lower density seems to be better for large triangular traps, but it's difficult to find any definite answers to how thickness and density correlates.

My triangles are 60*60*84 cm. How will rockwool of 30 kg/m3 compare to rockwool of 60 kg/m3 here?
Attached Thumbnails
Density for big triangular corner traps-stastenderplater-medium-.jpg  
Old 1st April 2010
  #2
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Quote:
How will rockwool of 30 kg/m3 compare to rockwool of 60 kg/m3 here?
With out lab testing it would be hard to say, but you should be fine with the 30 kg
Old 1st April 2010
  #3
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Quote:
Originally Posted by bwo View Post
Lower density seems to be better for large triangular traps, but it's difficult to find any definite answers to how thickness and density correlates.
Read the text Sound Insulation by Lahy. It gives an academic explanation of the relationship between density and air flow resistance. We use density as an indicator for the air flow resistance.

IOW it is well known, just not in musician level acoustics.

Andre

Last edited by avare; 13th April 2010 at 02:44 PM.. Reason: Corrected HTML errors
Old 13th April 2010
  #4
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[QUOTE=avare;5263212]
Quote:
Originally Posted by bwo View Post
Lower density seems to be better for large triangular traps, but it's difficult to find any definite answers to how thickness and density correlates./QUOTE]
Read the text Sound Insulation by Lahy. It gives an academic explanation of the relationship between density and air flow resistance. We use density as an indicator for the air flow resistance.

IOW it is well known, just not in musician level acoustics.

Andre
Do you have a link?

I've made one and used 30kg/m3 rockwool. It definetly performs well, but I'm wondering if I should have used material with higher density. In the process of building a second one now and would be nice if anyone has any more input.
Old 13th April 2010
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[QUOTE=bwo;5302389]
Quote:
Originally Posted by avare View Post
Do you have a link?
Lahy, Sound Insulation. Expanding what I wrote above, this a text for acoustics experts, not just recording studios. Excellent text, and very academic.

Quote:
I've made one and used 30kg/m3 rockwool. It definetly performs well, but I'm wondering if I should have used material with higher density. In the process of building a second one now and would be nice if anyone has any more input.
How deep is your bass trap? If it is 300 mm or more, then a denser material would have provided worse performance.

Andre
Old 13th April 2010
  #6
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[QUOTE=avare;5302623]
Quote:
Originally Posted by bwo View Post
How deep is your bass trap? If it is 300 mm or more, then a denser material would have provided worse performance.

Andre
As mentioned in the first post it's a superchunk and the triangles are 60*60*84 cm. Height is 130 cm.
Attached Thumbnails
Density for big triangular corner traps-diverse-003-medium-.jpg   Density for big triangular corner traps-diverse-005-medium-.jpg  
Old 13th April 2010
  #7
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Quote:
Originally Posted by bwo View Post
As mentioned in the first post it's a superchunk and the triangles are 60*60*84 cm. Height is 130 cm.

Sorry. The lighter material is better!

Andre

Last edited by avare; 14th April 2010 at 03:50 PM.. Reason: Corrected HTML
Old 14th April 2010
  #8
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wow now that is going to be one heck of a nice trap. thumbsup
Old 14th April 2010
  #9
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Thanks Glenn.

I didn't think I was going to be able to pull the fabric across the whole thing, so the first didn't look that nice (visible stables as seen in first picture). Have to redo that one later.

On the second one I added more wood on the top and on the bottom to make is easier to attach the fabric on the back. Hope that doesn't decease the performance. Cause the more open it's on the back the better right?

The second with the fabric strected over became quite nice looking, apart that it's large of course. It replaced triangels of 43*43*60 (60 kg/m3).

By the way. I assume it's ok to have a membrane panel standing close to it? My membrane absorbents have 15 cm of rockwool (60 kg/m3), plastic sheet on the front and a frame on the back that is almost 5 cm.
Attached Thumbnails
Density for big triangular corner traps-diverse-008-medium-.jpg   Density for big triangular corner traps-diy-002-medium-.jpg   Density for big triangular corner traps-diy-004-medium-.jpg   Density for big triangular corner traps-diy-006-medium-.jpg   Density for big triangular corner traps-diy-007-medium-.jpg  

Density for big triangular corner traps-diy-008-medium-.jpg   Density for big triangular corner traps-diy-009-medium-.jpg  
Old 15th April 2010
  #10
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That's fantastic...nice job!

Frank
Old 16th April 2010
  #11
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Quote:
By the way. I assume it's ok to have a membrane panel standing close to it? My membrane absorbents have 15 cm of rockwool (60 kg/m3), plastic sheet on the front and a frame on the back that is almost 5 cm.
That is fine.

BTW I saw you (I think that was you) at another forum (happen to check in but don't post there due to some nasty people) and sorry you got treated the way you did.
If you have questions on our Tri Trap please feel free to ask here and I will help as much as I can.
Old 16th April 2010
  #12
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Thank you Glenn. You guys are great. I'm done with the forum you are mentioning.
Old 9th January 2011
  #13
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Quote:
Originally Posted by avare View Post

Lahy, Sound Insulation. Expanding what I wrote above, this a text for acoustics experts, not just recording studios. Excellent text, and very academic.


How deep is your bass trap? If it is 300 mm or more, then a denser material would have provided worse performance.

Andre
In the interest of keeping a great thread going - I would like to build some 'superchunk' style traps very similar to the ones posted above (nice work bwo!), but the material I have access to (thermafibre 4" fire batts) has a density of 64kg/m3.
If I make the wall sides of the equilateral 12", I will have a trap face of about 17" and a depth of about 8.5" or ~ 215mm. Is this an optimal design based on the density of the mineral wool, or will the trap be too small to be effective? The ceiling is just shy of 8ft.

(Depending on how I cut the mineral wool, I can achieve trap depths of ~860mm, 430mm, 215mm etc... )

Or, would that insulation be used better in 2'x4'x4" or 2'x4'x8" panels placed in the corners?

Cheers,

low_z
Old 9th January 2011
  #14
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Quote:
Originally Posted by low_z View Post
I have access to (thermafibre 4" fire batts) has a density of 64kg/m3.
That will work fine. The deeper the trap, the lower teh frequency range it works down to.

Andre
Old 27th April 2011
  #15
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Hey BWO
Hows it going?? Noticed your bass traps...excellent job!! Im going to attempt this and hope mine turn out as well as yours. How are they working?? As far as the rockwool, we have a product in canada called safe and sound made by roxul. its density is 2.5 pcf or 40 kg/m3. Im thinking its fine for a deep trap such as yours....after using yours would you suggest denser or less dense material?? Denser material , Im assuming, could be had by packing more into the available space?? Let me know what you think.

Thanks
Doug
Old 28th April 2011
  #16
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Quote:
Originally Posted by bentfrog View Post
Hey BWO
Hows it going?? Noticed your bass traps...excellent job!! Im going to attempt this and hope mine turn out as well as yours. How are they working?? As far as the rockwool, we have a product in canada called safe and sound made by roxul. its density is 2.5 pcf or 40 kg/m3. Im thinking its fine for a deep trap such as yours....after using yours would you suggest denser or less dense material?? Denser material , Im assuming, could be had by packing more into the available space?? Let me know what you think.

Thanks
Doug
They perform very well. Below 100 Hz there are of course better options (resonators), but they will not work in a broad range. For an excellent result one really needs both.

I would think 40 kg/m3 for that size is fine. Probably not a big difference between 30 kg/m3 and 40 kg/m3. My guess, from building smaller chunks and comparing 65 kg/m3 to 45 kg/m3, that one with 40 kg/kg will perform a little better in the bass above 100 Hz and one with 30 kg/m3 will peform somewhat better below 100 Hz. But it will be minor.

Here's some pics of other superchunks I've built.
Attached Thumbnails
Density for big triangular corner traps-trekant-bassfeller-oppa-hverandre-002-large-.jpg   Density for big triangular corner traps-diy-tri-trap-001-large-.jpg  
Old 28th April 2011
  #17
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very nice!
Old 12th May 2011
  #18
tun
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Guys, sorry for hijacking. I've been reading as many threads as possible before I start my superchunks build. I've been trying to find a pink fluffy equivalent here in Thailand but as yet haven't had any luck.

One option I was considering is Rockwool RWA45 (45kg/m3), available in 120x60cm slabs, however after reading Andre's very helpful comments I now know that RWA45 wouldn't be suitable for a build like bwo's 60*60*84 cm superchunk.

So, just out of interest, may I ask what would be the ideal size of the triangle if I were to use RWA45 (45kg/m3)?

Many thanks in advance.
Old 12th May 2011
  #19
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As I said before without lab testing there is no way to really know, but I would think the 45 you can get will work pretty well.
Old 19th May 2011
  #20
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Quote:
Originally Posted by bwo View Post
Thank you Glenn. You guys are great. I'm done with the forum you are mentioning.

hehe what forum is that? we should all make accounts and go there an give them a taste of their own medicine!

heh
Old 19th May 2011
  #21
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Quote:
Originally Posted by ajbianco View Post
hehe what forum is that? we should all make accounts and go there an give them a taste of their own medicine!

heh
Acoustics Forum • Index page
Let them have it!
Old 20th May 2011
  #22
Fhl
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Nice work, bwo! Veldig bra jobba

May I ask what fabric you used? Where did you get it? I'm in the process of building several bass traps myself. Although I can't decide between only panels or corner traps (size issues).

Old 20th May 2011
  #23
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Quote:
Originally Posted by Fhl View Post
Nice work, bwo! Veldig bra jobba

May I ask what fabric you used? Where did you get it? I'm in the process of building several bass traps myself. Although I can't decide between only panels or corner traps (size issues).

For the biggest ones I used rockwool Flexi-A plater. You get them everywhere at stores like Montér, Byggmax, Byggmakker, Neumann Bygg, etc.

For the smaller ones (black) I used rockwool Murplater. I don't think anyone has those in stock, but they can order them for you.
Flexi A-plate :: Byggisolering :: Produkter :: AS Rockwool
Murplate :: Byggisolering :: Produkter :: AS Rockwool
Old 21st May 2011
  #24
Fhl
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Quote:
Originally Posted by bwo View Post
For the biggest ones I used rockwool Flexi-A plater. You get them everywhere at stores like Montér, Byggmax, Byggmakker, Neumann Bygg, etc.

For the smaller ones (black) I used rockwool Murplater. I don't think anyone has those in stock, but they can order them for you.
Flexi A-plate :: Byggisolering :: Produkter :: AS Rockwool
Murplate :: Byggisolering :: Produkter :: AS Rockwool
Thank you. Those are the same densities I've been looking at.
What about the textile fabric?
Old 21st May 2011
  #25
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Quote:
Originally Posted by Fhl View Post
Thank you. Those are the same densities I've been looking at.
What about the textile fabric?
Unless you want them to be reflectice you should buy acoustic or speaker fabric. Regular cotton fabric will reflect some. Biltema has speaker fabric I believe or I can recommend DMD fabric that comes in many different colors:
DMD ACOUSTIC FABRIC BY THE YARD
Old 21st May 2011
  #26
Fhl
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Quote:
Originally Posted by bwo View Post
Unless you want them to be reflectice you should buy acoustic or speaker fabric. Regular cotton fabric will reflect some. Biltema has speaker fabric I believe or I can recommend DMD fabric that comes in many different colors:
DMD ACOUSTIC FABRIC BY THE YARD
Excellent! Takk
Old 31st May 2011
  #27
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They look awesome

So is it better to have "superchunks" (i guess this is just rockwool cut into triangles) than to have full traps attached to the wall?

By full traps i mean large full panel bass traps from floor to ceiling?

Or superchunks from floor to ceiling?

Mark
Old 31st May 2011
  #28
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Quote:
Originally Posted by soundmagus View Post
They look awesome

So is it better to have "superchunks" (i guess this is just rockwool cut into triangles) than to have full traps attached to the wall?

By full traps i mean large full panel bass traps from floor to ceiling?

Or superchunks from floor to ceiling?

Mark
In corners yes. On flat surfaces (like frontwall and backwall) no. But remember that where the wall meets the floor and where ceiling meets the wall are also corners.
Old 8th June 2011
  #29
FDW
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Quote:
Originally Posted by soundmagus View Post
They look awesome

So is it better to have "superchunks" (i guess this is just rockwool cut into triangles) than to have full traps attached to the wall?

By full traps i mean large full panel bass traps from floor to ceiling?

Or superchunks from floor to ceiling?

Mark
As Ethan W. said in a post a long time ago, superchunks are slightly better than panels of the same size, if cost is no issue. But they are much much more expensive for not that much extra gain. So it's better to put more panels in corners than less chunks in corners.
Old 8th June 2011
  #30
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Quote:
Originally Posted by FDW View Post
As Ethan W. said in a post a long time ago, superchunks are slightly better than panels of the same size, if cost is no issue. But they are much much more expensive for not that much extra gain. So it's better to put more panels in corners than less chunks in corners.
I'd say three things to that:

- yes
- no
- it depends

Starting with the latter, I think it depends on how large the superchunk is going to be. If you are buildiung a whopper, then you would be better off with lower density "fluffy" stuff, which is far cheaper than panels. But you would not be able to straddle a corner with fluffy because it would not be rigid enough and would therefore be very tough to support. I have not calculated it, but I wuold guess that there would be either little price difference or perhaps the superchunk might be cheaper in a large design. More material needed for the superchunk, but much cheaper to buy. AND more effective.

As the trap gets smaller, then I think your point becomes more valid.....

Just my two pennies

Max
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