12" Super Monster DIY Bass Trap - too much?

[theron d]

Hey guys, I purchased this yesterday -it's a 703 FSK equivalent fiberglass panels package (4 panels x 3" in the package shown). I was thinking about covering with a fabric and then placing in the corners of my 18' L x 18' W room. They are FSK so I plan on leaving the first layer on (and removing the rest) to reflect back some of the high frequencies. The cardboard packaging is strong, I may cut the "meat" out of the sides top to allow a little more absorption. I will treat first reflection points with some 4 or 6" FSK panels.

Room is not an issue, I don't mind placing these in the corners. Has anyone done this before? 12" thick bass traps? Is this insane?

Thoughts, opinions, hatemail welcome...

Theron

[zotty]

Hey,

If I could make a recommendation, take those square panels and make superchunks out of them.

http://www.radford.edu/~shelm/acoustics/bass-traps.html

I think they sound awesome. super, super easy if looks don't matter. mine are just covered in thick poly matting, instead of "speaker cover" looks. Do cover them, they will flake when touched, dust and air quality. With the poly only covering (completely), I have seen no fibers, but it's only been 6 months.

My experience: More is better when absortion is needed, but if you cover the room, it will kill any ambience. It's balance, but in the corners, more seems better.

Getting things tamed without neutering the room. I think it takes experimentation (ongoing here)

[zotty]

Hey, sorry.

you may want to consider saving your prime reflective fiberglass for 2 x 4 traps, buy cheapo (8 lb) rockwool for the heavy corners. The absorbtion cooefs are about the same, and a lot cheaper. I still prefer 705, 703 over rockwool mess.

If you go this way, do the work in a separate area garage or park or something and transport the finished product. it's a mess!

Just some notes from my experiences, hope they are helpful to you.

[avare]

Originally Posted by theron d

Has anyone done this before? 12" thick bass traps? Is this insane?

Thoughts, opinions, hatemail welcome...

I think so. No it is not insane.

Are you familiar with Superchunks? It reads like you are building those. If you are not familiar with them, go to Studiotips.com and search for superchunks. You will be pleasantly surprised.

Andre

[theron d]

Sorry for the confusion, I was not planning on doing superchucks, a thought was to simply leave the panels in the cardboard box they shipped in and wrap it (after removing the FSK foils except for the facing one and cut the "meat" out of the strong cardboard box to allow side and top absorption)...I was thinking of doing this as a very quick and cheap way of building some bass traps. THis is just a thought, I'll probably change my mind several times over before I decide exactly how I want to do this...

thanks
Theron

Originally Posted by avare

I think so. No it is not insane.

Are you familiar with Superchunks? It reads like you are building those. If you are not familiar with them, go to Studiotips.com and search for superchunks. You will be pleasantly surprised.

Andre

[avare]

No quote from the post right above this one.

That should work great. I don't know exactly what it will do, but it will not be bad. Keep us informed on your results!

Andre

[theron d]

yes I will do a freq response of the room, before and after .....come this new year...
thanks
Theron

[Glenn Kuras]

Originally Posted by theron d

yes I will do a freq response of the room, before and after .....come this new year...
thanks
Theron

That should work well, but you are better to make twice as many that are 6" thick and cover more area in the room. Yes thicker is better but over all coverage is best.

Glenn

[theron d]

Thanks Glenn, yes got you there! But I have an opportunity to get those packages for dirt cheap so I'm going to really treat the corners good with 12" and then address the rest of the room properly with 4" and 6" traps. I dont want to kill the higher frequencies so I am going to have to play around with FSK. It's a great learning opportunity ......thanks everyone for your input...

Best
Theron

Originally Posted by Glenn Kuras

That should work well, but you are better the make twice as many that are 6" thick and cover more area in the room. Yes thicker is better but over all coverage is best.

Glenn

[avare]

Cost is always a factor. You mentioned that you can get the material at a very low cost. BBC in the RD 1994-12 details how 6" of absorbent is not effective below 100 Hertz and in 1992-11 how 12" is flat down to 50 Hertz in absorption. If it is economically viable go with the 12" and play with the facing for high end ambience. Good luck and let us know the results!

Absorbingly impressed,
Andre

[jwl]

Leaving the 703 in the box might be interesting. The question will be, what effect does the cardboard have on the absorption?

Most likely, it will reflect starting at a certain frequency, so it will be less likely to deaden the room. Probably a good thing.

Plus, the cardboard should also have an effect on how the low end is absorbed. This will have to do with stiffness and mass of the cardboard, and how/if it touches the 703. It is also possible (likely?) that you may get some additional bass absorption out of it.

So yeah, this will be tough to make look good but it should work.

Try it and see, report back....

[bpape]

If you're getting it that cheap, then 12" of thickness can certainly help. Now, let's do the math though

If you take the same amount of material that it would take to do 6" of thickness straddling the corner, you can make solid chunks that are 17x17x24" of the same height as the 6" straddling.

That will give you a full 24" face exposed and also give you approx 12" of thickness at the angle AND 17" of absorbtion along the boundaries.

The cardboard may or may not help depending on your particular needs and as has been said, it's very unpredictable. The other solutions are knowns.

Bryan

[JC.]

I think 703 could be too dense (to high gas flow resistance) to take advantage from the full 12". Therefore it maybe a waste of material.

It's only a concern - I have no prove for it. But I have read some academic papers about sound absorption in the past which indicates that.

[avare]

Originally Posted by JC.

I think 703 could be too dense (to high gas flow resistance) to take advantage from the full 12". Therefore it maybe a waste of material.

It's only a concern - I have no prove for it. But I have read some academic papers about sound absorption in the past which indicates that.

Test results are the bottom line. The absorbent in the BBC RD 1992-11 tests is the equivalent of 703. It works.

Happy New Year!

Andre

[JC.]

Unfortunately, it seems hard to find a data sheet for RW2, but I think you're wrong. As far as I know RW2 is not equivalent to 703.

Happy New Year! :-)

[avare]

Look at the numbers in BBC RD Report I have mentioned twice already, including the in the last post to you.

Andre

[Ethan Winer]

Originally Posted by theron d

12" thick bass traps? Is this insane?

Not insane at all. It seems to me the ideal way to treat a small to medium size room is with at least one foot thick fiberglass on every single surface except the floor. If you could fit two to three feet thick everywhere, all the better. Then cover much of the fiberglass with card stock or similar so the extreme absorption is limited to bass frequencies. I'm not saying this is practical! But it's the ideal to aim for.

--Ethan

[JC.]

Originally Posted by avare

Look at the numbers in BBC RD Report I have mentioned twice already, including the in the last post to you.

Andre

Hi Andre,
I know the BBC RD Report 1992-11 and I looked at the numbers, that's why I think you maybe wrong.

From the Report page 7:

"Fig.2 shows the theoretical absorption coefficients of various depth of a porous absorber, calculated assuming a flow resistivity of 6000 MKS ralys/m. This value is typical of that measured mineral wool with similar densities to that of RW2 grade Rockwool. Although the value used is only a estimate of the flow resistivity for RW2 Rockwool, the shapes of the absorption coefficient curves do not depend strongly upon the flow resistivity value"

703 has a flow resistivity of 23600 mks rayls / m and the BBC paper suggests that the flow resistivity of RW2 is in the range of ~6000 MKS ralys/m. That's why I searched the data sheet from RW2 - I want to know the exact value.

I think this is a big difference and therefore you cannot say that RW2 is the equivalent of 703. Please tell me if I overlooked something.

By the way... happy new year! :-)