would this be an effective BASS TRAP material (very cheap)?

angelo · « **on:** 26 Jan 2005, 09:49 pm »

i found this at home depot for $6, it's used as a molding to form tube concrete and is made of hard paper

dim: 10" x 48"

would this be an effective bass trap if i fill it with fiber glass inside, seal both ends and cover it with fabric?

thanks in advance,

angelo

Ethan Winer · « **Reply #1 on:** 27 Jan 2005, 05:07 pm »

Angelo,

> would this be an effective bass trap if i fill it with fiber glass inside, seal both ends and cover it with fabric? <

Not really, because the cardboard will reflect a lot of the sound before it can get into the fberglass. The cheapest bass trap is simply a bale of fluffy fiberglass, left in the plastic wrapper.

--Ethan

Rob Babcock · « **Reply #2 on:** 27 Jan 2005, 05:10 pm »

I was just gonna suggest Ethan might know but he beat me to it!

Seriously though, what if you were to swiss-cheese the tube with a 4" drill like you'd use to cut doorknob holes or a sheetrock saw, then wrapped it like in a fashing similar to Jon Risch's 'glass trap? Yeah, I realize it would be a bit of work, but it make it very easy to get a good seal around the bottom.

john4618 · « **Reply #3 on:** 27 Jan 2005, 05:32 pm »

Have you seen the five episodes currently on the DIY channel about building a Home Theater room -- they use tubes just like this and they fill them with sand and put one each of these tube bass traps (their words, not mine) behind each front main speaker.

The guy doing the room is a Home Theater professional with an engineering degree, so I’m assuming the sand is an effective media for bass traps -- but does anyone know why sand and the technical/acoustical explanation of using sand ?

Red Dragon Audio · « **Reply #4 on:** 27 Jan 2005, 07:20 pm »

http://www.knauffiberglass.com/index.cfm?fuseaction=prd.dspProdDetail&ID=1

These pipe insulators from Knauf come in densities from 4.25PCF - 6.00 PCF...most hover around the 4.25 PCF mark though. You can get them in varying diameters and thicknesses too. I think they range from 1/2" to 8" in thickness so they'd make some wicked bass traps.

Rob Babcock · « **Reply #5 on:** 27 Jan 2005, 07:24 pm »

They're a bitch to find, though. You pretty much have to try a plumbing or HVAC place. I've read they don't sell a lot of it to the public (not by design, just those type of places don't have slick storefronts).

angelo · « **Reply #6 on:** 28 Jan 2005, 12:32 am »

home depot have those but i think the biggest diameter i saw was about 4", i'll ask them if they can order bigger sizes...

drilling holes to the tube is not a bad idea, maybe i'll go that route.. thanks

angelo

Carlman · « **Reply #7 on:** 28 Jan 2005, 01:30 am »

I have access to pool noodles... they're made of closed-cell foam. Basically, they're like really big pipe insulation. I could bundle a few together and make a single column.

Would this make an OK bass trap?

Red Dragon Audio · « **Reply #8 on:** 28 Jan 2005, 01:47 am »

do you know what density they are?

If I am not mistaken, compressed fiberglass still acts as a better broadband bass absorber than foam. Ethan W. might have more conclusive information regarding this matter as I'm not 100% sure.

MaxCast · « **Reply #9 on:** 28 Jan 2005, 12:47 pm »

As I recall, closed cell foam dosent work as well. It sure would have high KAF...Kid acceptance factor.

Ethan Winer · « **Reply #10 on:** 28 Jan 2005, 07:08 pm »

Folks,

> I realize it would be a bit of work, but it make it very easy to get a good seal around the bottom. <

There is no point in sealing anything when building traps based on fiberglass. It's a complete waste of time and effort. Fiberglass is porous to begin with, so there's nothing to seal.

> they use tubes just like this and they fill them with sand ... The guy doing the room is a Home Theater professional with an engineering degree <

Which proves yet again that having a degree is no assurance of anything. I promise you, a tube full of sand will not absorb anything. Not even a little. It's an even bigger waste of time and effort than sealing fiberglass inside cardboard tubes.

As for pool noodles, those won't work either. Even if the material were the right type, which it's not, they're way to narrow to have enough surface area. Bass trapping is all about coverage - the more the better.

--Ethan

Red Dragon Audio · « **Reply #11 on:** 28 Jan 2005, 10:17 pm »

Here's a picture I did to help folks out when deciding where to put treatments. There is no science behind this, just looked at Ethan's site and numerous other acoustic pages on the web.

Panels in corners are 2"-4" thick, 2'x4', 4.25PCF rigid fiberglass panels creating corner bass traps. If you were to stack two in each corner, you'd have 2'wide x 8' tall bass traps.

The panels on the walls represent first reflection points absorbtion (which you can do on the ceiling too if you feel it necessary), and some absorbtion behind the speakers and listening seat.

Like I always say; season to taste

Rob Babcock · « **Reply #12 on:** 29 Jan 2005, 01:09 am »

Quote from: Ethan Winer

Folks,

> I realize it would be a bit of work, but it make it very easy to get a good seal around the bottom. <

There is no point in sealing anything when building traps based on fiberglass. It's a complete waste of time and effort. Fiberglass is porous to begin with, so there's nothing to seal.

I think you're supposed to seal the bottom so the air actually has to move thru the glass to get into the cyclinder. At least thats the way Risch explains it. Doesn't the air gap trapped inside a cylindrical glass bass trap serve a funtion, too? Otherwise you'd use solidly packed glass (this is only a guess on my part- I'm no expert!

).

To clarify, you'd swiss cheese the tube till it was basically just a big holey latticework. Then you'd wrap insulation around the tube, not in it. Then you'd wrap it in fabric to keep the fibres in. Glass is pourous, true, but obviously it impedes air movement or we wouldn't insulate with it! The sealing the tube at the top and bottome would simply to be ensure pressure can't leak around the glass instead of thru it.

Sound · « **Reply #13 on:** 29 Jan 2005, 02:07 pm »

Could a "tube" or bail of flufy fiberglass be placed in the corner BEHIND something else-- like a book shelf angled across the corner? So the empty space in the corner behind the bookshelf was filled with the material. I know some of the waves would be reflected off the books/wood etc. However would filling the space improve anything?

Tonto Yoder · « **Reply #14 on:** 29 Jan 2005, 02:35 pm »

Quote from: Sound

Could a "tube" or bail of flufy fiberglass be placed in the corner BEHIND something else-- like a book shelf angled across the corner? So the empty space in the corner behind the bookshelf was filled with the material. I know some of the waves would be reflected off the books/wood etc. However would filling the space improve anything?

Check out the PS Audio site--
http://www.psaudio.com/articles/listening_room_4.asp
In making their own soundroom, they build corner traps that double as bookcases (and hold subs on the bottom): they do indeed fill the space behind the bookcase. It would seem that their DIY, custom installation could be approximated by angling a prefabricated bookcase in a corner and sticking fiberglass behind it.

Ethan Winer · « **Reply #15 on:** 29 Jan 2005, 03:11 pm »

Rob,

> I think you're supposed to seal the bottom so the air actually has to move thru the glass to get into the cyclinder. At least thats the way Risch explains it. <

I know that's the way Jon explains it, but it's still not right. Again, rigid fiberglass is porous, so there's no way for air to be "trapped" inside, or forced through it, or however else you want to think of it. If sealing were necessary, flat panel traps wouldn't work at all. Think about that!

--Ethan

csero · « **Reply #16 on:** 29 Jan 2005, 03:35 pm »

Quote from: Tonto Yoder

Check out the PS Audio site--
http://www.psaudio.com/articles/listening_room_4.asp
In making their own soundroom, they build corner traps that double as bookcases (and hold subs on the bottom): they do indeed fill the space behind the bookcase. It would seem that their DIY, custom installation could be approximated by angling a prefabricated bookcase in a corner and sticking fiberglass behind it.

I particulary like this:

" We are particualrily excited to buy books for this project because we don't need to go for content, rather looks alone will do the job! Probably bordering on heresy, this method will work!"

Tonto Yoder · « **Reply #17 on:** 29 Jan 2005, 03:53 pm »

Quote from: csero

I particulary like this:
" We are particualrily excited to buy books for this project because we don't need to go for content, rather looks alone will do the job! Probably bordering on heresy, this method will work!"

I read a decorating magazine in which they profiled book dealers who sold, not by content, but by color and by the foot! So decorators would call them up with an order for 6 feet of red books, four of blue etc etc.

Sound · « **Reply #18 on:** 29 Jan 2005, 09:24 pm »

Tonto,

Thanks for the sight info! I will most likely go that route as the wife likes to keep the room looking "together." A happy wife is a happy husband

explaining various things I have read in this forum may be difficult "Honey, why are there four punching bags in every corner of our movie room?" Or "Honey, the kids are playing with the pink stuff in the corners they broke open and they are all ichy and red,

Question: Is there a minumum size for the bass trap? I won't make the book shelf as large as the one on the sight as my room is a bit smaller.

JLM · « **Reply #19 on:** 29 Jan 2005, 10:57 pm »

Sound,

The minimum size of bass trap is zero.

Generally speaking, the bigger the better.