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post #1 of 28 Old 08-17-2011, 12:27 PM - Thread Starter
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I know it is posted around on how to make bass traps, but there seems to be some variation.

Would buying something like this:
http://www.atsacoustics.com/item--Ow...f-6--1011.html
or
http://www.atsacoustics.com/item--Ro...f-6--1006.html

Then cutting it in half to make 2 24x24" pieces, then cutting those in half diagonally to make triangles. Then covering that with linacoustic such as:


Then covering it in some type of GOM such as:
http://www.acousticalsolutions.com/g...ric-data-sheet

I'm new to all this, just don't want to mess up

Also, for the acoustic panels, just use one of the first two insulators in a frame, covered with GOM?

Thanks!
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post #2 of 28 Old 08-17-2011, 12:44 PM
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Quote:
Originally Posted by Roshy View Post

I know it is posted around on how to make bass traps, but there seems to be some variation.

Would buying something like this:
http://www.atsacoustics.com/item--Ow...f-6--1011.html
or
http://www.atsacoustics.com/item--Ro...f-6--1006.html

Then cutting it in half to make 2 24x24" pieces, then cutting those in half diagonally to make triangles.

porous insulation is velocity-based (converts kinetic energy via particle velocity into heat). as such, it needs to be placed at areas of high particle velocity to be effective.

particle velocity and pressure are inversely proportional. hence, directly at the boundary where pressure builds, velocity goes to zero (as the waveform is about to reflect and reverse direction). much like a billiards ball on a pool table. maximum velocity occurs at 1/4wavelength for a particular frequency.

since we are discussing LF absorption, the wavelengths become very long ... and reaching this 1/4wavelength distance is simply not feasible in small spaces. absorption is still efficient well before that, but it is wise to have an understanding of what is going on before proceeding.

as such, the further the material spaced from the boundary, the more effective it will be (as you are placing the insulation further towards areas of high particle velocity).

placing porous insulation directly against the boundary is very ineffective for LF modal issues - as that is an area where pressure is maximum and velocity is approaching zero.

bear in mind too that adding an air-gap between the insulation and the boundary


Quote:
Originally Posted by Roshy View Post

Then cutting it in half to make 2 24x24" pieces, then cutting those in half diagonally to make triangles. Then covering that with linacoustic such as:

there is no data that i am aware of that insists that using multiple types of insulation (gas-flow-resistivity) is any more effective.

the StudioTips SuperChunks (corner chunks/triangles) - are surely effective at mid/high LF absorption (addressing freq response via modal issues as well as LF decay times) - but are not very effective for the lower octaves.

what is important regarding porous insulation is the gas-flow-resistivity
values. if you are limited by how much real estate (corner space in your room), then you will have thinner corner traps and will function better with a material with higher gas-flow-resisitivity. (OC703, OC705, equivilant mineral wool, etc). but, as learned above, the thicker the panel (either with thick absorption or absorption with a large air-gap), will perform better for LF absorption.

the ideal way to do this is to make very thick traps of cheap, pink fluffy insulation (which has a low gas-flow-resistivity), and one could loosely fill large plastic bags of this insulation and stack into the corners.

it entirely depends on the design constraints of the individual. but, the thicker the traps, the lower the GFR value material you will want to use.

a simply idea i have is to take your typical 48"x24" batts (OC703, etc) and instead of making 6" thick panels that straddle the corner .... turn these panels on their sides such that they are 48" wide and 24" tall, and then stack those from floor to ceiling. it will provide you with a "thicker" trap (material + air gap spacing from boundary) than a 34" faced corner triangle trap and will also not require any cutting

choice of fabric isn't terribly important for the LF corner porous traps for modal issues. although many will quickly over-deaden their rooms due to the fact that the corner trap is broadband not just for LF but for the specular range as well. as such, many apply reflective surfaces to the outer face of the corner trap to reflect some mid/HF specular content back into the room.

Quote:
Originally Posted by Roshy View Post

Also, for the acoustic panels, just use one of the first two insulators in a frame, covered with GOM?
Thanks!

for broadband panels to combat specular reflections (that function as 'rays'), you will need to use thick enough insulation such that the entire specular reflection is attenuated to the required gain (eg., -20dB, or whatever your design requirements are).

for these, the fabric most certainly needs to be 'breathable'.
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post #3 of 28 Old 08-17-2011, 12:47 PM
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localhost, you seem to be an absolute wealth of room treatment information and a lot of what you say seems to contradict the common wisdom. Do you have a summary page of how to do acoustic treatments, or links to your favorite FAQs or instructions?
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post #4 of 28 Old 08-17-2011, 12:48 PM
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bear in mind there are also 'pressure-based' bass traps ... but they are much more difficult to design and you need to know the measured (specific) issues in your room in order to go on from there.

but, pressure traps can be placed at areas of high pressure which is right against the boundary ... so thick, protruding insulation which takes up ridiculous amounts of real estate is not your only option.
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post #5 of 28 Old 08-17-2011, 12:50 PM
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Quote:
Originally Posted by jonnythan View Post

localhost, you seem to be an absolute wealth of room treatment information and a lot of what you say seems to contradict the common wisdom. Do you have a summary page of how to do acoustic treatments, or links to your favorite FAQs or instructions?

what specific "common wisdom" are you referring to regarding contradictions?


there are many approaches to solving particular issues within a room. no one right answer. many have design constraints such as real estate, wife factor, aesthetics, cost, etc. and as such, the solutions change based on design constraints.
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post #6 of 28 Old 08-17-2011, 02:39 PM - Thread Starter
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I read all that, and it went way over my head. I don't know how to measure the room, or anything like that. I was hoping to just do what is common and absorb some bass, and throw up acoustic panels at the first reflection points, and see how it sounds.

I gather by your answer that what I said I was thinking of doing is wrong for bass traps, but right for the acoustic tiles as long as I use around say 2"? (that's how much it went over my head, haha).

Is there any good rule of thumb on what to do for bass traps? I was planning on following one of the methods of making your riser a bass trap as well. Should that be enough most likely? Or would I probably need more?

Thanks, and sorry I'm stoopid
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post #7 of 28 Old 08-17-2011, 02:50 PM
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Its very difficult when we know nothing about your room.....I'd look at ASC traps if you just want something off the shelf.

....otherwise, because you're a bit behind the knowledge curve - try this.

Peter the Greek

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post #8 of 28 Old 08-17-2011, 05:50 PM
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Not DIY, but a good option:

http://gikacoustics.com/gik_tri_trap.html

A more DIY approach:

http://forum.studiotips.com/viewtopic.php?f=8&t=535

The latter forum has several long and well documented discussions about the effectiveness of alternative corner mounted broadband absorbers
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post #9 of 28 Old 08-17-2011, 07:47 PM - Thread Starter
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Thanks. That article is along the lines of what I have read. Cut the oc703 in half, then in triangles. I'll probably just do that in as many corners are accessible, and along with my riser hope it will be enough. From eha I've read, if you build a riser the right way, put a couple traps in, and take care of first reflections, you should be pretty good. Was just trying to confirm that here, but I'm not sure if I did or didn't after all the replies, haha
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post #10 of 28 Old 08-17-2011, 08:25 PM - Thread Starter
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I'll probably use the cheaper AFB 2" as well, save some money
pjoseph24 likes this.
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post #11 of 28 Old 08-17-2011, 09:04 PM
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Quote:
Originally Posted by Roshy View Post

Thanks. That article is along the lines of what I have read. Cut the oc703 in half, then in triangles. I'll probably just do that in as many corners are accessible, and along with my riser hope it will be enough. From eha I've read, if you build a riser the right way, put a couple traps in, and take care of first reflections, you should be pretty good. Was just trying to confirm that here, but I'm not sure if I did or didn't after all the replies, haha

how much space are you willing to give up in the corners of your room? let's start with this very specific design constraint.

and please take a few moments to play around with:
http://www.whealy.com/acoustics/Porous.html
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post #12 of 28 Old 08-17-2011, 09:49 PM - Thread Starter
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I have ALOT of room in the ceiling to give up, the ceiling is 11' tall in the back of the room. From what I read in the FAW, and master thread, and links from those, it sounds like you can mount the bass traps wherever any 3 planes come together. So I could put them in the ceiling too then? How do you mount something like that?

I'll have to mock it up to see if I can fit bass traps in the front corners along with covering the front wall in the insulation as well. Just did that, looks like it would fit in the front if I used the cuts where you make 12" triangles, so 8 per 2 x 4 panel. The 24" ones would be tighter and push the R and L speakers out further. How close can they be to your R and L fronts? If they can be really close, then I could fit the 24" cut ones (so 4 triangles per panel).

I also have gobs of space in the ceiling, if I knew how to attach it up there.
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post #13 of 28 Old 08-17-2011, 10:05 PM
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I did pretty much what you suggested, except without linacoustic on top - just Roxul AFB triangles stacked, and then covered with speaker cloth on the front. In my case, the speaker cloth is mounted on removable panels similar to speaker grills - so if I measure and determine that I need less HF absorption in the corners, I can always go back in and add a thin layer of plastic or whatever to reflect HF.
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post #14 of 28 Old 08-18-2011, 06:46 AM
 
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If I were to make round columns of free insulation, what would I use for the outside to hold it all in?
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post #15 of 28 Old 08-18-2011, 06:48 AM
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Quote:
Originally Posted by localhost127 View Post

bear in mind there are also 'pressure-based' bass traps ... but they are much more difficult to design and you need to know the measured (specific) issues in your room in order to go on from there.

but, pressure traps can be placed at areas of high pressure which is right against the boundary ... so thick, protruding insulation which takes up ridiculous amounts of real estate is not your only option.

We are actually in the process of testing some "pressure based" traps at Riverbank. If you would like I can send you the results once I have them. You seem to be as geeky as me about this stuff.

Glenn Kuras
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http://www.gikacoustics.com

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post #16 of 28 Old 08-18-2011, 06:52 AM
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We are actually in the process of testing some "pressure based" traps at Riverbank. If you would like I can send you the results once I have them. You seem to be as geeky as me about this stuff.

that would be wonderful, thanks!
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post #17 of 28 Old 08-18-2011, 06:54 AM
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Quote:
Originally Posted by Roshy View Post

I read all that, and it went way over my head. I don't know how to measure the room, or anything like that. I was hoping to just do what is common and absorb some bass, and throw up acoustic panels at the first reflection points, and see how it sounds.

I gather by your answer that what I said I was thinking of doing is wrong for bass traps, but right for the acoustic tiles as long as I use around say 2"? (that's how much it went over my head, haha).

Is there any good rule of thumb on what to do for bass traps? I was planning on following one of the methods of making your riser a bass trap as well. Should that be enough most likely? Or would I probably need more?

Thanks, and sorry I'm stoopid

The rule of thumb in my book is no less then 4" (2'x4' panel) of rigid fiberglass straddling the corner. From there you can go wider, thicker or fill the area with triangles floor to ceiling. If you want to go one step further you can go with soffit bass traps which I believe is the best, but not cheap and or easy to build. Here is a layout with triangle bass traps floor to ceiling (wall to wall corners) and soffit traps in the ceiling to wall corners around the room.


Glenn Kuras
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http://www.gikacoustics.com

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post #18 of 28 Old 08-18-2011, 06:57 AM
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Quote:
Originally Posted by localhost127 View Post

that would be wonderful, thanks!

Email me if you would through my company website and I will put you in my "reminder" folder.
You can find my contact info here (sorry I don't want the web spider picking up my email due to spam)
http://www.gikacoustics.com/contact_us.html

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post #19 of 28 Old 08-18-2011, 07:33 AM
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Quote:
Originally Posted by myfipie View Post

Email me if you would through my company website and I will put you in my "reminder" folder.
You can find my contact info here (sorry I don't want the web spider picking up my email due to spam)
http://www.gikacoustics.com/contact_us.html

I'll do same Glenn - send you email thru company website.

btw, I take it that's a rendering not a real picture?
The iStockphoto thing somehow does not fit in with a real room decour.
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post #20 of 28 Old 08-18-2011, 07:50 AM
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I'll do same Glenn - send you email thru company website.

btw, I take it that's a rendering not a real picture?
The iStockphoto thing somehow does not fit in with a real room decour.

Yes it is a rendered picture. Was not my favorite image either but sometimes you have to pick your fights. Kind of like the spouse factor.

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post #21 of 28 Old 08-18-2011, 07:55 AM
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Originally Posted by mtbdudex View Post

I'll do same Glenn - send you email thru company website.

btw, I take it that's a rendering not a real picture?
The iStockphoto thing somehow does not fit in with a real room decour.

BTW my art tastes are a bit eclectic.


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post #22 of 28 Old 08-18-2011, 08:11 AM
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Quote:
Originally Posted by myfipie View Post

BTW my art tastes are a bit eclectic.


Rock on! Now that's Art and Acoustics in harmony.

If you like, I could license my NASA APOD August 5, 2011 to GIK, some of your customers may find it a little more "soothing" in their 2 channel listening room...
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post #23 of 28 Old 08-18-2011, 10:24 AM
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Quote:
Originally Posted by mtbdudex View Post

Rock on! Now that's Art and Acoustics in harmony.

If you like, I could license my NASA APOD August 5, 2011 to GIK, some of your customers may find it a little more "soothing" in their 2 channel listening room...

mmmmmmmmmmmmmm interesting, very interesting. I will take a look and email you.

BTW any guesses who the painting is on my panel?

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post #24 of 28 Old 08-18-2011, 10:58 AM
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Originally Posted by myfipie View Post

BTW any guesses who the painting is on my panel?

DD Ramone...do I get a free copy of it now that I answered the question?

Beautiful panel by the way, looks more like a photo then a painting!
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post #25 of 28 Old 08-18-2011, 04:22 PM
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DD Ramone...do I get a free copy of it now that I answered the question?

Beautiful panel by the way, looks more like a photo then a painting!

Wow I am impressed you knew that!! The Painter is from Munich Germany, Florian Sussmayr. He actually took that picture back in the 80s (?) and painted it around 5 years ago. I saw it at a gallery showing he had in Munich and always loved the painting. At the time it sold for around 5K (to much for my blood) but now is worth, I believe 30 to 40K (I could be totally wrong on that number). Well to make a long story short I emailed him and asked if he would sell me a digital copy. Within 24 hours he emailed me back and said he could do even better and gave it to me. He did make me promise though that I would never sell a copy or give it to someone else (which I am sure everyone understands why). You should see some of the other work he has done. Really great stuff, if your into that kind of art.

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post #26 of 28 Old 08-19-2011, 07:07 AM
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Quote:
Originally Posted by cybrsage
If I were to make round columns of free insulation, what would I use for the outside to hold it all in?
I have round column bass traps in my room. I used large diameter sonotube cut into quarters. I intstalled wooded ribs, top and bottom caps and moulding. Then I cut vertical sections out of columns to let higher freq in...the bass waves pass through the cardboard sonotube. I then wrapped with batting followed by suede and layered the back with ats acoustics fiber panels then .....done. They probably aren't as effective as the normal corner chunk design but they look great and work.
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post #27 of 28 Old 08-19-2011, 10:07 AM
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Roshy
I posted this in another thread , might be useful for you to look over how others have done theirs (corner and ceiling shown in these threads)

Quote:


There are already "fixed" bass trap threads, here are links to them.

AVS site:

Show us your custom made corner bass traps (pics)
(btw, as of 2/5/0-11 pepar updated his pict links, I need chinaclipper and pred02 to do same )
Other site:
Gearslutz.com, here is a link to their "How I built my bass (broadband) traps..." sticky, over 31 pages of info!
http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/87464-how-i-built-my-bass-traps.html

I added my own twist to building corner superchunk with "green" material, some might like a different approach.
https://www.avsforum.com/avs-vb/showthread.php?p=20588838#post20588838

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post #28 of 28 Old 08-19-2011, 10:12 AM - Thread Starter
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Thanks! I will check them out!
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