anyone have these that could provide some feedback, what exactly do these do and what should i expect thanks
http://cgi.ebay.com/Dark-Charcoal-Acoustic-Foam-Bass-Absorbers-Traps-8pk_W0QQitemZ260347877287QQcmdZViewItemQQptZLH_DefaultDomain _0?hash=item260347877287&_trksid=p3286.c0.m14&_trkparms=72%3A1234|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A0 |293%3A1|294%3A50

Avoid those types of "traps." They are basically just air, and have no mass. Try some good models at places like gikacoustics.com

JP

Yes, real bass traps and acoustic panels that absorb are made from insulation, not foam.

According to their website their NRC ratings are pretty good, much better the OC703 for example. I'd like to hear from someone who's actually tried them.

How about the Auralex base traps? Same issues?

I cross posted this question in the acoustics thread in the dedicated home theater forum here (http://www.avsforum.com/avs-vb/showthread.php?p=15593981#post15593981).

anyone have these that could provide some feedback

Corner foam is not very effective as bass traps for a number of reasons, not the least of which they're too small to get down to usably low frequencies. There are much better brands out there.

--Ethan

Those you linked to are to small. I have them. I also have the much bigger ones and I did notice a change in my sound. Everyone in my room has noticed the change in sound as well. They are doing something. Again, avoid the traps you linked to, too small.

Corner foam is not very effective as bass traps for a number of reasons, not the least of which they're too small to get down to usably low frequencies. There are much better brands out there.

--EthanCan you be more specific. The ones linked are 8". how about 10 or 12 or the 14" ones?

Edit - Also, their NRC numbers are pretty good as well, how does that play into this?

You would have much greater results using OC703 cut in triangles for the corners A 4'x2' panel would yield 4 trangles.Then stack from floor to ceiling.

Kg

You would have much greater results using OC703 cut in triangles for the corners A 4'x2' panel would yield 4 trangles.Then stack from floor to ceiling.

KgI appreciate your opinion. I've seen the pages about the Studiotips SuperChunk This (http://forum.studiotips.com/viewtopic.php?t=535) diagram yields 8 triangles per sheet. I'm looking for someone to quantify the differences.

well these traps look very similar in how they look to the auralex bass traps...i own an entire room of auralex traps...all 4 corners from floor to ceiling as well as some of their other products that are used for early reflections...i use that on parts of the side walls and ceiling as well as behind my front 3 speakers...i did build one "superchunk" or whatever you want to call it out of OC703...i do think those are better but not by a whole lot IMO...the auralex traps can be bought at guitar center and you can buy a can of spray adhesive at lowes or home depot to put them up with for about 5 bucks or so...are they the best? no...do they suck? no...the auralex are quick, easy, and MUCH cheaper than building your own out of OC703...but if cost is no issue and you want something better then the OC703 traps are the way to go...i just personally dont think they are that much better than auralex

I appreciate your opinion. I've seen the pages about the Studiotips SuperChunk This (http://forum.studiotips.com/viewtopic.php?t=535) diagram yields 8 triangles per sheet. I'm looking for someone to quantify the differences.

Foam tends to absorb the higher bandwidth region more than the lower. You can over deaden the top end and still not significantly reduce the first few octaves. Did the NRC ratings you look at specify the foams rating by Hz? If not its not very useful.

Did the NRC ratings you look at specify the foams rating by Hz? If not its not very useful.
The first number is the foam, the 2nd is 4" of OC703 per bob (http://www.bobgolds.com/AbsorptionCoefficients.htm)

Overall NRC 1.35 - 1.15
NRC at 125 HZ 1.25 - 0.84
NRC at 250 HZ 1.26 - 1.24
NRC at 500 HZ 1.47 - 1.24
NRC at 1000 HZ 1.42 - 1.08
NRC at 2000 HZ 1.24 - 1.00
NRC at 4000 HZ 1.29 - 0.97

good stuff guys i do plan to combo theses with acoustic panels just thought this would compliment the panels nicely, at that price i just cant see how it could hurt

good stuff guys i do plan to combo theses with acoustic panels just thought this would compliment the panels nicely, at that price i just cant see how it could hurtI'm thinking the same thing. Putting the wedges in the corner and getting 703 for the walls.

I expect the 12" wedges will provide less absorption then the 703 wedges because they are smaller, but the foam ones will look and fit better.

The first number is the foam, the 2nd is 4" of OC703 per bob (http://www.bobgolds.com/AbsorptionCoefficients.htm)

Overall NRC 1.35 - 1.15
NRC at 125 HZ 1.25 - 0.84
NRC at 250 HZ 1.26 - 1.24
NRC at 500 HZ 1.47 - 1.24
NRC at 1000 HZ 1.42 - 1.08
NRC at 2000 HZ 1.24 - 1.00
NRC at 4000 HZ 1.29 - 0.97

Whats the absorption rating at 80hz and 40hz? Thats where most people cross their sub in and in the middle of its bandpass respectively.

Whats the absorption rating at 80hz and 40hz? Thats where most people cross their sub in and in the middle of its bandpass respectively.Good question. I wasn't able to find that information on their site. Neither was I able to find it for OC703 either (or the Roxul Rockboard, or JM 814 or). It's also not available, as near as I can tell on the GIK or ATSAcoustics sites.

They all seem to use the same scale I posted. Bob Gold's site, the one I've seen referenced all over as the place to look for such things, all uses that same scale.

ok i have located the info check it out and please tell me what it means? rather they are decent or not, i think ima try them either way i just can justify paying so much for Auralex, who seem to use acoustic foam as well? Oh and what type of spay adhesive should i use? thanks
http://www.foamandupholstery.com/foam_corner_kits.htm

ok i have located the info check it out and please tell me what it means? rather they are decent or not, i think ima try them either way i just can justify paying so much for Auralex, who seem to use acoustic foam as well? Oh and what type of spay adhesive should i use? thanks
http://www.foamandupholstery.com/foam_corner_kits.htmI must say that I find their statements less than convincing. First, the NRC specs do not link to a particular item except for NC-168 which they say is sound proofing and a bass trap, two very different applications/goals. Second, the NRC specs at the top of the page are not associated with any specific product, as far as I can see. Third, simply judging from similar specs at Bob Gold's, I am amazed at these (and, thus, somewhat skeptical).

Good question. I wasn't able to find that information on their site. Neither was I able to find it for OC703 either (or the Roxul Rockboard, or JM 814 or). It's also not available, as near as I can tell on the GIK or ATSAcoustics sites.

They all seem to use the same scale I posted. Bob Gold's site, the one I've seen referenced all over as the place to look for such things, all uses that same scale.

I have a 11.5x14x8 room. When I first got into HT the friend who really introduced me to it brought over a bunch of super chunks. They dropped the rooms RT60 significantly in the upper region but not down low. I was shooting for .250 across the board but my 20hz - 200hz was an alarming .770. Heard how well the OC703 did and ordered a case of it. (actually it was knaufboard but all the specs I can find says they're nearly the same thing) 6 2'x4'x2" panels cleaned the room up much better than the superchunks. Not much over .290.

Now I dont know if its due to the material or not but just after I put my treatments up I read a post by Dennis Erskine saying not to use foam because it lacks bass absorption. The magic I saw could be due to the differences in the way the two different types of treatments were hung. The superchunks when right into the tri-corners (4 top corners of the room) and wall-wall intersections. (2 corners completely treated, 2 with about 1.5' of treatment) I placed my fiberglass treatments differently. 1 on each side wall at the first reflection point for my center seat and 1 in the center of each wall ceiling corner. So 2 flat on the walls (2" spaced) and 4 straddling a wall ceiling corner.

At this point I document everything with screencaps and labels out the ying yang. Unfortunately when I first got into this and was testing the superchunks I wasn't as vigilant. Perhaps I can convince him to bring them back over and test the room with my standard treatment vs my standard and his super chunks.

I must say that I find their statements less than convincing. First, the NRC specs do not link to a particular item except for NC-168 which they say is sound proofing and a bass trap, two very different applications/goals. Second, the NRC specs at the top of the page are not associated with any specific product, as far as I can see. Third, simply judging from similar specs at Bob Gold's, I am amazed at these (and, thus, somewhat skeptical).As for #2, I was curious as well so I sent them an email earlier today, here is their response:

The NRC ratings for NC-154 and product NC-160 is the same. If you have any other questions or additional information please feel free to email me back.
Thanks,
Christina
(248)-284-0002
foam4you@hotmail.com

Are they lying, stretching the truth, misleading, or, horrors, bucking the conventional wisdom, I don't know. The cost of their 12" wedges are actually a tad more then if I went to Denver and bought 8 sheets of 703.

Maybe if this thread stays around long enough, we'll find someone who knows the answer.

As for #2, I was curious as well so I sent them an email earlier today, here is their response:

The NRC ratings for NC-154 and product NC-160 is the same. If you have any other questions or additional information please feel free to email me back.
Thanks,
Christina
(248)-284-0002
foam4you@hotmail.com

Are they lying, stretching the truth, misleading, or, horrors, bucking the conventional wisdom, I don't know. The cost of their 12" wedges are actually a tad more then if I went to Denver and bought 8 sheets of 703.

Maybe if this thread stays around long enough, we'll find someone who knows the answer.Umm. Each of those model designations come in 5 different sizes. To what and to how many do those numbers apply? Very sloppy.

Any company that spells "Bass Traps" as "Base Traps" has lost all credibility. :eek:

Craig

I have a 11.5x14x8 room. When I first got into HT the friend who really introduced me to it brought over a bunch of super chunks. They dropped the rooms RT60 significantly in the upper region but not down low. I was shooting for .250 across the board but my 20hz - 200hz was an alarming .770. Heard how well the OC703 did and ordered a case of it. (actually it was knaufboard but all the specs I can find says they're nearly the same thing) 6 2'x4'x2" panels cleaned the room up much better than the superchunks. Not much over .290.

Now I dont know if its due to the material or not but just after I put my treatments up I read a post by Dennis Erskine saying not to use foam because it lacks bass absorption. The magic I saw could be due to the differences in the way the two different types of treatments were hung. The superchunks when right into the tri-corners (4 top corners of the room) and wall-wall intersections. (2 corners completely treated, 2 with about 1.5' of treatment) I placed my fiberglass treatments differently. 1 on each side wall at the first reflection point for my center seat and 1 in the center of each wall ceiling corner. So 2 flat on the walls (2" spaced) and 4 straddling a wall ceiling corner.

At this point I document everything with screencaps and labels out the ying yang. Unfortunately when I first got into this and was testing the superchunks I wasn't as vigilant. Perhaps I can convince him to bring them back over and test the room with my standard treatment vs my standard and his super chunks.By super chunks, do you mean the triangle 703's?

I'm honestly flying blind here. Everything I've read said to treat the corners. Then go after reflection points. That advice also came from GIK when I mentioned doing the treatment in phases. The only measurements I've done is using an SPL meter running an MP3 of white noise I got from one of more popular acoustic treatment sites. The front corners measure 5-10db's higher then then the seating position.

The right thing for me to do is to spend a lot more time and get the right measurements. sigh :)

Umm. Each of those model designations come in 5 different sizes. To what and to how many do those numbers apply? Very sloppy.Great point and one that crossed my mind. Yes, sloppy is a good word and seems to fit.

Great point and one that crossed my mind. Yes, sloppy is a good word and seems to fit.Sloppy was used tongue in cheek. :rolleyes:

Sloppy was used tongue in cheek. :rolleyes:Well now I'm totally confused, what exactly do you mean then?

Ah the joys of communication in forums :)

By super chunks, do you mean the triangle 703's?


No it was the brand name of a foam treatment line.

Well now I'm totally confused, what exactly do you mean then?

Ah the joys of communication in forums :)I mean that I suspect that either they do not know what they are talking about or worse.

I just found this (http://www.hometheatershack.com/forums/home-audio-acoustics/4668-generic-foam-bass-traps.html) which seems fairly informative.

I just found this (http://www.hometheatershack.com/forums/home-audio-acoustics/4668-generic-foam-bass-traps.html) which seems fairly informative.Very interesting. I guess there is a reason I haven't found any "buzz" about these guys on any of the normal forums.

I guess it's back to deciding if I cut triangles or just straddle the walls with 4" of 703.

Thanks everyone for your input.

The ones linked are 8". how about 10 or 12 or the 14" ones?

Still too small. Minimum useful width is 24 inches.

their NRC numbers are pretty good as well, how does that play into this?

NRC and absorption coefficients are useless for assessing bass traps because they ignore the size of the traps! Not sure how deeply you want to get into this, but my article from Sound & Vibration magazine explains all of the problems with measuring and comparing bass traps using the standard test procedures:

Alternative Test Methods for Acoustic Treatment Products (http://www.realtraps.com/art_testing.htm)

--Ethan

Still too small. Minimum useful width is 24 inches.



NRC and absorption coefficients are useless for assessing bass traps because they ignore the size of the traps! Not sure how deeply you want to get into this, but my article from Sound & Vibration magazine explains all of the problems with measuring and comparing bass traps using the standard test procedures:

Alternative Test Methods for Acoustic Treatment Products (http://www.realtraps.com/art_testing.htm)

--Ethan
Thanks Ethan, that (and the links) was great reading (well, so far I've just skimmed the other links).

Based on the article you linked, would you say, as a 2'x4'x4" panel straddling a corner would absorb more/less/same as a 4' high wedge (with a 24" front), assuming both are made of the same material?

NRC and absorption coefficients are useless for assessing bass traps because they ignore the size of the traps!
Hi Ethan. Just curious, the OC 700 Series datasheet (www.owenscorning.eu/docs/products/700series_DataSheet.pdf) shows a major roll-off below 250Hz for the plain OC703, whereas the faced panels show a much flatter broadband response down to 125Hz. I'm confused by this, since the fact that they list the panels as placed against a solid backing to me suggests that any acoustic-reflective properties of the facing would be superfluous at best in that application.

In any case, what, if any, advantage/disadvantage is there that faced panels have compared to the plain when used as a "freestanding" corner-straddled bass trap?

[edit]

I just read the article you'd mentioned above, as well as the one it referenced regarding this at http://www.ethanwiner.com/density.html

Nevermind. :o

I just got some rockboard 60 and was also wondering how it would work as a freestanding corner straddled bass trap

well these traps look very similar in how they look to the auralex bass traps...i own an entire room of auralex traps...all 4 corners from floor to ceiling as well as some of their other products that are used for early reflections...i use that on parts of the side walls and ceiling as well as behind my front 3 speakers...i did build one "superchunk" or whatever you want to call it out of OC703...i do think those are better but not by a whole lot IMO...the auralex traps can be bought at guitar center and you can buy a can of spray adhesive at lowes or home depot to put them up with for about 5 bucks or so...are they the best? no...do they suck? no...the auralex are quick, easy, and MUCH cheaper than building your own out of OC703...but if cost is no issue and you want something better then the OC703 traps are the way to go...i just personally dont think they are that much better than auralex


I originally had some base traps built out of acoustic cotton and when I switched to the auralex one it made a big difference.

I just got some rockboard 60 and was also wondering how it would work as a freestanding corner straddled bass trap
The rockboard has acoustic characteristics very similar to the OC703 "standard" although I understand it is more difficult to work with. I have no personal experience however. When I was searching locally, I was told there was a 2-3 month backlog, so I plan on getting OC703 next week and build my panels.

I just got some rockboard 60 and was also wondering how it would work as a freestanding corner straddled bass trap
The rockboard has acoustic characteristics very similar to the OC703 "standard" although I understand it is more difficult to work with. I have no personal experience however. When I was searching locally, I was told there was a 2-3 month backlog, so I plan on getting OC703 next week and build my panels.

Yeah, I abandoned the foam, Ethan's articles made a lot of sense.

would you say, as a 2'x4'x4" panel straddling a corner would absorb more/less/same as a 4' high wedge (with a 24" front), assuming both are made of the same material?

A solid wedge absorbs more, but only a little more. If the cost of materials is not an obstacle, then filling is best. Otherwise, it's better to spread the absorption around to other corners using more total panels. Remember, most rooms have 12 corners, not only 4.

--Ethan

Nevermind. :o

Okay. :D

Also, the difference between 703 and 705, and faced versus unfaced, depends on the thickness. The difference at 1 inch thick is very different than the difference at 4 inches thick.

--Ethan

The rockboard has acoustic characteristics very similar to the OC703 "standard" although I understand it is more difficult to work with. I have no personal experience however. When I was searching locally, I was told there was a 2-3 month backlog, so I plan on getting OC703 next week and build my panels.

I have both in my HT room and I have "Utra-touch" cotton...which also works and has the same specs as OC703, Rockwool60.

The cotton is the BEST to work with because it will not itch you, cut you, stink or get into your cloths.

I built corner triangle chunks in my room using ALL of them they all WORK very well!!! I will never touch fibre glass crap again...OC703 is great but its a nightmare to touch, work with.

btw, buy electric meat carvers to cut these sheets, it works wonders. I bought B&D brand from Walmart for $10.

Here is the ultra touch cotton link

http://www.bondedlogic.com/ its green friendly stuff ;)

I have both in my HT room and I have "Utra-touch" cotton...which also works and has the same specs as OC703, Rockwool60.

The cotton is the BEST to work with because it will not itch you, cut you, stink or get into your cloths.

I built corner triangle chunks in my room using ALL of them they all WORK very well!!! I will never touch fibre glass crap again...OC703 is great but its a nightmare to touch, work with.

btw, buy electric meat carvers to cut these sheets, it works wonders. I bought B&D brand from Walmart for $10.

Here is the ultra touch cotton link

http://www.bondedlogic.com/ its green friendly stuff ;)Thanks, where did you get the cotton stuff, what R value and how did you use it?

By the way, someone was asking about you in the sticky acoustics thread in the dedicated home theater forum, wondering how you were making out :)

Hi,

Here are a couple other sites for cotton (BAC - bonded acoustical cotton) that I ordered from and work very well (thickness from 1" - 4"):

http://sensiblesoundsolutions.com/index.php?cPath=22&osCsid=2b07819bb239c4652c1e47e0f92f6404
Can buy in bulk from this site.

and

https://www.soundaway.com/SearchResults.asp?Cat=91

They have worked well for me also. As penngray mentioned, I also won't touch fiberglass again, such a mess and pain.

Ethan, thanks again for being so informative, enjoyed reading your articles (site pack FULL of great info). Will you ever be using BAC for your products in the future? We're trying to keep everything green, and fiberglass is not a material I would like to have in the house, especially with kids who could accidentally tear acoustical treatment (hopefully not).

Thanks,
Ray

By the way, someone was asking about you in the sticky acoustics thread in the dedicated home theater forum, wondering how you were making out

I was done with it and enjoying the room the past 6 months so I stopped posting. I also go into building my own speakers with active crossovers so I moved on from the room treatments.

The room could be better....I still get goosebumps when watching movies or gaming and the expression on the faces of friends and family is priceless :D :D


Thanks, where did you get the cotton stuff, what R value and how did you use it?

I ordered it online somewhere...and this http://www.bobgolds.com/AbsorptionCoefficients.htm will give you all the info you need.

I ordered it online somewhere...and this http://www.bobgolds.com/AbsorptionCoefficients.htm will give you all the info you need.Thanks, I never scrolled down far enough to see it, duh.

I got a price locally for the 24" 3.5 inch stuff for about $75 for 126sqft.

Thanks, I never scrolled down far enough to see it, duh.

I got a price locally for the 24" 3.5 inch stuff for about $75 for 126sqft.I bought a bundle of the cotton. I cut wedges for the first corner and man does that stuff compress. I figured I'd need just over 3 8' batts (33" across front of wedge) for each corner and the damn stuff is flattening out so much I will need more then 4. Time to step back and think about this. I don't want to go out and by another bundle and only use 1/4 of it.

I bought a bundle of the cotton. I cut wedges for the first corner and man does that stuff compress. I figured I'd need just over 3 8' batts (33" across front of wedge) for each corner and the damn stuff is flattening out so much I will need more then 4. Time to step back and think about this. I don't want to go out and by another bundle and only use 1/4 of it.

David,

If you order more and have extra, make some 2'X4' Absorption panels and hang them on the wall at reflection points (I made mine using 2'x4' peg board and 1"x4" pine, actual size of pine is closer to 1/2" x 3 1/2", and covering with acustically transparant cloth). They can also be hung at ceiling coner midpoints for bass trapping in those areas (angled from ceiling to adjoining wall).

Ray

David,

If you order more and have extra, make some 2'X4' Absorption panels and hang them on the wall at reflection points (I made mine using 2'x4' peg board and 1"x4" pine, actual size of pine is closer to 1/2" x 3 1/2", and covering with acustically transparant cloth). They can also be hung at ceiling coner midpoints for bass trapping in those areas (angled from ceiling to adjoining wall).

RayThanks Ray, that's pretty much exactly what I decided to do. When I found out about this material I was thinking of using it just for bass traps and buying 703 for the panels. With the settling developing I rethought it and came up with the same idea you had. For $75 I could get 6 703 panels (42sqft), while $75 gets me 126sqft of the cotton material.

I'm not decided exactly on the frame. I was thinking of just building a backing frame. One thought was building a 1"x2" frame (with cross bracing). I would lay the material on the frame and wrap it. That would make the material very rounded along the edges. It looks and works great in my mind. In practice, I'm not so sure :).

Thanks Ray, that's pretty much exactly what I decided to do. When I found out about this material I was thinking of using it just for bass traps and buying 703 for the panels. With the settling developing I rethought it and came up with the same idea you had. For $75 I could get 6 703 panels (42sqft), while $75 gets me 126sqft of the cotton material.

I'm not decided exactly on the frame. I was thinking of just building a backing frame. One thought was building a 1"x2" frame (with cross bracing). I would lay the material on the frame and wrap it. That would make the material very rounded along the edges. It looks and works great in my mind. In practice, I'm not so sure :).

Let me know how that works for you. I tried it and it just was not a smooth professional finish (the cotton does not compress very evenly along a whole side). So, I went to framing. Let me know how you accomplish a smooth finish if you find a way.

Thanks,
Ray