cheap foam

[colterphoto1]

Someone here mentioned a competing product to the auralex foam wedges and bass traps. Supposedly it was a former vendor of there's or a current supplier who had a separate line that was much less expensive. I've searched and searched and cannot locate the thread. Can anyone help?

I currently have a concrete block basement gym area that I have a HT setup in. It definitely needs some acoustical control and I was hoping to make some inexpensive gobo type panels that could be moved or possibly hung on the walls that could be utilized later when I finish the basement.

Michael

[michael hurd]

I think that it was foam by mail, selling on e-bay. However someone else might chime in.

[BS Button]

I'll chime in here.

[colterphoto1]

Todd, what do you mean.....

M

[colterphoto1]

Todd or Artto or anyone. Can you give any reassurance about the cheapfoam products being worthwhile at all versus a name brand like Auralex? I don't know what or how much my cinder block basement needs, but it sure needs something. Concrete floor, real plaster ceiling. It's just unlistenable down there.

Michael

[DrWho]

Here ya go: http://stores.ebay.com/Foam-Factory-Inc_W0QQssPageNameZviQ3asibQ3astoreviewQQtZkm

Seems they sell a lot more than just acoustic panels too

Don't forget about using some Sklyline RPG diffusors on the cieling as well (not sure if there are cheaper alternatives around)

[michael hurd]

Colter, I think B.S. Button just made a funny, and it went over your head! []

[colterphoto1]

well, he does sell foam products, so I thought naturally he would come to my rescue with a truck load of gratis foam products...

M

[BS Button]

I gotsta know what product?

[BS Button]

Isn't Hurd the paint guy? I've got a project for ya. Can you apply a baked on "black" krinkle finish? PM me..

[sfogg]

I use the Foambymail.com foam in my theater. I have a combination of

the 2,3 and 4" foam. It works very well and made a huge difference

compared to not having it with regards to slap echos and such.

Avoid the 1" stuff though, it does next to nothing. Also, don't use the

aerosal glue they sell. Use Liquid Nails, it holds much better. If you

want to be able to move it around later get some think luan board and

glue the foam to it then hang that from the wall.

Shawn

[formica]

Foam-by-mail are the guys mentioned in that other thread you were

looking for... the specs they publish on their products highly resemble

those published by Auralex. They were not performed by an

independent lab though. They use an open foam with the same

density.

Foam by Mail sell both through their website and eBay but

ironically their eBay "buy it now" pricing was lower last time I

checked.

I use the Foambymail.com foam in my theater.

I didn't realise you used some of their products... as I was

looking for an independent opinion. Good to know you liked their

performance... did you try any bass traps?

ROb

[colterphoto1]

thanks guys, now to figure out which frequencies are the offenders and which products to purchase. Any thoughts?

Should I just run my system flat, use my test cd and db meter in several listening positions to determine which thickness product to buy, or just get some misc foam pieces and do a couple corners of Lenrd-type, some 3" and some 2"???

Michael

[travisc]

your still screwing around with the flat eq on that reciever? Man everytime I do that its like putting a wet blanket over the Corns. If your trying to do room corrections dont eq to a flat response first. Thats like drywall after painting!! Colter I have been enjoying the eq set to front. I get the fronts unaltered and and everything else gets tuned to them. Good luck with the room treatments.

Wayne

[sfogg]

Rob,

"Foam by Mail sell both through their website and eBay but ironically their eBay "buy it now" pricing was lower last time I checked."

Yup, when I bought mine it was dramatically cheaper through ebay but I think they adjusted their pricing somewhat since then. The 4" stuff was around half the cost for example and they let me buy as much of it as I wanted at the ebay price. Ended up purchasing far more then I needed. My tiny theater with all the double drywall walls/ceiling and such was extremely live before hand and just sounded nasty. After the treatments it improved dramatically. Spent maybe $400 with them and it was extremely well worth the cost.

"I didn't realise you used some of their products..."

So far so good as long as you avoid the 1" stuff or the aerosal glue they sell.

My theaters front wall is all 4" foam and the side walls up front are 3" transitioning to 2". In the rear I have a horizontal line of 4" foam on the rear wall which moves onto the side walls at 2". The entire ceiling is 2" foam.

When I first put the foam up I used their glue. On the walls it sort of worked but from time to time I have had to reglue some of the panels.

I originally put the 1" stuff up on the ceiling with the spray glue. Next day some of the panels were loose so I reglued them. Day after that a few panels had fallen down... reglued.....

.... day after that about half the panels had fallen off the ceiling. At that point I pretty much flipped out and ripped it all down. Bought a bunch of Liquid Nails Heavy Duty at HD and put up the 2" panels with that. Since then not one has even gotten loose and it has been over a year now. Turned out for the best though since the 2" had a much better effect then the 1" stuff.

The only other slight complaint I have is the foam has a slightly sparkly look to it. With the front projection setup light spill on the foam lights it up a little more then I'd like. Not a huge thing but worth mentioning. At some point I might get around to covering the foam with fabric but it isn't much of a problem.

".. did you try any bass traps?"

No, I haven't tried their bass traps yet. I use EQ though to help tame the resonances. At some point I may give their bass products a whirl. I have also just considered filling the area between the screen (hangs out from the wall) and the front wall with stacks of foam. That would give me 20 or 22 inches of foam on the front wall of the room. Bass bouncing off the front wall would have to pass through it twice so I'd assume it would give a fair amount of absorption. Realistically I probably can't do that though as my heat/ac is also behind the screen so I need to give it some room to breathe.

Shawn

[michael hurd]

I just actually looked at the 4" foam wedge product on ebay, and saw the absorption co-efficeints, along with the NRC rating. This is the Foam by mail product.

t

1" Wedge

2" Wedge

3" Wedge

4" Wedge

2-1/2" Eggcrate

Bass Absorbers

Overall NRC

0.52

0.81

0.88

1.07

0.75

1.35

NRC at 125 HZ

0.09

0.13

0.22

0.32

0.20

1.25

NRC at 250 HZ

0.12

0.29

0.48

0.87

0.33

1.26

NRC at 500 HZ

0.33

0.89

1.04

1.23

0.68

1.47

NRC at 1000 HZ

0.65

1.08

1.07

1.11

0.99

1.42

NRC at 2000 HZ

0.96

0.97

0.94

1.08

1.01

1.24

NRC at 4000 HZ

1.01

1.04

1.08

1.10

1.03

1.29

Testing for the NRC ratinc was done by the Reverb Room (ASTM C423)

[michael hurd]

Foam is nice because it does not shed debris, however, if you can use a different product, possibly covering it, consider the Roxul RXL 40 mineral fibre batts. They are: semi-rigid, non-combustable ( service temp range of 450 F ), cut easily with a serrated knife, and inexpensive.

32 square feet of the Roxul RXL 40 4" thick insulation set me back $ 40 cdn, at an industrial supply house. This is 4 panels, 4" thick x 2 feet x 4 feet. $ 40 cdn = $ 34.18 u.s.

48 square feet of the 4" thick foam by mail wedge product is $ 69.99 u.s at the buy it now special price on e-bay. $69.99 u.s. = $81.89 cdn

One of the differences is that the " blades" on the foam product will add a diffusion element as well as straight absorption. Also, it is nice looking, Roxul rockwool...no.

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rxl40.pdf

[PrestonTom]

Michael,

This is perhaps putting the cart before the horse. I recommend first determining what portions of the spectra you are most concerned about.

Foam is a bit tricky but there are some rules of thumb. The foam will have absorption coefficients listed, preferably the entire function (absorption as a function of frequency) will be listed. In some cases there will only be a single number listed (e.g. NRC weighted average), this may or may not be useful.

The foam mave have a wedges carved into it. This will extend the effective bandwidth over which it absorbs (to the lower frequencies)

First, if the foam is shaped into wedges, the depth of wedge will deternine the lower frequencies that will be effectively absorbed (this is a relative statement). As a rule, the wedge would be about 1/4 wavelength (1000 Hz or 2 octaves above middle C) is about 13 inches for the wavegth so the wedge would need to be at least 4 inches in depth. Spinning through this fact, foam or fiber glass wedges are not very good for lower frequencies since they would be incredibly large.

Second, how the material is mounted does matter. The absorption coefficients listed should specify this (frequently for home material they do not bother). One trick is to mount the material on some sort of drape/sheet and space it away from the wall. This can help the material absorb even lower frequencies (to an extent). How ever the trick is most effective if the spacing is 1/4 to /2 wavelength. Again, this limits the practicality.

Foam is not the only solution: cloth, drapes etc can also help.

The problem is how to tame the low frequencies. This is where annoying standing waves come in to play. Low frequency waves are large and will effectively "not see" the material. There will be little absorption and little "breaking up' of the waveform. In this case the solution is a large space and physical devices like wave traps and resonators. This is more elaborate and there is a degree of tuning required. The WAF is especially tricky. Sometimes speaker location and furniture can help (not by eliminating the standing waves, but by moving them in their in location or frequency). However imaging could be impacted.

My advice is to do the homework ahead of time since the solutions (esp at low frequencies) can be costly. For the mid and high frequencies, try tacking up some old carpet on various positions on the walls, ceiling and extra (or less) carpet/pads on the floor. This will give a rough approximation of what might be gained with room treatment (or a reange of frequencies).

What is sometimes neglected is that a room entirely devoid of standing waves/reflections is not necessarily the goal (anechoic chambers do not sound very pleasant). Besides that goal would be very expensive. Usually folks want to tame reflections in certain areas to the mid-range so that imaging is more accurate (along with taming some spectral problems). In extreme cases, reverberation may also be excessive. Usually, folks are most concerned with the low frequencies, so the the bass has a more uneven response. Again, this region is the tricky and expensive one.

Note, at no point have I mentioned the use of an equalizer. If one is used, is should be done after the room treatment is complete, used sparingly, and not used to even out majpr probelms at the very low frequencies. In my opinion ...

Good luck,
-Tom

[colterphoto1]

your still screwing around with the flat eq on that reciever? Man everytime I do that its like putting a wet blanket over the Corns. If your trying to do room corrections dont eq to a flat response first. Thats like drywall after painting!! Colter I have been enjoying the eq set to front. I get the fronts unaltered and and everything else gets tuned to them. Good luck with the room treatments.

Wayne

Travis, this room treatment is for my basement workout/small HT room, which is concrete block and has the Yamaha RSV850, so no eq unless I add one- I've got lots I could use but got to do the room first.

Thanks for your notes though. I do use the FRONT setting when I do the YPAO, don't know that it matters that much will all CW, but at least the front two get the least amount of tweaking with that setup.

Michael

[travisc]

Michael, ya know I have been thinking about that all day, I shouldnt assume your all Cornwall HT would sound bad(though I do seem to remember you telling me it did) with the eq set to flat. My surrounds are book shelves that are wall mounted(they are not horns). I am sure an all Cornwall or horn system for that matter makes all the difference with the auto eq function. Sorry for misunderstanding

ya got to get all this stuff so DR. who can do his stuff with you basement?

Wayne