[vpolineni]

I've decided to add some more room treatments for my listening room.... with a budget of about 150 dollars.  I found a deal for some 3" thick foam... the question is, should I go with wedge style or eggcrate?  Does one type particularly work better than the other?  The other option is fiberglass panels.... are these more effective?  FWIW, I've considered minitraps from realtraps.com but they're just too expensive for me.... also, I currently have eighth's nerve roompack installed.  thanks in advance.[/b]

[Ethan Winer]

VP,

> should I go with wedge style or eggcrate? <

First, any foam that is not intended for acoustic use, such as packing or bedding foam, will not do anything for you.

Second, what are your problems and what are you trying to accomplish? If you need to reduce overall ambience and echoes, foam panels will do an acceptable job. But if you have bass problems, and pretty much every room does, thin foam panels will not help that.

>The other option is fiberglass panels.... are these more effective? <

Yes. For a given panel thickness, rigid fiberglass is 2 to 6 times more effective than acoustic foam.

--Ethan

[vpolineni]

ethan, thanks for the reply.. the foam in question is designed for acoustic purposes....mainly, i'm looking to treat my first reflection points but the excess foam I will have will go up on the front wall... given that it's 3.5" thick, will it be helpful at all in bass absorption?

[Ethan Winer]

VP,

> i'm looking to treat my first reflection points <

Yes, even two inch thick foam is acceptable for that use.

> the excess foam I will have will go up on the front wall <

Make sure you treat the first reflection points on the ceiling too, before deciding what's excess.

>given that it's 3.5" thick, will it be helpful at all in bass absorption? <

Not much, if it's attached flat on a wall. If you place several flat panels together to make them a foot thick and put them in the room corners, that will help at low frequencies.

--Ethan

[vpolineni]

ethan, thanks for the great input... i used the mirror trick to find my first reflection points on my walls.. how do i find them on my ceiling?

[Ethan Winer]

V,

> how do i find them on my ceiling? <

Same way. I have an extendible pole with a suction cup I bought at a hardware store to change the light bulbs high up on my ceiling. I took my wife's hand mirror and secured it to the suction cup with a couple of rubber bands. That worked really well, and the rubber bands flex enough to keep the mirror flat against the ceiling as I move it around.

I'll also mention that you don't even need a mirror unless your walls or ceiling are angled. In a room with parallel surfaces, the RFZ point is always on the side walls and ceiling, halfway between your ears and the loudspeakers. I have an angled ceiling in both my living room home theater and my recording studio, so I needed the "mirror on a stick" to be sure I found the right places on the ceiling. But for most rooms you can just use a tape measure.

--Ethan

[BrunoB]

Has anyone experience with closed shell foam for room treatment?
I think that closed shell foam could be used in conjunction with open cell foam and fiber glass to adsorb bass.

As far as I know, all acoustic foams are open cell (they act like a sponge in contact with water). Sound goes through very easely and does not adsorb much bass. Closed cell foams, on the other hand,  might adsorb sound by a membrane effect. The big advantage is that they don't need to be thick. I lined my speaker with closed cell rubber foam (very similar to Durafoam). I noticed an increase in bass output. Because of this, I was thinking of buying two rolls of Durafoam to line my back wall. Or may be Carlman would suggest a better or cheaper alternative?



Bruno