Acoustical Treatments Master Thread - Page 218

Interesting.

Not sure that I can sense the increased spaciousness in the recording. The fully treated room is impressive sounding in the video (though a little too utilitarian looking for a home theater!). The untreated/fully treated contrast is instructive and probably even more extreme in person.

What was most interesting: Adding the diffusion to a room that already has good absorption really allowed the bass to be better defined -- which is usually something I associate with trapping rather than diffusion.

Maybe that's because your diffusers ALSO do some bass trapping. But it's interesting that that is what jumped out at me most.

^^^ Yes, the improvement in bass frequency response and ringing is due to the diffusors also working as bass traps. As for increased spaciousness, that's not so much what comes through in the video. It's more not hearing the boxy hollow type sound you'd usually have when recording music playing through loudspeakers.

--Ethan

Came across this brief but cool article on Microsoft's anechoic chamber:
http://gizmodo.com/5372268/microsoft...nd-goes-to-die

Trampoline floor sounds pretty cool!

Anyone ever use insulated sheathing similar to the stuff sold a Lowes or Home Depot? I guess it is made out of "Expanded Polystyrene" so Im not sure what the acoustic asorbtion properties would be. Im thinking about making my own acoustic panels out of it.
http://www.lowes.com/pd_15357-10477-...96_4294937087_

What is the difference between the yellow and pink fiberglass batting? I see the yellow go in the walls and pink go in the ceilings. This isn't the OC703 that I goes on after the drywall either.

I made these 3 diffusors about 3-4 years ago, should I cover them with fabric making them into "cubes" or should I follow the shape? the fabric is called Duck cloth, its cotton and you can see light through it but it is very stiff feeling so Im not sure how transparent it is. Its far from speaker grille cloth.

Mark,
If you want to fabric them and you have a fabric store nearby, take a look at 'broadcloth'.
I saw some yesterday a JoAnn and it looked like it might work good for your app.
Nice mix of transparency, workable structure, and available in lotsa colors.

http://www.bobgolds.com/AbsorptionCoefficients.htm is your friend.

Hi Mark,

You can always test any material by placing it in front of a speaker and performing near field tests on it. If it is more than -3dB, it won't work for your purposes. Best wishes!

I have a sample of GOM, Anchorage. I did the "breath" test and was a bit surprised... the cotton shirt I am wearing had less resistance...am I missing something?

Yep your test is right. You dont want to use that in front of speakers and it will diminish high frequency absorption of acoustic panels covered in it. Use 701 for example instead.

While Anchorage looks awesome, it doesn't have the acoustic rating that FR701 (I believe) does. If you received samples from Interface Fabrics they will have information on each fabric's properties. Anchorage doesn't claim any acoustic transparency according to the samples I have. It looks cool, but...

OK, good stuff thanks guys.....so use 701 or even speaker cloth on the false wall... However, does this mean that if I find something close to anchorage at a fabric store I can use it over 703 and base traps? Basically I am asking if I can be more liberal in my selection of fabrics on the areas other than the false wall......THANKS.

Adding cloth across the face will increase absorption. Because the pressure at the mouth of each well is different, there is significant airflow across the face of the fins. Adding cloth impedes this airflow.

Following the profile is better, but again there may be an increase in absorption due to the increase in surface roughness.

What the Cox and D'Antonio "bible" has to say...

They advise against cloth covering, but if you must use it, they suggest it be spaced at least one well width clear of the fin faces.

Hmmm, I would have made them a little more towards the pretty side had I known that.........I guess I'll featherfill ( thick primer) and paint the wood ones and fabric the absorbing one

FR701 is class "A" fire rated. Everything posted so far on Anchorage is correct. It's cool-looking and comes in some vivid colors, but FR701 is a better choice acoustically.

Alright, so I made some acoustical panels, but did not make a frame for each. I just wrapped each OC703 sheet in burlap. My original plan was to secure them to the walls with velcro that plan failed mightily.

I am looking for some suggestions on this dilemma. My two current options are:

1) use liquid nails to attach pegboard to the back of each panel and hang like a picture
2) use t-pins straight through the panels and into the wall

I am just looking for any opinions on these two choices or interested in hearing some better options. Thank you.

yeah you have to use pegboard or something to the back of the absorbing material then wrap the fabric over that and stick the velcro to the pegboard, not the fabric and then velcro is more than sufficient. You could still do this if the material was stuck using spray adhesive

BURLAP?? Really? Cripes, that's what we used to buy horse feed in ... I can't imagine. I'd say scrap the burlap and use GOM or something similar for your next go-around. And build frames.

Tooj,

I assume the panels are rather light and at least 1" thick and the backs are not a hard surface?

If so; the following suggestion (may seem simple and crude) worked for me:

Use a pencil to lightly trace out the perimeter outline of your panel in it's desired location onto your wall.

Hopefully you can locate at least one stud behind the drywall inside your outline. Then pound in some extra long finish nails ~2.5". Pound these in until the exposed length is slightly shorter than the thickness of your panels.

Next carefully position the panel in front of the nail heads, and then carefully press the panel to the wall, the exposed head of the finish nail should impale your panel into place, and you are done?

Thanks for the replies. cuzed2, this seems like the easiest choice. I'll give it a try sometime this week.

Good Luck - let us know if it worked

I (may) have the opportunity to purchase some Roxul AFB 1.5" for a great price. My plan would be to double it up to 3" for my acoustic panels.

I've looked at Bob Golds website and see that the numbers for 3" panels are roughly the same regardless of brand/manufacturer.

Is there any reason I would not want to use this particular product?

Rob

The Roxul is just fine and personally, my preference in terms of overall quality control from the factory.

Bryan

Thanks Bryan.

On a side note, could I get away with 1.5" panels at the first/ceiling reflections and make up the difference in low absorption with corner chunks of the same material?

What I'm getting at is will there be a big audible difference with 1.5" panels vs. 2" panels at the first reflections, all else being equal?

Yes...that'll work just fine.


Not a huge difference.

Having difficult time finding 1" diffusors.......these are the only two I've found:

RPG Bad Panels which are not true diffusors

or

Auralex which are 1" plastic step wedges.

Are there other 1" thick diffusors that can be recommended?

Thanks

One inch is not very deep for a diffusor ... or an absorber.

Right. Why do you want a 1" diffuser anyway?

I'm sure that it has something to do with aesthetics.