Do you cover fiberglass with anything beside burlap?

michaelv · « **on:** 12 Jul 2005, 07:24 pm »

Hi,
Burlap is loose weave and i'm afraid that the particles from OC 703 will escape into the air. So , i was wondering which type of cover do you use beside burlap to cover outside frame?

Also, i now realize that making acoustic panel is time consuming...

thanks.

gongos · « **Reply #1 on:** 12 Jul 2005, 07:36 pm »

I covered mine with fabric. I don't you have to worry much about the particles, unless you're constantly disturbing the panels. The fiberglass doesn't jump off itself as fas as I know.

gravy · « **Reply #2 on:** 12 Jul 2005, 08:10 pm »

Quote from: michaelv

Hi,
Burlap is loose weave and i'm afraid that the particles from OC 703 will escape into the air. So , i was wondering which type of cover do you use beside burlap to cover outside frame?

Also, i now realize that making acoustic panel is time consuming...

thanks.

I used speaker grill cloth, black, as per some good suggestions here on the forum.

warnerwh · « **Reply #3 on:** 12 Jul 2005, 09:17 pm »

I put batting over the fiberglass, then burlap. This helps make sure the fiberglass can't get out.

bpape · « **Reply #4 on:** 12 Jul 2005, 10:16 pm »

Lightweight Muslin is another option. It's cheap, easy to work with, and tight enough to hold things in pretty well. If you want, use 2 layers.

As long as the panels you're covering are being built to absorb full range instead of bass only, it will do fine.

michaelv · « **Reply #5 on:** 13 Jul 2005, 05:44 pm »

thanks, everyone.

I think putting cotton batting over fiberglass before wrap fabric around the frame is a good idea. One thing i notice that burlap is itchy too and not easy to wrap like cotton fabric. However, cotton fabric is too tight so i'm afraid that it will reflect too much sound.

bpape · « **Reply #6 on:** 13 Jul 2005, 07:25 pm »

The lightweight muslin fabric is just fine. It will pass air easily.

ScottMayo · « **Reply #7 on:** 14 Jul 2005, 08:44 pm »

Quote from: michaelv

Hi,
Burlap is loose weave and i'm afraid that the particles from OC 703 will escape into the air. So , i was wondering which type of cover do you use beside burlap to cover outside frame?

Denser (11oz) burlap has worked well for me. $2.90/yard (4' wide) if you buy a lot of it from http://www.bestpakcompany.com/burlap_colors.htm . (They don't admit to that price, you have to pester them.)

bpape · « **Reply #8 on:** 17 Jul 2005, 10:57 pm »

It all depends on what kind of absorber you're covering. If it is something that is supposed to absorb high frequencies anyway, then something denser would be fine. If you're covering something like FRK or a stretched membrane that is supposed to reflect the highs, stick with something more acoustically transparent.

michaelv · « **Reply #9 on:** 18 Jul 2005, 03:21 pm »

last night i put only 2" thick panel in two corner and 2" thick panel on the sides for first reflection point. The lower/ mid bass improved a lot.

So, i'tm thinking of spacing the panel 1" away from the wall ( at first reflection point) and i will do the same thing for other two panel in the rear. Do you think 1" away from wall is ok? I'm just trying to improve bass a little more.

thanks.

Ethan Winer · « **Reply #10 on:** 18 Jul 2005, 05:44 pm »

Michael,

> Do you think 1" away from wall is ok? I'm just trying to improve bass a little more. <

In that case the best thing you can do is double up the thickness of the corner panels so they're four inches thick instead of only two. Thicker isn't needed so much for panels on the side walls, but it really makes a difference at bass frequencies for corner panels.

--Ethan

michaelv · « **Reply #11 on:** 18 Jul 2005, 07:55 pm »

Ethan, thanks for the advice.

what happen is i have already made 2 panels (2" thick each) with cover and everything. I will have tie them up. I guess extra burlap won't be a problem. I must say that i'm happy than ever and it's much much better than foam panel.

Ethan Winer · « **Reply #12 on:** 19 Jul 2005, 03:20 pm »

Michael,

> i have already made 2 panels (2" thick each) with cover and everything. <

So use those at the first reflection points on your side walls, and build more (at least four more) four inches thick for the corners.

--Ethan

michaelv · « **Reply #13 on:** 19 Jul 2005, 06:30 pm »

Ethan,
Do you mean 4 of 4" panels? Right now, i have two 4" panels in corners in front of the speaker. The bass is way better. I think will get two more (4") for the rear corner (behind speakers).

Ethan Winer · « **Reply #14 on:** 19 Jul 2005, 08:38 pm »

Michael,

> i have two 4" panels in corners in front of the speaker. <

Great, you're way ahead of me.

With corner bass traps, the more the better. Two in the front corners is a good start. Eight total will give you awesome results.

--Ethan

michaelv · « **Reply #15 on:** 19 Jul 2005, 10:14 pm »

Looks like i'm going to squeeze more out of my saving for the rear bass trap

Do you hang wall panel behind speaker too? If so , how do i know the exact location? ( with the mirror method, i can locate the position of speaker on sidewall, but not the rear) THis is for 2 channel listening room only, no HT.

thanks again.

Ethan Winer · « **Reply #16 on:** 20 Jul 2005, 02:45 pm »

Michael,

> Do you hang wall panel behind speaker too? <

On the front wall, in front of you? I don't see much value in that, unless the room is too live sounding anyway. In that case the front wall is just another place to put absorption. Usually, echoes off the rear wall behind you are more damaging. Especially if the wall is not far behind you.

--Ethan

michaelv · « **Reply #17 on:** 20 Jul 2005, 05:40 pm »

Ethan,
the rear wall behind me is 2ft away from my seat. My listening room is not too live, so i think it's ok. How do you tell which position to put the absorbtion? any suggestions? Note that there is small window in the rear wall too.

thanks.

Ethan Winer · « **Reply #18 on:** 21 Jul 2005, 03:12 pm »

Michael,

> the rear wall behind me is 2ft away from my seat <

That's really close. The problem is comb filtering which creates a series of many peaks and deep nulls in the response. If you put thick absorption on the wall you can minimize that problem above the bass range. But you'll still have a huge null at 141 Hz and a peak at 282 Hz, and maybe a lesser null at 424 Hz. This is why I always suggest setting up so the loudspeakers fire the long way down the room. That puts the rear wall as far behind you as possible.

> How do you tell which position to put the absorbtion? <

I guess it's time once again to link my Acoustics FAQ:

www.ethanwiner.com/acoustics.html

--Ethan

Carlman · « **Reply #19 on:** 21 Jul 2005, 03:31 pm »

Quote from: michaelv

Ethan,
the rear wall behind me is 2ft away from my seat. My listening room is not too live, so i think it's ok. How do you tell which position to put the absorbtion? any suggestions? Note that there is small window in the rear wall too.

thanks.

I wish I had 2'... That would be great! My couch is against my rear wall, with my head about 1' from the rear wall, maybe less. I've tried moving around but with very little room to play with, a wife, decor, etc., there's only so much you can do.

Thanks for the tips, Ethan...

-C