[ooheadsoo]

I'm posting this here just in case anyone is interested. These were constructed after reading many of Ethan Winer's posts and articles and a few tips taken from Jon Risch's diy panel trap.

I call it the "Ghetto Panel."

Fiberglass: 48 sq.ft. 3lb. pcf 2" Certainteed brand rigid fiberglass panels(6) - ~$71
Burlap: $3 a yard, ~$4.65 per panel, total x 4- ~$18.60
Frame materials: lumber - $1.09 a piece x 6, 4 packages of corner braces $2.74ea., upholstery nails x 2 $1ea. - ~$21

Total ~ $111
Please note though I purchased 6 panels of fiberglass, I only purchased enough other materials to assemble 3-4 traps. For 2 more panels, you would probably need another $22 or so.

Tools: drill, philips screwdriver, hammer

Here's what the raw panel looks like for those who don't know. (I didn't.)

Some tools, minus hammer.

The lumber cut up by a home depot employee. When choosing the lumber, I asked for the cheapest 1x2 they had. A good thing to do is to try to pick pieces that are actually flat. I wanted to get on to making my panels so I didn't pay attention to it. It's not bad, but for those perfectionists...you probably already knew that didn't you?

Here's that bracket I chose. You can probably save a buck or two by buying cheaper brackets without included screws and buying the screws separately...but I wanted to go build my panels, not hunt down screws It also would probably be easier to use a flat bracket unlike the ones I chose.

Here's the assembled frame. I predrilled holes for the brackets and then screwed them in by hand.

Here I placed the fiberglass on top of the burlap and the frame on top of the fiberglass. Then I flipped it over and nailed in like so:

I used 2.5" nails I already had lying around the house.

After nailing the fiberglass to the frame, flip it over so that the fiberglass side is facing the burlap. Then, fold the edges of the burlap over and use those thumbtacks/whatever to secure them.

Flip it over when you're done and this is what you get: Genuine Ghetto Panel.

Takes me about an hour per panel. Use more thumbtacks if you can spare them. The burlap loosens up by itself over time and the creases diminish. You could consider ironing it I guess...

 

[Wmcmanus]

Hey, not bad for an hour or so and $111. You should consider using an iron or steamer for that burlap and then stretch it a bit more as well, but maybe that is the perfectionist in me speaking...

 

[ooheadsoo]

I actually had that in my edit before seeing your post

I did add a couple more thumbtacks after taking the picure so it's not quite as bad as it is in the picture. The burlap also loosens up by itself over time just a tad so the wrinkles aren't as prominent.

Btw, the burlap doesn't stretch tight. It'll kinda just keep stretching until you tear it apart. The best solution is probably ironing it, which I seriously considered, but I got lazy

It's supposed to be ghetto, you know?

Here's my room right now. I haven't mounted the panels yet and the left panel is unassembled, it just has a piece of burlap draped over the fiberglass.

 

[Wmcmanus]

Ok, gotcha. The ones I've seen that are done professionally must also use some form of liquid adhesive as well because the burlap is essentially 'baked' on much like the liners that are used for the interior of cars.

 

[skiguy411]

Hey let me know if there is a major difference. I have been thinking about doing something like this.

 

[Mr.PD]

I am not familiar with rigid fiberglass panels. How rigid are they? Would plain old rolls of fiberglass work? The frame should hold them fine, wouldn't it?

There must be an advantage to rigid panels that I am not seeing.

 

[Sovkiller]

Is there any noticeable difference between those, and those pieces of foam, that cover the wall in the anaechoic chambers....???

 

[ooheadsoo]

Rigid fiberglass is compressed fiberglass. It's a whole lotta fiberglass in less space. Regular fiberglass works but you'd need like over 8" thick of it to get the same use out of it. Preferably, I would have gotten the 6lb.pcf stuff but I wanted to just try it out.

I don't think they use foam in anechoic chambers

Fiberglass performs a lot better than foam. Have a look at the specs: http://ethanwiner.com/acoustics.html#mhf%20absorbers

The "typical" foam Ethan used in the comparison is a MAJOR brand, quite pricy. I don't remember which one it is now, but in my search for foam vs. fiberglass, I ran across those exact specifications. I think that the foam specs are for 4 inches of foam too. The fiberglass specs are for 2 inches, like I'm using.

I'll get to the preformance in a bit.

 

[Tuberoller]

Hey there. I made panels using acoustic foam and some using compressed glass. I think the different materials perform differing tasks. The foam seems to effect bass reflection and the glass seems to have more effect on upper and midrange. I constructed mine to look more like picture frames and covered them with painted silk fabric. They look great and do an excellent job. Right now they're sittin' in a box cause I still don't have my room back together yet.

 

[Sovkiller]

Other ideas, more complex of course, if you look closer to the right they use foam there.....

 

[ooheadsoo]

Hey tubes. It's funny you say that because the specs are half way the opposite. Fiberglass has way better absorption at the bottom end according to the NRC coefficients. For 3lb stuff like I got, the fiberglass is almost twice as good at bass absorption than foam for the same thickness. The 6lb. stuff has an even higher coefficient. The coefficient represents the percentage of sound that the material absorbs at that frequency, as per my understanding. Incidentally, fiberglass performs just as well as foam in the higher frequencies too. Well, this is according to the specs as they determined them in anechoic chambers. Is it possible they fudged the numbers? I guess so, but the fiberglass isn't even an audiophile product aimed at consumers. The only place I found that stocked the stuff was a big warehouse that specialized in selling insulation for construction. Btw tubes, tests made by various people I read about found that burlap was the most transparent fabric they could find. Others either didn't let the sound pass through as well or, even worse, reflected sound off of it. Maybe the silk you used had something to do with your results. That would be interesting to find out.

Eager to hear any more experiences you have, tuberoller!

Sov, I'm not sure, but I think some of those things are either hemholtz (sp?) resonators or just diffractors. I think in the top picture they may just be diffractors because I think I see a bass trap at the very bottom of the pic unless it's a cylindrical subwoofer. If it's a bass trap, it's usually filled with fiberglass afaik. Might be a bit small to be a bass trap...The resonators are the traditional way to bass trap but each one only has a specific frequency it absorbs, meaning you need lots of them custom made for your room and listening position. Not exactly ideal. Fiberglass bass traps trap a large range of frequencies. I see the foam at the back. I wonder why. It looks like it's behind the main speakers. If I used foam, I think I would have used them in front of the mains, but that's because I believe the specs. Tubes has a different experience with his foam that says otherwise, so who knows. I'm suspicious of the silk though. I've read that diffractors are only good when you want to keep the room ambience, like in a large concert hall. Otherwise, it's better to absorb the energy carefully. People disagree on this though.

 

[Orpheus]

Quote:

The foam seems to effect bass reflection and the glass seems to have more effect on upper and midrange.

usually it's the other way around... or at least the foam is there mostly for the upper-range. if you buy auralex, they will specify the frequency range where the dampening works, and by how much. it depends mostly on the thickness and the shape of the foam. the fiberglass is usually used for bass traps..., at least that's the most common use. but i'm not sure why.

 

[ooheadsoo]

It's use in bass traps is directly related to its NRC coefficient, which measures how well it absorbs a specified frequency. Simply put, foam doesn't absorb low frequencies, fiberglass does. In fact, fiberglass seems to absorb most everything really well at least up to 4000hz according to the numbers.

 

[ooheadsoo]

I mounted the two front panels. Unfortunately, I am unable to space them out from the walls at this moment and this has really hurt the effect of the panels. I also have them lower than they were when they were sitting on my desk and that has hurt the clap test severely while standing. Luckily my seated position is fine. With these panels, detail is enhanced and focus is sharpened. I understand that this is becuase it reduces early reflections which will confuse the ear. It was even better when the panels were farther from the walls. This is because the sound has time to lose energy before hitting the wall and passing through the panel a second time. This is bar none the greatest tweak I have experienced. The clap test is measurable, no doubt. As for what I hear in the imaging, that's subjective, but like I said, what I hear is better detail, little to no confusion in the soundstage placement of instruments, and better depth. Without the panels, on some recordings, sometimes the placement of the instruments is a bit confusing, especially if I'm trying to locate a particular voice among a mass. This confusion is much lessened now and I hardly ever experience it, if at all. The depth was significantly better than it is now when the panels were farther out from the walls, but as it is now, it's still better than it is normally without the panels. Instruments leap into focus better. I still don't hear depth like some people claim, saying they can hear like 20 feet beyond the speakers. Maybe it's some other part of my system or maybe they're blowing smoke, who knows. Subjectively, I think the burlap hurt the performance compared to plain fiberglass too, but I have no way to substantiate that claim. In any case, people who have access to anechoic chambers have already found that burlap is the best fabric and having exposed fiberglass is not an option.

 

[Orpheus]

you know, the #1 best thing you can do for your listening room is to rearrange everything to be symmetrical. that hall on the right side is not good. your panels are really cool, good job, but you'll get a much better effect if your room is even, and the panels are also symmetrical.