Acoustic panels

[Rodny]

Need input on DIY acoustic panels. Thanks

[ThomasW]

Here's a link to my webpage for DIY acoustic panels. It's a bit out of date but should get you started.

[dyazdani]

Here's a link to my post on another forum.

DIY Panels

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Edit: by moderator.

The HT-Guide admin prefers not linking into other forum threads. So I've taken the links and the information from that thread and placed it in this post....

Some frames ready for fiberglass:

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Varous stages of completeness:

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Corner panel ready for fabric:

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Reflection point panel ready for fabric:

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Panels ready for final fabric trimming:

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Panels temporarily located around room:

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Poly-Fil, batting that they use in quilts, etc. I used it on the big traps basically to take up a little space. I used 1x6 lumber and 5 sheets of fiberglass, so there was about 1/2" left over.

The panels that are in the corners are 5" thick, the panels on the front wall and at the reflection points are 2" thick with a 1.5" space behind them.
All panels are 2'x4'.

In case you are wondering, I cut the triangles out of a 4x8 sheet of Lauan.

As fas as hanging, I didn't do anything special. The panels on the front wall are hung with standard picture hangers and braided wire. I installed eye bolts on each inside edge of the frame and ran the wire between them.

The corner panels were a little trickier. I used the same eye bolts but have two shorter pieces of wire, one on each bolt. I then used two picture hangers (50lb capacity).

No problem. If you do decide to build the frames, here are a couple of tools that cut my production time way down.

1) corner clamps: used to hold the 1x's while screwing them together

2) staple gun/brad nailer: the obvious use is for the fabric, but where it really helped was nailing the triangles to the frames. I was using a hammer at first, probably saved me 4-5 minutes per panel.

3) chop (miter) saw: I don't have one, I used a table saw and a standard circular saw instead. If I end up making more, this will be a requirement!

The frame also helped me to keep everything square since I used multiple 1" slices of fiberglass.

As far as weight: the 5" thick panels weigh about 26lbs and the 2" panels weigh about 16lbs.

I was worried about the weight of the bigger variety at first, but it turned out fine. Actually, since they hang from two points, it's less force on the wall than the thin panels.

[Rodny]

Thank you.

[thylantyr]

Is anyone worried about using fiberglass even though you have some acoustic transparent cloth to hold the fibers from entering
your environment? For some reason, I'm ultra paraoid about doing
this. What if I install a thin layer of polyfill or batting on top of the
fiberglass to ensure fibers stay put ?

[dyazdani]

Sorry about the link...

I used some PolyFill between the fiberglass and the fabric on a few panels. The glass is actually bonded pretty well, so I wasn't all that concerned with it.

Another idea I had was to spray down the outside surfaces with spray adhesive.

[ThomasW]

In the 'real world' I worked in healthcare (level I trauma center where they filmed the Denver "Knife & Gun Club" Emergency Room episodes) for a many decades. And personally I think the 'scare' about fiberglass is a bit overblown.

Certainly it's not a good thing to breath the fibers (wear a dust mask, gloves, coveralls.) But if the fibers were a serious public health issue, insulation installers everywhere would be dropping dead, and they aren't.

If one buys the Corning 703 compressed fiberglass panels there are fewer issues with loose particles, since the fibers are bonded together.

[Dennis H]

Yup, MDF is worse than fiberglass. It's not a good idea to breathe either one but it's nothing to lose sleep about if you take reasonable precautions.

[dyazdani]

Yep, the fiberglass is bonded very well assuming you get "ductboard" type panels (703, etc). I bought fiberglass with kraft/foil on one side. I ripped that off which disturbed the fiberglass a bit. I just made sure to put that side inward when I stacked the sheets in the panel frame.

[thylantyr]

My understanding is. 703 would not work for high
frequency absorption if the material is 'solid', don't you
need a 'loose fill' on the panel ? I can see installing both to
make a panel more of a 'jack of all trades' where the solid
fiberglass can be the subtrate then fill the loose glass on
top, then polyfill on the glass to contain particles, finish
it off with grill cloth. Would that work?

layers in a panel;
703
loose glass
polyfill
grill gloth

The reason fiberglass bothers me is.. If I stand near it, I
start to get itch with vary little manipulation of the
product, hence those particles must be coming loose
and geting airborne, I visualize nasties entering your lungs
unless you contain them.

MDF doesn't have that effect. It's solid, you have to cut it
or sand it to create dust. House are built with the
fiberglass being covered not exposed so that's why it's accepted. I don't think anyone would 'sign off' a house if the fiberglass is exposed to the environment.

/paranoid
/lol



I guess people are more brave than me ;x(

I will probably experiment with some panels...

[Dennis H]

703 works fine for high frequencies.

http://johnlsayers.com/Stuff/AbsorptionCoefficients.htm

[cjd]

FWIW, the issues with fiberglass really only exist when it's being installed/worked with, which is usually done by people that work with it day-in, day-out.. Once it's in a panel and relatively still, it'll be fine - just like the stuff in your attic and walls and basement and everywhere else it exists in your house.

In fact, you are as likely (if not more likely) to have fiberglass dust filtering through the house when it shakes with the application of a little bass. Or wind. Or earthquakes, if you're in that part of the world.

C

[thylantyr]

703 works fine for high frequencies.

http://johnlsayers.com/Stuff/AbsorptionCoefficients.htm

Oddly enough, I can't recall people using 703 on DIY
loudspeaker enclosures. Maybe I didn't pay attention,
but if it's that good you'd expect it to be used alot in
DIY speakers?

I guess what is needed is Acousta-Stuf 'testing' to compare with, I haven't seen numbers for that material.
I know it works but what is the best recipe for higher frequencies?

[thylantyr]

FWIW, the issues with fiberglass really only exist when it's being installed/worked with, which is usually done by people that work with it day-in, day-out.. Once it's in a panel and relatively still, it'll be fine - just like the stuff in your attic and walls and basement and everywhere else it exists in your house.

In fact, you are as likely (if not more likely) to have fiberglass dust filtering through the house when it shakes with the application of a little bass. Or wind. Or earthquakes, if you're in that part of the world.

C

This is how I view the issue.

Home
Exposed fiberglass behind drywall = isolation.
Plastic encased fiberglass {less cutoff ends}, as is
without drywall = isolation.

DIY Sound Panels
Exposed fiberglass behind thin 'speaker grill cloth' = not 100% isolated.

Plastic encased fiberglass shouldn't be used in DIY panels
because there is no HF absorption, the sound will bounce off the plastic case {maybe use it for LF?}.

I see more 'health risk' by having exposed 'loosely filled'
DIY panels vs. fiberglass hiding behind a sealed off
attic or wall using drywall.

I'm using my 'common sense' card I pulled out of my
back pocket because I'm not a expert on the subject.

I don't have fiberglass insulation in the attic, there is some
paper based stuff that is blown in. When I take my 500w
shop light up there I see particles in the air even without
aggitation of the materials. I would never go up there without a mask :lol:

[RobP]

If fiberglass bothers you, then how a pure cotton alternative? I could not find the acoustical values of it as of yet.

[RobP]

found the chart.

[cjd]

Fiberglass at rest = OK

think of it that way.

You're probably not sticking your face in the panels and breathing, or taking them for a spin on the dance floor. It is likely they will sit in one spot and not move.

My basement has exposed fiberglass insulation.

Recycled cotton for insulating is becoming more available these days. Neat stuff, if it's acoustically any good it's definitely a nice alternative IMHO.

Wool would be too I bet. Just not sure the price would be right.

C

[RobP]

CJD, Wool would be nice :T

Thylantyr, I wouldnt worry about the fiberglass myself. If you really want to worry about what we fill our lungs up with at home do some research on dust mites and what they leave behind in your bed that you sleep in. :E
Sleep Tight. :rofl:

[Dennis H]

The point is the 703 panels are saturated with glue so there are no loose fibers except maybe when you're cutting the stuff. Exposed batt insulation can have loose fibers but covering it with cloth will hold them in. If you're paranoid, you can use a thin layer of polyester quilt batting as an extra shield. There are differences in fiberglass batting quality. The good stuff is all long fibers with no short particles to float in the air. Miraflex is the best but they aren't making it any more -- too bad.

[dyazdani]

I believe that cotton and wool will also work, however it doesn't come in a density that would absorb anything very low. You'd have to get a thick amount and compress it down.

If the only thing keeping you from getting 703 or similar fiberglass panels is the fear of dust, I would go ahead and get them. They are long fibers, bonded very well. The only dust that is created is when you cut them to length or rip off the facing.

[thylantyr]

I forgot to mention, the data you linked to 703 showed
up to 4000hz. I was confused because compressed fiberglass or any other 'solid' material would reflect high frequencies, but then is 4000hz really a high frequency ? :lol:

I haven't seen data on loose fiberglass tested at higher than 4khz, but I'd imagine it would have a better batting average over compressed. Point is, maybe both are needed in a composite panel design.

There is one fella on AVS that sells the acoustic cotton,
something to check out. Wool would be cool. Does this stuff
go up in flames? :rofl:

When in doubt, borrow Sauron's crystal ball and take a peek into the future :W

[PMazz]

I lined my brothers M8 MTMs with unfaced 2" 703. As you can see, it's a pretty stable product. It would make an excellent DIY acoustic panel with not much effort.

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Pete

[thylantyr]

I lined my brothers M8 MTMs with unfaced 2" 703. As you can see, it's a pretty stable product. It would make an excellent DIY acoustic panel with not much effort.

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Pete

I see said the blind man. I thought 703 was denser than that, my bad. I can see know why it works well.
I'll just have to make some test panels to see how it works,
time to buy a particle counter :twisted: :lol:

[ThomasW]

I was doing a little research for an article and found Bob Golds' amazing website.

This should be bookmarked by anyone interested in DIY acoustic panels

[Dennis H]

Hehe, looks like he "borrowed" and spiffed up the page I posted above.

http://johnlsayers.com/Stuff/AbsorptionCoefficients.htm

Edit: oops my mistake. I did a "view source" and Bob Gold's page is the original. ops: