The AM Forum

How much difference would it make using bedding foam instead of acoustic foam?

I'm sure you've seen the bedding/packing foam that looks like an egg crate design. I'm wondering how well that would work versus the more expensive route of buying acoustic foam. I know that the peaks and valleys on acoustic foam is molded with more of an isotropic shape to prevent sound reflection but would the bedding foam do pretty much the same? Surely it won't look as pretty but I'm not really concerned with that. I'd just like to have some sound deadening and anti reflection material on the hard walls here in the shack.

Carpeting the walls is another possibility. For now the walls are wood paneling.. I know, so 70's but hey, the rent is cheap, and the property is prime for antennas, so what the hell. I'm allowed to do anything I want to the house/property to make it comfortable, but I want to do so without investing a ton of money.

Go for it. I would use the bedding foam. It should make a world of difference for a too-live room acoustically. Even just adding draperies over the walls, not carpet, will help quite a bit. I imagine the expensive studio foam tiles would be ultimate, but the difference between it and your method isn't worth the expense. Come to think of it, I believe I remember some smalll market broadcast studios that have used bedding foam. You have less choice over color of course.

I imagine bedding foam is probably fire safe for those dummies who smoke in bed but you might want to check its flammability.

Years ago when I was just a pup, radio stations used egg cartons nailed to the wall.  You can paint them different colors for an electic look to match any personality you might want.

Yes check into fire resistance. Remember the outrageous fire in that club in Maine? It went up like a match stick. The home videos showed people trampling on each other to escape the fast spreading fire. Of course, I know you aren't going to have pyrotechnics(?) in your Ham shack.
Fred

"I know you aren't going to have pyrotechnics(?) in your Ham shack."

No one can say for sure...  ;D

Actually, that was up in Providence RI not to far from here which is what prompted me to post that previous post.  The lawsuits are still flying around.

Homebrewing = smokes and explodes = pyrotechnics

Yes that was the band Great White..

Rhode Island night club fire (http://en.wikipedia.org/wiki/Rhode_Island_night_club_fire)

How about beige acoustic tiles, an on-air sign and a big clock?

(http://www.coutant.org/owens.jpg)

Don't find those tiles around too often anymore..
Didn't they contain asbestos fiber?

The fickled finger of mouse found this on the Armstron website. gots the data. and thats the truth .........   klc



http://www.armstrong.com/commceilingsna/market_segment_results.jsp?mId=1.0&useAreaId=93.0&x=33&y=5

Oh man I remember using those acoustic tiles with all the holes. Some sh-- head decided it would be a good idea and painted them turning them into hard flat reflective surfaces. I also remember using the egg flats but we put them into a covered frame. In a small talk booth we also used the bedding foam.We made a wooded frame for it and covered the whole thing in a heavy fabric that looked somewhat like a really good quality burlap.It actually looked quite nice as you could not see the foam underneath and it sure worked well.

Absolutely do NOT use any sort of foam on your room's surfaces!! Imho that is.

Several reasons:
- it all burns with extremely toxic smoke and fumes
- it all outgasses nasty chemicals, including formaldehyde
- soon enough it crumbles off layers of nasty micro particles of foam that you breathe
- and even if you discount all of the above - it's a very poor acoustic absorber

The foam that is sold that is made up of multiple surfaces is also sprayed with a latex paint type material (might be paint) so that it a) acts as a diffuse reflector (the painted surfaces) and b) acts as a multi frequency absorber (to spread the ratty absorption spectra).

Imho there are better ways to go.

The best commercial way to go is the stuff that Dow Corning (and others) sell for walls. It's been advertised on TV for basements recently. It's a fabric covered 2" or 4" thick "hard" fiberglass panel. If you look on their site you'll see how it absorbs relatively evenly with respect to frequency. The 4" works down to the bass regions. Fyi, the silly "eggcrate foam" stuff probably stops working by >1000Hz.

This stuff is also available as an unfinished "batt" without the fabric.
The same sort of stuff is used on the 2x4ft "acoustic tiles" for dropped ceilings, but it's only 1/2" thick, and it has usually plastic on the white side.

One can take the fiberglass stuff and enclose it in a simple "frame" and cover that with ur garden variety fabric and have a removable, jim dandy, and effective absorber. Make the frame up in sizes that are attractive and/or convenient for ur use. You do not not need to have 100% coverage of a wall or ceiling at all. 50% coverage of 4" thick will make the room reasonably dead at that.

Think of it this way - if the absorption is sufficiently good (in terms of dB) each area that is absorptive is like having a completely open window for the frequencies that the area absorbs well.

The other method that is also useful is to make the same frame deal up, and simply put a face and rear of mesh - window screen is one way to go - and fill the frame with regular 6" thick fiberglass house insulation or rock wool. Cover as before with a suitable looking fabric - open weave for max HF absorption, and something tighter for a bit less. You can pick colors and/or patterns to suit.

The fiberglass framed absorbers WORK.

The advantage of fiberglass over some other materials that are not foams is that the fiberglass is light and inexpensive. Polyester fiberfill works even better than fiberglass, btw. But costs more. There are things that absorb better than fiberglass but they weigh more.

Foam eggcrate stuff - not.

Fyi, there are various methods of making "bass absorbers" that use both Helmholtz methods and...geez what is that called now...adiabatic vs. iso-something ...ummm they use a membrane to convert LF energy into "heat" energy... you can find them online, if you need bass control too.

Skip the foam.

The carpet on the wall will work also - again the thickness will play a role in the lowest frequency that it will actually absorb - by LF the carpet tends to be invisible, so keep that in mind - the path length counts as you go lower in frequency. Carpet is better and safer than foam.

So, I vote for the carpet and/or the frames with absorptive material inside.

Foam sucks.  ;D  ...Just my opinion on it.

          _-_-WBear2GCR

The oxygen free type foam makes all the audio in the room sound better. And since it has no oxygen, it won't burn.

Sorry Huzman,

Ur misinformed on the foam.

The proper foam uses genuine Admiral Fawlsey's Fresh Pressed Virgin Snake Oil Resins in the formulation. Accept no substitutes!!

             _-_-

Bear, good advice on the Dow Corning schtuff.  IIRC thats the shizzle that's intended for basement home theaters so it's designed with acoustics in mind.

Is this stuff similar to a spun-woven fiberglass matt that is firm rather than hard" It can be cut with either a saw or a sharp knife? Man I have been out of the biz too long and completely forgot about this stuff. When we renovated our studios we bought a truck load of the stuff and covered it with a nice fabric and mounted it on the walls using laths with drywall screws.The laths were loaded with drywall screws first and then the laths were screwed to the walls.The studio looked like a torture chamber with all the screws sticking out. :) The cut-to-fit- panels were then simply pressed over the screws to "hang" them on the wall. I will agree that if this is the same material, and it sound like it, it is GREAT. The stuff we used had no backing on either side. I sure turned a highly reflective cinder block wall into a dead wall in a hurry.We used the 2 inch stuff and covered almost every square foot of exposed wall space in the studios.( I still can't believe I forgot about that stuff)

Lol. Where do I get some of that stuff!

What are you trying to attenuate, Randy? bad vibes inside the room, or to keep noises from passing into and outside the room.

If it's bad vibes inside the room, yes, carpeting on the walls works great. For the old radio room, I went to a carpet store and bought every mill-end they had in gray and at least 4 feet wide.  The carpet went on the walls from the ceiling to 4 feet down, and I then paneled from the beltline down to the floor, with a chair rail molding to break the two surfaces.

You heard how the room sounded.

In the new place now, I bought some acoustic curtains from a theater supply house. They were used, and they're floor-to-ceiling. A trip to the dry cleaners, and they hang in front of equipment shelving on the left side wall, and another set is hung right behind me as I address the console. 

The heavy, dual layer pleated curtains soak up tons of reflective acoustics from the glass window in front of me and the sliding glass porch door to my right.

They're not expensive. The weight made shipping nearly as much as the curtains.