Best DIY Sound Dampening Materials?

Do you have any recommendations on sound dampening materials for a DIY project? I have a wonderful system, but a not so wonderfully small space (12 feet x 12 feet), and I need to dampen the acoustics off the walls and floor.

For the walls, I'm considering taking 4 inch foam (do you have any recommended purchasing sources?), cutting 4x3 foot squares, framing it, canvasing it and hanging a series of these pictures up on the walls (painting the canvas a slight hue of the wall paint). To keep peace with the girlfriend, I need to dampen my room in an aesthetically pleasing way - yes, she's worth it. So, will this work? Are there better alternatives?

For the floor, I'd like to create a removable 16x16 inch wall to trap and avoid the Allison affect. Am I crazy?

Help ... please!

Try painter canvas, actually I'm using it in my listening room(12ft by 14ft) with very good result and my speakers are hugh! I built some gaint wood frames and stable the canvas in it and then I hang it in the wall like painting. Works wonderful!!!
Dds_hifi, instead of dampening the room, consider diffusers that will make your room physically smaller but acoustically much larger without losing energy to the dampening materials. Read Steve Deckart's fascinating article about his experience adding DIY diffusser panels to his 13x15 room:

If you're interested in following up on this path, in addition to Mr. Deckart's DIY plans, Tom_nice has some plans he has offered to send to people in the past. See the following Audiogon thread:

Or, take a look at the sources Jon Risch has published in his posting to Audio Asylum:
I think if you do a search in one of the Asylum forums, you'll find someone that did a direct comparison between the Decware Diffusers and Risch's absorption panels. For sake of removing bias from the comparison, the person had several people listen to the system and then vote accordingly. While every situation and room is different, i think that Jon's panels won by a landslide in that specific installation. Keep in mind that tonal balance WILL be altered by either of these. Both of them are relatively cheap to build. Sean
I'll be glad to paste my DIY RPG-style diffusor plans--one and two dimensional--into an email, to give you a quick look at them. Aesthetically acceptable? Not for me to say, but my wife is willing to see them as modern sculptures. You'll need serious bass absorption too, I'm afraid, to overcome the room modes associated with your square room. A recent idea on that comes from Bob Riggle, former Arcici designer who has a fabulous isolation platform, by the way. He's made something like an Argent Room Lens with 4" PVC tubes joined at the bottoms to form an 180 degree continuous tube, and he says it absorbs (in Helmholtz resonator fashion) down to 30 Hz. I haven't tried it yet myself.

My email:
An afterthought: why not read F. Alton Everest's "Sound Studio Construction on a Budget" or his "Master Handbook of Acoustics", 4th Edition, and, along with seeing a huge list of absorption and diffusion devices, learn how to analyze your room's resonant modes--simple arithmetic, and it will tell you where your problems below 300 Hz are. The "Sound Studio" book discusses all kinds of rooms, some smallish.
Tom nice,

Thanks! I'll definitely get those two books. From my perspective, this is a relatively low cost way to signficantly improve my sound quality. I'm surprised more people don't manage this side of their listening experience.

I'll email you for your diffuser plans.

Thanks again!
I have been told by two manufactures that putting canvas in front of acoustic foam is not a good idea. Apparently the canvas prevents the sound waves from being absorped by the foam. Heard this from Sonex and Immedia-both told me I wasted my money on the foam I put behind two oil paintings.
I have a 12x14 room with 4x4x2inch Sonex on both side walls, front and back walls covered w/oil paintings. Don't have much of a problem w/reflected waves. Use a heavy rug for the floor.
Good luck!