[Mike-48]

I've seen several questions about mounting acoustic foam without marring the walls.  Here is the method I've used for 10 years with success.  I use artist's stretcher strips, pieces of wood that can be bought in 1" increments at art supply stores.  The advantage is that these come with prefab mitered corners that are very strong, so with a little glue you can get a true 24" x 48" (or whatever) rectangular frame.  For an example, look at
http://www.dickblick.com/zz072/09/products.asp?param=0&ig_id=6061"> this description on an art-supply site .

The foam can be glued to the stretcher frame, which in turn can be hung to the wall like a picture (with wire between screw-eyes in the frame and a single small nail in the wall).  I use self-adhesive felt on the wood where it will contact the wall to prevent rattling.

There is about 1/2" air space between the foam and the wall, which adds to the absorption.

This works like a charm with Sonex foam.  The wood is not visible from the front.  To make it look nicer, you could wrap the foam with Guilford fabric and staple it to the wood, but I haven't done so.

Hope folks find this useful.

[nathanm]

Good idea, but technically speaking you still have to "mar" the walls with the nails.  Personally I've given up on the not-marring-the-walls approach, said "fock it" and used T-pins and picture hanger clips.  Did I mention that drywall is a very very very bad thing to stick sharp objects into?

I think the best approach for total non-invasiveness would be to build floorstanding panels that you just lean against the wall.  Mine are mounted on that melamine wood whatsits but those flex and are fairly heavy.  I think corrugated plastic would be the cat's ass.  Foam core would be good too - light weight and rigid, but you'd have to get 40x60" panels, which sure aren't cheap. Then again, I haven't been able to find a good cheap source of corrugated plastic either.  Hmph.  2'x6' would be nice I think.

Even more dreamy would be walls covered entirely in female velcro fabric like they use in display systems with male velcro on the foam.  Better still, foam that is held to the wall by the force of sheer will.

[Mike-48]

Nathan,

A picture nail does mar the walls, as you say, but I figure any good painter can make it disappear with spackle (when the time comes).  I never had a landlord who objected to normal picture-hanging holes.  There probably are some, though.

Picture nails (the kind with an angled disc at about 60 degrees to the nail) seem to hold better than plain brads, but still, drywall is a horrible substance on many counts.  If you've ever lived in a house with old walls of plaster, horsehair, and wood lath, you know how much quieter such rooms are.  The construction soaks up sound like a sponge, and the uneven thickness of the plaster (much thicker than drywall) prevents resonances.  But drywall is a lot cheaper to put up, and that's progress.

You had some other interesting ideas.  As to free-standing panels, I have some of the stretcher-mounted foam leaning against the walls in a couple of places, and they work well.  I do think there's probably an advantage to having the back of the foam uncovered, rather than mounted to a rigid sheet, but I'm no acoustician....

...Mike

[MaxCast]

If you mount to peg board you can use the 1" on center holes to match up with the 16" on center wall studs.  I do like the picture fram look though.