Building sound attenuating panels

Going back to my previous post on the home theater room, I had mentioned about the sound panels.  In doing research, I found that the most cost-effective solution was to build my own panels from compressed fiberglass insulation.

The panels need a couple of characteristics.  First of all, it has to be compressed fiberglass.  This is not typical fiberglass rolls that are just smooshed

 together.  It is a different product.  That being said, it is difficult to find.  Most local home and hardware stores don't carry it.  Secondly, the panel has to be covered with some sort of fabric to prevent stray (and itchy) fiberglass fibers from running free into the room.  The fabric has to be sonically translucent.  That is, it can't reflect the high frequency sounds because that would be just be like doing nothing.  You need to let the sounds penetrate the panel so they can be absorbed.

So, where to get the material?  After much research, I found an insulation supplier (Paragon Pacific) near Southcenter mall who sold the stuff.  This place is a warehouse, so it was a bit odd to only buy six panels, but they were very accommodating.  I have purchased from them several times now.  Their cost was about $13 for a 4'x2'x2" thick panel of the 3 lbs/cu ft variety.  The package looks like this:

My first attempt at a fabric to cover the panel was to use speaker fabric that I picked up at the fabric store.  Essentially, cut the speaker fabric to the right size then fold it around the panel and glue it with spray adhesive.  The look was OK, but not all that great.  The next challenge was to figure out how to mount them on the ceiling.  I tried several methods, but eventually I went with industrial strength velcro...which worked great...for about two months when the adhesive gave up.  By the way, for the wall panels, I decided to mount the fiberglass panels to a backer board, then mount the backer board to the wall.  This works, but it makes them a little heavy.

The solution to all of this was to buy manufactured bags from a company called

Ready Acoustics.  They can provide completely assembled panels or just sell you the bags and then you put the insulation in the bags.  I chose to order the high frequency bags and use my already purchased insulation.  The bags are of a very high quality and you can pick out of a variety of colors.  They also come with several built-in straps for hanging.  While they are not cheap ($30 per bag), it is worth it in the long run.

Note that I still had to use the speaker fabric method for the non-standard size panels.  I have smaller 4'x1' panels behind each of the front speakers and some 2'x2' panels behind the main seating area.