Started on my traps last week. Read all I could find on this forum (thanks to Ethan and Glenn for their advice). The goal is 16 - 20 traps. Keeping it inexpensive was also a priority.
Here's what I did.
Went with the simple wood frame with 2 sheets of 2" insulation wrapped in muslin.
I spec'ed out 703 but it was a bit too pricey for my limited budget. Went with this insulation made by Thermafiber called Safing. 4lb density. Word to the wise - this stuff is nasty. Really dusty, but once covered in a frame and cloth is nice and clean. Easy to cut as well. I wasn't originally planning on covering the back of the panels but after handling the insulation realized that it would shed so I had to buy more cloth. The muslin I got was 62" wide/ yard which is perfect for these traps.
Went with 1x2x6 lumber from Home Depot. Two pieces make one frame. Measure 48" for the sides and 21" for the top/bottom. This leaves you with two small 3.5" pieces that you can use for stand-offs. This places the insulation slabs exactly 4" off the wall. I stapled the frame together first then reinforced it with 2" screws after drilling pilot holes (to prevent the wood from splitting).
When stapling the cloth I found that stretching it too tight makes the front edges rounded. Pull just enough to keep the cloth slightly taught. When the panel is mounted, you can use Downy wrinkle releaser to get rid of any wrinkles. Just spray on, smooth over, and let dry.
I mounted the corner traps using simple L-brackets. I bent them up slightly so that when the traps were placed on them the brackets would hold them in place against the ceiling. The bottom corner panels were mounted the same way, pressing against the panel above it.
Side panels and clouds were mounted using wall anchors and picture hanging wire. I stacked my speaker stands on top of each other to hold up the panels as I hung them.
I wanted to be able to shift the side panels from side to side if needed. Using a few washers as spacers I mounted a 12" piece of 1x2 on the wall. L-brackets were attached to the wood stand-offs on the panel with leaving a 1/4" lip to hook behind the 1x2 on the wall. Now I can slide the panel side to side to adjust the first reflection point. The stand-offs were mounted close to center of the panels so that panels appear to be floated off the wall.
The front panels, and clouds are full bandwidth absorbers all other panels that aren't placed in first reflection points have a sheet of 2 mil plastic between the insulation and front covering to keep the room from sounding too dead.
The difference was evident as soon as I mounted two of the corner traps. The room had a 20 db dip at around 300hz that pretty much disappeared. As more panels went up the bottom end got much flatter. However a dip at 120 Hz became evident as more traps went up. My desk at the moment is a solid core door on top of two metal filing cabinets. I placed a panel in front of it (where your legs would go under the desk) and the dip was reduced. I'm sure the file cabinets are resonating too. Otherwise everything seems to be relatively flat +/- 6db.
The pictures are pretty self explanatory.
All the ego disks on the side walls have come down...
Materials
Cloth backing
Insulation on Cloth Front
Ready to be stapled
Corner Mount
Frame with stand-offs
L-Bracket on stand-off
Wall Mount
Right Side
Left Side
Back Wall / Closet
Front of room
Here's some measurements made with Room EQ Wizard and a Radio Shack dig meter.
Before....
After...
14 panels up another 6 to go. (Corner next to door, two rear side panels, and 4 ceiling corner traps).
Just gotta work out that dip at 120......