Acoustical Room Treatment Panels

Intro:  With the guidance of Dave Elledge (dBe) I made some acoustic panels for my small front bedroom (Listening Room B).  Before, my 12' by 10' room was a very bright with very poor imaging and soundstage.  Now, the sound is much more balanced with near-holographic imaging.  This project cost me about $75 and was well worth every penny.  

Knauf (pronounced "Kanoff" for some reason) fiberglass duct board was used.  This 1" thick material has a fairly stiff structure and a foil backing.  Comes in 10 foot by 4 foot lengths.
 Hey check out the car!

Since this product is made from fiberglass, it is recommended to wear rubber gloves while handling.  I used a utility knife and yardstick to cut the duct board.

The business (yellow) side of the panel was covered in a 1/2" layer of Dacron batting.  Then the panel was covered in an attractive unprocessed (natural) cotton cloth.  I used a Jersey knit (it was on sale).  This allowed me to stretch the wrinkles out of the cloth for a nice, smooth finish.  Muslin could also be used but may first require ironing.  The cotton was adhered to the foil side of the panel with Latex caulk.

A bead of caulk was put down, cloth folded over, then smoothed with a putty knife.   Made a very durable bond.

Ends were snipped, folded and adhered with caulk for a tidy finish when viewed from the front.

One panel was made 12 feet long.  The two pieces were spliced together with packing tape.  An additional scrap piece was used caulked in place for further support.

Mounting brackets were added to one panel to allow it to be hung on a door.  1/4" hard board was caulked to the back of the panel.  Galvanized sheet metal was then screwed to the hardboard.  The sheet metal was folded over the top of the door and secured with small screws at the top of the door.   Holds great and looks slick.

T-pins were used for mounting onto walls.  The pin above is shown for display purposes.  The pin below has been toe nailed through the panel and into the wall.  Wow, that pic sure looks like crud.

The panels installed in to Listening Room B.  This is the rear wall behind the listeners head.  Notice corner panel top left.  To make a long story short:  Where two walls meet it's called a corner - bad for bass.  Where three walls meet it's also called a corner - but very, very bad for bass. 

Boy, I sure did compress these pics!  Oh well, you get the idea.

The panel on the left is for early reflection.  The taller panel to the right is a corner panel.  It's a small room and I'm trying to smooth out bass response as best I can.

 The front and back wall are parallel and the panel above on the front wall made the biggest difference with the hand clap test.   It's only 1' by 4'.  Just goes to show you - it's not the size, it's what you do with it.

The 12 foot panel is to the right.  The room has a vaulted ceiling.

A panel was hung on one of the sliding closet doors.  This can be pushed along it's track in order to best deal with the early side reflection from the right.

Conclusion: As each panel was installed, I stopped to play some music, do some critical listening, and take some measurements.   I also did a lot of informal "hand clap" tests along the way.  Since the room was small, I figured I would need a lot of panels to make the walls "disappear".  However, now that I've lived with this setup for many months, I feel I might have added one or two panels too many.  When you walk into the room, you instantly notice (feel) a big drop in the ambient sound that's normally always around you.  It's not so bad that you feel like your brain is being sucked out though your ears (like in an anechoic chamber).  A typical loudspeaker may sound a bit soft on the top end in this room.

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