[rajacat]

My listening room has a very low ceiling (7'-6"). I'm looking for an effective acoustical material for the  first reflection point. 1" thick or less would be ideal. The ceiling is sheet rock with blown in cellulose for insulation.

Raj

[Glenn K]

oc 703, 705 or mineral wool will work, but really you want them to be 2" if you can do it. 1" just is not enough. 

Glenn

[rajacat]

Hmmm....Does regular 1/2' cellulose soundboard that you can buy at many lumberyards, have any positive acoustical properties? Fiberglass needs to be covered and a frame constructed because it can't be hung on its own and the thickness would be a problem. Maybe I could coat soundboard with heavily textured paint, the type that is used to texture drywall, to create an irregular surface for some marginal diffusive qualities.

Raj

[bpape]

The sound board is more for isolation rather than absorbtion - it's not a good choice for this application.  Even 1" fiberglass is only going to be effective down to say 300Hz and even then it's marginal.  1/2" seriously don't bother.  You'll completely miss the vocal range.

Textured paint isn't going to do much of anything either - not even a marginal improvement. 

Wish there was a better answer.

Do you have a lot of NBA friends?  I mean 7'4" not exactly something you'll hit your head on

The other option is to cut a hole in the drywall and build a box above the ceiling where the reflection points are.  Fill that with absorbtion and cover with nice cloth.  This costs no headroom and you won't lose any isolation.

Bryan

[rajacat]

The sound board is more for isolation rather than absorbtion - it's not a good choice for this application.  Even 1" fiberglass is only going to be effective down to say 300Hz and even then it's marginal.  1/2" seriously don't bother.  You'll completely miss the vocal range.

Textured paint isn't going to do much of anything either - not even a marginal improvement. 

Wish there was a better answer.

Do you have a lot of NBA friends?  I mean 7'4" not exactly something you'll hit your head on

The other option is to cut a hole in the drywall and build a box above the ceiling where the reflection points are.  Fill that with absorbtion and cover with nice cloth.  This costs no headroom and you won't lose any isolation.

Bryan

No, no NBA friends.

Of course if I do the cut the hole in the ceiling option, I better not move my speakers. Nice idea tho..I will probably go with 1-1/2. Would accoustical cotton work?

Raj

[laserman]

Hi Raj, you are going to have to bite the bullet and go with 2" but don't forget to add an additional 2" of air space between the panel and the ceiling.

I had an issue with the AC/heat ductwork plenum being located in the first reflection area of my basement ceiling, thereby lowering the ceiling to a similar height as you are faced with.  I went with 2" thick 2'x4' panels end to end and suspended them from the ceiling using some picture hanging cable wire and two 8' long wood dowel runners (supported on each end and in the middle).  I was able to go directly into the ceiling joist with drywall screws but it could have been just as easy using those plastic inserts first if I didn't have the joist since the panels are not that heavy.  I did this to minimize the fix when I move and take them down (only six small drywall screw holes).  My wife refers to them as "clouds."  IMHO, they work equally as well as the first reflection on the side walls.

[rajacat]

Hi Laserman,

Wow! Now I'm going to need a 2" airspace also. Well...I guess I should get the panels first and then experiment with placement and hope for the best.

Raj

[bpape]

2" airspace will extend the low frequency efficiency quite a bit.  But, 2" flat on the underside will certainly do a decent enough job.

Bryan