Ok, updates and wierd results to share. Contrary to our thoughts.

I set up a RTA reading in the kitchen directly above one of the ATMOS locations. First I measured before removing the insulation. I didn't take a screen cap but am kicking myself now. To test I wrapped a knucle against the top of the box as it hung in the ceiling.

I went ahead and removed the backing insulation and thought all was well... Until I repeated the measurement. Here is what it read. The RTA ran as I went downstairs and wrapped on the box and came back. A worst case scenario test. The peak values were stored as the blue lines in each octave. It peaked at about 55db at 200hz. Ignore the reading in the right top corner. It is the RTA ambient room db in the kitchen after the peak reading.

Insulation Removed


I swore the values were worse with the insulation removed so for the heck of it I put it back and resecured the box for another measurement. I wrapped harder than before just to be sure....

Insulation Replaced



The peak was reduced to 45db at 200hz. A 10db drop in the world of sound isolation is pretty significant. Anyway, it seems the reason this wild result occured was how poorly 1/2" MDF acts as a speaker cabinet. The insulation was actually acting as a damping agent for the rear panel. With it removed it rang like a bell.

What I can't decide is if the lower frequency readings reduced with insulation removed vs replaced can be trusted. It was a pretty makeshift test and for all I know a truck could have driven by while I was downstairs to skew the result.

I'm glad Nick pointed this out so I could discover this completely by accident.

Last edited by Serenity_Now; 01/20/15 12:19 AM.