The journey continues. In my 2-channel room I have wanted to do something to treat my flat ceiling.
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Most folks here don't know, but I have been working on this room for over a year, measuring, building & adding DIY acoustic treatments and measuring some more. I have made good progress in the 200+hz range.
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I have bass issues as well as center image focus issues on speakers with cone & dome topology (point source). My thought on the latter was I needed something to diffuse ceiling reflections. My ceiling in this room is ~9' made out of sheetrock.
My idea on how to address both issues was build something to diffuse sound above ~1.5khz and absorb bass frequencies. The final concept was to build a floating ceiling using PVC decorative panels mounted to a 1" x 6" frame and fill it with rock wool.
With the help of my long-suffering wife in mounting the contraption, it is complete and installed. It is 79" square and hangs ~6" from the ceiling. I have not had a chance to critically listen yet, but I have done some measurements.
Below is a photograph of the device as well as before and after spectrograms. Notice the improvement in the decay time, especially in the challenging low-end frequencies. The prominent energy peaks (room modes) in the 50 Hz to 200Hz region are much shorter and dissipate far more quickly. This is due to the panel acting as an effective, deep-cavity bass trap in addition to being a diffuser.
Floating Ceiling
Before
After
