I have resolved some side and cross side reflection issues I had by replacing my 1st reflection broadband traps with same-size horizontally mounted polys with 180 degree vertical dispersion design.
Any strong side-wall and cross side-wall reflections (withing the designed frequency range) are redirected in a vertical fan pattern which attenuates the signal arriving at the ear. The re-directed energy is still in the room but now has a longer path to your ears so things do not sound as dull and the attenuated arrival time is longer.
Since it is mounted horizontally, it could extend the entire length of the sidewalls without incurring any of the issues associated with arrays of vertical mounted polys.
In short, the solid surface poly worked better than an OC-703 based broadband panel for those 1st reflections (as verified by REW sweeps in the sensitive [1-7]kHz range).
There are online poly/radius/cord calculators that can be used to design various sized polys with desired dispersion ranges.
.
2022/03/30 Historical Records CENSORED
