Mark. Yes, that is exactly what I did. I moved the panels into the bathroom so they would not interfere with measurements. I then set up, calibrated and measured to get the untreated graph.
From there, I put the treatments in position and measured again: no moving the mike, no level adjustments. I have measured at this position on at least 4 occasions, so with slightly different mic positions, and always get the 40Hz hole
FWIW, the reason that corners are good (as I understand it anyway) is that you can treat multiple modes (length & width, axial & tangential) in one place. It has to do with the way modes accumulate in corners.
So, I to hope you are wrong this time. I am contemplating making a set of thinner pannels to see what the difference is between the two.
