I recently purchased a Beyerdynamic MC833 (MS/XY) mic.
It is a single point mic with three capsules, L, R, and M, for mid. (The side is formed from L-R.)
The mic sounds good at low volume, but at higher volumes (PA recording), I hear terrible distortion, like tearing or clipping. This is in the Mid channel in MS recordings. XY (L and R caps) sound fine.
OK, I looked at the diaphragms. They are 1/2" gold mylar diaphragm, open inside the head of the mic.
Well, the M channel has some "decay" at the edge of the diaphragm. I can't tell if the gold is come off, or just colored/oxidized somehow.
OK, what could be the cause of this. This was a "B stock" mic, so maybe it was broken by someone else?
Could I have caused this damage, eg., by leaving it my car out in the cold (in the box). I know I did that once, but I have not otherwise abused the mic.
Thanks for any help...
Richard