Alberto Cima wrote:
that's what happened to me.
It was a quick test, just to see if the 2 mics are ok.
Maybe I made something wrong.
I put the mics, side by side, in the center of my room
and recorded a signal from a speaker 2 m (about 6-7 ft) away.
When I reversed the polarity I didn't hear any sound.

That's what's supposed to happen.

Perhaps the noise floor of my studio is higher then the
difference between my km184's.
Or I just made some dumbass error.
I'm still learning.

If the two microphones are identical and they are at the same place in
space (or really close anyway), when you invert one of them, the signals
from the two will cancel out and you will get nothing.

If the two microphones are almost identical but not quite, you will get
the difference signal between them.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."