"Scott Dorsey" wrote in message

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.

Is it possible to get the mics close enough for this to work with a
broadband sound source?

I'm pretty sure that it's impossible because of our inability to make 2 mics
occupy the identical same space at the same time.

I think it might be possible if you synchronized two recordings made with
identical sources. However it would take a sample rate of about a MHz to get
the synchronization required. Been there, done that.

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.

I seriously doubt that a really broadband sound source like keys jangling
would even get you close.

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

Also, if they occupy different chunks of space.