rob aylestone
Moderator
I've never had much success nulling matched pairs using the polarity reversal. I know two of some of mine are supposed to be matched, but none of them null properly. Putting two next to each other facing a speaker is a much better test. Get a stereoscope up in the display, pan one left and one right and then play a 20-20K sweep tone. If the mics are a match, then in the stereo meter you get a steady line , but as the sweep tone goes up, you can see the line go left and right a bit as the response changes. Obviously the ideal is no image shift at all, but the sweep tone line always seems to move. The best matched mics just move the least.