NTK capsule question

[dres]

Hi people,
just out of morbid curiosity can anyone tell me what the "holes" you can see in the capsule are ? In my simplistic understanding I thought a capacitor was simply two conductive plates separated by an insulator - the reality looks more complicated. I've noticed these on other condenser mics too.

 

[Harvey Gerst]

There are two types of "holes" actually. First of all, if there were no holes at all, the mic would be an "omni" mic, and the enclosed air would be trapped, causing a large resonant peak around 5 to 7kHz.

Some of the holes (those that only go part way thru the backplate) are to increase the size of the chamber behind the diaphragm, lowering the resonant point.

The holes that go all the way thru are there to create the cardioid pattern, by letting a small part of the sound come in from the backside to cancel the response from the front, creating the cardioid pattern.