This is for Nakamichi lovers.
DSatz explain very nicely the basic design of condenser microphones. Who knows little about it as I do, please read it first.http://taperssection.com/index.php?topic=178968.msg2211904#msg2211904
I bought an old JVC microphone. It has Primo cardioid capsule, the same capsule as Nak300 - CP1. This capsule had released nut that hold the rear chamber with backplate. Probably someone has looked inside. So I carefully opened it too. (I assembled it back, capsule works, but I'll have to try it in concert).
The assembled capsule is shown in Figure 1 and 2. After disassembly Figure 3, backplate Figure 4, backplate with rear chamber Figure 5.
It's electret capsule. Diaphragm is permanently charged, it is not energized by phantom power like in true condenser mics. Mic is receiving on backplate (gegenelektrode, I like this word) very weak electrical signals that is generated by the movement of charged diaphragm. Then the signal is brought to the JFET, where it is amplified.
Function of backplate and rear chambers is described by DSatz, see link above. Holes in this backplate have a special arrangement, dumping is seen in some holes too (Figure 4). Contact for an output electrical signal is on the backplate center from behind, partially visible wire through holes.
The entire capsule and the rear chamber is probably the same for cards and omni (Figure 6). The only difference is that the cards have rear chamber partially opened on back - see yellow seal (Figure 5). This seal is regulated by black plastic nut (Figure 6). I will try to tighten this nut in future and I will let know the effect.