Nick from micbooster.com here, just a couple of things regarding these capsules.
Operating voltages - these are specified as below.
EM258? 1.5V - 10V
EM200? 3V - 10V
EM204? 3V -10V?
Of course it is the internal FET which has to handle these voltages.? If you look at the sort of FET that might be used in an electret capsule they are often spec'd around 20 volts VDS. In Primo's data sheets, unless otherwise mentioned, the voltage referred to is a typical voltage, rather than a maximum or minimum. It is also one of the test conditions at which some of the other figures have been calculated.
Not as as selling ploy but just for information, although the EM200 and EM204 are end of line, we do have quite a good stock of each type, in terms of DIY quantities.
