As I suspected from the start, I believe your capsules are good and the problems you had are elsewhere.
Thanks Jerry. To start with while I was reducing cabling length I shorted either the bias IC or a cap - diode around it. When I sort that out I will try all the meters you suggested.
Just a couple of quick questions
Is it ok to leave one side of the dual capsule disconnected with it's lead on? Is it a possible cause of interference and lack of signal sensitivity?
Does it matter if I connect the center of the capsule on the bias pcb and the backplate on the high impedance one or vice versa? Does it affect the microphone output?
