Stripdown of an AKG CK91 Blueline cardiod capsule. I bought tge CK91 and SE300b off ebay for a good price but in receiving it the output was very low and with little or no HF in the signal. It was also very susceptible to pops and breaths. The capsule seemed to charge up giving reasonable output but then fading away. Not much inside the thing. Thought I d post just for interest. I quite like the blueline series but low output and self noise very apparent. Prefered to the Oktava Mk 012 I also have but even that seems like a 'hot' mic compared with the AKG.
The membrane part is not taught and has some ripples in the surface. Possible cause of issues. I ve not tested the pcb yet but will do when time allows.