AK... active capsules are part of the variable miniature microphone system. Together with the KM 100 output stage AK... active capsules form a complete microphone. AK 30 and KM 100, for example, make up the KM 130.
AK 30 is a diffuse-field equalized pressure transducer with a free-field treble boost (approx. 7 dB at 10 kHz). The frequency response in the diffuse sound field is flat up to 10 kHz.