Microtech Gefell KEM 975 Microphone  with Delta-Capsule

The Cardioid Plane Microphone KEM 975 is a new design of the patented instantaneous line array
microphone principle, which is already in use in the KEM 970. A completely new circuit design has
been developed; besides the well-proven ceramic capsules of the M 300 series, Microtech Gefell
have developed a low-noise preamplifier system for the KEM 975. Also, the construction of the
housing has been completely revised without changing any of the critical dimensions of the Line
Array itself; as the capsule positioning and relationship is an integral part of the design. The result
of the revision is a shorted overall body length.
Compared to the KEM 970, the KEM 975 Cardioid Plane Microphone has an increased dynamic
range. There are 5 switch settings covering the entire Line level. Microtech Gefell’s well-proven
optical principle to generate the capsule polarisation voltage is also used in the KEM 975 – this
eliminates any “nasties” on the power line getting into the audio circuit.
IRT München (Institut für Rundfunktechnik), who originally designed and patented the line-array
microphone and licensed Microtech Gefell to manufacture it, have significantly enhanced the
directivity at low frequencies by the addition of a patented assembly that adds an extra microphone
capsule mounted at the rear. This additional capsule assembly is available as an optional
The advantage of this new construction, coupled with the improvements in lowering the noise floor,
mean that the new KEM 975 is also suitable for music recordings as well as sound reinforcement,
broadcast and video conferencing applications.
By using an optimised filter system, the sound of the rear capsule is summed with the sound of the
Microphone Line Array. The output of the complete arrangement is provided at the 3-pin XLR
output connector of the N 975 power supply. Signal integration is automatically enabled (“plug and
play principle”) when the Delta-Capsule system is connected to the KEM 975 microphone.
Power supply
The N 975 power supply is connected to the microphone by a 5-pin XLR cable. The new power
supply is available either as a half width 19” – 1U rack unit or, alternatively, as table-top variant.