MKH Story

The MKh STory
Page 6
A new microphone line is born
A new microphone line was designed at the beginning of the 1980s to feature identical technical data as far as
the differences were not dictated by the specific directional characteristics. Importantly, the frequency response
should be flat for all types. The microphones should be neutral, without adding or omitting sound details.
The RF circuitry was completely redesigned, now utilising amplitude modulation (AM) instead of phase modulation.
This was evident, as the capsule is comprised of two capacitors with opposite varying capacitances. The capsule
was combined with a centre-tapped coil to form an RF bridge. The capsule capacitances functioned like a capacitive
potentiometer with the diaphragm as the wiper. This circuit exhibited an extraordinary linearity.
The cardioid MKH 40
The MKH 40, as the first microphone of the new symmetrical-capsule MKH
line, was launched in 1985.This microphone actually incorporated all the
essential specifications of the future microphones. The frequency response
was virtually flat from 40 Hz to 20 kHz, and the directional characteristics
were stable over a wide frequency range. The distortion was extremely low,
and the equivalent noise level of 20 dB(CCIR) and 12 dB(A), respectively,
set a new milestone. The high sensitivity of 25 mV/Pa provided an interference-free operation even with long
cables and reduced the noise contribution of the microphone amplifier considerably. Switches for pre-attenuation
and bass roll-off were also incorporated, with the bass roll-off switch compensating for the proximity effect.
The positive response of the sound engineers was encouraging. This indicated that the technical efforts had not
only improved the measured results, but also yielded audible improvements in normal recording situations.
The omnidirectional MKH 20
The next microphone requested by many sound engineers was an
omnidirectional one. This type of microphone was rediscovered at the onset
of digital audio because it enabled the engineer to include more authentic
room acoustics than other microphone types. The MKH 20 (launched in
1986) met these expectations as its low noise performance revealed even
faint tonal structures.
With omnidirectional microphones, usually a decision has to be made between versions optimised for free-field or
diffuse-field applications. The MKH 20 is switchable to both characteristics and, in addition, is supplied complete
with a removable pressure ring enabling fine-tuning of the treble balance.