Microtech Gefell KEM 970 Line Array Microphone
The Cardioid Plane Microphone is a multi-capsule microphone system with a unique directional characteristicsthat are largely independent of frequency. On the horizontal axis the KEM 970 has the characteristic of a cardioid microphone, whilst on the vertical axis the characteristicsresemble a shotgun microphone with a very narrow acceptance angle of about 30°.The directional pattern is therefore particularly well suited to the most frequently encountered situations where the source to be recorded is widely spread, or moving across the horizontal plane and sound arriving from other directions needs to be attenuated.
Attenuated sound may consist of unwanted noiseor reflections from surfaces such as ceilings, tablesor the floor. Mounting the microphone physically onits side can significantly reduce feedback problemsfrom sound reinforcement loudspeaker installationson the side walls.
For effective use of the highly directional nature ofthis microphone, a good understanding of thedirections from which wanted and unwanted soundsarrive is important. The more care taken in positioningthe KEM 970, the better the results obtained will be.Integrated front facing indicator lights help inpositioning the microphone accurately.
Acoustic treatment to improve a room can be an extremely costly exercise, and perhaps not even possible when trying to achieve the average 5 dB increase in operating level that the KEM 970 provides.An added benefit of the KEM 970, as shown in Fig.3,is its ability through skilled use of the sensitivity characteristics, to compensate for level changes if the sound source moves closer to the microphone.
Initial experience gained from practical applications in TV production, stage-sound reinforcement and presenter amplification at lecterns, confirms the fundamental theoretical benefits of the Cardioid Plane Microphone across a wide range of varied applications. The KEM 970 was developed in cooperation with the Institut für Rundfunktechnik (IRT) in Munich. The particularity of the KEM 970 is the characteristic that the directional distribution of the sensitivity is a non-rotational-symmetrical pattern in relation to the reference axis.
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Application
as a table microphon
Table
mounting the KEM 970 as in Fig. 4 allows microphone the to reject unwanted noise
or reflections generated by the table surface.
Comb
filter effects generated by table reflections, or paper rustling noises from the
desk, etc. are all attenuated significantly. Also apparent from Fig. 4, is the
microphones’ immunity to sound from overhead or ceiling mounted sound
reinforcement loudspeakers in the vicinity of the presenter. This significantly
raises the threshold of feedback, providing much greater resistance to
howl-round.
Application
at the speakers stand
With
the KEM 970 positioned as shown in Fig. 4, the presenter has much greater
distance and lateral freedom of movement, without the normally attendant quality
problems that could be expected with conventional microphones.
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Animated
speakers are therefore unlikely to move outside the coverage area of the KEM
970. The low sensitivity of the microphone to off-axis disturbances, such as
rustling of manuscripts on the desk, or reflections from the surface is a
welcome advantage. Sensitivity to adverse influences from overhead sound
reinforcement installations is effectively reduced compared with conventional
microphones.
As
an emergency backup, a second KEM 970 can be mounted on the other side of the
desk. When two microphones are mounted symmetrically on either side of the desk,
the view of the speaker from the auditorium or a camera is not impaired. By
contrast, the conventional arrangement of multiple microphones often compromises
the view considerably. |
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application for interactive video conferences, live
conferences
Application
on the stage
As
an example application, one or more KEM 970 microphones can be placed on floor
stands near theedge of the stage, directed towards the area occupied by the
actors.If the configuration shown in Fig. 3 is used, then undesirable noise
emanating from the stage floor isconsiderably reduced.
If
a sound reinforcement system is in use, the highly directional sensitivity of
the KEM 970 on a single axis also adds increased immunity to feedback when
compared to other commonly used microphones.
It
is easy to imagine a numerous other applications for the KEM 970, such as
creating acoustic effects inradio drama production. Different acoustic scenes
can be simulated by an actor changing position aroundthe areas of varying
sensitivity to influence the ratio of direct to diffuse sound.
