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Neumann KMR 81 i Shotgun Microphone |
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Product Code: KMR81i
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The KMR 81 is a shotgun microphone with a high directivity that
remains within the acceptance angle independent of the frequency.
The advantage is that a sound source, for example an actor on stage, will not
change its apparent tonal balance when moving within this area.
Applications
Shotgun microphones are particularly useful in recording situations where a
microphone cannot be positioned within the desired distance of the sound source
to produce a sufficiently loud signal level.
Typical applications are film and video recordings, where the microphone should
not appear in the picture.
The KMR 81 has been specifically designed for electronic news gathering.
Acoustic features
In principle, Neumann shotgun microphones use a combination of a pressure
gradient transducer and an interference tube. If the wavelength of the frequency
is longer than the tube length, the microphones work as pressure gradient
transducers. At higher frequencies they operate as interference transducers for
lateral sound. Off-axis sound sources are picked up with reduced level, but
without coloration.
Therefore, the microphones are well suited to record individual instruments of
an orchestra. The pickup areas of several shotgun microphones may even overlap
as, for example, during recordings on a large stage, without causing any
problem.
The KMR 81 is less sensitive to wind and pop noise when compared to the KM 150
miniature microphone with a similar high directivity. The shotgun microphone
features extremely low self noise, good impulse response, and high output level.
Polar patterns
The KMR 81 is a shotgun microphones with a very directional characteristic.
The microphone capsule is positioned inside a housing tube that is acoustically
open but has a high flow resistance. The directional pattern of the microphone
is lobe shaped. The attenuation of lateral sound is practically independent of
the frequency. The KMR 81 has a frequency independent directivity within a
pickup angle of 90� for audio signals that determine the tonal balance of the
program material.
Filter and attenuation
The microphone has a 10 dB attenuation switch to prevent the input of the
following unit from overloading.
A second switch activates a 200 Hz high-pass filter. Toward the lower
frequencies the sensitivity of the microphone is attenuated by approximately 15
dB at 50 Hz. The frequency range above 200 Hz is unaffected.
Use on location
The shotgun microphone features very high output capability and a remarkably low
self-noise level.
Its low power consumption, light weight, and low sensitivity to wind and
handling noise, makes it an ideal tools for news gathering on location.
Small dimensions, together with a balanced center of gravity, make handling easy
without any whiplash effect.
However, when on location and during strong wind conditions, we recommend using
an additional wind screen (included as standard accessory). The wind screen is
made of polyurethane foam.
For mobile use a handle and an elastic suspension are available. |
� Interference tube microphone with shotgun
directional characteristic
� Interference/pressure-gradient transducer
� High lateral and back attenuation
� 90�-recording angle
� Switchable filter or preattenuation features
� Extensive accessories for outdoor use
� Light weight: 145 g |
| Acoustical operating
principle |
Interference transducer |
| Directional pattern |
Supercardioid/lobe |
| Frequency range |
20 Hz ... 20 kHz |
| Sensitivity at 1 kHz into 1
kohm |
18 mV/Pa |
| Rated impedance |
150 ohms |
| Rated load impedance |
1 kohms |
| Equivalent noise level,
CCIR) |
23 dB |
| Equivalent noise level,
A-weighted) |
12 dB-A |
| Signal-to-noise ratio, CCIR) (rel.
94 dB SPL) |
71 dB |
| Signal-to-noise ratio, A-weighted) (rel. 94
dB SPL) |
82 dB |
| Maximum SPL for THD 0.5%) |
128 dB |
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Maximum SPL for THD 0.5% with
preattenuation) |
138 dB |
| Maximum output voltage |
1.3 dBu |
| Dynamic range of the microphone amplifier
(A-weighted) |
116 dB |
| Supply voltage (P48, IEC
61938) |
48 V ± 4 V |
| Current consumption (P48, IEC
61938) |
0.8 mA |
| Matching connector |
XLR3F |
| Weight |
145 g |
| Diameter |
21 mm |
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Length |
226 mm |
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