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Neumann USM
69 i Stereo Microphone |
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Product Code: USM69i
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The USM 69 i
stereo microphone has two separate dual-diaphragm capsules. These are mounted
vertically and rotate against each other. The directional polar patterns can be
selected separately for each capsule. The capsules operate independently from
each other.
Applications
The USM 69 i condenser stereo microphone is a studio microphone for intensity
stereo recording. It is suitable for XY and MS recordings.
Construction
The microphone consists of the amplifier section and the capsule head. The
amplifier section contains two microphone amplifiers operating independently
from each other. They have an extremely low self noise.
Two completely separate microphone capsules are positioned closely above each
other within the capsule head. Their diaphragms are made out of gold-sputtered
polyester film. The upper capsule rotates against the lower one over a range of
270�. Color markings on the lower capsule system help to identify the angle by
which the upper capsule has been rotated.
When sound waves reach the microphone capsules from different directions they
will generate audio signals with different intensity only, but not with time
differences, since the capsules are in close proximity and the sound arrives at
both capsules simultaneously. The result is an intensity stereo signal that can
be summed together for excellent mono compatibility without causing
interference.
Polar patterns
The USM 69 i has two built-in rotary switches. The five polar patterns of both
capsules can be selected at the microphone itself. Therefore, no special AC
power supply units or powering adapters are necessary.
The two outputs attach directly to any 48 V phantom powered connectors.
In addition to the usual polar patterns: omnidirectional, cardioid, and
figure-8, we have added a hypercardioid and a wide-angle cardioid pattern.
A built-in DC converter generates the required capsule polarizing voltages.
Electrical features
The amplifiers feature high output capability and extremely low self noise.
Distant sound sources, as well as very loud sound sources at close range can
therefore be recorded without any problem.
Each amplifier has an active filter. It effectively suppresses subsonic
interference as caused by wind or structure borne noise. At the same time, the
filter prevents the output transformers from overloading through very low
frequency energy.
Use as a mono microphone
The microphones may also be used as completely independent mono microphones.
There are many applications when it is important to have a second mono
microphone as a backup, or when the outputs of microphones with different polar
response characteristics must be available simultaneously.
The outputs of the two microphone channels can be linked (cascaded). In addition
to the individual directional patterns, other characteristics are available
through the combination of both channels.
Operational safety
Both microphone systems operate completely independent from each other.
The second amplifier will be unaffected, even in case of a faulty ground of the
supply voltage for one of the channels, or a short circuit in one of the
outputs.
The microphone is reliable in mono usage, even if only one of the systems is
operated and connected. Its simple and redundant circuitry guarantees a low
failure rate.
Should the DC converter ever fail, a diode circuit within the microphone ensures
that both systems will remain operational. The cardioid pattern is automatically
chosen. The sensitivity is reduced by 3 dB. |
�
Switchable stereo microphones
� Two pressure-gradient transducers with double membrane capsules
� MS- or XY-stereophony
� Capsules rotary by 270�
� Very low noise
� Aperture and pick-up angles freely choosable
� Directional characteristics reproducibly switchable, omni, wide angle cardioid,
cardioid, hypercardioid, figure-8 |
| Acoustical operating
principle |
Pressure gradient transducer |
| Directional pattern |
Omnidirectional,
wide-angle cardioid, cardioid, hypercardioid, figure-8 |
| Frequency range |
20 Hz ... 20 kHz |
| Sensitivity at 1 kHz into 1
kohm |
13 mV/Pa |
| Rated impedance |
150 ohms |
| Rated load impedance |
1 kohms |
| Equivalent noise level, CCIR |
24 dB |
| Equivalent noise level,
A-weighted |
13 dB-A |
| Signal-to-noise ratio, CCIR (rel. 94 dB
SPL) |
70 dB |
| Signal-to-noise ratio, A-weighted (rel. 94
dB SPL) |
81 dB |
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Maximum SPL for THD 0.5
% |
132 dB |
| Maximum output voltage |
3 dBu |
| Dynamic range of the microphone amplifier
(A-weighted) |
119 dB |
| Supply voltage (P48, IEC
61938) |
48 V ± 4 V |
| Current consumption (P48, IEC
61938) |
2 x 0.7 mA |
| Matching connector |
XLR5F |
| Weight |
510 g |
| Diameter |
30 + 48 mm |
| Length |
293 mm |
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