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The RSM 191 is a
stereo microphone system consisting of the microphone and the MTX
191 A matrix amplifier. It has an adjustable pick-up angle and high
directivity. The microphone has two separate capsule systems, a
hypercardioid element and a figure-8, both in a short shotgun.
Together they generate the mid and the side signals.
The matrix amplifier controls the width of the stereo image by
changing the gain of the side signal relative to the middle signal
in six 3 dB steps. The output signals of the matrix amplifier are
either mid-side (MS) or left/right (XY). The signals are converted
through transformerless sum-and-difference circuitry.
The balanced, transformerless technology permits the use of long
cables between the microphone, the matrix amplifier and the
following mic input of other signal processing equipment.
Applications
The RSM 191 system is an ideal microphone system for:
Outdoor stereophonic news coverage, even in extremely noisy
surroundings;
Stereo recordings for film and television where the actors are
recorded simultaneously with acoustic ambiance, or an
orchestra;
Stereophonic motion picture sound where the width of the sound
image must match the camera viewing angle.
Construction
The RSM 191 consists of a capsule head containing two separate
transducer systems and an amplifier section with two independent
transformerless microphone amplifiers.
An interference tube system with a hypercardioid characteristic
generates the middle signal, while a horizontal figure-8 assembly
provides the side signal.
Acoustic features
The RSM 191 achieves its high directivity and special acoustic
features through a unique construction. The microphone capsule
assembly is mounted inside a housing tube that is acoustically open
but has a high flow resistance.
This results in a high driving force for the diaphragm, even with a
low pressure gradient factor of the capsule. Therefore, the
microphone can suppress unwanted off-axis interference to a
considerably higher degree than other microphones without such an
interference tube.
The middle system (M-signal) combines high attenuation of lateral
sound incidence, similar to a hypercardioid characteristic (which
is about 10 dB), with the large front-to back ratio of the
super-cardioid characteristic.
Therefore, sound from the rear is likewise attenuated by
approximately 10 dB. This design approach makes the microphone less
sensitive to wind or pop noise than other shotgun microphones.
The side system (S-signal) consists of two single capsules arranged
back to back, closely behind the interference tube (M-signal)
capsule. Arrows engraved on the microphone housing show their
orientation.
The uniform and balanced performance characteristic of the
microphone system is achieved without resorting to corrective
resonance effects. Therefore, the microphone maintains an excellent
impulse response, reproducing all transient phenomena in music and
speech without coloration. The entire internal construction is
decoupled from the housing to avoid structure borne and handling
noise.
Electrical features
The output signals of the included matrix amplifier are in either
MS or XY format. The small capsules are mounted in close proximity
to ensure transparent and coloration-free stereo sound with
excellent mono-compatibility. The stereo acceptance angle is
variable and controlled remotely.
Filter and attenuation
For the handling of very high sound pressure levels, a 10 dB
attenuation can be switched ON to avoid overloading of the
following equipment. To suppress structure borne noise, a high-pass
filter in the matrix box provides cutoff frequencies of 40 Hz, 80
Hz, and 200 Hz.
Battery supply
The RSM 191 system is fed from either 2 x P 48 phantom power or
from a 9 V battery inside the matrix box. One alkaline battery
provides 8 hours of operation.
Delivery range
The complete miocrophone system comes in a robust aluminum carrying
case.
Along with the microphone and the matrix amplifier the case
contains a windscreen, the special interconnecting cable and an
adapter cable that splits the 5-pin XLR output of the matrix
amplifier into two 3-pin XLR connectors for channels I and II to
connect with the following equipment.
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