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Neumann M 147
Tube Microphone |
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Product Code:
M149TUBE
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The M 149 Tube* is
a variable dual-diaphragm microphone. The K 49 capsule � well-known from the
legendary U 47 and M 49 microphones � is followed by a tube functioning as an
impedance converter. In contrast to earlier concepts � utilizing a transformer �
the tube is complemented with a transformerless output circuit design. The M 149
Tube can thus feed long microphone cables without any coloration.
Two slide switches are located below the large, acoustically very open
headgrille. The switch at the front allows selection one of nine directional
patterns. The slide switch at the rear operates a seven-step high pass filter.
It allows a very fine adjustment of the cut-off frequency.
Applications
There are nine polar patterns to choose from, making this microphone an ideal
choice for a wide range of recording situations.
As its ancestors, the M 149 Tube is a superb vocalist microphone, not only
because of the capsule, but also due to its modern circuitry, characterized by
extremely low noise level.
Acoustic features
The M 149 Tube is addressed from the front, marked with the Neumann logo. Also
on the front is the switch for the selection of the polar patterns.
The capsule is mounted elastically inside the headgrille to eliminate structure
borne noise. The surface below the capsule is shaped like a cone to disperse any
reflected sound from the acoustic upper half space. This avoids any interference
with the primary sound arriving at the capsule directly.
A large headgrille surrounds the capsule. It is acoustically very open and
therefore increases the sonic realism.
Polar patterns
The polar pattern switch selects one of nine directional patterns:
omnidirectional, wide-angle-cardioid, cardioid, hypercardioid, figure-8, and one
additional intermediate pattern between each major position.
Electrical features
The circuit of the M 149 Tube microphone has been developed to exceed
traditional designs. We have selected a modern tube (triode) and combined its
exceptional transmission characteristics with the advantages of our proven
transformerless output circuit.
The aim was to provide a more controlled environment for the audio signal on its
path from the capsule to the output section.
The final stage is an integrated amplifier, especially designed for such
applications. It features very low distortion (THD < 0.002 % at � 10 V), very
low self-noise, and high output current capability.
As a result, the tube circuit is completely decoupled from the microphone output
and its characteristic response curve will be unaffected by very high signal
levels or varying load conditions.
The lower output impedance and higher output current capability allow cable
lengths up to 300 m (1000 feet) without any degradation of the audio signal.
The tube amplifier changes the high impedance of the capsule and adds 10 dB of
gain to the audio signal, providing optimum operating specifications. The wide
dynamic range is impressive, as peak output can be �10 V, at 20 mA.
The ideal operating point of the tube is maintained throughout its entire life
expectancy. Plate current and filament voltage are constantly regulated. A
sensor circuit monitors and compensates for any voltage drop across the
microphone cable. The tube is heated up slowly through inverse current limiting
to guarantee long life. Optimum operating conditions are reached within a very
short time.
Filter
A seven-position slide switch is located on the back of the microphone. It
selects a high-pass filter, advancing in half-octave steps between 20 Hz and 160
Hz (-3dB). This filter is useful to suppress rumble from air-conditioning and in
windy situations.
In addition, the filter provides an effective tool to control the audio signal
when the microphone is used at close distance and therefore proximity effect
alters the program material.
Delivery Range
The specifically designed N 149 A power supply unit feeds the M 149 Tube through
an 8-core cable. The output connector for the audio signal is a 3-pin XLR. The
output signal is balanced.
The microphone comes as a set in an attractive aluminium case, together with the
8-core microphone connecting cable, the N 149 A power supply with plug-in mains
unit, the EA 170 full elastic microphone suspension and a dust cover. |
� Switchable
tube microphone
� Transformerless circuitry
� High output level
� Pressure gradient transducer with the M 49 capsule
� Acoustically very open wire mesh cage
� Nine directional characteristics: omni, wide angle cardioid, cardioid,
hypercardioid, figure 8, and one intermediate position each
� 7fold switchable low frequency roll-off |
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Acoustical operating principle |
Pressure gradient transducer |
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Directional pattern |
Omnidirectional, wide angle cardioid, cardioid,
hypercardioid, figure-8 plus one intermediate position each |
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Frequency range |
20 Hz ... 20 kHz |
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Sensitivity at 1 kHz into 1 kohm |
34/47/62 mV/Pa |
| Rated
impedance |
50 ohms |
| Rated
load impedance |
1 kohms |
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Equivalent noise level, CCIR |
28/25/23 dB |
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Equivalent noise level, A-weighted |
16/13/11 dB-A |
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Signal-to-noise ratio, CCIR (rel. 94 dB SPL) |
66/69/71 dB |
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Signal-to-noise ratio, A-weighted (rel. 94 dB SPL) |
78/81/83 dB |
| Typical SPL (tube characteristic) |
K < 0,5 %: 120 dB, K < 5 %: 136 dB |
| Maximum
output voltage |
18 dBu |
| Dynamic
range of the microphone amplifier (A-weighted) for < 0,5% THD (for < 5% THD) |
101 (121) dB |
| Powering |
Power supply N 149 A |
| Matching
connector |
Microphone: DIN 8F, Power Supply: XLR3F |
| Weight |
730 g |
| Diameter |
70 mm |
| Length |
201 mm |
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