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 new N 149 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 power supply with plug-in
mains unit, the
EA 170 full elastic
microphone suspension and a dust cover.
N 149 V - Vintage Power Supply
As requested by many recording engineers an optional power supply in the typical vintage design is available: The N 149 V. It handles all
mains voltages from 100 V to 240 V, 50 or 60
Hz.
Mains power is connected through a standard
IEC 320
mains socket.
The three available versions of the N 149 V just differ in their
mains power cable.
Features:
- 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
Specifications:
Acoustical operating principle: Pressure gradient transducer
- Directional pattern: Omnidirectional, wide angle cardioid, cardioid, hypercardioid, figure-8, plus one intermediate position each
- Frequency range: 20 Hz...20 kHz
- Sensitivity at 1 kHz into 1 kohm: 34/47/62 mV/Pa*
- Rated impedance: 50 ohms
- Rated load impedance: 1000 ohms
- Equivalent SPL CCIR 468-3: 28/25/23 dB*
- Equivalent SPL DIN/IEC 651: 16/13/11 dB-A*
- S/N ratio CCIR 468-3: 66/69/71 dB*
- S/N ratio DIN/IEC 651: 78/81/83 dB*
- Typical SPL (tube characteristic):for K < 0,5 %: 120 dBfor K < 5 %: 136 dB
- Maximum output voltage: 18 dBu
- Dynamic range of the microphone amplifier cardioid DIN/IEC 651 for < 0,5% THD (for < 5% THD): 101 (121) dB
- Powering: Power supply N 149
- Matching connectors:Microphone: DIN 8FPower supply: XLR 3F
- Weight: 730 g
- Diameter: 70 mm
- Length: 201 mm