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
The slide switch at the rear operates a seven-step high pass filter
. It allows a very fine adjustment of the cut-off frequency
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
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
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
A large headgrille surrounds the capsule
. It is acoustically very open and therefore increases the sonic realism.
The polar pattern
switch selects one of nine directional
, and one additional intermediate pattern between each major position.
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
The tube amplifier
changes the high impedance
of the capsule
and adds 10 dB
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.
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.
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
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
power is connected through a standard IEC
The three available versions of the N 149 V just differ in their mains
- 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
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