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.
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.
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.
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 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
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/Pa1)
Rated impedance: 50 ohms
Rated load impedance: 1 kohms
Equivalent noise level, CCIR2): 28/25/23 dB1)
Signal-to-noise ratio, (rel. 94 dB SPL): 66/69/71 dB1)
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 connectors: Microphone DIN8F, Power supply XLR3F
Weight and Dimensions
What's in the box
- M 149 Tube Microphone
- N 149 A Power supply incl. power cable
- KT 8 Connecting cable
- EA 170 Elastic suspension
- Aluminium case
- Dust cover