Microphones/Preamplifiers

Nor1209

½" microphone preamplifier

The Nor1209 ½" microphone preamplifier has been designed for general use with most ½" condenser microphone of type WS2 or LS2 according to IEC 61094-4: Measurement microphones – Part 4: Specifications for working standard microphones.

The microphones may be pre-polarized or use externally supplied polarization voltage up to 200 V. By the use of adaptors,the preamplifier may be used for other microphone sizes. The frequency response covers the range from below 1 Hz to above 200 kHz.

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Flexible integration with professional sound level meters

The Nor1209 preamplifier is designed for flexible integration in professional noise measurement systems. It can be mounted directly on a sound level meter such as the Nor145, or connected to the instrument via a suitable cable when the measurement setup requires remote positioning of the microphone.

Integrated system check for reliable, traceable measurements

The preamplifier is equipped with the system check facility. By supplying a test signal voltage on one of the terminals, the capacitance of the microphone as well as the complete signal chain from the microphone cartridge to the indication of by the sound level meter may be checked.

High input impedance for accurate, compliant noise measurements

The voltage gain of the preamplifier is very close to one or correspondingly 0 dB. As the input impedance is 10 GΩ, the attenuation due to loading of the source will mainly be determined by the low input capacitance.

Features

Specifications

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Features

Low noise.
Wide dynamic range.
Wide frequency range.
Low output impedance.
System Check facility.
Large supply voltage range.
Detachable preamplifier cable.

Specifications

Frequency response (18 pF/small signal): 20 Hz – 20 kHz: ±0.1 dB

Nor1209_Freq-resp-(605x261px)

Gain: Typ -0.1 dB (-0.2 with 20 pF)
Input impedance: 10 GΩ, 1.4 pF
Output impedance: 50 ohm typical
Noise (20 pF dummy mic.):
A-weighted < 2.2μV (typ 1.8μV)
Lin (20 Hz – 20kHz) <6 μV (typ 3.8 μV)

Power supply:
Single: 28 V (1mA) to 120 V (2.8mA)
Dual: ±14 V(1 mA) to ± 60 V (2.8 mA)
Maximum signal output voltage (peak): ±10 to ±50 V (dep.on supply)
Temperature: -25°C to +70°C (operation)
Relative humidity: 0 – 90%

Length: 83 mm
Diameter: Body: 12.7 mm/Ring: 14 mm
Weight: 36 g

EC classification: As for Sound level meter Nor140.

Noise Nor1209

Noise considerations:
The figure above shows the typical frequency spectrum of the inherent noise of the preamplifier Nor1209 in one-third octave bands for transducer impedance of 20 pF. The A- and Z-weighted levels are also shown. 0 dB corresponds to 1 μV or to the sound pressure level when the microphone has the sensitivity 50 mV/Pa. Note that a real microphone with resistive impedances will have a higher noise level than a dummy microphone with similar capacitance.