TYPE 4949B

Automotive surface microphone with 2 coaxial cables and CIC

Designed for measurement of the true surface pressure, especially in automotive applications. It is well-suited for mounting directly on the car surface during wind-tunnel tests or for easy measurement in confined spaces, for example, on the firewall or the underside of a vehicle.

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Type 4949-B is optimised for measurement of the true surface pressure, especially in automotive applications. It is well-suited for mounting directly on the car surface during wind-tunnel tests or for easy measurement in confined spaces, for example, on the firewall or the underside of a vehicle.

USE SCENARIOS

  • Noise measurement on surfaces including glass and in confined spaces
  • Wind-tunnel testing
  • Low to medium noise measurements
  • Flush mounting
  • Connects to CCLD input

The optional mounting pads allow easy mounting of the microphone even on the curved surfaces of an automobile. Despite its small size, Type 4949-B is a rugged and stable measurement microphone. The microphone housing and the metallic parts of the diaphragm-backplate arrangement, including the diaphragm, are all titanium, ensuring uniquely high resistance to corrosion.

The diaphragm is flush with the microphone housing in order to minimise the wind-generated noise of the microphone. The microphone pressure-equalization vent is placed just next to the diaphragm on the front of the microphone. This is important since the static pressure can vary rapidly with position when the microphone is exposed to turbulent pressure fluctuations.

Surface Microphone Type 4949 has a built-in preamplifier for connection to CCLD inputs. The sensitivity of the microphone is optimised in order to achieve a good noise floor and still allow measurements at higher levels without clipping. The microphone supports IEEE 1451.4 (TEDS) for remote identification of the transducer and reading of its calibrated sensitivity. Type 4949 B also supports Brüel & Kjær’s proprietary Charge Injection Calibration (CIC) for remote verification of the complete, calibrated measurement channel.

Surface Microphone Type 4949 is yet another product based on Brüel & Kjær’s new patent-pending microphone technology. With this technology, it is possible to obtain the same high stability and uniformity as that of the traditional and well-known Brüel & Kjær microphones and preamplifiers.

Capacitance
pF
Dynamic range
– dB
Frequency range
– Hz
Inherent noise
dB A
Lower limiting frequency -3dB
Hz
Polarization voltages
V
Pressure coefficient
dB/kPa
Sensitivity
mV/Pa
Temperature coefficient
db/ºC
Temperature range
– C
Weight
gram