BRUEL & KJAER 4952 Notes For Users

Sound & Vibration Measurement A/S

General

Outdoor Microphone Type 4952 consist of 3 major parts:
•
An upper part, UA-1679, with windscreen and bird spike
•
A base with thread for pole mounting
•
An internal transducer part, consisting of the microphone cartridge and a preamplifier
No cable is included with Type 4952.
The connector on the microphone's transducer part is a male 7-pin LEMO 1B connector.
For connection to Brüel & Kjær standard LEMO Microphone Input Connectors, Cable AO-0414 should be used. Its order
number is:
•
Up to 99.9 m:
•
Above 99.9 m:
For connection to Brüel & Kjær Type 2260 and 2250 Sound Level Meters, Cable AO-0645 should be used. Its order number is:
•
Up to 99.9 m:
•
Above 99.9 m:
The preamplifier in the transducer part is equivalent to Brüel & Kjær Microphone Preamplifier Type 2669-C. Details on dynamic
range of the preamplifier with various loads are given in Brüel & Kjær Microphone Handbook, Volume 2 (BE1380-12),
Chapter 8. The Microphone Handbook can be viewed from the Literature section of the Brüel & Kjær Internet Site
www.bksv.com.
For Brüel & Kjær Sound Level Meters and Noise Monitoring Terminals supporting Outdoor Microphone Type 4952, the
recommended connecting cables and the maximum cable length are stated in their Technical Documentation.

Mounting and Assembling

Outdoor Microphone Type 4952 is designed to operate mounted vertically with the bird spike pointing upwards. The microphone
should not be mounted outdoors with other orientations.
The base of Outdoor Microphone Type 4952 has an inner thread that fits on the thread of normal 1" opening diameter water
pipes (ISO 228-1 G1). The transducer part and the upper part of the microphone are mounted on the base with bayonet
couplings. The microphone can be mounted on a tripod with Tripod Adaptor DB-4024. The adaptor fits into the thread of the
base.
The cable (not included with the microphone) must be led through the base.
Fix the base to the mast or tripod before you mount the transducer part in the base. In this way you avoid twisting the cable.
Connect the cable to the transducer part and mount the transducer part in the inner bayonet by placing it in the flanges and
turning it clockwise until it locks.
The upper part is mounted on the base with the transducer part in a similar matter.
The upper part as well as the transducer part is removed by turning it anticlockwise until it stops and then pulling it upwards.
The sensing point of the microphone is marked with a groove in the windscreen, that is, the microphone height should be
measured from the ground to the groove.

Acoustic Calibration

When calibration is needed, the upper part must be removed, and remounted after calibration.
With the Upper Part UA-1679 removed, an acoustical calibrator can be placed on the transducer part for calibration.
Recommended calibrators are Brüel & Kjær Sound Calibrator Type 4231, Pistonphone Type 4228 or Multifunction Calibrator
Type 4226.
A correction must be added to the sound pressure of the calibrator in order to obtain the calibration value for the Sound Level
Meter or Noise Monitoring Terminal used with the microphone. The corrections are given in the table below.
Frequency 250 Hz
Correction 0.0 dB
BR1733-11
Outdoor Microphone Type 4952
Notes for Use
AO-0414-D-nnn, where nnn denotes the length in decimetres
AO-0414-M-nnn, where nnn is the cable length in metres.
AO-0645-D-nnn, where nnn is the length in decimetres
AO-0645-M-nnn, where nnn is the length in metres
1 kHz
−0.17 dB
1