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Endevco® model EM40BE
¼-inch Prepolarized free-field microphone
Applications
Description
• High frequency measurements
The Endevco. microphone model EM40BE is a ¼-inch
precision condenser microphone for general purpose
measurements in open acoustic fields. It is a prepolarized
free-field microphone with a large dynamic range and a wide
frequency response.
• High level measurements
• Acoustic transient measurements
• Use with Endevco Isotron® preamplifiers
• Repairable
As a free-field microphone, the model EM40BE is for
measuring the sound pressure which existed before it was
placed in the sound field pointing towards the sound source.
The disturbing effects of its presence in the sound field
are minimal for most of its frequency range because of
its small dimensions. At higher frequencies, the effects of
reflections and diffractions generally lead to an increase in
the measured sound pressure levels. Fig.2 shows what these
are in a free-field for various angles of incidence. The model
EM40BE compensates for this to provide a flat frequency
response at an angle of 0° incidence in a free field (see
Fig.1).
Endevco Isotron preamplifiers are also available for use with
the model EM40BE, these are:
• ¼-inch Preamplifier model EM26CB
Endevco microphones comply with the specifications of IEC
1094: Measurement Microphones, Part 4: Specifications for
working standard microphones.
Non-corrosive, stainless materials are used in
manufacturing these microphones to enable them to
withstand rough handling and corrosive environments.
All Endevco microphones are guaranteed for 5 years and
are individually checked and calibrated before leaving the
factory. An individual calibration chart is supplied with each
microphone.
Endevco® model EM40BE
¼-inch Prepolarized free-field microphone
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Specifications
Frequency response:
10 Hz–40 kHz:
4 Hz–80 kHz:
4 Hz–100 kHz:
Nominal open circuit sensitivity:
at 250 Hz:
Polarization voltage:
Upper limit (3% distortion):
Microphone thermal noise:
Nominal cartridge capacitance:
Polarized:
Resonant frequency:
90° Phase shift:
Effective front volume:
Nominal at 250 Hz:
Static-pressure coefficient:
250 Hz at 25°C
Influence of axial vibration, 1 m/s2:
Temperature:
Range:
Mean coeff. (–10°C to +50°C):
Venting [1]:
IEC 1094-4 Type designation:
Dimensions
(with protection grid):
Length/Diameter:
(without protection grid):
Length/Diameter:
Diameter (diaphragm ring):
Threads:
Protection grid:
Preamplifier mounting:
Weight:
Accessories (optional)
Pistonphone
Isotron power supply
Signal conditioner
¼“ microphone preamplifier
± 1 dB
± 2 dB
± 3 dB
4 mV/Pa
0V
166 dB re. 20 µPa
30 dBA re. 20 µPa
5.2 pF
100 kHz
0.6 mm3
–0.014 dB / kPa
60 dB re. 20 µPa
–40°C to +120°C (-40°F to 248°F)
–0.01dB / °C
Rear vented
WS3F
10.5 mm / 6.9 mm (0.41 in / 0.27 in)
9.1 mm / 6.3 mm (0.31 in / 0.25 in)
6.0 mm (0.24 in)
6.35 mm - 60 UNS
5.7 mm - 60 UNS
1.75 g (0.06 oz)
Model EM42AA
Model 4416B
Model 133
Models EM26CB
Decibels re. level at 250 Hz
5
0
0º
-5
- 10
- 15
Fig. 1
10 Hz
100 Hz
1 kHz
10 kHz
100 kHz
Typical frequency response of model EM40BE (without protection grid). Upper curve shows
free-field response for 0°, lower curve shows pressure response
10
Decibels re. level at 250 Hz
30 º
90 º
4
60 º
2
Random
incidence
180 º
0
150 º
-2
-4
90 º
120 º
-6
-8
- 10
Fig. 2
0º
0º
8
6
100 Hz
1 kHz
10 kHz
100 kHz
Free-field corrections for various angles of incidence (without protection grid)
Continued product improvement necessitates that Endevco reserve the right to modify these specifications without notice. Endevco maintains a program of constant surveillance
over all products to ensure a high level of reliability. This program includes attention to reliability factors during product design, the support of stringent Quality Control
requirements, and compulsory corrective action procedures. These measures, together with conservative specifications have made the name Endevco synonymous with reliability.
APPLIES TO CALIFORNIA FACILITY
©ENDEVCO CORPORATION. ALL RIGHTS RESERVED 30700 RANCHO VIEJO ROAD, SAN JUAN CAPISTRANO, CA92675 USA
(800) 982-6732 • (949) 493-8181 fax (949) 661-7231 • www.endevco.com • Email: applications@endevco.com 051310