GRAS 40SA - GRAS Sound and Vibration

GRAS 40SA
Probe Microphone
Freq range: 2 Hz to 8 kHz
Dyn range: 40 dB(A) to 166 dB
Sensitivity: 3 mV/Pa
GRAS Sound & Vibration A/S
Skovlytoften 33, 2840 Holte, Denmark
www.gras.dk
The GRAS 40SA Probe Microphone is a small, compact
unit for sound-pressure measurements in small
enclosures, in harsh environments and in very close
proximity to sound sources. The high acoustic input
impedance at the tip of the probe minimizes its
influence on the acoustic field, while the stainlesssteel tube of the probe can withstand temperatures of
up to 800 ºC.
Technology
Typical applications and use
Acoustic-impedance measurements
Exhaust-system measurements
Near-field measurements
Measurements at high temperatures
Pressure-distribution measurements in
smallenclosures
Design
The GRAS 40SA is constructed with detachable stainlesssteel probe tubes which guide the acoustic signal to a
microphone inside the housing of the 40SA. After being
sensed by the microphone, the acoustic signal is passed
on to an impedance matching wave guide which
eliminates unwanted internal reflections. The result is a
smooth frequency-response ranging from 2 Hz up to 20
kHz. The internal microphone is connected to a low-noise
preamplifier with a high dynamic range; ensuring a
measurement range from approximately 40 dB to 166 dB
re. 20 μPa. The data sheet shows the preamplifier’s
connections via its LEMO plug.
The GRAS 40SA Probe Microphone is internally
compensated to equalize the internal pressure of the
microphone with the static pressure at the probe’s tip .
The static pressure within the 40SA will therefore adjust
itself to the static pressure existing at the probe’s tip;
which it does with a time constant of approximately 0.1 s.
The 40SA can be used with various probe lengths and is
delivered with four standard probe lengths, i.e.: 20 mm, 40
mm, 80 mm and 160 mm. Intermediate lengths can be
made by cutting these standard lengths. Also, the
stainless steel tubes can be bent to a radius as low as 5
mm without downgrading the system’s acoustics. A
flexible probe tube is also provided for use in
measurements where stiff stainless-steel tubes are not
practical. This does, however, slightly downgrade the
system’s acousticperformance.
The right angled design of the 40SA makes it particularly
well suited for measurements on exhaust-gas systems
and other machinery in general as well as for scanning
vibrating surfaces such as loudspeaker diaphragms and
cabinets.
The compact size, low weight and all-stainless-steel
Date 19-02-2018.
GRAS 40SA Probe Microphone
Page: 2
construction of the 40SA make it robust, easy to handle
and easy to mount.
The 40SA is provided with a 3 m integrated cable with a 7pin LEMO connector. Extensions cables are available.
Specifications
Page: 3
GRAS 40SA Probe Microphone
Frequency range (±3 dB)
Hz
2 to 8 k
dB(A)
40
dB
166
mV/Pa
3
Polarization voltage
V
200 V / Traditional
Power supply, single
V
120 to 28
Output impedance
Ω
55
Temperature range, operation
°C / °F
-25 to 700 / -13 to 1292
Temperature range, storage
°C / °F
-40 to 85 / -40 to 185
Temperature range with GRAS preamplifier, operation
°C / °F
-25 to 70 / -13 to 158
Dynamic range lower limit (microphone thermal noise)
Dynamic range upper limit
Set sensitivity @ 250 Hz (±2 dB)
Connector type
3 m 7-pin LEMO
CE/RoHS compliant/WEEE registered
Weight
Yes/Yes/Yes
g / oz
Frequency response for various lengths of stainless-steel probes
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
Date 19-02-2018.
40 / 1.4110
Dimensions
Length (housing): 83.8 mm
Diameter: 12.7 mm
Probe tube outside diameter: 1.25 mm
Probe tube inside diameter: 1 mm
Date 19-02-2018.
GRAS 40SA Probe Microphone
Page: 4
Ordering Info
GRAS 40SA Probe Microphone
Included items
GRAS GR0265
Pistonphone adapter for stainless steel probe
GRAS GR0266
Pistonphone adapter for flexible probe
GRAS GR0267
Heat sink and tool
GRAS RA0326
Calibration coupler
GRAS GR0263
1.3 mm insert pin for calibration coupler
GRAS GR0266
1.6 mm insert pin for calibration coupler
GRAS YY0004
Pair of pliers
GRAS YY0005
File
GRAS MI0016
Silicon grease
GRAS EK0018
Teflon tubing (L=0.5 m, Dia.: 1.6 mm)
GRAS GR0258
20 mm probe tube
GRAS GR0259
40 mm probe tube
GRAS GR0260
80 mm probe tube
GRAS GR0261
160 mm probe tube
GRAS GR0401
Flexible probe tube
GRAS SK5546
Needle for cleaning
Optional items
GRAS AA0008
3 m LEMO 7-pin - LEMO 7-pin Cable
GRAS AA0020CL
Customized Length LEMO 7-pin - LEMO 7-pin Cable
GRAS 12AA
2-Channel Power Module with gain, filters and SysCheck generator
GRAS 12AQ
2-Channel Universal Power Module with signal conditioning and PC interface
GRAS 42AA
Pistonphone, Class 1
GRAS 42AP
Intelligent Pistonphone, Class 0
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
Date 19-02-2018.
Page: 5
We Make Microphones
Tradition
Innovation
Quality
Since the establishment in 1994,
GRAS has been 100% dedicated to
developing and manufacturing
high-quality measurement
microphones and related acoustic
equipment.
We work with everybody with an
interest in sound or noise within
the fields of aerospace,
automotive, audiology, consumer
electronics, noise monitoring,
building acoustics and
telecommunications.
At GRAS we know that in order for
you to trust your measurement
results; signal quality, stability and
robustness are essentials. We
design and build them to perform
under real life conditions – and
beyond.
GRAS Sound & Vibration A/S
Skovlytoften 33, 2840 Holte, Denmark
www.gras.dk
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