GRAS 48LX-4 UTP Line-Array, 4 Channel, Medium Pressure

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Acoustic measurements in laminar and turbulent airflow require low-profile microphones to avoid disturbing the sound field. This is why we at GRAS have developed the UTP microphones – Ultra-thin Precision microphones.

UTP microphones are surface-mounted condenser microphones with all the expected quality and precision of a classical measurement microphone. They beat any flush- or surface-mounted microphone on the market - superior performance, unbeatable price, fast and repeatable mounting – and should be a first choice for cost-effective, high-precision testing.

The GRAS 48LX-4 is a line array with four UTP microphones. It is only 1.35 mm (0.05 inches) in height and, therefore, ideal for measurements in boundary layers and turbulence.

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Superior Performance - Unbeatable Price

Explore the benefits, the very small things which make the BIG difference.

Quality Data
UTP provides accurate data from precision measurement microphones manufactured to narrow specifications. All LX versions have TEDS.

Low Profile
With a height of 1.35 mm the door to a whole new world of what can be measured in boundary layers and turbulent flow opens.

Simplified Cabling
The line array configuration provides easy connection and avoids acoustic interference from messy cabling.

GRAS UTP Microphone 48LX-4

Easy Mounting and In-situ Verification
As shown below, 48LX-4 is easily mounted using masking tape. Once mounted, the setup can quickly be verified in-situ, a major advantage when you want to check the integrity of your measurement setup.

Cost-saving Solution
Easy mounting, CCP interface with integral cabling and in-situ verification all add up to reduced setup time and faster measurements- with reliable data.

Flow-optimized Fairings
Rubber fairings with a rise angle of 6.5 degrees ensure minimal disturbance to the sound field/airflow.




Easy Mounting and In-Situ Verification

The UTP microphones are easy to mount and remove, even in confined spaces. 
48LX-4 line-array is mounted using masking tape. Reproducing a previous setup can be done quickly, and geometry is maintained.

Fast and reliable in-situ verification saves time and increases confidence.
A special verification adapter with a soft cushion allows for quick, easy, and reliable in-situ verification. Four distance spacers ensure that the correct volume is achieved and that this volume can easily be reproduced.

Even on curved surfaces, this verification method is so precise that dismounting is not necessary.

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Freq range: 20 Hz to 20 kHz (±1 dB)
                      10 Hz to 70 kHz  (±3 dB)
Dyn range: 54 dB(A) to 170 dB
Sensitivity: 0.6 mV/Pa (±3 dB)
Channels: 4
Use: For aeroacoustic measurements

GRAS 48LX-4 UTP Line-Array, 4 Channel, Medium Pressure



48LX-4 is an Ultra-thin Precision (UTP) surface microphone line array for aeroacoustic testing.

It consists of four low-profile ¼ CCP medium-pressure condenser microphones. They are mounted with rubber fairings in a line array configuration on a flexible PCB. The height is 1.35 mm and the angle of the fairings is 6.5 degrees.

It has TEDS for easy channel identification. The four channels are connected to a 15 pin D-Sub connector. The total cable length is 3 m.

48LX-4 line array is easy to mount and demount. The flexible PCB/plastic strip is about 10 mm wider than the microphones on each side. Therefore, the array can be mounted using masking tape straddling the top side of the strip and the structure.

Remounting is easy, and the geometry of the mounting can easily be maintained and used in a different location or measurement setup.

The strip can be bent along its length, making it possible to mount it on curved surfaces.

Typical applications and use

48LX-4 is for low- to medium-level surface pressure measurements on planar and curved surfaces for measurements in boundary layers and turbulence, for example in

  • Wind-induced noise measurement on vehicles.

  • Wind-tunnel testing.

Field Verification

For sensitivity verification in the field using a sound calibrator, a special adapter is available, the RA4800 Adapter for Sensitivity Verification of Flush/Surface Microphones. RA4800 is furnished with a round, soft pad similar to those used on over-the-ear headphones. This pad ensures a sealed cavity for the calibration signal. Read more here.

With this adapter, quick and convenient in situ sensitivity verification is possible, and therefore it is possible to check the integrity of the measurement setup immediately before measurements.


For sensitivity and frequency calibration, The RA4803 Sensitivity and Frequency Calibration Kit for 48LX-4/48LX-8 is available.

This kit contains an adapter for sensitivity calibration with a pistonphone and an electrostatic actuator for frequency calibration.

48LX-4 is checked and calibrated before leaving the factory. An individual calibration chart is supplied with each microphone and includes an individual pressure frequency response.

Quality and warranty

GRAS microphone sets are made of components from our proven standard portfolio and are all manufactured of high-quality material and branded parts, which were chosen and processed to ensure life-long stability and robustness. All parts are manufactured and assembled at the factory in Denmark by skilled and dedicated operators in a verified clean-room environment.

The warranty period is two years.

The warranty covers defective materials, and workmanship for the sensor element, printed circuit board, and housing.

Cable and connectors are covered by a six-month warranty period.


Should you by mistake damage or destroy a microphone element or the cable, we offer repair or exchange service for the entire line array.

GRAS Sound & Vibration continually strives to improve the quality of our products for our customers. Therefore, the specifications and accessories are subject to change.




Frequency range (±1 dB)
20-20 k
Frequency range (±3 dB)
10-50 k
Dynamic range lower limit (microphone thermal noise)
Dynamic range upper limit
Sensitivity @ 250 Hz (±3 dB)
dB re 1V/Pa
Sensitivity @ 250 Hz (±3 dB)
Output impedance
Power supply min. to max.
2 - 10
Microphone venting
Temperature range, operation
°C / °F
-20 to 70 / -4 to 158
Temperature range, storage
°C / °F
-40 to 85 / -40 to 185
Temperature coefficient @250 Hz
dB/°C / dB/°F
-0.03, Typical
Static pressure coefficient @250 Hz
Humidity range non condensing
% RH
0 to 80
Humidity coefficient @250 Hz
dB/% RH
Influence of axial vibration @1 m/s²
dB re 20 µPa
Sensitivity difference between microphones @ 250 Hz, max.  dB
Phase difference between microphones, 20 Hz to 20 kHz degrees ±5
TEDS UDID (IEEE 1451.4) - one for each microphone   I27-0-0-0U
Connector to strip   15 pin D-Sub male
Height mm 1.35
Dimensions single sensor, width x length mm 9 x 18
Dimensions strip, width x length mm 50 x 260
Weight g / oz 20 / 0.71 (excl. cable)
160 / 5.64 (incl. cable)


Frequency curve typical 48LX ny

48LX 1 4 8 noise test


The frequency response is within ±3 dB up to 70 kHz


48LX-4 can be mounted on a curved surface. The radius of the bend must be at least 500 mm, corresponding to an arch with a height of 16.8 mm.


LX 4 minradius



48LX 4

Ordering info

Included items

GRAS 48LX-4  UTP Microphone Line Array, 4 Channel, Medium Pressure, with cable
GRAS DB0507 Mounting Tape for 48LX Series Line Arrays

 Optional items

GRAS RA4800 Adapter for Sensitivity Verification of Flush/Surface Microphones
GRAS RA4803 Sensitivity and Frequency Calibration Kit for 48LX-4/48LX-8
GRAS AA4800-4 1.5 m 48LX-4 Splitter Cable D-Sub/4 × BNC Male
GRAS AA4801-4 1.5 m 48LX-4 Splitter Cable D-Sub/4 × Microdot Male
GRAS AA4802-4 1.5 m 48LX-4 Splitter Cable D-Sub/4 × SMB Female
GRAS AA4803-4 1.5 m 48LX-4 Splitter Cable D-Sub/4 × Infiniteband
GRAS AA4804-4 1.5 m 48LX-4 Splitter Cable D-Sub/D-Sub 25
GRAS AA4810 5 m 48LX Extension Cable D-Sub/D-Sub
GRAS AA4811 10 m 48LX Extension Cable D-Sub/D-Sub
GRAS DB0507 Mounting Tape for 48LX Series Line Arrays

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