GRAS 48LA UTP Microphone, High 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. They combine the advantages of the classical measurement microphone – wide frequency range, accuracy, and repeatability – with an ultra-small form factor.

The GRAS 48LA is only 1 mm in height, and therefore it is ideal for measurements in boundary layers and turbulence.

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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.

Low Profile
With a height of 1 mm the door to a whole new world of what can be measured in boundary layers and turbulent flow opens.

Easy Mounting and Verification
As described below, mounting is easy, and once mounted, the setup can easily and quickly be verified in-situ, a major advantage when you want to check the integrity of your measurement setup.

GRAS UTP Microphone 48LA

Small Form Factor
48LA can be used in small or difficult-to-access spaces where conventional microphones must give up.

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
Fairings with a rise angle of 6.5 or 7.5 degrees ensure minimal disturbance to the sound field/airflow.

 

 

Easy Mounting and In-Situ Verification

48LA is easy to mount and remove. 
It can be mounted in a hard fairing which can be used as a permanently mounted dock. A click-mechanism ensures easy and stable mounting. The microphone can easily be removed, leaving the mounting position ready for future measurements. The fairing is secured with double-sided adhesive tape.

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)
                       16 Hz to 31.5 kHz (±3 dB)
Dyn range: 64 dB(A) to 184 dB
Sensitivity: 0.12 mV/Pa (±2 dB)
Use: For aeroacoustic measurements

GRAS 48LA UTP Microphone, High Pressure

Technology

Introduction

48LA is an Ultra-Thin Precision (UTP) high-pressure surface microphone for aeroacoustic testing.

It is a revolutionary new design that has made it possible to combine a 1/4" condenser microphone with a form factor that makes it the world's smallest measurement microphone.

The height of the microphone is 1 mm. It has a built-in preamplifier. The integrated cable connector is Microdot male. The total cable length is 3 meters.

Typical applications and use

48LA is for high-level surface pressure measurements on planar and curved surfaces. Because of its low profile, It is ideal for measurements in boundary layers and turbulence, e.g. for

  • Wind-induced noise measurement on vehicles

  • Wind-tunnel testing

  • In-flight testing of airplanes

Mounting

48LA can be mounted using the RA4810 Hard fairing for 48LA/48LX-1, with click mount, and the included double-sided adhesive mounting pad. The fairing has a locking mechanism that makes it possible to install and remove the microphone without removing the fairing. The fairing has an angle of 7.5 degrees.

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.

Calibration

Accessories for sensitivity and frequency calibration are available.

For sensitivity calibration, the RA4801 Adapter for Sensitivity Calibration of 48LA/48LX-1 is available. This adapter is suitable for use with a pistonphone or sound calibrator fitted with a 1/2" coupler.

For frequency calibration, the RA4802 Actuator for Frequency Calibration of 48LA/48LX is available. RA4801 and RA4802 are also available as a set, the RA4805

48LA 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 for the 48LA is 2 years.

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

Cable and connectors are covered by a 6 months warranty period.

Service

Should you by mistake damage or destroy your microphone, we offer an exchange service at a reasonable cost and short turn-around time.

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

 

 

Specifications

Frequency range (±1 dB)
Hz
20 to 20 k
Frequency range (±3 dB)
Hz
16 to 31.5 k
Dynamic range lower limit (microphone thermal noise)
dB(A)
64
Dynamic range upper limit
dB
184
Set sensitivity @ 250 Hz (±2 dB)
mV/Pa
0.12
Set sensitivity @ 250 Hz (±3 dB)
mV/Pa
0.12
Output impedance
Ω
<50
Power supply min. to max.
mA
2 to 10
Microphone venting
Front
Temperature range, operation
°C / °F
-20 to 85 / -4 to 185
Temperature coefficient @250 Hz
dB/°C / dB/°F
-0.02
Static pressure coefficient @250 Hz
dB/kPa
-0.0003
Connector type
Microdot 10/32
Weight
g / oz
1 / 0.035 (excl. cable) 4 / 0.14 (incl. cable)

 

Frequency curve typical 48LA

The frequency response is within ±3 dB up to 31.5 kHz

Dimensions

 

 

48LA LX w hard fairing

Ordering info

Included items

GRAS 48LA  UTP Microphone, High Pressure, with 3-meter cable
GRAS RA4810 Hard Fairing for 48LA/48LX-1, with click mount, double-sided self-adhesive mounting pad included         
GRAS AE0046 Microdot Female - BNC Male Adapter

 Optional items

GRAS RA4800 Adapter for Sensitivity Verification of Flush/Surface Microphones
GRAS RA4801 Adapter for Sensitivity Calibration of 48LA/48LX-1
GRAS RA4802 Actuator for Frequency Calibration of 48LA/48LX-1
GRAS RA4805 Actuator & Pistonphone Adapter Kit for 48LA/48LX-1. This kit includes RA4801 and RA4802.
GRAS RA4810-2 Hard Fairing for 48LA/48LX-1, with click mount, 10-pack, mounting pads are included
GRAS RA4810-10 Hard Fairing for 48LA/48LX-1, with click mount, 50-pack, mounting pads are included
GRAS DB0475 Self-adhesive Mounting Pad for Hard Fairing

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