Microphone GRAS 48LA UTP, áp suất cao

48LA is an Ultra-thin Precision (UTP) surface microphone for aeroacoustic testing.
It is a low-profile ¼″ CCP high-pressure condenser microphone. The microphone is only 1 mm high and can, therefore, be mounted in air flow without disturbing the sound field.

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 ¼″ 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 m.

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 7.5º.

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 ½″ 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 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.

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 km
Dynamic range lower limit (microphone thermal noise)	dB(A)	64
Dynamic range upper limit	dB	184
Sensitivity @250 Hz (±2 dB)	dB re 1V/Pa	-78.4
Sensitivity @250 Hz (±2 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	-55 to 85 / -67 to 185
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	dB/kPa	-0.0003
Humidity range non condensing	% RH	0 to 80
Humidity coefficient @250 Hz	dB/% RH	-0.01
Influence of axial vibration @1 m/s²	dB re 20 µPa	73
Connector type		Microdot 10/32
Weight	g/oz	1 / 0.035 without cable / 4 / 0.14 with cable