G.R.A.S. 40LA 1/4" CCP Precision Surface Microphone, High Pressure

Freq range: 5 Hz to 70 kHz
Dyn range: 56 dB(A) to 178 dB
Sensitivity: 0.5 mV/Pa

Typical applications and use

  • Aerospace industry
  • Wind-induced noise analysis on airplanes
  • In-flight measurements
  • Wind-tunnel testing
  • Acoustic-fatigue testing


Just 2.5 mm thick, the 40LA has an integrated CCP preamplifier and is delivered with a built-in TEDS chip, which enables it to be programmed as a complete unit.

The 40LA requires a constant-current power supply, such as the G.R.A.S. 12AL CCP Supply or any other CCP compatible power supply. Close manufacturing tolerances, together with the advantages of the TEDS chip, provide the 40LA with a high degree of interchangeability; a major advantage which excludes accounting for individual characteristics.The 40LA is both very stable and robust. It has an integrated 1.5 m coaxial cable with a Microdot connector and is delivered with a supple, detachable silicon-rubber fairing. G.R.A.S 40LA is also available with customized cable lengths – see Ordering info for more options. Because of its lightness, the microphone with fairing can readily be mounted on surfaces using double-sided adhesive tape. The broad temperature range makes the 40LA well-suited for the aerospace industry. All G.R.A.S. microphones are individually checked and calibrated before leaving the factory. An individual calibration chart is supplied with each microphone.

Frequency range (±1 dB) Hz 10 to 20 k
Frequency range (±3 dB) Hz 5 to 70 k
Dynamic range lower limit (microphone thermal noise) dB(A) < 56
Dynamic range upper limit with G.R.A.S. CCP preamplifier dB 178
Set sensitivity @ 250 Hz (±2 dB) mV/Pa 0.5
Polarization voltage V 0
Power supply (Constant Current Power) mA 2 to 20
Microphone venting Front
Output impedance Ω <50
Temperature range, operation °C / °F –55 to 100 / -67 to 212
Temperature range, storage °C / °F -40 to 85 / -40 to 185
TEDS UTID (IEEE 1451.4) 27 v. 1.0
Connector type Microdot 10/32
CE/RoHS compliant/WEEE registered Yes / Yes / Yes
Weight g / oz 3 / 0.101

Typical pressure frequency response


G.R.A.S. GR0933 Adhesive tape, pre-cut, single-sided
G.R.A.S. GR0934 Adhesive tape, pre-cut, double-sided
G.R.A.S. MI0031 Cleaning tissue
G.R.A.S. AE0046 Adapter, BNC male to Microdot female
G.R.A.S. GR1252 Silicon-rubber fairing


1/4" Precision Surface Microphone with customized cable length, high pressure. Specify the length in cm. (e.g. 40LA-CL0350 specifies a 350 cm  cable (3.5 m)). Maximum cable length is 5 meters.
G.R.A.S. 12AQ Power Module (2-ch.)
G.R.A.S. 42AP Intelligent Pistonphone with built-inprecision barometer (250 Hz or 251.2 Hz,114 dB ±0.05 dB) (recommended)
G.R.A.S. 42AA Pistonphone(250 Hz, 114 dB ±0.08 dB)
G.R.A.S. GR1297 Aluminum fairing
G.R.A.S. OP0025 Kit for Sensitivity Calibration of Surface Microphone Sets
G.R.A.S. OP0026 Kit for Frequency Calibration of 1/4" Surface Microphone Sets