G.R.A.S. 40PH CCP Free-field Array Microphone

Freq range: 10 to 20 kHz
Dyn range: 32 dB(A) to135 dB
Sensitivity: 50 mV/Pa

Typical applications and use

  • Multi-channel measurements
  • Sound-field analyses
  • Sound-power measurements
  • Concurrent spatial and transient measurements


Array microphones are designed to be mounted on large or small arrays. Such systems are typically used for measuring and locating noise sources, and here the phase match is important to get good accuracy in the measurements. An important characteristic of array microphones are precisely that the microphones are phase-matched.

40PH has a wide useful frequency range reaching up to 20 kHz and a large dynamic range topping at around 135 dB,  the peak value before visible clipping.

It 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 G.R.A.S. 40PH requires a constant current power supply, e.g. 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 40PH with a high degree of interchangeability; a major advantage when used in multiples forming arrays and matrices.

The low cost of the 40PH is a key consideration when setting up measurements requiring a multiplicity of concurrent transient and spatial data.

Calibrating the 40PH with a G.R.A.S. pistonphone, e.g. G.R.A.S. 42AA, is as straight forward as calibrating any other G.R.A.S. 1/4-inch microphone.

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 50 to 5 k
Frequency range (±2 dB) Hz 5 k to 20 k
Frequency range (±3 dB) Hz 10 to 50
Dynamic range lower limit (microphone thermal noise) dB(A) < 32
Dynamic range upper limit dB 135
Set sensitivity @ 250 Hz (±2 dB) mV/Pa 50
Power supply (Constant Current Power) mA 2 to 20
Microphone venting Front
Output impedance Ω < 50
Temperature range, operation °C / °F -10 to 50 / -50 to 122
Temperature range, storage °C / °F -40 to 85 / -40 to 185
Influence of axial vibration @1 m/s² dB re 20 µPa 50
TEDS UTID (IEEE 1451.4) 27 v. 1.0
Connector type SMB
CE/RoHS compliant/WEEE registered Yes / Yes / Yes
Weight g / oz 5.50 / 0.20

Phase Match


50Hz  - 100Hz


100Hz  - 3kHz


3kHz  - 5kHz


5kHz  - 10kHz


Frequency response according to IEC 61672-1

Typical frequency response

Upper curve shows free-field response at 0°, lower curve (dotted line) shows pressure response.

G.R.A.S. Sound & Vibration reserves the right to change specifications and accessories without notice.


Optional items

G.R.A.S. AA0027

3 m SMB - BNC Cable

G.R.A.S. 12AL

1-Channel CCP Power Module with A-weighting filter

G.R.A.S. PR0002

Array Module

G.R.A.S. AM0364

Windscreens (set of 6)

G.R.A.S. RA0092

Rain-protection cap

G.R.A.S. 42AA

Pistonphone, Class 1

G.R.A.S. 42AG

Multifunction Sound Calibrator, Class 1

G.R.A.S. Sound & Vibration reserves the right to change specifications and accessories without notice.