G.R.A.S. 41AO Environmental Microphone System

Dyn range: 14 dB(A) to 146 dB
Sensitivity: 50 mV/Pa

Typical applications and use

  • Outdoor-noise measurements
  • Aircraft-noise monitoring
  • IEC 61672 measurements
  • Simple field calibration


With an externally-polarized Free-field Microphone 40AF and Preamplifier 26AK. Alternatively, Preamplifier 26AJ, with aSysCheck * feature, is available. By applying a SysCheck signal to pin 1 of the preamplifier, the response of the system will reveal any drift in sensitivity.

In both cases the reference direction for measurements is along the axis of symmetry - (i.e. 0° angleof incidence) for measurements according to IEC 61672, typically aircraft-noise monitoring.

Simple field calibration

All that is required is unscrewing the windscreen and mounting a pistonphone/calibrator directly onto the exposed microphone.

Desiccator unit

A desiccator unit (e.g. G.R.A.S. AL0014) is available if the 41AO is to be placed outdoors for extended periods. It screws directly onto the base of the 41AO and removes moisture from the air entering the unit.

* A standard feature of most G.R.A.S. Power Modules (e.g. 12AK) used for powering Microphone Preamplifiers

Dynamic range lower limit (microphone thermal noise) dB(A) 14
Dynamic range upper limit dB 146
Set sensitivity @ 250 Hz (±2 dB) mV/Pa 50
Polarization voltage V 200
Power supply, single V 28 (single) / ± 14 to ± 60 (dual)
Power consumption mA 0.7 (± 14 V) / 2.3 (± 60 V)
Output impedance Ω 75
Temperature range, operation °C / °F - 30 to 70 / - 22 to 158
Connector type 3 m 7-pin LEMO
CE/RoHS compliant/WEEE registered Yes/Yes/Yes
Frequency response according to IEC 61672-1


Included items

G.R.A.S. AM0370 Complete Windscreen for 41AO
G.R.A.S. AA0008 Preamplifier extension cable with 7 pin LEMO to 7 pin LEMO

Optional accessories

G.R.A.S. AM0029 Pole adapter
G.R.A.S. AL0014 Desiccator Box for 41AO
G.R.A.S. AM0009 Windscreen for 41AM/CN/AL/AO
G.R.A.S. 42AA Pistonphone, Class 1
G.R.A.S. 42AP Intelligent Pistonphone, Class 0