G.R.A.S. 40EU 1" Ext. Polarized Reference Pressure Microphone

Freq range: 2.6 Hz to 8 kHz
Dyn range: 9.6 dBA to 146 dB
Sensitivity: 50 mV/Pa
  • 40EU 1

Introduction

The 40EU is an IEC 61094 LS1P 1" externally polarized pressure microphone that is rear-vented.

It is a 1" pressure microphone that is ideal for measurements in couplers used for testing earphones. When flush-mounted, it can measure sound pressures at boundaries. It is highly suited as a laboratory-standard microphone.

40EU is individually factory-calibrated and delivered with a calibration chart stating its specific open-circuit sensitivity and pressure frequency response.

Typical applications and use

40EU can be used in precision reciprocity calibrations because it is a linear reversible transducer. This means that the electrical energy emitted by the 40EU is strictly or linearly proportional to the acoustical energy it receives. This is exactly what is required for such calibrations. When carefully handled, the 40EU can retain its calibrated properties for many centuries.

The 40EU is also highly suited as a laboratory reference for secondary calibration of working-standard microphones.

Compatibility

The 40EU requires a standardized ½" LEMO preamplifier and an input module that supports this technology with a 7-pin LEMO connector.

System verification

For daily verification and check of your measurement setup, we recommend using a calibrator like G.R.A.S. Sound Level Calibrator 42AB

For proper sensitivity calibration, we recommend using a pistonphone like G.R.A.S. Intelligent Pistonphone 42AP

Quality and warranty

All G.R.A.S. microphones are made of high-quality materials that will ensure life-long stability and robustness. The microphones are all assembled in verified clean-room environments by skilled and dedicated operators with many years of expertise in this field.

The microphone diaphragm, body, and improved protection grid are made of high-grade stainless steel, which makes the microphone resistant to physical damage, as well as corrosion caused by aggressive air or gasses.

This, combined with the reinforced gold-plated microphone terminal which guarantees a highly reliable connection, enables G.R.A.S. to offer 5 years warranty against defective materials and workmanship.

Service

If you accidentally damage the diaphragm on a G.R.A.S. microphone, we can—in most cases—replace it at a very reasonable cost and with a short turn-around time. This not only protects your investment, but also pleases your quality assurance department because you don't have to worry about new serial numbers, etc.

Calibration

Before leaving the factory, all G.R.A.S. microphones are calibrated in a controlled laboratory environment using traceable calibration equipment.

Depending on the use, measurement environment, and internal quality control programs, we recommend recalibrating the microphone at least once a year.

Frequency range (±2 dB) Hz 2.6 to 8 k
Dynamic range lower limit (microphone thermal noise) dB(A) 9.6
Dynamic range lower limit with G.R.A.S. preamplifier dB(A) 14
Dynamic range upper limit dB 146
Dynamic range upper limit with G.R.A.S. preamplifier @ +28 V / ±14 V power supply dB 142
Dynamic range upper limit with G.R.A.S. preamplifier @ +120 V / ±60 V power supply dB 146
Open-circuit sensitivity @ 250 Hz (±1 dB) mV/Pa 50
Open-circuit sensitivity @ 250 Hz (±1 dB) dB re 1V/Pa -26
Resonance frequency kHz 8
Microphone cartridge capacitance, typ. pF 56
Microphone venting Rear
IEC 61094-4 Compliance LS1P
Temperature range, operation °C / °F -40 to 150 / -40 to 302
Temperature range, storage °C / °F -40 to 85 / -40 to 185
Temperature coefficient @250 Hz dB/°C / dB/°F -0.01 / -0.006
Static pressure coefficient @250 Hz dB/kPa -0.0016
Humidity range non condensing % RH 0 to 100
Humidity coefficient @250 Hz dB/% RH -0.0013
Influence of axial vibration @1 m/s² dB re 20 µPa 67
CE/RoHS compliant/WEEE registered Yes / Yes, Yes
Weight g / oz 32 / 1.129

Typical frequency response

Optional items

G.R.A.S. RA0073

Adapter for 1” Microphone and ½” Preamplifier

G.R.A.S. RA0017

Adapter for 1” Microphone and ½” Preamplifier