G.R.A.S. 40PK CCP Free-field QC Microphone, Short

Freq range: 10 Hz to 20 kHz
Dyn range: 25 dB(A) to 145 dB
Sensitivity: 18 mV/Pa

Typical applications and use

  • Production-line testing of drivers, receivers, and microspeakers
  • Measurements in confined spaces


The 40PK is very short and can therefore be used in confined spaces where its bigger equivalent, the 40PP cannot be used. Close manufacturing tolerances provide the 40PK with a high degree of interchangeability – a major advantage when used in production-line test setups.

The standard SMB connector of the 40PK ensures an easy-to-handle setup and supports the use of standard RG174 cable all the way from the microphone to the input module.


The integrated CCP (Constant Current Power) preamplifier requires a constant-current power supply, such as the G.R.A.S. 12AL 1-Channel CCP Power Module with A-Weighting filter, or any other CCP compatible power supply or input module. The built-in TEDS (Transducer Electronid Data Sheet, according to IEEE 1451.4) chip provides information about the microphone that can be used by systems designed for use with TEDS.

To fully benefit from its short length, the cable with an angled SMB connector should be choosen (see the tab Ordering info).

System verification

The functionality of TEDS is very useful for determining what microphone is connected to your respective input channels. However, it is not a check of whether the microphone is within specifications or not. For daily verification and check of your measurement setup we therefore recommend using a sound source like the G.R.A.S. 42AB Sound Level Calibrator.

For proper sensitivity calibration we recommend using a reference sound source like the G.R.A.S. 42AP Intelligent Pistonphone.

Frequency range (±2 dB) Hz 10 to 20 k
Dynamic range lower limit with G.R.A.S. preamplifier dB(A) <25
Dynamic range upper limit dB 145
Set sensitivity @ 250 Hz (±2 dB) mV/Pa 18
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 -10 to 50 / 14 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 3.5 / 0.12346

Typical frequency response

Length (incl. connector): 34 mm
Diam.: 7 mm

Optional items

G.R.A.S. AA0027

3 m SMB - BNC Cable

G.R.A.S. AA0082-CL

Customized Length SMB - BNC Cable

G.R.A.S. AA0078

3 m SMB angled - BNC Cable

G.R.A.S. AA0081-CL

Customized Length SMB angled - BNC Cable

G.R.A.S. AL0028

7 mm Microphone Holder, POM

G.R.A.S. AL0005

Swivel head

G.R.A.S. AL0006


G.R.A.S. 12AL

1-Channel CCP Power Module with A-weighting filter

G.R.A.S. 12AQ

2-Channel Universal Power Module with signal conditioning and PC interface

G.R.A.S. 42AB

Sound Calibrator, Class 1

G.R.A.S. 42AP

Intelligent Pistonphone, Class 0