TYPE 4189

½" Prepolarized Free-field Microphone

Type 4189 is designed for high-precision, free-field measurements where a microphone with high sensitivity is required. Being prepolarized, the microphone can be used with both DeltaTron and classical preamplifiers.

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Type 4189 is our best-selling microphone for 15 years because it produces the best results in its class, and will keep doing so for decades to come, with both CCLD and classical preamplifiers. In addition, this provides great results for electroacoustic measurements like loudspeaker and microphone measurements, and has earned our customers' trust over many years.


  • Precision sound measurement
  • Premium class sound level meters
  • Equipment complying with IEC 61672 class 1

The microphone is a general-purpose workhorse microphone designed for high-precision, free-field measurements with high sensitivity over a frequency range of 6.3 Hz to 20 kHz. Being prepolarized, Type 4189 is especially well suited for battery operated equipment and operation in environments with high humidity. The microphone is universally useful in almost every measurement scenario, it is especially well suited for battery operated equipment –  which is why it is fitted as standard to some of our world-leading sound level meters.

Use of Free-field Microphones

At higher frequencies, reflections and diffractions causes a pressure increase in front of the diaphragm of a microphone. If not corrected, for this would result in an increased output voltage.

A free-field optimisation means that the frequency response of the microphone has been designed in such a way that the free-field response at 0 degrees incidence is flat. This microphone is optimised for use with the protection grid in place.

Free-field microphones are commonly used for sound measurement in an anechoic chamber or far away from reflecting buildings, etc. Another area for free-field microphones is for general electroacoustic measurements purposes like loudspeaker and microphone measurements.

Type 4189 is suited for use in class 1 Sound Level Meters and for all high-precision acoustic measurements where a robust and stable free-field microphone with an upper frequency of 20 kHz is required.

Manufacturing and Stability

A press-fitted, stainless-steel diaphragm ensures superior long-term stability and mechanical robustness  Type 4189 will withstand the 1 m drop test of IEC 60068-2-32.

All Brüel & Kjær Measurement Microphones are assembled in a clean room to ensure that the microphones maintain their inherent low noise floor and high stability, even when used in environments with a combination of high humidity and high temperature.

Type 4189 TEDS Microphone Set

TEDS Microphones Type 4189 is available in TEDS combinations with either classical or DeltaTron type preamplifier.

The TEDS microphone is considered one unit and has been sealed in a clean environment. The TEDS is programmed with the loaded sensitivity of the actual cartridge and the data is therefore readily available.

The default TEDS template is to IEEE P1451.4 but TEDS to IEEE 1451.4 is available on request.

14 pF
Dyn. range
14.6 – 146 dB
Freq. range
6.3 – 20000 Hz
Inherent noise
14.6 dB A
Lower limiting frequency -3dB
4 Hz
Free field
Polarization voltages
Pressure coefficient
-0.01 dB/kPa
50 mV/Pa
IEC 61094-4 WS2F
Temperature coefficient
-0.006 dB/ºC
Temperature range
-30 – 150 ℃
Sound field
Microphone type
Free field