1/4" FREE-FIELD MICROPHONE, EXTERNAL POLARIZED
Free-field microphone designed for high-level and high-frequency measurements over a frequency range of 4 Hz to 100 kHz.
TYPE 4939
Using stainless steel diaphragm and protection grid, Type 4939 Microphone is built to withstand rough environments and can be used in high-temperature measurements up to 150°C (302°F).
The microphone requires an external polarization voltage and must therefore be used with a classical preamplifier. Externally polarized microphones can be used at higher temperatures without severe changes in measurement sensitivity.
¼-inch Free-field Microphone Type 4939 Datasheet (bp1851) | Data Sheets | English |
Standard | IEC 61094 |
Sound field | Free field |
Polarization voltage | 200V |
Sensitivity | 4 mV/Pa |
Lower limiting frequency | 4 Hz |
Higher limiting frequency | 100 kHz |
Inherent noise | 28 dB(A) |
Upper limiting of dynamic range | 164 dB |
Diameter | 1/2 inch |
Venting | Side |
Minimum Temperature | -40 °C |
Maximum Temperature | 150 °C |
Minimum Temperature | -40 °F |
Maximum Temperature | 302 °F |
A laser-welded, stainless-steel diaphragm ensures superior long-term stability and mechanical robustness. Type 4939 will withstand the 1 m drop test required by IEC 60068-2-32.
The microphone is assembled in a clean room, ensuring that the microphones maintain their inherent noise floor and high stability, even when used in environments with a combination of high humidity and high temperature.
Type 4939 is available in a TEDS Microphone set with different variants of classical preamplifiers. 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 in the transducer. The default TEDS template is according to IEEE P1451.4 but TEDS to IEEE 1451.4 is available on request.
The sensitivity can be calibrated at 250 Hz by using Pistonphone Type 4228 with ¼-inch Adaptor DP 0775. The actuator response can be measured using Actuator UA 0033 with Adaptor DB 0264.
The free-field response can be obtained by adding the type-specific, free-field correction to the actuator response.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.
This will bring together HBM, Brüel & Kjær, nCode, ReliaSoft, and Discom brands, helping you innovate faster for a cleaner, healthier, and more productive world.