<强>1/8"麦克风风，外部极化
压力场麦克风，专为在狭窄空间进行频率范围为6.5Hz至140kHz的甚高频测量而设计。
TYPE 4138
4138型专为高级别和甚高频测量和在密闭空间中的测量而设计。TYPE 4138 是外部极化的，必须与经典前置放大器一起使用。
| 1/8-inch Pressure-field Microphone Type 4138 | Data Sheets | English |
| Standard | IEC 61094 |
| Sound field | Pressure field |
| Polarization voltage | 200V |
| Sensitivity | 1 mV/Pa |
| Lower limiting frequency | 6.5 Hz |
| Higher limiting frequency | 140 kHz |
| Inherent noise | 43 dB(A) |
| Upper limiting of dynamic range | 168 dB |
| Diameter | 1/8 inch |
| Venting | Side |
| Minimum Temperature | -30 °C |
| Maximum Temperature | 100 °C |
| Minimum Temperature | -22 °F |
| Maximum Temperature | 212 °F |
Pressure-field microphones should be used for making measurements in small, closed couplers or close to hard, reflective surfaces. Such microphones are optimised to have a flat frequency response in a pressure field. Because of its small size, Type 4138 can also be used for random-incidence measurements at audio frequencies, where its frequency response is less dependent on angle of incidence.
Type 4138 requires an external polarization voltage and therefore must be used with a classical preamplifier such as Brüel & Kjær Type 2670 together with 1/8-inch to 1/4-inch Adaptor UA-0160.
The sensitivity of Type 4138 can be calibrated at 250 Hz using Pistonphone Type 4228, or at 1 kHz using Sound Calibrator Type 4231, in both cases using Adaptor DP-0774.
The pressure-field response can be measured using Electrostatic Actuator UA-0033 with Actuator Adaptor DB-0900.
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.
