Microphone Preamplifiers

2669-B 1/2-Inch Microphone Preamplifier

2669-B 1/2-Inch Microphone Preamplifier

Preamplifier Type 2669-B is designed to operate over a wide range of temperature, humidity and other environmental conditions.


  • Sound measurements with Brüel & Kjær 1/2″ (1″, 1/4″ and 1/8″ with adaptor) and compatible microphones
  • General-purpose preamplifier and high-impedance input probe for Brüel & Kjær measuring instruments


  • Compact LEMO connector at preamplifier: LEMO 0B 7-pin.
  • Full electromagnetic compatibility (EMC)
  • Very low inherent noise, high input impedance
  • Low output impedance and high output current allows use with long extension cables

The preamplifier has a very high input impedance presenting virtually no load to the microphone. The high output voltage together with an extremely low inherent noise level gives a wide dynamic range. You can connect ½” microphones directly and 1″, ¼” and 1/8″ types using adaptors.

The preamplifier, cable and its connectors all fulfil EMC requirements. You can verify the condition of the microphone, preamplifier and cable on-site using its patented charge injection calibration technique.

The low output impedance and high output current capability means that you can use long cables between the preamplifier and your measuring instrument without loss of signal quality.


Diameter: 1/2
Optimised for: Acoustical
Connector at preamplifier: LEMO 0B, 7-pin
Connector at instrument/cable: B&K, 7-pin
Calibration facility: Charge Injection Calibration
Polarization voltage support: Yes
Supply voltage: ± 14 to ± 60
Max output voltage (peak): 55
Max output current (peak): 20
Frequency range: 3 to 200000
Attenuation: < 0.35
Noise A-weighted, typical: 1.9
Noise 22,4 Hz to 300 kHz, typical: 8.2
Input impedance: 15||0.3
TEDS UTID: 1025 from serial number 2221155