TYPE 2673

½-inch microphone preamplifier with insert voltage facility

Designed to allow calibration of ½" and 1" condenser microphones by the insert voltage technique


Designed to allow calibration of ½" and 1" condenser microphones by the insert voltage technique, either in conjunction with the reciprocity method or with a known sound source. The insert calibration facility is used for reciprocity and insert voltage calibration of condenser microphones in accordance with IEC 1094 – 1: 1992 and ANSI S1.10.


  • Insert voltage calibration of condenser microphones for open-circuit voltage determination
  • Calibration of condenser microphones with respect to reciprocity calibration methods
  • General sound measurements in connection with Brüel & Kjær condenser microphones


  • Full electromagnetic compatibility (EMC)
  • Detachable cable for easy installation
  • Compact LEMO connector for connection to instrument input socket (adaptor for Brüel & Kjær connectors provided)
  • Wide dynamic range
  • Very low attenuation
Type 2673 consists of a high impedance input stage and an output stage giving a low output impedance for driving long cables and the Driven Guard surrounding the input stage. The thread which accepts the microphone cartridge is isolated from the preamplifier housing to allow an insert-voltage signal to be applied in series with the microphone for determination of the microphone’s open-circuit sensitivity. ½-inch Microphone Preamplifier Type 2673 is very similar in design and performance to Type 2669. The main difference is that Type 2673 includes an insert voltage calibration facility.

Connector at preamplifier
LEMO 0B, 7-pin
Connector at instrument/cable
LEMO 1B, 7-pin
Calibration facility
Insert Voltage Calibration
Polarization voltage support
Supply voltage
± 14 to ± 60
Max output voltage (peak)
Max output current (peak)
Frequency range
3 to 200000
< 0.05
Noise A-weighted, typical
Noise 22,4 Hz to 300 kHz, typical
Input impedance