Old Bird 21c details
The mic comes with a 1 kHz high pass filter to help minimize road, aviation, or surf noise, etc. Manual settings allow this filter to be removed or augmented to 2 kHz (v2020 & v2024).
A series of five short tones is produced when the 21c mic is first powered, and thereafter once every hour. The tone is detectable by Old Bird flight call detectors "Tseep" and "Thrush" and is useful for verifying operation of the microphone, documenting changes in ambient noise levels, and gauging microphone sensitivity over time.
In the v2020 & v2024 mic design, red LED lights on the circuit board within the 21c mic illuminate when the mic is powered.
Instructions for setting up the Old Bird 21c (v2020/v2024) microphone
Instructions for setting up the original Old Bird 21c (v2010) microphone
