No.20 Sound calibration using with calibration signal (for Microphone)
Core Sound - The Importance of Individual Calibration for Ambisonic Microphones Fedele De Marco asked about the importance of calibration for ambisonic microphones. He also asked which of the manufacturers do calibration.
Yamaha OEM Yamaha Calibration Microphone Originally Shipped With RX-V2075, RXV2075, RX-A3070, RXA3070
McIntosh Labs Calibration Mic Microphone with Cable Part No. 036188 | Reverb