You can use any omnidirectional condenser measurement microphone.
Please note that we will not be able to consult the calibration outcome if you are not using an individually calibrated microphone.
It is possible to use ARC, ECM8000, EMM-6 among other microphones, just keep in mind that for the most accurate results we highly recommend using a microphone with available individual calibration data*.
ARC and ECM8000, generally aren't sold with individual calibration, so they are not best for precise measurements (usually problems with frequencies above 8 kHz), but will get the job done to some extent. EMM-6 have individual mic calibration files are available here.
USB measurement microphones are not supported and will not work correctly with the measurement software due to word clock issues.
If you have your microphone's frequency response data, please refer to this article to find out how to make it compatible with the Reference 4 Measure app.
*We cannot provide calibration files for third-party microphones, please contact the manufacturer of the microphone for more information.