I found time to trace calibration file for the ECM-999 and the B&K 4155. The difference between the curves of the two microphones is interesting.
ECM-999 classic electret calibration, and the correction to apply is low compared to the XREF20 2dB vs 4dB. The B&K 4155 curve seems to be a deviation.
My measurement seems a little noisy, I'll try to replace the XLR microphone cable to see if I have improvements.
B&K 4155, it seems to be a deviation of the curve.
I found old photos of my jig, an old version.
ECM-999 classic electret calibration, and the correction to apply is low compared to the XREF20 2dB vs 4dB. The B&K 4155 curve seems to be a deviation.
My measurement seems a little noisy, I'll try to replace the XLR microphone cable to see if I have improvements.
B&K 4155, it seems to be a deviation of the curve.
I found old photos of my jig, an old version.