Measurement Mic Tests
Harmonic Distortion
The following is a look at the 2nd and 3rd harmonic distortion measurements from each respective microphone taken at the 10/20/40/80cm distances.
Since the output from the driver is constant an ideal microphone should show little change in the measured harmonic distortion relative to the SPL at the capsule (the different measurement distances). However this is not the case here as almost every microphone tested has either rising self distortion with increased input level and/or noise masking the true distortion level.
Earthworks M23
Distortion falls some as the mic is moved closer I can only assume this is due to the SNR increase at the higher levels. I should note that even at the 80cm distance (gives the lowest SNR) the 2nd harmonic distortion measured is lower in level then any other microphone tested even if at the closer distances as well.
Almost ideal, minor differences in the FR at the four distances are the likely source for most the differences between these four measurements.
Behringer ECM8000
One shows very minor rise in 2nd harmonic distortion while the other jumps a decent amount at the closer/higher levels.
Both match each other well in the 3rd harmonic, they are noise limited at the 80/40cm distances and then self distortion rises at the 10cm distance.
Apex 220
A2000's ACM192
Worst of the Mics when it comes to 2nd harmonic distortion performance, ~1% even when below 100dB input level.
Dayton UMM-6
One shows just slightly worse 2nd harmonic distortion levels then the other at the close distances, both do fairly well here, not quite at M23 level but clearly better then the rest of the mics.
Again one of the two mics is worse then the other but these show noise spikes in the mix as well (an issue I've seen with the UMM-6's)
MiniDSP UMIK-1
Best 3rd harmonic performance outside of the M23, too bad 2nd harmonic is poor.
MiniDSP UMIK-2
Internal mic gain set to 0dB
UMIK-2 takes the title as the 2nd worst performing in 2nd harmonic distortion at high levels.
Worst performing in 3rd harmonic distortion at the 10cm distance.