It's not really the magnitude of the impedance peaks that are of interest. Since these are transducers with much less powerful motors than conventional drivers....and they are essentially resistive....the magnitude of the peaks is not indicative of the SPL rises created by the membrane sections.
If I were to take six different measurements with the microphone very close to the center of each of those "sections" you'd see a much more exaggerated effect.
An impedance sweep is a much easier way to determine their frequency. You can see visually the resonant frequency of each section and not deal with all the variables (and spend all the time) involved in SPL measurements.
It's not easy to subjectively evaluate the effect of the tuning buttons since most folks only have one set of speakers. I have two sets (actually three
) sets of MMG's and I've auditioned two left speakers and also two right speakers. The two pairs sound different from each other in the bass area. I have to attribute that to the sympathetic panel tuning you realize when pairing speakers like that.
The power amp (a good one) couldn't care less about small impedance peaks like this. It's functioning as a voltage source and the very small current changes at these resonant points are minor.
Hope that helps.
Cheers,
Dave.
