Speaker distortion under voltage drive and current drive

[pma]

Please let me contribute to not so often discussed theme of speaker distortion. I have done some research measurements on this topic in past years and would like to present it here. The simplest way is to put some links to my web page, so in case you are interested in the subject, please have a look.

Results of distortion measurements of a tweeter under voltage and current drive
http://pmacura.cz/speaker_dist3.htm

Introduction to speaker current non-linearity even in case it is driven from a perfect, distortion-less voltage source
http://pmacura.cz/speaker_dist.htm

Measurement of distortion of speaker current under voltage drive due to non-linear speaker impedance
http://pmacura.cz/speaker_dist1.htm

 

[Head_Unit]

Very interesting Pavel! Have you presented this anywhere else? Like Audio Engineering Society?

I'm puzzled by the "current drive" since those measurements say 1V RMS. Does this mean for the IM FFT you are adjusting the current output to get 1V across the speaker terminals? i.e. kind of following the inversion of the impedance curve, as you say?
...ah but if so, at the same drive voltage, how can the distortion be lower? Mmm, due to less variation of the acoustic parameters as compared to voltage drive?

Then for the lower distortion plots, the SPL is held constant like 103.4 dB?

It strikes me that "inversion of the impedance curve" will be slightly faulty since as you say all the parameters alter a bit under drive conditions...and surely also further when the diaphragms become nonlinear. I'm feeling somehow there should be a way to measure and equalize that in real time, like how some PA systems run a response FFT by using the music being played by the band as a kind of MLS.

 

[sepp2gl]

Hi Pavel,
...this thread seems to have an "open ending".
Was there any further exchange with Head_Unit about this topic?