Consider the following. Suppose an electrostatic speaker is
reproducing 60Hz at a peak-to-peak excursion of 0.25".

That means its maximum velocity would be around 30 inches
per second. That's less than 1/4 of 1% of the speed of sound!

It appears that a practical inter-electrode gap for an electrostatic
speaker might be 2 mm or about 0.05". I believe that bad things
might happen if the diaphragm traversed a great deal of that gap.

In the +20 example posted at http://www.pcavtech.com/techtalk/doppler,
the cone excursion was very roughly on the order of 1/8". There was
a ton of distortion, almost all of which was AM distortion, not FM.

I deliberately chose an obviously extreme (!!!) situation to make the point.


I admit it, my interest in Doppler distortion was peaked by someone
who had doubts about high-Xmax woofers because of the exposure
to Doppler distortion.

piqued