William Sommerwerck wrote:
Consider the following. Suppose an electrostatic speaker is reproducting 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!

Right, but this is a speaker that has a huge surface area and therefore has
a very low total excursion. This is a _good_ thing. When your woofer
excursion starts getting to be an order of magnitude larger, the numbers
change. But the large surface area of an electrostatic panel means you can
get considerable bass without substantial excursion... which is good because
nonlinearities in the field become a big issue when there is substantial
excursion.

All correct, but multi-way dynamic systems with such large excursions eliminate
much of the potential for Doppler distortion, simply because the higher
frequencies are reproduced through a separate driver.

In most cases, yes. When Doppler distortion becomes a big problem is in
systems like the Lowther when you have both large excursions and wide
bandwidth through a driver. Or, in coaxial systems, where the seperate
driver is still using the bass driver cone. In typical multi-way systems,
the issue is much smaller.

Note, also, that such a large excursion would usually occur on a bass transient,
not during "normal" (???) music.

Right. But what if if the string section is playing a nice long note that
is held for a while, and there is a hit on the tympani? Can you hear the
strings being modulated? The "Ondekoza" track I submitted to one of the RAP
CDS should be a real torture test since it has some clean flute notes combined
with heavy low end . I can't hear any modulation at all on the Magnepans,
but I can hear lots on my father's old Wharfdales (which have 6 dB/octave
crossovers on the top and bottom and run the midrange full range).
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."