"tony sayer"
In article

Electrostats may not be completely time coherent, but as they have a
single driver,

But they don't.


** The ESL 63 / 988 is highly phase ( time ) coherent and uses 8
independent panels.

Production units are tested in the factory against a calibrated reference
unit using 1 kHz square wave drive. The signal from a measurement mic 2
metres on axis of the unit under test is viewed on a scope and must
produce
a good square wave there.

Yes that is very impressive How many moving coil designs could do
that....



** None - when you include both the good square wave and close frequency
/ phase matching.




............ Phil