In article , Serge Auckland
wrote:


The width of the ELS63 is 66cm, a wavelength of 2.64 metres has a
frequency of 130Hz (I mistakenly multiplied by 2, not 4 in my original
post, my apologies.) So, I would expect the ELS63 to have a reducing
bass output below 130 Hz. Why doesn't it?

What am I missing?

Note that the 'piston mass' for an ESL is tiny compared with a dynamic
speaker unit. This means that when you apply a drive voltage to the plates
of an ESL you generate a pressure differential between the front and back
surfaces of the diaphragm. At LF some air can easily whoosh around from
front to back. But this simply allows the diaphragm to move more quickly in
response to the applied E-field, and so maintains the same pressure
difference between front and back.

The effect is to allow the speaker to maintain the ability to generate the
same sound pressures for a given applied field as you lower the frequency.
This can't be perfect, of course, as away from the local soundfield region
you will get cancellation effects. But what you may be missing is that the
relationship between the air (radiation) and mass impedances for the ESL
are unlike those for the conventional dynamic unit.

The real problem is that the diaphragm excursions become too large if you
want high sound pressures at LF

Slainte,

Jim

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