MartinLogan 839ESL9CH, User Manual

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12
ELECTROSTATIC ADVANTAGES
How can sound be reproduced by something that you are
able to see through? Electrostatic energy makes this possible.
Where the world of traditional loudspeaker technology deals
with cones, domes, diaphragms and ribbons that are moved
with magnetism, the world of electrostatic loudspeakers deals
with charged electrons attracting and repelling each other.
To fully understand the electrostatic concept, some back-
ground information will be helpful. Remember when you
learned in a science or physics class that like charges repel
each other and opposite charges attract each other? Well,
this principle is the foundation of the electrostatic concept.
An electrostatic transducer consists of three pieces: stators,
the diaphragm and spacers. The diaphragm is what actually
moves to excite the air and create music. The stator’s job is
to remain stationary, hence the word stator, and to provide a
reference point for the moving diaphragm. The spacers pro-
vide the diaphragm with a fixed distance in which to move
between the stators.
As your amplifier sends music signals to an electrostatic speaker,
these signals are changed into two high-voltage signals that are
equal in strength but opposite in polarity. These high voltage
signals are then applied to the stators. The resulting electrostatic
field, created by the opposing high voltage on the stators, works
simultaneously with and against the diaphragm, consequently
moving it back and forth, producing music. This technique is
known as push-pull operation and is a major contributor to the
sonic purity of the electrostatic concept due to its exceptional
linearity and low distortion.
Since the diaphragm of an electrostatic speaker is uniformly
driven over its entire area, it can be extremely light and flexible.
This allows it to be very responsive to transients, thus perfectly
tracing the music signal. As a result, great delicacy, nuance and
clarity is possible. When you look at the problems of traditional
electromagnetic drivers, you can easily see why this is so ben-
eficial. The cones and domes which are used in traditional
electromagnetic drivers cannot be driven uniformly because of
their design. Cones are driven only at the apex. Domes are driv-
en at their perimeter. As a result, the rest of the cone or dome
is just “along for the ride”. The very concept of these
drivers requires that the cone or dome be perfectly rigid,
damped and massless. Unfortunately, these conditions are not
available in our world today.
To make these cones and domes move, all electromagnetic
drivers must use voice coils wound on formers, spider assem-
blies, and surrounds to keep the cone or dome in position.
These pieces, when combined with the high mass of the cone
or dome materials used, make it an extremely complex unit
with many weaknesses and potential for failure. These faults
contribute to the high distortion products found in these driv-
ers and is a tremendous disadvantage when you are trying to
change motion as quickly and as accurately as a loudspeaker
must (40,000 times per second!).
Cut away view of an XStat electrostatic transducer. Notice the simplic-
ity due to minimal parts usage. Cut away view of a typical moving coil driver. Notice the complexity
due to the high number of parts.
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