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Logos User's Manual
The Electrostatic Concept
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
background 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: the
stators, the diaphragm and the
spacers.
See Figure 1. 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, to provide a
reference point for the moving
diaphragm. The spacers
provide 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 tech-
Magnet
An Electromagnetic Transducer
An Electromagnetic Transducer
An Electromagnetic Transducer
An Electromagnetic Transducer
An Electromagnetic Transducer
Surround
Cone
Dust Cap
Voice Coil Former
Magnet Assembly
Magnetic Gap
Voice Coil
Basket Assembly
Spider
An Electrostatic Transducer
An Electrostatic Transducer
An Electrostatic Transducer
An Electrostatic Transducer
An Electrostatic Transducer
Stator
Spacer
Diaphragm
nique 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 electromag-
netic drivers, you can easily see why this is so beneficial.
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 driven 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 require that the cone
or dome be perfectly rigid,
damped and massless.
Unfortunately these condi-
tions are not available in our
world today.
To make these cones and
domes move, all electromag-
netic drivers must use voice
coils wound on formers,
spider assemblies, and
surrounds to keep the cone
or dome in position.
See
Figure 2. These pieces, when
combined with the high mass
of the cone or dome materi-
als used, make it an ex-
tremely complex unit with
many weaknesses and
potential for failure. These
faults contribute to the high
distortion products found in
these drivers and is a
tremendous disadvantage
when you are trying to
change motion as quickly and
as accurately as a loud-
speaker must (40,000 times
per second!).
Figure 1
Figure 1
Figure 1
Figure 1
Figure 1. Cut away view of an electrostatic transducer.
Notice the simplicity due to minimal parts usage.
Figure 2.
Figure 2.
Figure 2.
Figure 2.
Figure 2. Cut away view of a typical moving coil driver.
Notice the complexity due to the high number of parts.