Acoustat Model 4 Brochure

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FULL-RANGE ELEMENT ELECTROSTATIC SPEAKERS

Model Two + Two
Model Three
Model Four

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range electrostatic
Introduced about two
ago. it was immediately
_ ' Wthis technology would
» . truly superb speakers of
-, futureThe future has arrived.
. .The Acoustat full-range-element
- -static speaker systems
represent the culmination of over 20
7. years of design and development,
;- beginning with the bold assumption
that It was possible to build such
a system without compromise. . .one
capable of high sound pressure
levels, without crossovers, one that
would be more reliable than any
speaker of any type.

The new Acoustat speaker systems
have achieved these goals-and
more. At last. the ideal music
transducer (the electrostatic) is
available in a manageable size and
price range. And not only is it reliable,
it is virtually indestructible.

What makes the
Acoustat Speakers
Unique?

ELECTROSTATIC ELEMENT

All Acoustat speakers utilize full-
range-element electrostatic panels
to reproduce all frequencies in the
audible spectrum without splitting
the frequency spectrum with separate

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FIGURE 1 Electrostatic
Operating Principle
The eleotmmtic transducerLs composed ofa
thin Mylarmembrane (diaphragm) stretched
and mmined between two acoustically
open wire grids. The diaphragm is connected
to a high-voltage lowcument bias supply
which provides an elecaostatic charge that
becoma trapped in the diaphragm The
aoowtregrids. receivinga high-volmge audio
from the plus/minus outputs of the
[2) interface, provide an electric field
gamma: theaudio signal In the praence
an audio signaL the electric field ever-ts
Wmmeeleotmstaticchargethat is
rapped In the diaphragm These forces are
vans/erred to the diaphragm causing the
diaphragm to move in synchronization with
these brces

woofer, mid-range, and tweeter
drivers. This crossoverless design
does not suffer from the distortions
that crossovers cause. The ideal
method of reproducing musical
waveforms would be to exactly reverse
the process of the recording micro-
phone. . .and for that matter, the
full-range-element function of the
human ear. Only with the electrostatic
transducer can this ideal method

be realized.

FULL RANGE ELEMENT

Just like the human ear and the
microphone. Acoustat speakers
employ a single diaphragm covering
all frequencies, from deepest bass to
highest treble. This means the

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FIGURE 2-The Musical Wavefront

The forces acting to move the dynamic
transducers cone produce very different
results than the electrostatic transducer With
a dynamic transducer. the application of
the driving force only to the aper of the cone
necessitates a sufficiently stiff cone to
prevent buckling and defamation of the
cone structure. Such a stiff cone. even if

it is made of an erotic lowmass material
must have considerable mass which
degrades its transient response capability
significantly In addition, the forces applied
to the apex do not act uniformly over the
cone surface and cause it to breakup" into
numerous vibrational modes, only one of
which is representative of the original signal

original waveform is not broken into
pieces dissimilar in terms of color-
ations, time of arrival. and phase.

It has been well documented that
even small changes in phase are
readily audible. and can degrade the
clarity and definition of musical
transients, upsetting the homogeneity
and coherence of the stereo image.

Each speaker contains several
panels angled for horizontal
dispersion, but electrically they
perform as a single unit. All are driven
full-range.

Figure 2 illustrates the problems of
the typical loudspeaker which are
due to the limitations of dynamic
(magnetic) type drivers. The uniform
wavefront of the Acoustat speakers
contain all the spatial and harmonic

Information as originally recorded.

It gives breathtaking imagingand ,

accurate depth perspective that are
reminiscent of a live concert. Since
a multi-element system with cross-
overs simply cannot reproduce all
this music information correctly, truly
accurate recreation of the original
musical performance is impossible.

LOW MASS RADIATOR
WITH INTIMATE DRIVE

Again, the human ear, the micro-
phone, and Acoustat speakers all
utilize a very low mass diaphragm.
intimately driven over its entire
surface. The diaphragm of the
Acoustat speaker is only .00065
inches thick, and weighs only as much
as an equivalent size volume of air
only 7 millimeters thick! This super-
light diaphragm is then driven over
its entire surface by the audio signal.
This gives the audio signal several
million timm more control over air
motion than is possible with a cone
or dome type speaker. and several
hundred thousand times more
control than a planar magnetic or
ribbon type speaker, where the audio
signal force is only present at
the voice coils-not on the actual
diaphragm that moves the air.

A diaphragm of such extreme
lightness, in combination with an
actuating force that is uniformly
distributed over the entire surface
of the diaphragm. results in a trans-
ducer whose transient response
closely duplicates the electrical input.
The net result is a diaphragm motion
that is a replica of the electrical
forces acting upon it, with all sections
of the diaphragm surface moving
with highly accurate phase and
amplitude linearity throughout its
excursion. at all frequencies.This
characteristic of Acoustat loud-
speakers results ln an amazingly
open, well-defined sound, with
preservation of detail at all
listening levels.

Because the radiating area of
dynamic (cone) drivers tends to be
small, their impedance match to the
air is quite poor. The Acoustat
electrostatic, with its large radiating
area. is a much better acoustic
impedance match to air, particularly
in the difficult low frequency range.
This in conlundlon with the patented
MK-lZl Interface, is the reason
for the excellent low bass response
of the Acoustat speakersn