Acoustic research ar 9 brochure

Page 2

THE AR9: A NEW. 4-WAY, ELM-STMIOINO
SPEAKER SYSTEM WITH IMPORTANT OESION
REFINEMENTS THAT MAKE "THE MST
PERFEOT SOIINO REPROOIIOER IN AR HISTORY.

The history of AR has been a history of
technical innovation and refinement.

AR invented the acoustic suspension
Speaker design which is used today by
loudspeaker makers all over the world.

AR invented the dome high range
driver which provides excellent dis-
persion with improved power-handling
capability.

AR led the way with liquid-cooled
high-range drivers and. in addition. a
host of manufacturing and testing pro-
cedures all aimed at the perfection of
sound reproduction-truth in listening.

Now with the introduction ofthe
AR9. new technical features and design
refinements create a startling new level
ofdefinition and flat response in a loud-
speaker s 'stem.

The A 9 is nothing less than the
finest. most truthful loudspeaker sys-
tem we have ever heard or measured.
Here are the reasons.

ELEOTRIIII} AIITIIATE
m

Designing good bass reproduction in a
sound system must always be a com-
promise.

The engineer wants a system that
will produce strong bass. At the same
time he wants the system well enough
damped (that is with low Q) to give fiat
response all across the bass range.

Unfortunately. the law s of physics
make these two objectives incompat-
ible for as damping increases. volume
falls off. Thus the well-damped system
inevitably produces low volume. or as

the engineers put it rolls otfthe curve"
at some point as fre uency goes down.

But now. in the A 9. three design
features combine to solve this problem
better than it has ever before been
solved. For the first time we have a sys-
tem that is virtually fiat down to 28 Hz
(see charts below). comes in with a
more than acceptably low Q of .5. and
reproduces bass frequencies with star-
tling power and clarity.

How have AR designers managed to
bend the laws ol'phystcs.

First. the AR9 uses two 300mmt 12")
woofers connected in parallel. At any
volume setting each of them moves only
half the distance a single dn'ver would
have to move to produce the same vol-
ume level. Thus the woofers are able to
handle more power without distortion
or breakup.

Second. a large enclosure ( IZO liters»
is used to create a system with a low
resonant frequency.

Third. and the real secret weapon.is
a sophisticated new crossover network
- an important step ahead in speaker
design. This crossover is designed with
special circuitry that acts like an auto-
matic transmission and helps control
bass response. It allows the system to
have maximum damping at the resonant
fre uency (thus low Q) while maintain-
ing ass output. Above the resonant
frequency it shifts electronically to
maintain flat response across the bass
spectrum.

Ifall this sounds a bit esoteric. the
results are anything but! The AR) is
unique in its ability to pump out tre-
mendous bass with minimum distortion
and minimum fall-offin volume at low
frequencies. Test instruments are not

required to prove the point. Your ears
can hear the dilierence.

TWO WINNERS.
SOIENTTFMALLY PLAOEO

All loudspeaker systems interact with
their environments.

Thus any speaker placed next to a
wall creates reflective audio images of
itself.just as a candle creates a visible
image of itself behind the surface of a
mirror when laced in front of it.

When a re ected audio image is out
of phase with the original created by
the speaker itself. the two tend to cancel
each other and the result is a dip in the
speakers output. The dip may vary
with the size ofthe speaker and its
placement. but in any speaker system
with a front-mounted woofer the dip is
always present.

By facing the two woofers of the
AR) sideways instead ofdirectly into
the room. the relative position of the re-
flected image has been changed so that
the dip it creates occurs above the 200
H7. crossover frequency of the woofers.

Placement of the low midtange
speaker has been calculated so that its
inherent di occurs hdmi' the 200 Hz
crossover requency.

Thus the dip which cannot be elimi-
nated has been manipulated so that it
has no audible consequences - another
reason for the startlingly flat and con~
stantly smooth response curves you see

below .
REVISED OROSSOVER
NETWORKS

The crossover networks in the A R9
are the most expensive and sopliisti~
cated ever used in an AR speaker
system.

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