Owner's Manual
Table Of Contents
-!-.
I
•Incident/Reflected/Absorbed
•
JBL
Control
®
Contractor
series
speakers
-.l--
are
designed
as
fixed
installation
loudspeaker
systems
for
use
in
a
variety
of
environments.
Performance
may
nevertheless
vary
from
room
to
room
because
of
differences
in
the
acoustical
setting.
Since
an
enclosed
room
-+
presents
acoustical
boundaries
(walls
,
floors
&
ceilings),
sound
indoors
exhibits
quite
complex
behavior.
Each
time
a
sound
wave
strikes
a
boundary
,
·
-·
7
part
of
the
wave's
energy
is
reflected
and
part
is
absorbed
(see
diag
. 1
).
Reflection
&
absorption
are
dependent
on
the
frequency
of
the
sound
wave
···
-+
and
the
angle
at
which
it
strikes
the
boundary.
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CONCR8E
· ' . c '
•
Absorption
-
When
designing
your
system,
note
that
.
people
and
furniture
absorb
sound,
while
glass
and
tile
reflect
sound
.
The
percentage
of
energy
that
a
boundary
absorbs
is
often
expressed
by
an
absorption
coefficient
of
the
boundary
material,
where
an
absorption
coeffic
i
ent
of
1
=complete
absorption
and
O=perfect
reflective
surface
(see
diag.
2)
.
ON
E L
OUD
SPEAK
ER MULnPLE
QU
I
ET
SPEAK
ERS
•
Reverberation
-
Reverberation
is
the
reflected
sound
waves
continuing
to
bounce
between
the
boundaries
,
losing
energy
with
each
reflection.
When
sound
strikes
the
reflec-
tive
boundaries
of
a
room
,
after
a
time
the
room
is
filled
with
random
reflected
sound
waves
.
Music
and
speech
become
unintelligible
(see
diag.
3A).
To
minimize
reverberation
in
a
highly
reverberant
room,
it
is
advisable
to
install
more
speakers,
and
play
them
at
lower
levels
(see
diag
.
38)
.
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