JBL 6290 User Manual

SECTION
Ml
OPERATING
INSTRUCTIONS
3.1
GENERAL
The
power
amplifier
should
be
Installed
and
connected
to
the
signal
source
and
the
loudspeaker
system
according
to
Section
II.
Set
the
mode
switch.
Set
the
Level
controls
to
minimum,
and
after
the
preceding
equipment
is
providing
a
stable
signal,
turn
the
power
amplifier
on.
NOTE;
IT
IS
ALWAYS
A
SAFE
OPERATING
PRACTICE
TO
TURN
THE
POWER
AMPLIFIER
ON
LAST,
AND
TURN
IT
OFF
FIRST.
THIS
PREVENTS
ANY
POSSIBLE
TURN-ON/TURN-OFF
TRANSIENTS
OR
EXCESS
LEVELS
THAT
MIGHT
BE
GENERATED
IN
THE
LINE
LEVEL
SIGNAL
PROCESSING
EQUIPMENT
FROM
REACHING
THE
LOUDSPEAKERS.
3.2
TURN
ON
AND
SYSTEM
CHECK
Apply
program
material,
and
be
ready
to
monitor
the
speaker
output.
Turn
on
the
POWER
switch,
and
observe
the
STANDBY
indicators.
No
sound
will
be
audible
because
the
protection
relays
have
not
yet
connected
the
output
stages
to
the
five-way
binding
posts
.
After
a
few
seconds,
the
relay
will
actuate
as
the
STANDBY
indicators
turn
off.
Increase
the
Level
controls
until
a
suitable
listening
level
Is
reached.
3.2.1
A
NOTE
ON
AMPLIFIER
COOLING
If
the
ventilation
Is
Insufficent,
the
amplifier
may
reach
an
unacceptable
temperature
level.
The
protection
circuit
will
open
the
output
relays
until
a
safe
operating
temperature
Is
reached.
If
such
thermal
cycling
should
occur,
recheck
for
obstructions
and
make
sure
a
supply
of
fresh
cool
air
is
available
to
the
rack.
3.3
CLIP
INDICATORS
Overload
conditions
are
monitored
separately
for
each
channel.
The
channel’s
front
panel
CLIP
Indicator
will
turn
on
when a
signal
approaches
the
clipping
level
of
the
output
stage.
The
Indicator
will
remain
on
long
enough
to
be
seen
even
If
the
signal
is
only
a
brief
transient.
To
avoid
audible
distortion,
when
the LED
indicator
flashes
often,
either
lower
the
level
of
the
source
feeding
the
amplifier
or
turn
down
the
amplifier’s
Level
control.
Input
signal
levels
up
to
+20 dB
(7.75
V
RMS)
can
be
accomo-
^
dated
by
the
Input
stage
without
overload.
It
Is
difficult
to
clip
I
I
1-1

JBL 6290 Specifications

General

Brand	JBL
Model	6290
Category	Amplifier
Language	English