antenna
will
provide
better
reception.
Two
single
wires are required
to
make an AM
outdoor
antenna. First, connect one end
of
a single
wire
to
the AM
ANTENNA
terminal on the rear
panel, and the
other
end at a very high position
outdoors. Next, connect the
other
single
wire
between
the
"G"
terminal and an earth ground
(such as a water pipe).
(Refer
to
Figure 11.)
FM
QUAD
RADIAL
OUTPUT
JACK
In antic
ipat
ion
of
discrete 4-channel stereo broad-
casts,
your
Model
4270
is equipped w
ith
an FM
QUAD
RADIAL
OUTPUT
jack. The signal avail-
able at this jack is the unequalized
output
of
the
FM
discriminator
.
It's
frequency response cha-
racteristics and signal level are ideal
to
drive any
4-channel adaptor. This jack can also be used as
a simple white-noise generator
for
frequency
response check
of
loudspeakers
or
amplifiers.
For
this
application, release FM
MUTII\lG
Switch
of
the Model
4270
in FM mode and
tune
off
from
any
FM signal.
FM DE-EMPHASIS SWITCH
Selects
75J.LS
or
25J.LS
FM DE-EMPHASIS
for
accurate reception
of
Dolbyized FM signals.
DOLBY
FM PRESET
LEVEL
CONTROLS
These
factory
-adjusted controls govern FM out-
put
level
to
the
DOLBY
circuit. These controls
are
for
the
use
of
a
qualif
ied technician
only.
MUTING
LEVEL
CONTROL
Adjusts
the
threshold
of
the inter-station
muting
circuit.
Turning
this
control
counter
-clockwise
w
ill
lower
the threshold
to
permit
reception
of
weak signals.
POWER
MODE
SWITCH
Switches
from
25 watts x 4 operation
to
70 watts
x 2. In
the
2-channel mode,
only
the
front
speaker terminals are used.
BE
CERTAIN
THAT
THE
UNIT'S
POWER
SWITCH IS
OFF
BEFORE
OPERATING
THE
POWER
MODE
SWITCH.
NOTE: When operating
the
unit
in
the
70W x 2
mode, all speaker terminals are "above
ground".
Consequently, the use
of
any switching
or
testing
system
which
employs a
common
ground
will
activate
the
l
imiting
circuits and should therefore
be avoided.
PRE
OUT,
MAIN
IN
JACKS
For
normal operation, these jacks are inter-
connected
with
the supplied jumpers. When
connecting an external
unit
(equalizer, reverbera-
tion
unit,
etc.), remove
the
jumpers and connect
the PRE
OUT
jacks
to
the external
unit's
inputs.
In
turn,
connect
the
external
unit's
outputs
to
the
MAIN
IN jacks.
It
is possible to create a higher powered 4-channel
system by adding an external
amplifier.
If
the
external
amplif
ier has
less
than 70 watts x 2,
it
should be used
to
drive
the
rear speakers.
If
the
external
amplifier
has more than 70 watts x 2,
it
should be used
to
drive
the
front
speakers. In
each
case,
the
rear panel POWER
MODE
Switch
should be set
to
the
70Wx2
position.
CONNECTING
AN
EXTERNAL
AMPLIFIER
FOR
REAR
CHAI\II\IELS
To use an external
amplifier
for
the rear chan-
nels, connect the
REAR
PRE
OUT
jacks
to
the inputs
of
the external amplifier. In
turn,
connect
the
rear speakers
to
the
output
terminals
on the external
amplifier.
The
4270
will
then
supply
the
power
for
the
front
speakers and the
external
amplifier
will
supply the
power
for
the
rear speakers.
CONNECTING
AN
EXTERNAL
AMPLIFIER
FOR
FRONT
CHANNELS
To use an external
amplifier
for
the
front
chan-
nels, connect
the
REAR
PRE
OUT
jacks
to
the
FRONT
MAIN
IN jacks. Connect
the
rear speak-
ers
to
the
FRONT
speaker terminals on the
4270
.
Then, connect the
FRONT
PRE
OUT
jacks
to
the
inputs
of
the external
amplifier.
In
turn,
connect
the
front
speakers
to
the
output
terminals on the
external
amplifier.
The
4270
will
then supply
the power
for
the rear speakers and
the
external
amplifier
will
supply the power
for
the
front
speakers.
CHASSIS
GROUND
BINDING
POST
Permits connection
of
the
ground
wire
from
a
turntable
or
other
component
to
reduce hum.
MAIN
AND
REMOTE
SPEAKERS
Sixteen
quick
-connect terminals are provided
eight
for
main speakers and eight
for
remote
speakers. (Refer
to
"CONNECTING
THE
4270"
and
"REMOTE
SPEAKERS".)
12
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