JBL 6290 - Input Impedance and Terminations; Five-Way Binding Post Output Connectors; About Output Polarity and Bridged Mono Connection

2.5.4
FIVE-WAY
BINDING
POST
OUTPUT
CONNECTORS
Five-way
binding
post
outputs
have
been
chosen
because
they
allow
connections
to be
made
quickly,
they
facilitate
polarity
reversals
for
speaker
"phasing,”
and
they
can
handle
high
current
with a
great
margin of
safety.
See
Figure
2-4.
The
preferred
connection
method
Is
to
use a
dual
banana
plug
for
each
speaker
cable.
Simply
Insert
each
plug
Into the
corres-
ponding
channel's
red
and
black
binding
posts.
See
Figure
2-5.
In
the
absence
of a
dual
banana
plug (or
two
single
banana
plugs),
loosen
the
plastic
terminal
nut, wrap
the
stripped
and
twisted
wire
end
clockwise
around
the
terminal,
and secure
It by
tightening
the
nut.
NOTE;
Tin
the
wire
ends
with
solder
to
prevent
unraveling,
but
avoid
excess
solder
as
it
can
promote
cable
breakage.
Smaller
speaker
cable
can
be
pushed
through
the
hole
In
the
binding
post
shaft,
but we
recommend
heavier
gauge
cables
to
wrap
around
the
shaft.
If a lug
Is
Installed
on
the
cable,
loosen
the
terminal
nut,
push
one
"leg"
of
the lug
through
the
hole
In
the
shaft,
and
tighten
the
nut.
2.5.5
ABOUT
OUTPUT
POLARITY
AND
BRIDGED
MONO
CONNECTION
In
normal
stereo
operation
(or
dual
mono), a
positive-going
signal
applied to
pin
#3,
the
phone
jack tip,
or
the
+
terminal
of
the
barrier
strip
will
cause a
positive-going
signal
to
appear
at
the red
output
binding
post
of
that
channel.
In
bridged
mono
operation
the
two
amplifier
channels
are
driven
from
the
Channel
A
Input,
but
Channel B
Is
Internally
reversed
In
polarity.
The
speaker
Is
connected
between
the
two
red
binding
posts
(the
black
posts are
not used
In
bridged
mono
mode).
In
this
case,
a
positive-going
signal
applied
to the
Channel A
Input
appears
as a
positive-going
signal
at the
Channel A
red
binding
post
and as
a
negative-going
signal
at the
Channel B
red
binding
post.
See
Figure
2-6.
NOTE:
The
two
channels'
binding
posts
are
clustered
to
facilitate
mono
connection
across
the
red
posts
with a
standard
dual
banana
plug.
DO
NOT CONNECT
THE
TWO
RED
BINDING
POSTS
TO
EACH
OTHER,
and DO
NOT GROUND
EITHER
SIDE
OF
THE
OUTPUT
IN
BRIDGED
MONO MODE.
2.6
INPUT
IMPEDANCE
AND
TERMINATION
Audio
engineering
has
Its
roots
In
the
telephone
Industry,
and
I
1-4