Harman Kardon 75+ - Installation and Setup; Ventilation and Speaker Placement; Power Requirements and Fusing; Speaker Connection and Impedance

INSTALLATION
VENTILATION
Although
your
new
receiver
rarely
develops
high
heat,
it
is
recommended
that
you
leave
the
back
of
the
cabinet
open.
If
this
is
not
possible,
provide
several
large
holes
or
slots
as
low
and
as
high
up
in
the
cabinet
back
as
possible.
As
an
alternative,
holes
may
be
provided
in
the
sides,
bottom
or
top
of
the
cabinet.
Remember
that
really
effective
ventilation
requires
provision
for
cool
air
to
enter
at
the
bottom
and
hot
air
to
leave
at
the
top.
A
minimum
clearance
of
two
(2)
inches
should
be
allowed
on
each
side
and
in
the
rear,
between
the
chassis
and
the
cabinet,
and
three
(3)
inches
are
required
above
it.
Isolate
any
accessories
which
might
interfere
with
ventilation.
For
example,
do
not
drape
plastic
or
rubber
covered
interconnecting
cables
over
the
equip-
ment.
POWER REQUIREMENTS
Connect
the
AC
line
cord
to
any
outlet
furnishing
117
volts,
60
Hz
AC
current.
The
voltage
may
vary
between
105
and
125
volts.
An
auxiliary
AC
power
outlet
is
provided
on
the
rear
panel
of
your
receiver.
Any
accessory
equipment
(tape
recorder,
phonograph
record
player,
etc.)
may
be
connected
to
this
receptacle
and
will
be
controlled
by
the
POWER
switch
on
the
front
panel.
FUSING
A fuse is a safety device used to protect the receiver against possible
damage due to overload or short circuits. The 75+ receiver employs five
protective fuses. All five are located on the rear panel.
The AC fuse labeled 3A-3AG Slo Blo is used to protect the power supply
of the entire system. The other four fuses labeled 4A-3AG LEFT, RIGHT, FRONT
and BACK, protect the output stages of the receiver.
The output of your receiver has been designed to operate with a MAXI-
MUM of 4.0 amperes of current in each channel. Under certain conditions, it
is possible to draw more than 4.0 amperes through the output stage which
would, in turn, blow the speaker fuses. This could be caused by using multiple
speaker systems where the total impedance falls below 4 ohms. (See ‘'CON-
NECTING THE SPEAKERS’’).
In the event of fuse failure, replace ONLY with the same fuse type used.
NEVER replace with a fuse of a higher rating. To do so will NOT protect your
receiver and could result in severe damage to it which will not be covered under
the warranty policy.
SPEAKER PLACEMENT (See Fig. 1)
The speakers will be referred to as LEFT and RIGHT, FRONT and BACK.
Placement of the back speakers will vary with your room size, seating arrange-
ment
and
acoustics.
At
times,
it
may
be
advantageous
to
place
the
back
speakers
in
line
with
the
listener,
either
aiming
them
at
the
listener,
the
rear
of
the
room
or
against
the
side
wall.
It
has
been
acknowledged
that
omni-
directional
speakers
(i.e.
Harman/Kardon
HK50)
serve
well
as
back
speakers
in
a
4-CH
setup
because
they
do
not
beam
the
sound
at
the
listener.
This
gives
the
illusion
of
far
greater
airiness
and
comes
closer
to
the
sound
at
a
live
con-
cert.
We
have
illustrated
several
ways
of
arranging
the
back
speakers.
Some
experimentation
may
be
required
before
you
obtain
optimum
sound
dispersion
and
total
surround
sound.
If
you
listen
predominantly
to
classical
music
it
is
recommended
to
reflect
the
back
speakers
off
the
walls,
or
aim
them
away
from
the
listener.
This
will
tend
to
soften
the
sound
and
create
a
more
natural
ambience.
If
you
listen
predominantly
to
contemporary
music
it
may
be
advan-
tageous
to
place
the
back
speakers
in
the
corners
and
beam
them
into
the
room.
CONNECTING THE SPEAKERS
Use
any
type
of
wire
to
connect
your
speakers
to
your
receiver.
However,
it
should
be
pointed
out
that
the
heavier
the
wire,
the
lower
the
loss
of
power.
Ordinary
lamp
cord,
or
zip
cord
as
it
is
sometimes
called,
is
excellent
for
this
application
since
it
can
be
dressed
easily
around
the
molding
and
it
is
usually
heavy
enough
to
extend
great
lengths
without
an
appreciable
loss
in
power.
Do
not
drive
tacks
or
staples
through
the
center
of
the
wire
since
this
can
result
in
a
short
circuit
which
would
either
cut
the
volume
level
down
considerably
or
short
out
the
sound
completely.
It
is
permissible
to
use
approximately
50-60
feet
of
heavy
gauge
speaker
connecting
wire
for
each
speaker
without
loss
of
volume.
CONNECT
YOUR
SPEAKERS
WITH
CARE,
AVOID
SHORTS.
DO
NOT
CON-
NECT
THE
SPEAKERS
WITH
THE
POWER
ON.
WORK
CAREFULLY
TRIMMING
ALL
LOOSE
WIRES
ON
THE
REAR
OF
THE
SPEAKERS
AND
RECEIVER.
THE
RE-
CEIVER
HAS
BEEN
DESIGNED
TO
PREVENT
DAMAGE
FROM
MOMENTARY
ACCIDENTAL
SHORTING.
HOWEVER,
REPETITIVE
SHORTING
CAN
DAMAGE
THE
OUTPUT
DEVICES.
The
75-4
connects
two
pairs
of
speaker
systems
for
the
front
channels,
and
another
two
pairs
for
the
back.
Any
pair
may
be
driven
independently
or
a
combination
of
two
pairs
may
be
driven,
as
selected
by
the
MAIN
and
REMOTE
Speaker
Switches.
Connect
them
to
the
receiver
as
instructed
in
the
diagrams
(Fig.
2
and
Fig.
3),
taking
care
not
to
confuse
the
FRONT
and
BACK,
LEFT
and
RIGHT
channels,
and
the
plus
and
minus
polarities.
Sufficient
care
should
be
taken
not
to
short
circuit
the
plus
and
minus
leads.
‘SPEAKER IMPEDANCE
Each
speaker
system
connected
to
your
75+
must
possess
an
impedance
of
from
4
to
16
ohms.
Should
you
wish
to
drive
two
pairs
of
speaker
systems
simultaneously,
they
should
all
have
an
impedance
of
8
ohms
or
more.