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9
Appendix
A:
Installation
Before
beginning
Ihe
installation of your amplifier,
please
carefuUy
note
the
following:
It
is
always wise
to
remove
power
from
the
unit and
tum
the
input
leve\
controls off
while
making
connections
-
especially
if
the load is a
loudspeaker
system.
This
will
elim inate any chance
of
loud
blasts
or damage to
the
loudspeakers.
A.l
Mounting
The
0-75
can
be
mounted into
a
standard 19 inch wide
equipment
rack
or
a custom
cabinet
of your
own
design.
It
occupies 1.75
inches of vertical rack space.
I:
1
•
O'lY!'O
,
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•
l,J
o
0
I
:1
~5
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•
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Fig.
A. 1
0-75
Mounting
Dimentions
A.2 Wiring
The
input
and
output jacks arc located on
the
rear panel.
Please
use
care in making
connections,
selecting
signal
sources
and
controlling
the
output
level.
The
load
you
save may
be
your ownl
Crown is
not
liable
for
any
damage
done
LO
loads due
to
careless
amplifier usage and
deliberateovCI'pOwcring.
The
D·75
may
be
operated
in either STEREO
(Dual or
two-channel)
or
MONO
mode by
switching the
stereo-
mono switch
on the
rear panel
of
the amplifier.
There are
VERY IMPORTANT
wiring
differences
between
these
two
modes
which are
discussed
next.
A.2.1 STEREO
The
instal
lation is very intuitive
in
STEREO
mode.
The
input
of
Channell
feeds the
output
of the
same
channel
as
does the
input
of
Channel
2.
To put
the
amplifier
in
stereo
mode,
slide the Stereo-Mono
switch
at the back of
the
amplifier downward.
Be very careful
not
to
shan
the
two
Outputs together
while
in
STEREO
mode and observe
cOITCCtloudspeaker polarity.
The
load
impedance
should
not
be
less
Ihan
4
ohms
at either
channel.
CAUTION
:
Never
paraUellhe two outputS
by
directly
tying them ;ogelher
or
parallel
them with the
output
of
any
other
amplifier.
Such connection does
not
result
in
increased
power
output
and can possibly cause
the
unit
to
fail.
A.2.2 MONO
Installing
lhe
amplifier
in
MONO mode
is
very
different.
MONO
mode
is
activated
when
the Stereo-Mono
switch
is pushed upward. In
this
mode
only the
Channel
I input
should
be used.
DO
NOT
USE
THE
CHANNEL
2
INPUT
or
signal
leveL
Keep
the
Level
conlTOl of
Channel 2
tumed
complelCly down.
Note: The input jack and Level
control
of
Channel
2
are
not defeated in
MONO mode. Any
signal fed
into
Channel
2
will beat against
the
signal
in
Channel I.
The Output wiring is
very different,
too.
The
polarit}'
of
the
output
of
Channel
2
is
inverted
so
it
can
be
bridged
with
;he outpUl
of
Channel!. The
OUlPLlts Qf both
channels receive
the
same
signa!
from
the
inpul
of
Channel
I.
The flfSt and
mOSI common
configuration
connects the
positive lead
from
the
loudspeaker
1
0 the
red post
or
positive
temlinal
of
Channel
I and the
negative
lead
(0
the
red
post
or positive
terminal
of
Channel
2
(the
inner
black
POSts are
not used). This
method,
called "bridged·mono,"
produces
lhe
single highest-powered
output and
is
the
configuration refClT"'...d to
in
section
7.2
of the
Spccifia;tions.
The load
impedance
should
not
be
less
tha.'!
8 ohms
in this
mode.
CAUTION: Be
certain
that
all equipment
(meters,
switches, ctc.)
connected
10 the MONO
output
lines
are
balanced. Both
sides
of
the
line
must
be totally
isolated
from
the
input
grounds. Ir
this is
not smctly
observed.
severe oscill::ltion
may
result.
A.3
Input
The
unbalanced
inputs
have
a
nom
inal
impedance
of
25
K
ohms
and
will accept
most
line-level
outputs. The XLR
inputs are
20
K
ohms
balanced
and
10K
ohms unbalanced
(pin
2
is
non
inverting).
There are
three
precautions
to
take when connecting
to
the
inputs: I)
Keep
undesirable
signals
off the inputs, 2)
Avoid
ground
loops
and
3)
Avoid
feedback
Ix:twcen an output and an inpuL
Large sabsonic
(subaudible)
frequen cies are
sometimes
prCSCnt
in
tJle
inpm
signal
and
can overload, overheat or
oth~rwisc
damage loudspeakers. To remove such
Appendix
A
A·1
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