Page 10
CP660
Six Channel Amplifier
Reference Manual
3.3.2 Audio Input Connection
The
CP660’s input panel is modular, meaning it is avail-
able with either barrier block inputs, or RCA inputs. The
modules can easily be changed if the situation arises
where you may need to make a change in the configu-
ration of your system.
The unbalanced RCA inputs have a nominal imped-
ance of 10 k ohms and will accept the line-level output
of most devices.
The balanced inputs have a nominal impedance of 20 k
ohms and will accept the line-level output of most de-
vices.
Proper input wiring depends on two factors: (1) whether
the input signals are balanced or unbalanced, and (2)
whether the signal source floats or has a ground refer-
ence. Please refer to Figs. 3.2 and 3.3 for proper input
wiring.
To put the amplifier into Dual mode, turn it off, slide the
Dual/Mono switch to the Dual (left) position, and prop-
erly connect the output wiring. Be sure to observe cor-
rect loudspeaker polarity and be careful not to short the
two outputs.
CAUTION: Never tie an amplifier’s outputs together
directly, and never parallel them with the output of
another amplifier.
Such connections do not result in
increased output power, but may cause overheating
and premature activation of the protection circuitry.
MONO MODE
Mono mode is used to drive loads with a total imped-
ance of at least 8 ohms. If Mono mode is used, twice the
normal output voltage is produced from a single chan-
nel, providing the needed power to drive distributed
loudspeaker systems or speakers with greater output
requirements.
Mono mode wiring is very different from Dual mode and
requires special attention. First, turn the amplifier off.
Then select Mono mode on the channels you desire by
sliding the Dual/Mono switch to the MONO (right) posi-
tion. Both outputs will receive the signal from the odd-
numbered channel, with the output of the even-num-
bered channel inverted so it can be bridged with the
odd-numbered-channel’s output. DO NOT USE THE
EVEN-NUMBERED CHANNEL’S INPUT or the signal
level and quality may be greatly degraded. Also, keep
the even-numbered channel’s Level control turned
down completely (counterclockwise).
Note: The even-numbered channel’s input jack and
Level control are not defeated in Mono mode. A signal
feeding the even-numbered channel will work against
the odd-numbered channel’s signal, and usually results
in distortion and inefficient operation.
Connect the load across the two positive (+) output ter-
minals. The positive lead from the load connects to the
odd-numbered channel’s positive terminal, and the
negative (or ground) lead from the load connects to the
even-numbered channel’s positive terminal. Do not con-
nect the output grounds ( ). Also, the load should be
balanced (neither side shorted to ground).
CAUTION: Connect only balanced equipment
(meters, switches, etc.) to the Mono output. Both
sides of the line must be isolated from the input
grounds or oscillations may occur.
Input Wiring
1. Use only shielded cable. Cables with higher
density shields are better. Spiral wrapped shield
is not recommended.
2. When using unbalanced lines, keep the cables
as short as possible. Avoid
cable lengths greater than 10
feet (3 meters).
3. Do not run signal cables to-
gether with high-level wiring
such as loudspeaker wires or
AC cords. This reduces the
chance of hum or noise being in-
duced into the input cables.
4. Turn the entire system off before changing con-
nections. Turn level controls down before power-
ing the system back up. Crown is not liable for
damage incurred when any transducer or com-
ponent is overdriven.