Installation; Mounting; Cooling; Wiring - Crown DC-300A II Reference Manual

DC-300A II Power Amplifier

3 Installation

Your amplifier is designed for standard 19 inch
(48.3 cm) rack mounting. Before mounting, determine
whether you need to change the amplifier's internal set-
tings for your application.
Your amplifier's internal settings make it possible to
change the input sensitivity from the default 26 dB gain
to a sensitivity of 0.775 volts. If you need to operate
your amplifier with an input sensitivity of 0.775 volts, or
if you want more information on input sensitivity, please
refer to Section 7 before proceeding.

3.1 Mounting

The DC-300A II can be mounted into a standard
19 inch (48.3 cm) wide equipment rack. It occupies
7 inches (17.8 cm) of vertical rack space. Mounting
screws and washers are provided with the unit. Al-
though units can be stacked, this practice is not rec-
ommended. Instead, mount multiple units in a rack
leaving air space between them. Also, before mount-
ing the amplifier, please read about the amplifier's cool-
ing requirements in the section that follows.
1.5 in
3.8 cm
5.5 in
14 cm
POWER
7 in
17.8 cm
10.5 in
26.7 cm
10.5 in
26.7 cm
0.875 in
2.2 cm
Fig. 3.1 Mounting Dimensions

3.2 Cooling

Your amplifier does not have a cooling fan. To prevent
overheating, sufficient ventilation is required. Equip-
ment racks or cabinets should have perforated top and
bottom panels. This is especially important if more than
one amplifier will be mounted in the same rack. When
CHANNEL 1 I0C CHANNEL 2
30 30
40 20 40 20
50 10 50 10
0 0
19 in
48.3 cm
mounting, we recommend that you allow a 1.75 inch
(4.45 cm) space above and below the unit. If you
mount it with the front panel up, be sure to provide air
space above and below the unit. Inadequate cooling
can cause the built-in thermal protection circuitry to be
activated prematurely. Overheating like this can also
cause the front panel to become warm. Applications
requiring sustained use at high output power levels
may require the installation of a cooling fan.

3.3 Wiring

Figure 3.2 depicts three of the most common ways to
install a DC-300A II in a sound system. All input and
output jacks are located on the back panel. Please use
care in making connections, selecting signal sources
and controlling the output level. The load you save may
be your own! Crown is not liable for any damage done
to loads due to careless amplifier usage and deliber-
ate overpowering.

3.3.1 Mode of Operation

The DC-300A II may be operated in either Dual (ste-
reo) or Bridge-Mono mode by setting the Dual-Mono
switch on the back panel of the amplifier. There are
very important wiring differences between these two
modes which are discussed next.
D U A L
Dual mode installation is intuitive. The channel 1 input
feeds the channel 1 output, and the channel 2 input
feeds the channel 2 output. To put the amplifier in Dual
mode, turn off the amplifier and slide the Dual-Mono
switch to the left as you face the amplifier's back panel
(see Figure 3.2). Be careful not to short the outputs
together, and observe correct loudspeaker polarity.
CAUTION: Do not tie the two outputs together.
Never tie an output to another amplifier's output.
M O N O
Amplifier installation in Bridge-Mono mode is very dif-
ferent. First, only the channel 1 input should be used.
DO NOT USE THE CHANNEL 2 INPUT. For best re-
sults, disconnect all channel 2 input sources and turn
the channel 2 level control fully counterclockwise (off).
Note: The channel 2 input and level control are not de-
feated in bridge-mono mode. A signal fed to channel 2
will work against the signal feeding channel 1.
To activate Bridge-Mono, move the Dual-Mono switch
to the right as you face the amplifier's back panel. Both
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