Technical information
Page 16
Com-Tech Power Amplifiers
Reference Manual
correct loudspeaker polarity (see Figure 3.4) and be
careful not to short the two outputs.
CAUTION: Never tie an amplifier’s outputs together
directly while in dual mode. 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.
Note: To parallel multiple amplifiers for fail-safe redun-
dancy, contact Crown’s Technical Support Group.
B R I D G E - M O N O
Bridge-Mono mode is used to drive loads with a total
impedance of at least 8 ohms (see
Parallel-Mono
if the
load is less than 4 ohms). If Bridge-Mono mode and 70-
volt output are used together, twice the normal output
voltage is produced from a single channel to drive 140-
volt distributed loudspeaker systems. If you will be us-
ing 140-volt output, you may need to cross-reference
the ratings of the step-down transformer taps with
Crown’s constant voltage computer (see Section 8.3). If
you need a single channel with higher power to drive a
70-volt line, use Parallel-Mono mode.
uted loudspeaker system, the constant voltage output
varies with the output power rating of the amplifier. With
8/4-ohm output in Dual or Parallel-Mono mode, the
Com-Tech 210 can drive a 25-volt line, the Com-Tech
410 can drive a 35-volt line, the Com-Tech 810 can drive
a 50-volt line, and the Com-Tech 1610 can drive a 70-
volt line. Using Bridge-Mono mode, these voltage lev-
els are doubled for a single channel. Again, to
effectively use different constant voltage levels, you may
need to cross reference the ratings for the step-down
transformers’ taps using Crown’s constant voltage com-
puter (see Section 8.3).
D U A L
Dual mode allows each amplifier channel to operate in-
dependently like a “dual mono” or stereo amplifier. And
if you select both Dual mode and 70-volt output, each
output channel can drive a 70-volt line. Installation is
intuitive: Input Channel 1 feeds output channel 1, and
input Channel 2 feeds output Channel 2.
To put the amplifier into Dual mode, turn it off, slide the
dual/mono switch to the DUAL
(center) position, and
properly connect the output wiring. Be sure to observe
Fig. 3.5 Wiring for Dual 70-Volt Mode
+
COM
+
COM
+
–
+
–
70 VOLT STEP-DOWN
TRANSFORMERS
16, 8, OR 4 OHM
16, 8, OR 4 OHM
70 VOLT LINE
MIXER
LOUDSPEAKERS
Com-Tech Amplifier
CHANNEL 1
CHANNEL 2
CHANNEL 1
CHANNEL 2
DUAL 70 VOLT MODE
(BOTH CHANNELS)
TURN OFF THE AMPLIFIER
BEFORE CHANGING
THE DUAL/MONO SWITCH.
TURN OFF THE AMPLIFIER
BEFORE CHANGING THE
OUTPUT MODE SWITCHES.
70
VOLT
70
VOLT
8/4
OHM
8/4
OHM
CH1
CH2
BRIDGE
MONO
DUAL
PARALLEL
MONO
P
R
E
S
S
R
E
S
E
T
PUSH TO RESET
CH-2 CH-1
0
dB
.5
1
2
3
4
5
6
7
8
910
11
13
15
17
19
21
25
32
0
dB
.5
1
2
3
4
5
6
7
8
910
11
13
15
17
19
21
25
32
CH2 CH1
+– +–
Programmable
Input Processor (P.I.P.)
BB
REMOTE