Dual 70 volt mode (both channels), Fig. 3.5 wiring for dual 70 volt mode, Bridge mono dual parallel mono – Crown Audio Com-Tech "00 Series" User Manual

Page 14

Page 14

Com-Tech 200/400/800/1600 Power Amplifiers

140 volt distributed loudspeaker systems. If you will be
using 140 volt output, you may need to cross-refer-
ence 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.

WARNING: Both channels must be configured for the
same output mode (8/4 ohm or 70 volt) before switch-
ing to Bridge-Mono mode.

Bridge-Mono wiring is very different from the other
modes and requires special attention. First, turn the
amplifier off. Then select Bridge-Mono mode by sliding
the dual/mono switch to the right (as you face the back
panel). Both outputs will receive the signal from chan-
nel 1 with the output of channel 2 inverted so it can be
bridged with the channel 1 output. DO NOT USE THE
CHANNEL 2 INPUT or the signal level and quality may
be greatly degraded. Also, keep the channel 2 level
control turned down completely (counterclockwise).

Note: The channel 2 input jack and level control are not
defeated in Bridge-Mono mode. A signal feeding
channel 2 will work against the channel 1 signal, and
usually results in distortion and inefficient operation.

Connect the load across the two positive (+) output ter-

channel can be used to 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 center position, and properly
connect the output wiring. Be sure to observe correct
loudspeaker polarity (see Figure 3.4) and be careful
not to short the two outputs.

CAUTION: Never tie an amplifier’s outputs together di-
rectly, and never parallel them with the output of an-
other 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.

BRIDGE

MONO

DUAL

PARALLEL

MONO

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 4 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 out-
put voltage is produced from a single channel to drive

Use Dual 70 volt mode
for Fire Protective Sig-
naling applications (see
Section 9).

Fig. 3.5 Wiring for Dual 70 Volt Mode

COM

–

70 VOLT STEP-DOWN

TRANSFORMERS

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.

VOLT

8/4

OHM

8/4

OHM

CH1

CH2

BRIDGE

MONO

DUAL

PARALLEL

MONO

Programmable
Input Processor (P.I.P.)

–

C H - 2 I N P U T

–

C H - 1 I N P U T

ESS

R E S ET

PUSH TO RESET

CH-2

CH-1

19
21
25

∞

19
21
25

∞