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CH1 CH2
BRIDGED
STEREO
LEVEL
LINE INPUTS
VIDEO
AUDIO
L
R
1
RCA Type
Patch Cords
Preamp Outputs
ZPR68, etc.
PA640 Input Panel
PA640 Speakers & AC Panel
+ – – +
CH2 CH1
PROTECTION
SPEAKERS
+ –
BRIDGED
Be sure speakers are
connected with correct
polarity as shown.
Speaker Systems
Set
BRIDGED/STEREO
Switches to
BRIDGED position
CH3 CH4
BRIDGED
STEREO
LEVEL
LINE INPUTS
+ – – +
CH4 CH3
PROTECTION
SPEAKERS
+ –
BRIDGED
– +
Right
Left
+ –
1V
.2V3V
1V
.2V3V
Fig. 7 BRIDGED Mode Connections
INSTALLATION (cont'd)
Bridged Mode Connections
In general, it is recommended that the BRIDGED
mode not be used in multi-room applications
where several speakers are driven through room
volume controls and the like. For such applica-
tions, use the STEREO mode. Instead, use the
BRIDGED mode for single speaker, higher power
applications, such as in surround sound systems.
Use speakers with an impedance rating of 8-Ohms
minimum.
To make connections for the BRIDGED
mode, follow the steps given before for
stereo connections, but with the follow-
ing exceptions:
1. Connect RCA type patch cables
from the OUTPUT jacks of the
driving preamp or other source to
the PA640 LINE INPUT jacks
marked CH1, and/or CH3, and/or
CH5. Do this for just the amplifier
pairs you wish to run in the bridged
mode.
(Jacks marked CH2, CH4 & CH6
are disabled in BRIDGED mode).
Refer to Fig. 7.
CAUTION: Be sure power is OFF
when connecting or switching the
amp for BRIDGED operation.
2. Slide the BRIDGED/STEREO
switch to the BRIDGED position.
NOTE: Do this only on the amplifier pairs you
wish to run in the bridged mode!
3. Connect one speaker wire pair between the 4-
terminal "SPEAKERS" connectors on the
PA640 and the speakers as shown in Fig. 7.
Be sure to use only the two outer terminals
marked "+" and "–" on the 4-terminal connec-
tor as shown on the panel for BRIDGED
connections.
NOTE: Only one speaker is connected per amplifier
pair in the BRIDGED mode!
CAUTION: When operating in the BRIDGED mode
(particularly when bench testing the amplifier) do not
make a ground or any other kind of connection to the
amplifier speaker terminals other than those to the
individual speakers as shown. Failures caused by
inappropriate connections are not covered under the
warranty.
PA640