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Operation Manual
CH and CL Series Power Amplifiers
page 8
2.6 Switch Settings
Proper wiring depends on how you configure
your amplifier. The CH and CL Series offer vari-
ous modes of operation:
• Constant-voltage load
• 4/8-ohm load
• Stereo mode
• Bridge-mono mode
Let’s explain each mode of operation
Each output channel can be independently con-
figured to drive either (1) 4/8-ohm loudspeak-
ers, or (2) step-down transformers in a
distributed “constant voltage” loudspeaker sys-
tem. “Constant voltage” refers to 70V operation
with models CH1, CH2 and CH4 only. Also, the
amplifier can be configured for Dual or Bridge
modes. Various combinations of these modes
are possible.
CH and CL Series amplifiers can be configured
for either Stereo (dual channel) or Bridge (sin-
gle mono channel) modes of operation. To
switch your amplifier accordingly, set the
recessed “Stereo/Bridge” switch to the desired
setting as shown in Figure 2.8.
CH Series amplifiers only: Select 4/8 ohm
or 70V operation as appropriate for your appli-
cation and your amplifier. Select output opera-
tion by sliding the recessed Output Operation
switches to the desired position as shown in
Figure 2.9.
When the CH Series amplifier is set up for two-
channel (Stereo mode) operation, it is possible
to configure the output channels for either 4/8
ohm or 70V operation.
WARNING: If Bridge mode is used with
70V output, the amplifier will actually
deliver 140 volts.
WARNING: The two Output Operation
switches must be set to identical posi-
tions (4/8 ohm or 70V mode) when oper-
ating in Bridge mode. Never change
switch positions with power turned on.
CAUTION: Output Terminals are acti-
vated by selection of an output opera-
tion mode via the Output Operation
switches. All other Output Terminals are
inactive. For example, when 4/8 Ohm Opera-
tion is selected, the 70V connections are inac-
tive, with no audio present at those Output
Terminals.
Figures 2.9 through 2.16 on the following
pages show common ways to install CH and CL
Series amplifiers in a sound system. Input and
output terminals are located on the back panel.
CAUTION: Always disconnect the AC
power and turn the level controls off
when making or breaking connections.
This is very important when loudspeakers are
connected because it reduces the chance of
loud blasts that can cause loudspeaker dam-
age.
CAUTION: Never tie an amplifier’s out-
puts together directly while in Stereo
mode. Never parallel them with the out-
put of another amplifier. Such connections
do not result in increased output power, but
may cause overheating and premature activa-
tion of the protection circuitry.
Note: The Channel 2 input jack and Input Level
control are not defeated in Bridge mode. A sig-
nal feeding Channel 2 will work against the
Channel 1 signal, and usually results in distor-
tion and inefficient operation.
2 Setup
Figure 2.8 Stereo/Bridge Mode Switch
Figure 2.9 Channel Operation Switches
CH1
4/8 VΩ70 4/8 VΩ70
CH2
Channel Operation
Model CH4
Models CH1 and CH2