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The transformer module can be removed and the jumpers reinstalled if a balanced input is not required for the crossover network. The XLR
connector is now unbalanced as per previous discussion. If phone plug inputs to the crossover network are required, parallel crossover input jacks
(7) are provided. In addition, these jacks can be used to patch out full range signals to the other amplifier/speaker systems.
Care must be taken to
never remove the crossover network
or replace it
with the CS-400 power switch on.
The circuit used in the
crossover network receives bi-polar power through the socket, and removal or replacement could cause severe transients which can destroy the
speakers. Always be sure the mode switch is in the stereo position before operating the system. The individual volume controls on each channel
play a very important part in the use of this crossover network. As such, they represent a signal loss when they are operated at any setting other than
full clockwise. Certain speaker systems may require more signal on the low end than on the high end and consequently, a system balance can be
accomplished by reducing the high-pass level. Generally speaking, however, the two controls should be operated at approximately the same
setting and at least a setting of "7" or greater. Failure to observe this minimum setting could result in distortion due to the inability of some signal
sources to provide an adequate voltage swing to the crossover network.
Occationally a 70-volt line is required for a sound distribution system or in public address applications. This technique is generally used in
systems which have long cable runs between the power amplifier and the speaker systems. It is almost universal in distributed systems. The CS-
400™ can supply 70 volts RMS directly without matching transformers by using the bridge mode as shown in Diagram 4. The bridge mode for stereo
amplifiers is often misunderstood as to the actual operation and usage. In basic terms, when a two-channel amplifier is operated in the bridge mode,
the system is converted to a
single-channel
unit with a power capability equal to the
sum of both channels
operated continuously at a
load
impedance
equal to
twice
that of one channel. This is accomplished by providing an input to one channel, placing the mode switch in the bridge
position and connecting the load between the red binding post of each channel. In the case of the CS-400™, the active input is Channel A, the output
power is 400 watts, and the matched load is 8 ohms.
It must be pointed out that for proper operation,
both
wires of the output must "float" above ground. Since Channel A is the active channel, the
Channel A patch panel can be used to provide a balanced input through the use of a PL-2™. The Channel B volume should be set at "0" for lowest
noise. Overall system volume is controlled by the Channel A volume control.
Crossover modules can be used if desired since they are totally isolated from the power amp inputs but remember the CS-400™ power section
is effectively a single-channel amplifier in the bridge mode.
4
As you can see, the CS-400™ is a very flexible amplifier. We highly recommend that you become thoroughly familiar with every aspect of
operation before connecting any speaker system to it. Pay particular attention to the functions of the patch panel and the load impedance.
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