Peavey CS-900 User Manual

5. Car's must be taken to never remove a crossover module or replace it with the CS-900 power switch on. The complex circuitry
used in the crossover modules receives bipolar power through the socket, and removal or replacement could cause severe
transients which can destroy the loudspeaker system. Always turn the CS-900 oft first As an added feature, the bipolar power
lor the crossover islands can be supplied from either channel of the CS-900. Thus, If one channel should shut down for any
reason, the redundancy of the system will maintain operation of the crossovers,
6. The individual sensitivity controls on each channel play a very important role in the use of the crossover rrjodules. As such, they
represent a signal loss when they are operated at another setting other than full clockwise (maximum sensitivity). Blamped
speaker systems usually require less signal level forth© high frequency components because they are generally more efficient
Consequently, a system balance can be achieved by reducing tne high pass level. This is particularly important on non-Peavey
loudspeakers where the PL-500, PL-800 or PL-900 crossover modules must be used. These modules are referred to as "no pad
andequailzailon'types. Assuch, there isno reduction in high pass level. Consequently, the pad must be accomplished using the
high pass channel sensitivity control. The amount of pad required is always the difference between the efficiency ratings of the
high and low speaker components. Whenever Peavey loudspeakers are operated using the special crossovers (PL-SP-1,
PL-800-EQ, PL-900-EQ and PL-2000-EQ). the eeneitivity controls should be set et full clockwise settings (maximum sensitivity)
to provide maximum system headroom since ihe correct pad and equalization 1$ already provided m the crossover module.
Bridge Mode
The bridge mode on 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, it is converted to a single-channel unit with a power rating equal to the sum of both channels'
continuous power ratings, at a load rating of twice that of the single-channel ratings. For the CS-900, the bridge ratings are 900 watts RMS
(continuous) into 8 ohms (minimum load). Bridge mode operation Is accomplished by placing the mode switch (16) In the bridge position,
connecting the loaO between me red binding posts of each channel, and using Channel A as the Inputchannei. All functions of Channel Bas
an input are defeated. What actually happens from tne technical standpoint isthatcnannel B is supplied an input signal which is equal in
level but is out-of-phase from that oftheChannel A input signal (Le., when Channel A'ssignal is positive, Channel B’sslgnal is negative
and vise versa). Thus, the load (which is connected between the channels) sees the sum of theoutpul voltages of both channels (which is
then twice that of the single channel), and this load must be 8 ohms or greeter.
For the 05-900, the selection of bridge mode should invoke the following interesting question Where wouifl i need a 900 watt. 8 ohm
amplifier?” When you considerthe fact that there are Virtually no Sohm speaker components which can handle 900 wattsRMS (contrnuous)
safely, there are generally no practical applications for a bridged CS-900 m eimpie sound systems. The real purpose is to drive sound
distribution systems in very large public address applications. In the bridge mode, the CS-9(X3 can supply 70 or 100 volts RMS directly
without matching transformers. 70 volt distribution systems are very common in domestic applications where large numbers of relatively
small loudspeakers are used for background music and paging. Such systems require the use of 70 volt transformers at each loudspeaker.
tODvolt syslemsare morecommon in export applications-Occasionally a largespeaker array might require (orhandle) 900 watts RMS Info 8
ohms directly. This then might be a practical application.
Diagram 4 shows the actual arrangement for the CS-900 patch panel in the bridge mode. Notice the jumper plugs are inserted in the
transformer (10) and crossover (12) accessory sockets of Island A. ThesejumperpjugscausetheXLRconnectorofthis island to be wired in
the unbalanced configuration (as in Diagram 1) and completethe connection to the parallel bridge powerampinputjacks (formerly Channel
A poweramp input). The Channel A sensitivity control now determines the sensitivity of the bridge mode amplifier. The Channel B power
amp Input jacks and sensitivity control have been deleted since they serve no purpose in this mode and are actually electronically removed
from the circuit. Both sets of parallel'//' output phone iacks have been deleted on the diagram since these also are normally not used in the
bridge mode. Remember, the 8 ohm minimum load must be connected between the red binding posts If individual 4 ohm loads were
connected to each output (as in normal stereo applications) when the bridge mode is selected, Channel A would supply a normal In-phase
signal to rts respective load, but Channel B would supply an abnormal out-of-pnase signal to its respective load, and both of these signals
would be the Channel A source material (Channel B source material, if present, would be defeated). i~his i$ a very dangerous situation,
especially if the individual channels are being used tosupply high and low signals In thetyplcal biampconfiguration. Obviously, thespeaker
components on Channel B would no longer be supplied their Intended signal but rather an out-of-phase version of the Channel A signal,
which could destroy the aseocialed loudspeaker components. To minfmizethe possibility of this happening on the CS-900, whenever the
bridge mode Is selected, thestandby (‘0’) LEDand the LED array Itself on Channel B is defeated (off), just as if there was a fault condition on
Channel B. This provides a positive indication that the CS-900 is no longer in the stereo mode.
Often technicians fail into what we call "the bridge syndrome,''This Is designing a system for bridge mode operation when Indeed they
really don't need it.A typical exampleis where two4ohm speakerenclosuresare wired In series, creating an 8 ohm load, and this load islhen
driven in bridge mode. In this case, a C5-900 would deliver 600 watts RMS to each enclosure (a total of 900 watts for both). A much better
approach Is to use the CS-900 in the stereo mode end then connect one 4 ohm speaker enclosure fo each channel of the CS-900 and
daisy-chain the inputs. Each channel would still deliver 950 watts RMS to each enclosure (a total of 900 watts for both), but now you would
have a redundant system with the advantage of being able to adjust the individual levels If that is a desirable feature. Another frequent
application problem is driving a single 4 ohm enclosure In bridge mode. This is simply an example of not understanding that when bridge
mode is selected, the rated load specification Is twice that of smgfechanrjel operation. In this case, under continuous full power operation the
amplifier will thermal out.
Although bridge modeoperetlon is very easy to accomplish on the CS-900, and we have provided an indication means wheneverthe mode
is selected, again, alhorough understanding of the patch panel features will allowfurther expansion to morecomplexsystems. The following
list should provide more information toward these goals.

Peavey CS-900 Specifications

General

Brand	Peavey
Model	CS-900
Category	Amplifier
Language	English