Peavey CS 1200 User Manual

LED ARRAYS (2)
The CS-1200 has a tricolored LED array on each channel to indicate output power level. The array is calibrated in two different ways to offer
maximum flexibility as to usage. To the left of each array, the calibration is percent of full power output. The top LED, labeled 100%, will flash
when the CS-1200 has reached full RMS power output (600 watts RMS) on that respective channel. Operation at power output levels below
100% will naturally be indicated by lower LED readings. The lowest value indicated is 0.4% of full power, which corresponds to 2.4watts RMS
output. Operation below that power level will not be indicated since the lowest LED is calibrated at 0% or standby. This LED should be
illuminated whenever the amplifier is operating with AC mains power applied under zero signal conditions. To the right of each array, the
calibration is "dB below full power.’ 1 This is a very convenient scale which indicates the amount of power amp headroom left for any signal
condition. On thisscale. the lowest LED is labeled (infinity), which is consistent with the dB system. If fault conditions exist, such as a high
temp, thermal shutdown or a DC offset at the output (caused by the amplifier itself or externally induced at the input), this LED will go off and
remain off until the fault is cleared. You will also notice that this LED will not light for approximately two seconds during the power-up
sequence, and will go off very quickly during the power-down sequence. This is normal, indicating that the transient protection circuitry is
operating properly Should this LED ever fail to light after the normal power-up sequence, and no other fault conditions exist, then the mains
AC power to that channel might not be applied. Such a condition might be a blown fuse in that associated channel. If upon replacing the fuse
(with the same type and rating) it does not clear the problem, then the amplifier will require servicing by a qualified service technician. Since
the CS-1200 is a redundant two-channel amplifier, operation of the working channel Is unaffected by the down channel and continued
operation under these circumstances will in no way harm the amplifier and is considered normal operation.
DDT"* COMPRESSION
The CS-1200 is acompact and powerful amplifier that features a new type of dynamic compression. This compression system enables the
user to maximize the performance of the amplifier/speaker combination. We have determined through much research that the compression
circuitry should prevent the power amplifier from running out of headroom (clipping) and should be as simple to operate as possible to avoid
undue complication for the user. This compression system is activated by our exclusive DDT compression circuitry that senses conditions
that might overload the amplifier and activates compression when clipping is imminent. In other words, compression takes place whenever
signal conditions exist which prevent the amplifiers from faithfully reproducing the input signal. Threshold then is clipping itself and no
specific threshold control is provided. This technique effectively utilizes every precious watt availablefrom the power amplifier. Techniques
using external compressors and limiters are usually less effective, limit output power levels and require additional controls, which add
complexity to an already complicated system. The DDTsystem is an automatic, hands-off approach to the problem of amp clipping. Because
of the dynamics of music and vocals, it is quite common to activate the DDT compression circuitry almost constantly during a high level
performance since this was what it is designed to do; i.e., to maximize the dynamics available from the amplifier within its power output
capabilities regardless of power supply/AC line voltage variations and load impedance selection.
DDT'“ ACTIVE LED’S (3) (7)
The DDT active LED’s indicate when compression is taking place. As long as gain reduction is occurring, the LED will continue to light,
thereby giving a valuable indication of this unique compression function. The DDT function can be defeated on both channels
simultaneously by selecting the defeat position on the DDT compression switch (7) located on the back panel of the CS-1200. When the
compressor is defeated, the DDT active LED now indicates clipping, the condition where the amplifier is failing to faithfully reproduce the
input signal. Defoating the DDT compressor should not be taken lightly or simply as a matter of course. Most loudspeaker systems simply
can not handle the square wave power of the CS-1200 (1500 watts RMS), and defeatingthis valuable limit Is only asking fortrouble in the long
run. Often studio engineers feel the nood to defeatthe DDT compressorfor fear that it might color the sound in studio listening Occasionally,
external compressors/limiters are employed to automatically set the level of a particular system and thus, the unknowning technician will
defeat the DDT compressor thinking it is not needed. Those areexamples of not understanding theoperation of the DDT circuitry. The DDT
compressor is only activated when clipping is imminent. Until this occurs, it’s simply a passive friend. The only reason thatthedefeat switch
is there in the first place is to allow check-out and service technicians to evaluate the power amplifier at clipping. Valuable performance
information, such as ripple and regulation, can only be assessed when an amplifier is allowed to clip. Other than those times, we strongly
suggest that the DDT compressor switch be set in the active position and left that way.
THERMAL SYSTEM
The CS-1200 has a unique thermal system that employs a tunnel-like heat sink design to provide maximum cooling for the 32 power
transistors (16 for each channel). A single 100 CFM fan mounted on the back panel of the amplifier provides an almost unrestricted airflow
through the tunnel to provide the lowest possibleoperating temperature for the power devices. Thisapproach is so efficient that even music
power operation into 2ohms will not causeathermal shutdown unlesstheambient airtemperature is considerably higherthan normal (above
40° C). Under normal intermittent applications, low speed fan operation will provide adequate cooling. Since the CS-1200 is a redundant
two-chanrel amplifier, but only one fan is employed the fan circuitry is an independent system, separately fused internally. You will notice
that the heat sink components aredivided horizontally. The lower half contains Channel A output transistors, while the upper half belongs to
Channel B. The fan naturally provides equal cooling for both channels. Each channel has a separate built-in thermal sensor and separate
logic circuitry. If one channel heat sink reaches an operating temperature of 60° C, then its logic will cause high-speed fan operation
regardless of the other channel’s operating temperature. In other words, either channel heating will control the fan speed. Under normal
continuous usage at full-rated power output into the rated load, the thermal logic system will continuously monitor heat sink temperatures
and will automatically select the fan speed required to maintain safe operating limits for the power transistors.
HIGH TEMPERATURE LED'S (4)
Ifthe CS-1200 is continuously operated into 2ohm loadsor lower forany considerable length of timeor if theambient temperaiureof theair
supply were to becometoo hot to provide adequate cooling even under normal A ohm loading situations, then the amplifier internal heatsinks
could reach unsafe operating temperatures. When this occurs, then the thermal logic system will shut down the unsafe channel, causing the
high temperature LED to light and the "O’’ LED to go out on that channel. Since the CS-1200 is a redundant amplifier, the shutdown of one
channel will not affect theoperation of theother channel. After the unsafechannel cools down to safe limits, operation will be restored in that
channel. Normal operation will be indicated by the high temperature LED off and the“0” LED on. Continued operation under fault conditions
will in no way harm the amplifier, but because of the nuisance factor, steps should be taken to determine the problem and solve it. Because of
the very etficient design of the CS-1200 dissipation system thermal shutdown conditions will almost never occur unless there is truly an
external fault. For continuous operation, the CS-1200 requires a source of cool air. As an added help in locating mismatched or shorted
speakers, the DDT active LED is a powerful tool. If this LED flashes continuously at relatively low output power levels (indicated by low power
readings on the LED array), it is almost a sure sign that the amplifier loading is too low in value or that there might be a short Remember,
usually the power LED array should reach 100% indication before the DDT system is activated on any particular channel
The CS-1200 also has a fail-safe thermal mechanism built into the unit. If either channel thermal logic system should fail to cause thermal
shutdown in that channel or if the fan itself should fail, then this fail-safe system will shut down theentire amplifier, just as if you had turned off
the power switch. This is just one more protection that Peavey has incorporated into this unique amplifier as a backup system. If this should
ever occur, immediately seek professional help at a Authorized Peavey Service Center.

Peavey CS 1200 Specifications

General

Channels	2
Signal to Noise Ratio	> 100 dB
Input Impedance	20k ohms balanced, 10k ohms unbalanced
Weight	35 lbs
Dimensions	3.5" H x 19" W x 15.25" D