Peavey CS 800X4
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Operation
Operation Modes
Stereo Operation
For stereo (dual channel) operation, turn the amplifier OFF and set the mode select switches to the stereo position.
In this mode, the respective channels operate independently of each other, with their input attenuators controlling their respective levels.
Thus, a signal at channel 1’s input produces an amplified signal at channel 1’s output,
while a signal at channel 2’s input produces an amplified signal at channel 2’s output.
The same applies to channels 3 and 4 when their respective mode switch is in Stereo position.
Parallel Operation
For parallel operation (dual-channel operation through one input), turn the amplifier OFF and set the mode switch to the Parallel position;
both amplifier channels are then driven by the signal at channel 1’s input (no jumper wires are required).
Output connections are the same as in Stereo mode.
In Parallel mode, the input connectors on channel 1 and channel 2 are strapped together to allow patching to another amplifier or to channels 3 or 4.
Both input attenuators remain active, allowing you to set different levels for each channel.
Power and other general performance specifications are the same as in Stereo mode.
The same applies to channels 3 and 4 when their respective mode switch is in the Parallel position;
the input connectors on channels 3 and 4 are strapped together to allow patching to another amplifier.
Bridged Mono Operation
Two amplifier channels (1 and 2 or 3 and 4, respectively), can be bridged together to make a very powerful single-channel monaural amplifier.
Use extreme caution when operating in Bridged mode; potentially lethal voltage may be present at the output terminals.
To bridge the amplifier, slide the rear panel amplifier mode select switch to the Bridge position.
Direct the signal to channel 1’s input and connect the speakers across the not outputs (the "1+POS" and "2+NEG" Speakon® connector) for channel 1.
As with Parallel mode, both input connectors are strapped together to drive the input of another amplifier.
The same applies to channels 3 and 4. Connect the speakers across the "1+POS" and "2+NEG" Speakon connector for channel 3.
When operating in the bridged mode, both attenuators of a respective set of channels (i.e. channel 1 and 2 or 3 and 4)
must be in the same position so the speaker load will be equally shared between the channels.
Unlike Stereo and Parallel modes, in which one side of each output is at ground, both sides are hot in Bridged mode.
Channel 1’s side is the same polarity as its input with the minimum nominal load impedance being 4 ohms (equivalent to driving both channels at 2 ohms) in Bridged mode.
Driving bridged loads of less than 4 ohms will activate the DDT™ circuitry, resulting in a loss of power, and may also cause a thermal (overheating) overload.
Switches & Controls
Front Panel
Rear Panel
AC Power Circuit Breakers (1)
The CS 800x4 amplifier has two circuit breakers on the back panel.
If circuit breaker shuts off during normal use, push it back to the ON position once.
If it will not stay ON, the amplifier needs servicing.
Input Attenuators (2)
Whenever possible, set the attenuators fully clockwise to maintain optimum system headroom.
The four input atenuator controls located at the front panel decrease gain (signal level) for the respective amplifier channels in all modes.
Mode Select Switch (3)
When operating in Bridged mode, both attenuators of a respective set of channels (i.e. channels 1 and 2 or 3 and 4)
must be in the same position so the speaker load will be equally shared between the channels.
Indicators
CS Series amplifiers feature three front panel LED indicators per channel: PWR (power), SIG (signal) and DDT™ (Distortion Detection Technique).
These LED indicators inform the user of each channel’s operating status and warn of possible abnormal conditions.
PWR LED (1)
The Power LED indicates that its channel’s output relay is closed and the channel is operational.
SIG LED (2)
The Signal LED illuminates when its channel produces an output signal of greater than 1 volt RMS or 25 mV input with a 0 dB attenuation of the front panel knobs.
This is useful in determining whether a signal is reaching and being amplified by the amplifier.
If the Signal LED is illuminated but no sound is present, that means a signal is present at the amplifier but a problem may exist after the amplifier, such as in cables or speakers.
DDT LED (3)
A channel’s DDT LED will illuminate at the onset of clipping.
If the LEDs are flashing quickly and intermittently, the channel is just at the clip threshold,
while a steady, bright glow means the amp is clip limiting, or reducing gain to prevent severely clipped waveforms from reaching the speakers.
Protection Features
The CS 800x4 amplifier incorporates several circuits to protect both itself and loudspeakers under virtually any situation.
Peavey has made this amplifier as foolproof as possible by making it immune to short and open circuits, mismatched loads, DC voltage and overheating.
If a channel goes into the DDT™ gain reduction mode, the DDT LED illuminates.
The speaker load remains connected, but clipping percentage or output power is instantly reduced.
When a problem occurs that causes a channel to go into a protection mode, the PWR (Power) LED for that channel will turn off.
DC voltage on the output, excessive subsonic frequencies, or thermal overload will cause the channel’s output relay to
disconnect the speaker load until the problem is corrected or the amplifier cools down.
Distortion Detection Technique (DDT) Limiting
Any time a channel is driven into hard, continuous clipping, the DDT circuit will automatically reduce the channel gain to a level just slightly into clipping,
guarding the speakers against the damaging, high-power, continuous square waves that may be produced.
Situations that may activate the DDT circuit include uncontrolled feedback, oscillations, an improper equipment setting or malfunction upstream from the amplifier.
Normal program transients will not trigger DDT; only steady, excessive clipping will cause the DDT LED to illuminate.
LFC Impedance Sensing
The CS 800x4 amplifier features innovative circuitry for safe operation into any load.
When an amplifier senses a load that overstresses the output stage, the Load Fault Correction circuit adjusts the channel gain to a safe level.
Extreme load fault under high power levels will cause the signal to be muted for the associated channel.
This method of output stage protection is far more effective than the standard limiting found on conventional power amplifiers.
The LFC circuit is sonically transparent in normal use and unobtrusive when activated.
Thermal Protection
The internal fan will keep the amplifier operating well within its intended temperature range under all normal conditions.
If the heat sink temperature reaches 85°C, which may indicate an obstructed air supply, the channels will protect themselves by disconnecting their load and shutting down until the heat sink has cooled.
During this time, the PWR LED will go out, the DDT LED will stay lit and the cooling fan will continue operating at high speed.
Short Circuit
If an output is shorted, the LFC and thermal circuits will automatically protect the amplifier.
The LFC circuit senses the short circuit as an extremely stressful load condition and attenuates the signal, protecting the channel’s output transistors from over current stress.
If the short circuit remains, the amplifier will eventually thermally protect itself by opening both channel speaker relays, disconnecting the loads until the heat sink cools down.
DC Voltage Protection
If an amplifier channel detects DC voltage or subsonic frequencies at its output terminals, its speaker relay opens and disconnects the load to prevent speaker damage.
Turn-On/Turn-Off Protection
Upon powering-up, the amplifier mutes the input signals and stays in Protect mode with the speaker connect relays open for approximately four seconds.
This allows the internal power supplies to charge and the amplifier to stabilize.
After the relays engage, the signals slowly increase the muted signals to their normal level.
Also, when power is removed, the input signals are muted so that no thumps or pops are heard.
RampUp™ Signal Control
Whenever the CS 800x4 amplifier powers up or comes out of a protect mode, the RampUp circuit activates.
While the speakers are disconnected, the RampUp circuit fully attenuates the signal and activates the DDT LED.
After the output relay closes, the signal slowly and gradually raises to its set level.
The PWR LED will illuminate and the DDT LED will turn off when the signal is no longer attenuated.
The RampUp Signal Control circuit has some important advantages over the conventional instant-on circuits:
- 1. If a signal is present during power-up (or when coming out of protect), the speakers are spared a sudden, potentially damaging burst of audio power.
- 2. Because the gain is reduced until after the output relay closes, no arcing occurs at the contacts, thereby extending their useful life.
Speaker Protection
All loudspeakers have electrical, thermal and physical limits that must be observed to prevent damage or failure.
Excessive power, low frequencies applied to high frequency drivers, severely clipped waveforms and DC voltages can all be fatal to cone and compression drivers.
Peavey CS Series amplifiers automatically protect speakers from DC voltages and subsonic signals.
If using an electronic crossover, be extremely careful that the low and mid bands are connected to the correct amplifiers and drivers and not to those designed for a higher frequency band.
An amplifier’s clipping point is its maximum peak output power, and some of the higher powered Peavey CS Series amplifiers can deliver more power than many speakers can safely handle.
Be sure the peak power capability of the amplifier is not excessive for your speaker system.
Fuses may also be used to limit power to speaker drivers, although as current-limiting rather than voltage-limiting devices,
they are an imperfect solution, and as the weakest links, they only limit once before needing replacement.
Some poor-quality fuses have a significant series resistance that could degrade the amplifier’s damping of
the speaker’s motion and may even deteriorate the system’s sound quality.
If you elect to use fuses, check with the speaker manufacturer to determine the proper current rating and time lag required.
Do not drive any low frequency speaker enclosure with frequencies lower than its own tuned frequency;
The reduced acoustical damping could cause a ported speaker to bottom out even at moderate power.
Consult the speaker system specifications to determine its frequency limits.
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CS 800X4 Manual (pdf)