The Peavey CS
®
Series incorporates several circuits to protect the amplifier and speakers under virtually any situation. Peavey
has made the amplifiers as foolproof as possible by making them 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 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 or excessive subsonic frequencies will cause the
speaker protection relay for that channel to open, protecting the speakers. If an amplifier channel overheats, the relay for that
channel will open, disconnecting the load until the channel cools down, thus protecting the amplifier.
Distortion Detection Technique 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
CS Series amplifiers feature 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 speaker relay to disconnect the load 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 fans will keep the amplifier operating well within its intended temperature range under all normal
conditions. If a channel’s heat sink temperature reaches 85°C (which may indicate an obstructed air supply), that
channel will independently protect itself by opening the speaker relay to disconnect the load until it has cooled.
During this time, the PWR LED will go out and the cooling fans 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 channel may eventually thermally protect itself by
opening the speaker relay thereby disconnecting the load.
DC Voltage Protection
If an amplifier channel detects DC voltage or subsonic frequencies at its output terminals, the speaker protection relay
for that channel will open, protecting the speakers.
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 from muted to their normal level. Also, when power is removed,
the input signals are muted so that no thumps or pops are heard.
Protection Features
