Lexicon CX PROTECTION MODES, THERMAL PROTECTION, CURRENT PROTECTION, DC PROTECTION

Basic Operation Lexicon

2-8

PROTECTION MODES

The CX amplifiers are equipped to protect against overheating and

miswiring, as well as electrical failures such as short circuits, device

failures, internal faults, and DC output to the speakers.

The amplifier includes thermal protection for each channel, the

main power transformer, and chassis. If a heatsink temperature

exceeds 95˚C, the channel will deactivate and the corresponding

channel status LED will flash blue. When the heatsink cools to

normal operating temperature, the channel will automatically reac-

tivate and the corresponding channel status LED will return to

constant blue.

If the amplifier chassis exceeds a temperature of 58˚C, the amplifi-

er will shut down all channels and all the channel status LEDs will

flash blue. When the chassis cools to normal operating tempera-

ture, all of the channels will automatically reactivate and the chan-

nel status LEDs will return to steady blue.

If the main power transformer temperature exceeds 100˚C, the

transformer will deactivate, all channel status LEDs will no longer

be lit, and the red standby LED will flash rapidly. Once the trans-

former has cooled, it will automatically be reset and the amplifier

will operate normally. The channel status LEDs will return to

constant blue, and the red standby LED will no longer be lit.

The CX amplifiers use a combination of voltage and current infor-

mation to protect the output transistors. The amount of current

capable of being delivered to the load is dependent on how much

voltage appears across the output transistors. Inversely, this means

that the more output voltage available, the more current capabili-

ty available, which translates into higher power output.

In addition to the voltage and current thermal protection, the CX

amplifiers have a time dependent instantaneous current limit. The

amplifier is capable of delivering 20 amps peak into a load for a

short duration of time.

Each channel includes DC protection to prevent DC and frequen-

cies below 10Hz from reaching the speakers. If this protection

activates, the output relay will open and the corresponding front

panel channel status LED will flash blue. After approximately 4-sec-

onds, DC protection will be automatically deactivated. The relay

will close and the corresponding channel status LED will return to

constant blue. If DC or frequencies below 10Hz are still present, DC

protection will be automatically reactivated. The amplifier will

continue to engage this protection until the problem is no longer

present.