Basic Operation
Lexicon
COOLING SYSTEM
The LX Power Amplifiers use
PROTECTION MODES
The LX 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. A combination of dedicated circuitry and microprocessor control ensures that the amplifier will perform safely and reliably under extreme conditions.
THERMAL PROTECTION
JTS (Junction Temperature Simulation) provides an advanced level of thermal protection that allows the LX amplifiers to achieve maximum performance with a minimum number of output transistors. This design requires a smaller quantity of
JTS predicts the internal temperatures of output transistors to prevent them from overheating. To arrive at an accurate internal temperature prediction, JTS measures the output voltage and current each output transistor delivers and combines this informa- tion with heatsink temperatures. When an output transistor reaches its maximum allowable temperature, it is instantly restrict- ed until the temperature decreases.
JTS’s dynamic nature enables it to avoid the problems inherent in competing products that rely only on heatsink temperatures. Heatsink temperatures do not always correlate to the temperatures inside the output transistors. JTS is calibrated by device parameters, which allow it to predict overheating even if the heatsinks are relatively cool.
When JTS activates, a distorted signal will be present in the corresponding channel. Check the airflow around the amplifier and take the following measures:
•Provide additional cooling.
•Make sure speakers have adequate impedance ratings (see page
•Reduce system volume level.
In addition to the protection provided by JTS, the amplifier includes thermal protection for each channel and the main power transformer. If a heatsink temperature exceeds 115˚C, the channel will deactivate and the corresponding channel status LED will flash red. When the heatsink cools below 115˚C, the channel will automatically reactivate and the corresponding channel status LED will light blue.
If the main power transformer temperature exceeds 110˚C, the transformer will deactivate, all channel status LEDs will no longer be lit, and the standby LED will flash rapidly. The internal fans will automatically be set to full speed to cool the transformer. Once the transformer has cooled enough, it will automatically be reset and the amplifier will operate normally. The channel status LEDs will light blue, and the standby LED will no longer be lit.
