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©American Audio® - www.americanaudio.us - XLT Series Power Amplifier User Manual Page 12
Thermal Protection - If the amplifiers operating temperature runs over 105°C (221°F) the amplifier will go into thermal protection to
prevent damage from over heating. The Protect Indicator LED located on the front of the amp will light up, and the output signal will
be muted. The fans will start to run at max speed to allow the amp to return to a safe operating temperature. To prevent amplifier over
heating, make sure your input signal is not clipping (Red LED indicator located at the front), and that you are not overdriving the amp.
Make sure not block the airflow input and output vents and always use the amp in an enviroment that is no higher than 30°C (86°F).
Never use a speaker load that exceeds power or impedance ratings.
VHF Protection - If the amplifier detects a VHF signal or excessive feedback, the amplifier will enter VHF protection after 3 seconds.
The Protection Indicator LED located on the front of the amp will glow and the output will be muted. After 10 seconds the VHF protec-
tion mode will be disabled. After the protection circuit starts up, if the signal is still present the amplifier will remain in VHF protection
Clip Limiter - When the input signal overloads, the “CLIP LED’s” will indicate a signal overload, at this time, the master volume should
be lowered to reduce distortion. If the input gain level is not reduced the built-in limiter will activate. During signal overload, the lim-
iter will reduce the input audio signal enough to minimize the amount of clipping. A limiter takes the gain of an overloading signal and
reduces it, the reduction in gain reduces distortion that can cause damage to your speakers and amplifier. During normal operation
below clipping, and momentary clips on peaks, the limiter does not affect the audio signal and is inaudible. It will allow brief clipping of
peaks and will only activate when continuous, hard clipping occurs. During excessive clipping the limiter will reduce the audio signal
enough to minimize the amount of clipping. When the input signal decreases enough that clipping ends, the limiter will deactivate and
cease its gain reduction. The limiter has a fixed threshold and can not be adjusted. NOTE: If input signal is clipping or exceeds linear-
ity working range of input circuit, then the Clip Limiter will not work.
Short Circuit Protection - The XLT Series amplifiers all come with built-in Short Circuit Protection. If a short circuit is detected on
the output signal, the Clip and Protect Indicator LEDs will both glow. This protection makes the output transistors work at a safe
range and there will be no output from the amp. The amp will recover after 10 seconds after the terms of the short circuit have been
AC Local Power Protection - If the AC power voltage is lower than the required voltage (160V), the power supply will turn off auto-
matically until the power voltage is normal. NOTE: The correct AC main voltage is listed above the Power Cord input. Connecting to
the wrong voltage is dangerous and may damage the amplifier. Always be sure the source voltage for your areas matches the required
voltage for your amplifier.
DC Protection - If the output signal has a larger DC voltage (=2.6V), in order to protect the speaker, the DC protection circuit will start-
up. When the DC protection circuit starts up, the Protection Indicator LED (1) will glow and the amp will go mute.
Input/Output Protection - The input circuits are isolated by 10k resistors. An ultrasonic network uncouples RF from the output and
helps keep the amplifier stable with reactive loads.
Safe Power Levels at Different Output Loads: