O thermal protection leds, O distortion alert leds – Adcom GFA-7300 User Manual
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Thermal Protection LEDs
The GFA-7400/7300 are provided with a thermal protection circuit which will shut down the
individual amplifiers if its heatsink temperature reaches 85°C. The Thermal Protection LEDs will
light whenever the thermal protection circuit in its respective channel has been triggered and the
amplifier is inoperative. The thermal protection circuitry will typically be triggered by very high
power demands into impedances much lower than the amplifier is capable of driving at those
levels. If any amplifier channel’s output through the loudspeaker(s) ceases abruptly, and its
Thermal Protection LED glows, you will know that its heatsink temperature has become
unacceptably high and the circuitry is protecting the amplification devices. Please note that the
Power LED (O) will remain on and the amplifier will still be energized. Once the temperature of
the heatsink(s) drops to a safe operating level, that amplifier will automatically resume operation.
Activation of the Thermal Protection circuitry in any of the amplifiers in the GFA-7400/7300 is
an indication that the amplifier has been overdriven or that the load the loudspeakers are
presenting to the amplifier is unreasonably low. If you wish to prevent recurrent activation of the
thermal protection circuitry, you must reduce the volume-level demands or correct the load-
impedance condition which may be causing activation of this circuitry.
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Distortion Alert LEDs
The Distortion Alert circuit is a unique ADCOM distortion detection system which reads all
forms of non-linear distortion such as THD, IM, slew-induced, "clipping”, etc. The Distortion Alert
LEDs will light when distortion reaches approximately 1% regardless of impedance,
voltage/current phase angle or the reactance of the loudspeakers which the amplifier is driving.
Sometimes, when the amplifier is in use, the LEDs may occasionally flicker during high volume
listening, particularly if you are driving low impedances. This flickering is no cause for concern.
The LEDs are simply warning you that the amplifier is approaching its maximum power output into
the particular loudspeakers you are using. If, however, the Distortion Alert LEDs glow brightly or
are illuminated most of the time during playback, you are overdriving the amplifier and should turn
down your volume control to reduce the listening level, otherwise it may cause the Thermal
Protection to be activated or, in extreme cases, damage your loudspeakers.
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