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4.3. Indicators
XPA amplifiers include a simple yet effective indication system.
PROT indicators (4) show the absence of loudspeaker output signal. These indicators may light up for
following reasons:
1. During start-up, until the STANDBY time has passed. This time period is needed for the internal
operating voltages to settle.
2. A short circuit is detected at the loudspeaker terminals.
3. The amplifier is outputting direct current or very low frequency signals that could damage the
loudspeaker.
In any case, should these indicators light permanently, this is a sign of malfunction and the causes should
be investigated.
The clip indicators (3) light up just before the actual clipping threshold at the loudspeaker output is reached.
The clip detection circuit considers supply voltage oscillations, so that a dependable clip reading is achieved, even
when operating with unstable mains voltage. It is usual that the CLIP indicators shine following the bass
frequencies when the amplifier operates at high power levels, as these frequencies carry the main energy. Take
care that the CLIP indicators are not permanently lit.
Signal presence indicators SP (2) show the presence of a signal at the amplifier inputs. They light up when
the input level is greater than -40dB.
5. CLEANING
The front panel should not be cleaned with dissolvent or abrasive substances because silk-printing could
be damaged. To clean it, use a soft cloth slightly wet with water and neutral liquid soap; dry it with a clean cloth. Be
careful that water never gets into the amplifier through the holes of the front panel.
