Protections / Status Indicators; Signal Presence Indicators "Signal; Protection Indicators "Overload; Clipping Indicators "Clip - Ecler DT 4800 Notice D'emploi

4.4. Protections / Status indicators

All models feature a non-destructive protection system, leaving audio quality unaffected. The
automatic gain control processor consists in an VCA (Voltage controlled Amplifier) controlling the Input
Signal gain in high stress situations at very low load impedances (2Ω or lower). As opposed to
conventional compression or limiting techniques, the side-effects are not noticeable and most important,
neither dynamic range is reduced nor THD is increased.
Anticlip circuit: This "intelligent" system is an always active protection which constantly analyses
harmonic distortion caused by excessive signal excursion at the power amplifier's output and automatically
reduces the input level according to the transient duration. For transients shorter than 150 ms, it limits so
that 10% THD is allowed, while for transients longer than 150 ms, a maximum THD of 0.1% is allowed.
4.4.a) Signal presence indicators "SIGNAL" (5)
They show the presence of a signal at the amplifier inputs. They light when the
input level is approximately greater than -40dBV.
4.4.b) Protection indicators "OVERLOAD" (3)
Besides lighting up during stand-by mode (when switching on the unit), these
indicators will light up for following reasons:
1- Because there is a short-circuit at the amplifier output. In case of a permanent
short-circuit, the protections will disconnect the amplifier in less than 100µs. The
OVERLOAD indicators can also become active during continuous operation with non-
musical high frequency signals, reducing system gain and thus protecting the tweeters.
2- If the amplifier is supplying DC signal or very low frequencies that could
damage the loudspeaker. The protections detect frequencies under 4Hz.
If these indicators are permanently lit, this is a symptom of malfunction and the
cause should be investigated.
The Autoreset system will cyclically restart the amplifier after about 10 seconds. If the problem still
persists, please consult our Technical Services.
4.4.c) Clipping indicators "CLIP" (4)
They will light when the output signal is slightly under the true clipping threshold. It is usual that the
CLIP indicators shine following the bass frequencies when the amplifier operates at high power levels.
Take care that the CLIP indicators are not permanently lit.
4.4.d) Thermal protection indicator "THERMAL" (1)
It lights when the heatsinks reach critical operating temperature. The amplifier will automatically
restart as the temperature decreases.
8
THERMAL
STAND BY
OVERLOAD
CLIP
SIGNAL
THERMAL
STAND BY
OVERLOAD
CLIP
SIGNAL