LEM T5A, Owner'S Manual

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with the LEM sub-woofer T5SA.
14. CD PLAYER SW: this is the CD PLAYER PRESET
with a 100Hz high-pass fi lter for the use of the T5A
with the LEM sub-woofer T5SA.
15. WALL MOUNT SW: this is the WALL MOUNT
PRESET with a 100Hz high-pass fi lter for the use
of the T5A with the LEM sub-woofer T5SA.
16. MIC PLUG&PLAY: this PRESET can be used
when you connect a dynamic microphone directly
to the T5A input. The equalization contained in
this PRESET allows to get from the microphone
a brilliant and intelligible response even
without using a mixer. In addition the use of the
ANTI-FEEDBACK plugin allows the feedback
phenomena to be reduced to the minimum (see
the ANTI-FEEDBACK section).
8. The protection system
The DPPM module includes a series of digital algorithms
that allows very high level of protection of the speakers
and the amplifi ers to be achieved (see
fi g. 2 ).
- PEAK LIMITERS : they are able to avoid with
extreme precision the amplifi er’s clipping and, at the
same time, to control the maximum peak power sent
to the loudspeakers. The SIGNAL/LIMIT LED on the
module’s panel lights (RED color) when the LIMITERS
are active.
Note: even if the digital LIMITERS can work with
extreme precision and effi ciency, it’s always advisable
to avoid too high signal levels and to prevent the LIMIT
LED to blink
- LONG TERM POWER PROTECTION : this protection
acts when the T5A is used continuously at the
maximum power allowed for each loudspeaker. The
digital processor is able to detect if one of the system’s
loudspeaker is reaching the maximum temperature
allowable for its voice coil. In this case, the output signal
(and, consequently, the power applied to that speaker)
is slowly reduced in order to take back the system within
safety limits. The power reduction is maintained until the
critical condition remains. As soon as a normal working
condition is restored, the power is gradually taken back
to the nominal level. This protection, which is completely
automatic and doesn’t affect the dynamic performance
of the system, is able to prevent damages to the
speakers when the T5A is used in extreme conditions.
- LFC (Low Frequency Control) : this is a frequency-
dependent compressor able to perform an additional
protection over a limited frequency band where the
woofer is more liable to be damaged by excessive
power.
9. How the PLUGINS work
- MULTICOMP : it’s a multiband compressor made of
two separate compression units able to operate on two
user-selectable frequency bands (HIGH and LOW). The
MULTICOMP is used in some of the T4A’s PRESETS
for the system’s dynamic EQ, to obtain loudness effects
or to apply an additional protection on defi ned frequency
bands.
- NOISE GATE : it’s a dynamic fi lter able to eliminate the
background noise coming from the devices connected
to the enclosure input. The NOISE GATE fi lter is active
on all the T4A’s PRESETS (with the exception of the
STAGE MONITOR and MIC PLUG&PLAY PRESETS).
- ANTI-FEEDBACK : it’s a system able to identify
feedbacks and automatically reduce them by means
of 10 notch fi lters. 7 of the 10 available notch fi lters
operates in SINGLE mode, meaning that once they
have been placed on a certain frequency they remain
on that frequency until the RESET button is pressed.
The remaining 3 fi lters operate in AUTO mode and,
therefore, once they have been placed on a certain
feedback frequency, every time a new one is identifi ed
by the system, they move from the original one to the
new one. All the fi lters are reset every time the T5A is
switched off and, when it is switched on, they can be
activated again if some feedback frequency comes
out.
The ANTI-FEEDBACK PLUGIN is active in the STAGE
MONITOR and MIC PLUG&PLAY PRESETS. To make
the most of it we suggest to follow this procedure:
a. place the speakers and the microphones in their
usual positions;
b. raise slowly the microphone’s volume until the
feedbacks are produced by the speakers: the
system will place the notch filters on the feedback
frequencies;
c. if needed, move the microphone all around the area
where they will be used;
d. take back the microphone’s volume at its normal
level.
Now the notch filters have been placed on the
frequencies where the feedbacks are more likely to
appear and, therefore, in case the microphone level
is raised during the performance, they will be able to
reduce them.
ATTENTION!!!
The T5A’s ANTI-FEEDBACK in not able to eliminate
completely the feedbacks, but it can reduce the risk
that they happens during a performance. This allows
the use of the system at a higher level than usual
and also in critical conditions as, for example, with
the microphones placed in front of the speakers or