Montarbo T18A Manuel D'instructions page 13

Input sensitivity and clipping. How to avoid clipping
Every amplified speaker system is characterized by a value of input
sensitivity. The sensitivity is defined as the value of the amplifier's
input signal that will result in maximum power output.
An increase in input signal over that threshold will result, not in
increased power, but in a distortion phenomenon called 'clipping'
(output stage saturation).
In this condition, the speaker will operate improperly.
The diaphragm will exceed it's excursion limits, and the voice coil
will overheat beyond it's thermal limits, resulting in overheating
and premature failure. The active processors will help in avoiding
clipping, by reducing the amplifier gain and thus the input sensiti-
vity, but this type of protections may be overridden in very extreme
conditions.What the active processor cannot modify is a signal that
is distorted before getting to the active speaker's input.
The effects of this type of signal are the same as described above.
How to avoid clipping
The simplest way to avoid clipping is to check each level in the
signal's chain. Start from each input channel of the mixer and
adjust the gain control and the equalizer's controls so that the PFL
meter will never (or only occasionally) indicate more than 0dB.
In simpler mixers, check that the 'clip' or 'peak' indicator is always
off, or blinks only occasionally.
If these levels are exceeded, reduce the channel's input gain.
Once the desired mix is obtained, adjust the output level so
that it never exceeds the active speaker's or the power amplifier's
input sensitivity, as displayed on the master output VU-meter.
In models T18A, T15A and T12A the input sensitivity is 0dB.
3-way, bi-amplified, active loudspeaker systems
Hanging the T18A speaker. Tips and warnings.
The T18A loudspeaker system is equipped with M10 threaded
fittings to accommodate accessories for suspensions of the
enclosures. The first thing to do is decide which of the anchoring
points will be used for suspension. Once the anchoring points have
been determined, remove the dummy screws and replace them
with M10 eye bolts.
ATTENTION: whenever the eye bolts are removed you must be sure
to replace them with the dummy screws.
Please bear in mind that all hanging installation jobs are carried out
under the sole responsibility of the person doing the actual work
and must be done in full compliance with all the applicable safety
rules and regulations.
We do not attempt to provide detailed guidelines for all the poten-
tial ways in which these extremely flexible systems can be installed,
but do want to remind you that to ensure a safe installation, it is
necessary to adhere to the following:
1 - When hanging the speakers, use only means of suspension
(in accordance with the safety regulation valid in the country of
use) having a carrying capacity rated and guaranteed by the
manufacturer.
2 - Never depend on only one means of suspension for hanging
speakers (for example one chain); always use at least two of them
and make sure they are sufficiently strong. So, if one fails the other
will sustain the load.
3 - Never hook a speaker to the one above.
Each speaker must be individually hooked to the supports.
4 - Always make sure that the truss structure intended to support
the speakers is sturdy enough to hold their weight, even under
stressful, adverse conditions.
Always consider the effect of additional loads (for example, the
wind in case of outdoor installations).
T18A / T15A / T12A
ENGLISH
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