Applications - IMG STAGELINE MFE-16M Mode D'emploi

3 Applications

The MFE-16M is a digital feedback eliminator
specially designed for PA systems. It is used to
eliminate acoustic feedback. Feedback occurs
when a signal picked up by a microphone is
amplified and reproduced by speakers and then
picked up again by the microphone. Due to the
loop created, the signal is amplified again and
again resulting in an annoying whistling.
To eliminate feedback, the unit monitors the
input signal. When feedback occurs, it filters out
a narrow band of these feedback frequencies
via up to 12 notch filters for each channel. Thus,
a higher volume for PA applications is possible.
4 Connections
Insert the feedback eliminator into the signal
path where feedback is most likely to occur, e. g.
1. between the microphone preamplifier and
the power amplifier
2. for a mixer: into the input channel for the
vocal microphone (channel insert)
3. for a mixer: into the subgroup for the vocal
microphones (subgroup insert)
4. for a mixer with monitor output to reproduce
the sound for the musicians: between the
monitor output (e. g. Prefader Aux Send) and
the power amplifier
To prevent elimination of deliberate feedback
signals (e. g. from electric guitars), do not route
these signals via the MFE-16M. The easiest
way to do this is to connect the eliminator to an
insert jack of an input channel or to a subgroup
of a mixer where the deliberate feedback sig-
nals are not present.
Prior to making or changing any connections,
switch off the MFE-16M and the units to be con-
nected.
1) Connect the signal source (corresponding
output of a mixer, output of a microphone
preamplifier) to the jacks INPUT (13). For a
mono signal, only connect the jack LEFT/
MONO and engage the button MONO /
STEREO (5).
2) Connect the jacks OUTPUT (12) to the line
inputs of the subsequent unit. When return-
ing the audio signal to a mixer, connect the
jacks OUTPUT to the corresponding return
inputs, to two input channels or to a stereo
input channel
For the mono mode (button MONO /
STEREO engaged), only connect one of the
two jacks OUTPUT, if required. The same
signal is present at these jacks.
3) Connect the low voltage plug of the power
supply unit to the jack "9 V~" (11) and
the power supply unit to a mains socket
(230 V~ / 50 Hz).
5 Operation
CAUTION! For the time being, adjust the
power amplifier for the speakers or the output
signal of the mixer to a low volume; otherwise
feedback may occur and damage your hearing
before the final adjustment of the MFE-16M.
1) Switch on the unit with the POWER switch
(10) on the rear side. The blue LED ON (9)
lights up as a power indication.
2) For the mono mode, engage the button
MONO / STEREO (5); for the stereo mode,
disengage it.
In the mono mode, only the input signal
of the jack INPUT LEFT/ MONO (13) is
processed and fed to the two jacks OUTPUT
(12). The feedback detection is faster in the
mono mode than in the stereo mode.
3) To activate the feedback detection, engage
the button PROCESS (3).
4) To adjust the input level, turn up the control
INPUT LEVEL (1) to such an extent that the
red overload LED CLIP (2) briefly lights up
with music peaks. Then slightly turn back the
control until the LED goes out.
5) Match the output level to the subsequent unit
with the control OUTPUT LEVEL (4).
6) For initial operation
a) Set the sensitivity of feedback detection to
maximum: Starting from the upper posi-
tion BYPASS [LED of the button HOLD
FILTERS (6) and LED of the button AUTO /
FIXED ATTENUATION (8) flashing], turn
the control SENSITIVITY (7) counter-
clockwise to the next position MAX.
b) Set all notch filters to the maximum atten-
uation of 30 dB: If the LED of the button
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