AMCL2 Professional Series
AUTOMATIC MULTIBAND CONTROL LIMITER
INTRODUCTION
INTRODUCTIONINTRODUCTION
INTRODUCTION
The Automatic Multiband Level Control AMCL2 has
been specially developed to control the sound
pressure level in an environment.
A typical example would be an amplification system
in a public premises, which must guarantee a
maximum music programme level equal to and not
exceeding the legal limits. Use of the unit AMCL2, if
correctly regulated, allows you to indeterminately
respect such restrictions even in the face of involuntary
intervention on the signal source regulation.
On the contrary to what happens to traditional
equipment, l’AMCL2 ensures a result of the maximum
quality: the sound is not affected by modulation or the
awful effects of “pumping”. Thanks to the special
circuitry adopted, the musical message is rich in
clarity in the bass notes and highly defined in the
acute ones.
FUNCTION
FUNCTIONFUNCTION
FUNCTION
The Automatic Multiband Level ControlAMCL2 has
been contrived as unitary gain equipment, fitted with
just four regulators: the input level, the release time
and the controls on the threshold intervention.
The reduced number on controls on the front panel
makes installation and tuning easier.
A locking panel prevents possible tampering by
unauthorised persons, as required by law.
AVANTAGES OF MULTIBAND LIMITERS OVER WIDE
AVANTAGES OF MULTIBAND LIMITERS OVER WIDEAVANTAGES OF MULTIBAND LIMITERS OVER WIDE
AVANTAGES OF MULTIBAND LIMITERS OVER WIDE
BAND LIMITERS
BAND LIMITERSBAND LIMITERS
BAND LIMITERS
Wide band limiters are affected by a significant
problem: the spectral gain intermodulation. In practice
the level of one part of the spectrum controls the level
of the other. A typical example is when a voice is over-
ridden by a drum roll or the sudden insert of a
speaker that lowers the rest of the music programme.
The highest energy contained tends, in fact, to control
the rest of the entire spectrum. So when the lowest
frequencies exceed the threshold limit, the highest
frequencies are toned down causing the effect of a
deep output sound.
A multiband limiter, in contrast to a wide band limiters
not subject to this type of behaviour. A multiband
limiter actually separates the audio signal into more
frequency bands and processes each band
separately. However with such a system the
parameters to control are more numerous and
complex.
The Automatic Multiband Level Control AMCL2 uses
an intelligent circuit that automatically controls all the
parameters reducing the commands to a minimum.
AUTOMATIC THRESHOLD CORRECTOR
AUTOMATIC THRESHOLD CORRECTORAUTOMATIC THRESHOLD CORRECTOR
AUTOMATIC THRESHOLD CORRECTOR
A multiband limiter divides the audio signal in more
bands, limits each band individually, and adds them
together. The result of this addition could be, however,
to have a level different from the present threshold
The conventional method provides for a wide band
limiter that elaborates the addition single bands. In
this case the disadvantages of a wide band limiter
would be introduced as previously described. In the
AMCL2 the addition of the two bands is sent to an
automatic threshold correction circuit. If the addition
exceeds the reference value the circuit individually
modifies the threshold of each band. When the
addition returns to below the reference value, the
individual thresholds of each band returns to the
original value. Such a method protects the maximum
brilliance of the sound without introducing noticeable
distortions.
Finally the AMCL2 adopts a single automatic
correction circuit for both channels: this allows for a
perfect balance of stereo image ensuring an equal
limitation of both stereo channels.
RELEASE TIME
RELEASE TIMERELEASE TIME
RELEASE TIME
The release time regulation allows for the musical
programme density modification. An extremely short
release time gives a very narrow dynamic range that
can cause distortion at low frequencies. With a
moderately short release time the output is
maintained as near as possible to the maximum. With
quite a long release time the distortion is reduced
and a softer rounder sound obtained. An extremely
slow release time determines a lower average value
output especially if the musical programme contains
notably quick variations in level (transient).
POWER SUPPLY
POWER SUPPLYPOWER SUPPLY
POWER SUPPLY
This machine has been made for use with a power
supply of 230 Vac 50/60 Hz.
The auto-reset protection fuse is situated inside.
CONTROLS AND FUNCTION
CONTROLS AND FUNCTIONCONTROLS AND FUNCTION
CONTROLS AND FUNCTION
Control of threshold levels
Control of threshold levelsControl of threshold levels
Control of threshold levels
The Automatic Multiband Level Control AMCL2 has
three controls to regulate the threshold level. The first
(5 of Fig.1),distinguished by our logo COARSE, is
achieved by a commutator (switch) with a passage of
2dB, and a range of intervention from –20dBm to
+2dBm.
The second, much more precise and distinguished by
the logo FINE (6 of Fig.1), allows for preceding
regulation correction with a field of action from –1dB
to +1dB.
If the level of the music programme to be controlled
too high and the COARSE control not enough, it is
possible to insert a third control, distinguished by the
