Alesis ML-9600 Manual De Referencia
Chapter 5
30
A
LESIS
ML-9600 R
EFERENCE
M
ANUAL
5.4
C
DSP3:L
OOK
-A
HEAD
P
EAK
L
IMITER
The Look-Ahead Peak Limiter is designed to give you the ability to limit the highest peaks in a Track
and simultaneously bring up the gain of the Track in order to maximize its level before creating a CD.
This allows you to "squeeze" that extra couple of decibels out of the dynamic range, without squashing
your audio by hard compression or traditional limiting.
The limiter in the ML-9600 is very different than a traditional limiter, which is typically thought of as a
compressor with a high ratio setting. By virtue of all-digital processing, the limiter is able to "look
This allows you to "squeeze" that extra couple of decibels out of the dynamic range, without squashing
your audio by hard compression or traditional limiting.
The limiter in the ML-9600 is very different than a traditional limiter, which is typically thought of as a
compressor with a high ratio setting. By virtue of all-digital processing, the limiter is able to "look
ahead" in time to see audio level peaks. This allows the limiter to begin smoothly reducing the gain of
the audio so that when the peak does occur, it is limited to the desired value. In essence, the limiter
becomes a "perfect" limiter or one capable of attaining an infinity-to-one gain reduction ratio.
Another difference from a traditional limiter is that the "make-up" gain is automatically applied as a
function of the threshold level. This allows the limiter to act as a "maximizer", enabling you to bring
the audio so that when the peak does occur, it is limited to the desired value. In essence, the limiter
becomes a "perfect" limiter or one capable of attaining an infinity-to-one gain reduction ratio.
Another difference from a traditional limiter is that the "make-up" gain is automatically applied as a
function of the threshold level. This allows the limiter to act as a "maximizer", enabling you to bring
your Tracks very close to the maximum level allowed without clipping.
The final difference in this limiter is that the final output level can be fixed as a function of full-scale; i.e.
the limiter has infinity-to-one compression ratio with an extra gain stage at its output. This allows you
to decide what the peak output value of the audio will be (-0.2dBFS, for instance).
The final difference in this limiter is that the final output level can be fixed as a function of full-scale; i.e.
the limiter has infinity-to-one compression ratio with an extra gain stage at its output. This allows you
to decide what the peak output value of the audio will be (-0.2dBFS, for instance).
The Look-ahead peak limiter is perhaps best thought of as three discrete gain blocks:
•
The first gain block is dynamically adjusted so that its output level never exceeds the threshold
level (the "perfect" limiter).
level (the "perfect" limiter).
•
The second gain block adds make-up gain to the signal equal and opposite to the threshold value (a
threshold value of –10dBFS would have 10dB of make-up gain applied).
threshold value of –10dBFS would have 10dB of make-up gain applied).
•
The third gain block is a "scaling" gain block; it allows you to select the exact maximum output
level (as a function of full-scale). If this gain block were not there, the automatic make-up gain
would cause all signals that reached the threshold to equal 0dBFS.
would cause all signals that reached the threshold to equal 0dBFS.
There are only three parameters in the limiter DSP block, so it is extremely easy to set up and use. A
detailed look at each of the parameters follows.
Threshold
The Threshold parameter of the limiter sets the maximum output level from the first gain stage. No
detailed look at each of the parameters follows.
Threshold
The Threshold parameter of the limiter sets the maximum output level from the first gain stage. No
gain reduction is applied as the signal level approaches the threshold, but once it does, the limiter holds
the output of that stage to the threshold value. Make-up gain is applied to the audio after it has been
limited to the threshold value, so if audio is playing while the threshold parameter is adjusted
downward, the output audio will appear to get louder. The threshold parameter is adjustable from –
0dBFS to –65dBFS in 0.5dB increments.
the output of that stage to the threshold value. Make-up gain is applied to the audio after it has been
limited to the threshold value, so if audio is playing while the threshold parameter is adjusted
downward, the output audio will appear to get louder. The threshold parameter is adjustable from –
0dBFS to –65dBFS in 0.5dB increments.
Output Level
The Output Level parameter sets the absolute maximum output level from the limiter, as a function of
full-scale. A value of –0.1dB will limit the output audio to no greater than –0.1dBFS, regardless of input
level or threshold setting. The output level parameter is adjustable from 0dBFS to –65dBFS in 0.1dB
increments.
The Output Level parameter sets the absolute maximum output level from the limiter, as a function of
full-scale. A value of –0.1dB will limit the output audio to no greater than –0.1dBFS, regardless of input
level or threshold setting. The output level parameter is adjustable from 0dBFS to –65dBFS in 0.1dB
increments.
Release
The release parameter functions exactly like its counterpart in the compressor; it controls how long gain
reduction is applied to the audio after the input signal drops below the threshold. Release is adjustable
from 0 microseconds to 9.9 seconds.