Algorithm Manual Revision 4

ALC 6
172 System 6000 MKII Algorithms – Firmware version 6.5.0
threshold is exceeded on the LFE channel, LFE
is limited independently.
C, LR, LFE
If the threshold is exceeded in the Center chan-
nel, only that channel is limited. If the threshold
is exceeded in one of the other Main channels,
all Main channels excluding Center are limited. If
the threshold is exceeded on the LFE channel,
only that channel is limited. Note Profile setting
interaction.
Profile
Use Profile to optimize the adaptive true-peak
limiter based on content, or based on the output
platform.
For linear (baseband) delivery, and for most other
codecs including AAC, use “Dynamic” for sensi-
tive content, “Voice” for predominantly speech
or “Universal” for all-round adaptive settings.
For AC3 delivery, use the “AC3 Codec” Profile
setting.
For all settings except for “AC3 Codec”, the true-
peak threshold is the same for all channels. For
“AC3 Codec”, however, AC3 downmix headroom
is protected, while the dynamic properties are
the same as “Universal”.
ALC6 in use
For TC loudness adjustment processors, the
main goal is to facilitate a practical, high quality
audio signal-path compliant with the standards.
Hitting a Target number is important, but the
spirit of our new, transparent audio standards is
even more so. Merely adding a “sausage proces-
sor” at the end of a transmission chain is a mis-
understanding that should be avoided.
The first point of any loudness correction is to
make the static gain offset (“normalization”) as
relevant as possible. In ALC6, this always in-
volves a proper setting of the Input Level pa-
rameter on the Main page, so the dynamic
changes can stay as small as possible. Input
Level may be positive or negative, and it should
be adjusted based on the average input loud-
ness, see the following application sections.