TC Electronic DB4 MKII - Manual (Page 68)

ALC 5.1
64 DB4 / DB8 MKII Algorithms
Fig 2
The example shows transition jumps between
programs
1) without ALC5.1 and
2) including ALC5.1 in the signal path.
In the illustration, 11 broadcast programs were
put back over a period of 5 minutes and mea-
sured with Dolby LM100.
The goal in multi-platform broadcast should be
to use the same loudness measure for
– Production
– Ingest
– Linking
– Master Control Processing
– Logging
…thereby ensuring better audio quality not only
in DTV audio, but across all broadcast platforms.
ALC5.1 is ideally used with ITU-R BS.1770 based
loudness meters, such as TC Electronic LM6,
but can also smoothen out level jumps when
normalization is based on Dorrough, PPM, VU or
Dolby’s LM100 meter. ALC5.1 greatly increases
the usability of LM100 because it compensates
for its blind angle: Non-dialog material at unex-
pected mix-levels.
Features
Low latency (1 ms), high resolution loudness pro-
cessor for mono, stereo and 5.1 signals.
Loudness control adhering to ITU-R BS.1770,
EBU R128 and ATSC A/85
True-peak limiting adhering to ITU-R BS.1770,
EBU R128 and ATSC A/85
Presets
ALC5.1 presets are found in the “Loudness, Mul-
tichannel” Engine Factory Bank.
ALC5.1 presets have “Limit” in their name and
perform only negative loudness and peak level
correction. These presets cannot add gain.
ALC5.1 presets have “Correction” in their name.
They may perform both positive and negative
gain correction depending on the loudness of
the signal.
ALC5.1 algorithm – basic use
Two ALC5.1 processors may be loaded in DB4
(additional I/O may be required for two 5.1
streams), while DB8 accommodates two ALC5.1
processors plus room for 2 Stereo ALCs with an
additional I/O card. If the same audio route is
used at the station for changing format between
mono, stereo and 5.1, it may be of advantage to
use ALC5.1 universally rather than switching be-
tween different processor types.
The basic latency of ALC5.1 AES/EBU I/O is 1
ms, and processing is performed at 48 bit reso-
lution. ALC5.1 is primarily designed for use in
broadcast Ingest, Linking and Transmission.
To control ALC5.1 from a PC or a Mac, TC Icon
is used. Screen shots from TC Icon is shown on
the next pages.
ALC5.1 algorithm – main page
ALC5.1 algorithm – main page
Fig 3
TC Icon view of ALC5.1 Main page parameters.
Be sure to use Icon version 3.82 or higher when
controlling ALC5.1