TC Electronic DB4 MKII - Manual (Page 39)

DMix
English Manual 35
the Loudness Control cannot attenuate the sig-
nal at all.
Max Gain
Range: 0 to +20 dB
This is the maximum gain the Loudness Control
is allowed to perform. If set to 0.0 dB, the Loud-
ness Control cannot add gain to the signal at all.
Freeze Level
Range: -10 to -40 dB
Sets the minimum level required before the
Loudness Control will start adding more gain. It
would typically be set to avoid boosting signals
considered noise. The Freeze Level parameter
is relative to the Reference Level setting on the
Main page.
Freeze Hold
Range: 0 to 5 seconds
When the Input signal drops below the Lo Level,
the Gain Correction of the Loudness Section is
frozen for the duration of the Hold time. When
the Hold period expires, the Gain Correction falls
back to 0 dB gain.
Slow window
Level Trim
Range: -18 dB to + 18 dB
The processing resolution of DMix is 48 bit, so
it’s possible to also convert and correct loud-
ness manually without the risk of overloads. The
Level Trim can be used for permanent gain off-
sets or for risk-free live adjustments.
Level Trim is the perfect control for shifting
broadcast platform loudness target. While a tar-
get loudness of -23.0 or -24.0 LUFS is gener-
ally assumed for the HD platform, that’s too low
for mobile and pod platforms. (Remember how
“LUFS” is the same as “LKFS”. -24.0 LUFS is
the exact same loudness level as -24.0 LKFS).
A suitable loudness target for mobile platforms
is in the range between -11 and -18 LUFS/LKFS.
Based on investigation of the gain structure in
Apple devices, we suggest aiming mobile plat-
forms at -15 LUFS/LKFS. A higher mobile tar-
get level is possible, of course, but at the risk of
damaging audio integrity more than necessary.
(Details in the NAB 2011 BEC paper, “ITU-R
BS.1770 Revisited”, by Thomas Lund).
If the HD platform is aimed at -24 LUFS/LKFS,
and all programs consequently pre-normalized
to that level, DMix may in one pass do format
change, loudness adjustment, loudness target
shifting to -15 LUFS/LKFS, and true-peak limit-
ing. The Target setting in the Loudness section
of DMix should stay around -24 LUFS/LKFS,
while Level Trim should be set to +9.0 dB (the
difference between the HD target and the mobile
platform target).
Note: You may need to also move the All Thresh-
old parameter in the 5-band section up in order
not to invoke too much 5-band processing.
Ratio
Range: 1:1.25 to 1:6
Ratio is the adjustment factor used when the
Loudness section applies boost or attenuation
to aim at a certain Target Level. The higher the
ratio, the more rigid steering towards the Target
Level.
Example: With a setting of 1:2, the Loudness
control section adjusts the gain by 1 dB when
the input is 2 dB off target (if a gain adjustment
is allowed by the Max Attenuation and Max Gain
parameters).
With a setting of 1:1.25, the Loudness control
section adjusts the gain by 1 dB when the input
is 5 dB off target (if a gain adjustment is allowed
by the Max Attenuation and Max Gain param-
eters).
Average Rate (Avg Rate)
Time constants in the Loudness Control are
changed dynamically with the Input signal based
on computations by multi-level detectors. When