Orban Optimod-PC 1101, Operating Manual

Page: 111 / 258

OPTIMOD-PC INSTALLATION
2-55
Problems Specific to Dolby Digital Transmissions
Loudness incorrect compared to other Dolby Digital Transmissions
•
Review Setting Preset Loudness Correctly in Dolby Digital Transmission on page
2-42.
•
Be sure that the active
D
IALNORM
setting in the 1101 is the same as the
D
IALNORM
setting you are transmitting to consumers. Use a device like the Dolby LM100
Loudness Meter to read out the Dialnorm you are transmitting to your audience
(or simply check the Dialnorm setting of your Dolby Digital encoder). See
Setting
Preset Loudness Correctly in Dolby Digital Transmission on page 2-42.
•
Be sure that the 1101’s input drive level is set to produce normal amounts of gain
reduction. See step 4 on page 2-36.
Note that only “TV” presets are designed to produce calibrated loudness
when used with the 1101’s Dialnorm support. Any radio-style preset can
be edited to activate the Loudness Controller.
•
If the loudness controller is on, be sure that the
L
OUDNESS
T
HRESHOLD
control is
set to 0 dB. (In software version 3.1, this was changed from –10 dB to be more in-
tuitive.)
This matches the loudness controller’s threshold to the 1101’s active
D
IALNORM
value.
•
Once
D
IALNORM
is correct, be sure that your active preset is causing the 1101’s
L
OUDNESS
G
AIN REDUCTION
meter to indicate approximately 3 dB of gain reduction
on normal dialog. Adjust its
MB L
IMIT
D
RIVE
control if it does not. When the loud-
ness controller is operating normally, the 1101’s L
OUDNESS
L
EVEL
meter should be
peaking around 0 dB on dialog. If it is not and you are using a custom preset, you
might get better loudness control by slightly tweaking the
L
OUDNESS
T
HRESHOLD
control to make the
L
OUDNESS
L
EVEL
meter peak around 0, bearing in mind that
the correct setting is –10 dB for typical sound-for-picture processing. A maximum
variation of
±
1 dB will typically suffice.
If the 1101’s active D
IALNORM
setting is not the same as the D
IALNORM
set-
ting you are transmitting to your audience, the 1101’s Loudness Level
meter will be calibrated incorrectly, so even if the meter is peaking at 0
dB, loudness at the consumer’s receiver will not be correct.
Note that because the 1101’s Loudness Level meter shares the loudness
controller’s filterbank, the meter does not show the effect of the
L
OUDNESS
A
TTACK
control, which shapes the loudness controller’s gain re-
duction signal outside the loudness controller’s feedback loop. Therefore,
if you are using values of L
OUDNESS
A
TTACK
below about 50%, the loudness
of transient events may be significantly higher than the Loudness Level
meter indicates.
Loudness Controller reduces transient punch of programming
•
Reduce the amount of fast gain reduction in the loudness controller by setting
the
L
OUDNESS
A
TTACK
control closer to 0 %. This will allow more short loudness
peaks to pass through without attenuation by the loudness controller. We be-