OPTIMOD SURROUND PROCESSOR OPERATION
3-15
The loudness controller’s attack and release times are tuned to match the loudness
integration times of the ear and are program-adaptive. Only the attack time is user-
adjustable.
If you feel that the loudness controller is not controlling the loudness of commer-
cials or other subjectively loud program material sufficiently well, you may wish to
set the threshold lower, forcing the loudness controller to do more work. Conversely,
if the loudness controller is doing more gain reduction that you would like, you can
set the L
OUDNESS THRESHOLD control higher.
The loudness controller produces both fast and slow loudness control; the fast con-
trol rides on top of the slow control. You can easily see this dual-speed operation on
the L
OUDNESS GR meter. The LOUDNESS ATTACK control determines how much fast
control the loudness controller produces. As the control is turned down toward 0%,
it allows longer and longer loudness peaks to pass through.
Because of the system topology, the 8685’s loudness level meter assumes
that the L
OUDNESS ATTACK control is always set to 100% and does not in-
dicate the effect of lower settings. As long as the control is set to 50% or
higher, this limitation should not have any material effect on the loud-
ness level meter’s accuracy. However, it is wise to double-check the effect
of the L
OUDNESS ATTACK control on subjective loudness by listening tests
and/or use of an external loudness level meter like the free Orban Loud-
ness Meter for Windows, which uses the same algorithm as the 8685’s
built-in loudness level meter (www.orban.com/meter). The free Orban
meter is a two-channel device, but you can use it to assess the effect of
the L
OUDNESS ATTACK control by testing with stereo program material ap-
plied to the 8685’s Lf and Rf inputs.
The loudness controller may reduce the dramatic effect of certain sounds in enter-
tainment programming, like gunshots, explosions, or screeching tires. Operators may
therefore want to turn the loudness controller on during commercial breaks and off
during normal programming. Most sound-for-picture presets have the Loudness
Controller on. (Those that do not have “no LC” in their names.)The easiest way to
handle this situation is to start with your preferred preset, turn the loudness control-
ler off, and then save the result as a User Preset. Using one of the 8685’s remote
control mechanisms (like its GPI inputs), recall the “with loudness controller” and
“without loudness controller” presets as desired.
Slowing the L
OUDNESS ATTACK control provides another way to maintain the dramatic
impact of loudness transients in dramatic programming; it can let gunshots and the
like through while still constraining long-term loudness to a fixed threshold. While
this is an easy solution that does not require your automation system to tell the
8685 when to recall presets, it is not ideal because there are some short-term loud-
ness events, like sibilance, applause, and whistles, that can be annoying to audi-
ences.
In surround mixes with dialog mainly in the center channel, you can ef-
fectively control sibilance with the center channel Band 4 and Band 5
compressors. In the 2.0 processor, you can use the Speech-Mode B4 and
B5 compressor threshold controls to accomplish the same goal.
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