Orban OPTIMOD 6200, Operating Manual

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OPERATION ORBAN Model 6200
ing is increased, the audible distortion caused by limiting is increased. Lower settings
reduce loudness, of course, but result in a cleaner sound.
You may find it illuminating to recall several Factory Presets, adjust
LESS-
MORE to several points in its range, and then open the Full Control screen
to examine the trade-offs between the release time and
FINAL LIMT
drive
made by the factory programmers.
LC THRESH (Loudness Controller Threshold) sets the maximum subjective loudness
produced by the processing. “0” is a good setting for most DTV programming to ensure
that even highly processed commercials will not be objectionably louder than surround-
ing program material.
Because this is a threshold control, turning it to higher numbers raises the threshold,
which means it does less work.
According to CBS Laboratory’s research, no common meter, whether peak-reading, av-
erage-reading, or even r.m.s.-reading with frequency weighting, can indicate subjective
loudness well enough to be relied upon as an objective measurement tool to prevent
viewer complaints about loud commercials. True loudness meters incorporate elaborate
multiband psychoacoustic models, which agree with average listeners with an accuracy
of typically
±
2dB. Because listeners will disagree amongst themselves by as much as
4dB when asked to assess the loudness of a piece of program material by comparison to
a standardized tone or filtered noise,
±
2dB is about as much accuracy as is usable any-
way. This also means that a peak-reading or average-reading meter connected to the
6200’s output (with Loudness Controller activated) may vary quite a bit in its readings
with different program sources. This just shows the Loudness Controller at work and the
inability of a conventional meter to accurately assess loudness.
Note that the Loudness Controller determines the highest subjective loudness permitted
by the 6200 processing. If a commercial follows a piece of quiet program material whose
loudness never gets to the threshold of the Loudness Controller (for example, a quiet
outdoor scene), then the following commercial will still be louder. Esthetically, this is
unavoidable. The best one can do by automatic control is to ensure that commercials are
no louder than normally modulated sections of programming that surround the commer-
cials.
To defeat the loudness controller entirely, set the
LC THRESH
to
OFF.
For radio pro-
gramming, you will usually want to defeat the loudness controller.
The Multi-Band Structure
The Multi-Band structure consists of a slow gain-riding two-band AGC, a three-band
parametric equalizer, a five-band compressor, a dynamic single-ended noise reduction
system, an output mixer (for the five bands), and a look-ahead limiter.