Inovonics David IV, Installation & User Manual

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mat would justify a higher level of Limiter Drive, perhaps on
the order of
8dB
or more (the figure shown below the slider),
and classical or jazz music should use a lower setting, maybe
5dB or less.
Limiter Density
While
Limiter Drive
forces program peaks toward the 100%-
modulation point, Limiter Density serves a similar function for
the average level of the program.
The attack time of the DAVID IV peak controller is matched to
the delay of the limiter ‘lookahead’ feature. Limiter release, on
the other hand, has a dual-slope, ‘platform’ function, with a
quick release to the platform value, and then a much slower re-
lease of the platform itself. The limiter platform is based on
program average energy content, the working value of which is
adjusted with the
Limiter Density
slider.
With the Limiter Density slider fully ‘up’ ( 10.0 on the scale), limiter
release is fast over the entire release range, imparting greatest
density (loudness) to the program audio, but not without some
audible side-effects. As the slider value is scaled back, program
peaks will continue to reach 100% modulation, but the average
level of the program signal will be reduced. This allows the
program audio to retain more of its inherent dynamic range.
A proper setting of the
Limiter Density control is determined en-
tirely by subjective evaluation of the on-air sound. Density is
one very important quality of the station’s signature sound, and
no other control has a greater effect over perceived loudness.
The factory default value is a setting of
5.0
, the center of the
control range. No setting is considered a wrong one, but the
range extremes will probably be relegated to special situations.
Use your ears and consider the long-term listener fatigue effects
of very dense programming.
MULTIPLEX POWER CONTROL (BS.412-9)
The ITU
‘Recommen-
dation’
In 1998, the International Telecommunication Union (ITU), a
key European standards organization, published their Recom-
mendation ITU-R BS.412-9 , the culmination of several years’
work to study and mitigate interference between broadcast sta-
tions on the crowded European VHF-FM band.
Channel spacing, transmitter power and other assigned consid-
erations were major factors in this study, but insofar as audio
processing is concerned, the short version is that the ITU found
direct correlation between FM carrier modulation and audible
interference between stations on adjacent frequencies. What’s
more, it further found that modulation density was in large part
responsible for this interference; that is, not necessarily the ab-
solute peak deviation of the carrier but the r.m.s. power of the
modulating program signal integrated over a specified period
of time.