Orban OPTIMOD-FM 8600Si, Operating Manual

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OPERATION ORBAN MODEL 8600Si
gain reduction, the
MB L
IMIT
T
HR
control will have little or no effect. In our example,
the drive level to the MX peak limiter might be reduced by as little as 3 dB.
Another important difference between the
M
ULTIBAND
C
LIPPING
and
P
EAK
L
IMITER
D
RIVE
controls is that the
M
ULTIBAND
C
LIPPING
control setting is tracked by a hidden
M
ULTIBAND
C
LIPPING
control in the digital radio processing chain. Therefore, you can
adjust the
M
ULTIBAND
C
LIPPING
control in the FM chain without needing to reset the
HD L
IMITER
D
RIVE
control to ensure that the FM and HD channels are loudness-
matched. There is no such “hidden” HD control corresponding to the
P
EAK
L
IMITER
D
RIVE
control, so adjusting the
P
EAK
L
IMITER
D
RIVE
control requires you to manually
adjust the
HD L
IMITER
D
RIVE
control by the same amount to preserve the loudness
match in the two channels.
The Two-Band Structure
The Two-Band structure consists of a slow two-band gated AGC (Automatic Gain
Control) for gain riding, followed by an equalization section, a gated two-band
compressor, a high-frequency limiter, and a complex peak limiting system similar to
the one used in the Five-Band structure. Like the “Two-Band Purist” structure in
Orban’s OPTIMOD-FM 8200, the 8600Si’s Two-Band Structure is phase-linear
throughout to maximize sonic transparency.
The Two-Band structure has an open, easy-to-listen-to sound that is similar to the
source material if the source material is of good quality. However, if the spectral bal-
ance between the bass and high frequency energy of the program material is incor-
rect, the Two-Band structure (when its
BAND COUPLING 2>1
control is operated to-
ward 0%) can gently correct it without introducing obvious coloration.
The Two-Band structure is mainly useful for classical or “fine arts” programming that
demands high fidelity to the original program source.
The Protection Presets
There are two Protection Factory Presets. Both use the same DSP code as the Two-
Band Purist structure, but the AGC is defeated.
PROTECTION 0DB
sets the limiting threshold so that limiting almost never occurs,
while
PROTECTION 5DB
sets the limiting threshold so that program material at the
maximum normal input level (as determined by a PPM or VU meter monitoring the
input program line) produces an average limiting of 5 dB.
To set up the Protection Limiter, recall preset
PROTECTION 0DB
if you want limiting
to occur only when the program level exceeds the maximum normal input level as
determined by a PPM or VU meter monitoring the input program line. Recall preset
PROTECTION
5DB
if you want about 5 dB of limiting to occur at the maximum nor-
mal input level.