Orban OPTIMOD-FM 8700, Operating Manual

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OPTIMOD-FM DIGITAL OPERATION
3-55
band compressor/limiters. (Changing the setting of each B
X
T
HRESHOLD
control by an
equal amount would produce the same effect as changing the M
ULTIBAND
C
LIPPING
control by this amount.)
The M
ULTIBAND
C
LIPPING
control is partially redundant to the P
EAK
L
IMITER
D
RIVE
con-
trol because when the multiband compressors are producing a considerable amount
of gain reduction, both controls affect the level applied to the MX peak limiter. In
this case, these controls are effectively cascaded and their effect is additive. For ex-
ample, turning down the
M
ULTIBAND
C
LIPPING
control by 2 dB and turning down the
P
EAK
L
IMITER
D
RIVE
by 3 dB reduces the drive level to the MX peak limiter by 5 dB
when the multiband compressors are producing a considerable amount of gain re-
duction. However, when the multiband compressors are producing little or no 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. The Two-Band structure can be used with
the MX-style peak limiter (to achieve highest performance) or with an 8500-style
peak limiter (to achieve lower delay). Like the “Two-Band Purist” structure in
Orban’s OPTIMOD-FM 8200, the 8700i’s Two-Band Structure is phase-linear through-
out 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
balance between the bass and high frequency energy of the program material is in-
correct, the Two-Band structure (when its Band Coupling 2 > 1 control is operated
toward 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.
Setting Up the Two-Band Structure for Classical Music
To set up the Two-Band structure, recall preset
CLASSICAL-2B, CLASSIC-2B MX,
CLASSICAL-2B+AGC,
or
CLASSIC-2B+AGC MX
presets.