Orban OPTIMOD-FM 8700, Operating Manual

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OPTIMOD-FM DIGITAL OPERATION
3-71
Only the five-band MX presets have Band 5 A
TTACK
controls for the FM
analog processing. In the 8500-style presets, the band 4 and band 5 com-
pressors share one compression sidechain, although their associated clip-
pers and downward expanders operate independently.
MB Limit Thr (available in 8500-style presets only) sets the threshold of the clipping
distortion controller with reference to the threshold of the final clipper, in dB.
For best clipping distortion control, most effective setting for this control
is “0 dB” for almost all program material. However, the loudest and most
intense-sounding 8500-style presets rely on considerable clipping to
achieve their loudness and brightness. For these presets, we found it nec-
essary to set the
MB L
IMIT
T
HR
control substantially higher than “0” to
permit more clipping depth. In some cases, this results in substantially ob-
jectionable distortion artifacts with isolated program material. However,
this is the price to be paid for this extreme level of on-air loudness.
For the NEWS-TALK and SPORTS presets, we set the MB L
IMIT
T
HR
con-
trol slightly below “0.” This ensures the cleanest possible speech quality
at the cost of highest loudness. If you want higher loudness in these pre-
sets, you can edit them to increase the setting of the
MB L
IMIT
T
HR
control.
If you set this control too low, (and/or set the MB C
LIPPING
control too
high) the first artifact that you are likely to notice is intermodulation dis-
tortion between vocals and bass. Be aware of this possibility when you
are adjusting this control, because the effect sometimes becomes clearer
once you are accustomed to listening for it. Headphone listening will
usually increase the audibility of this artifact.
This control does not affect the HD processing chain.
Max Dist Ctrl; Speech Max Dist Ctrl (available in 8500-style presets only) limit the
maximum amount of final clipper drive reduction (in dB) that the 8700i’s clipping
distortion controller can apply in Music and Speech modes respectively, preventing
over-control of transient material by the distortion controller. Instead, the final clip-
per is permitted to control some of the transient material (to increase “punch”),
even though, technically, such clipping introduces “distortion.” A setting of 4 to 5
dB works best in most cases. Factory default is 5 dB for virtually all presets.
This control does not affect the HD processing chain.
HF Clip Threshold (available in 8500-style presets only) sets the threshold of the
multiband clipper in band 5 with reference to the final clipper threshold, in dB. This
clipper helps prevent distortion in the final clipper when the input program material
contains excessive energy above 6 kHz.
The Band 5 multiband clipper operates at 256 kHz and is fully anti-
aliased.
This control does not affect the HD processing chain.
B5 Clip Threshold (UL presets only) has the same functionality as
HF C
LIP
THRESHOLD (
above).
B4 Clip Threshold (UL presets only) sets the threshold of the multiband clipper in
band 4 with reference to the final clipper threshold, in dB.