Orban OPTIMOD-FM 8500S Operating Manual page 225

OPTIMOD-FM DIGITAL
MB Limit Thr 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 presets rely on considerable clipping to achieve their
loudness and brightness. For these presets, we found it necessary to set
the MB L
clipping depth. In some cases, this results in substantially objectionable
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
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
trol.
If you set this control too low, (and/or set the MB C
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 8500S-style presets only) limit
the maximum amount of final clipper drive reduction (in dB) that the 8500S's clip-
ping distortion controller can apply in Music and Speech modes respectively, pre-
venting over-control of transient material by the distortion controller. Instead, the
final clipper 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 8500S-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
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.
High Frequency Limiter sets the amount of additional gain reduction occurring in
band 5 when high frequency energy would otherwise cause excessive distortion in
the final clipper. It uses an analysis of the activity in the final clipper to make this de-
T control substantially higher than "0" to permit more
IMIT HR
OPERATION
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IMIT HR
con-
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IMIT HR
control too
LIPPING
LIP
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