Orban OPTIMOD-FM 8600Si, Руководство по эксплуатации

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OPTIMOD-FM DIGITAL OPERATION
3-5
Simple wideband look-ahead limiting can still produce audible inter-
modulation distortion between heavy bass and midrange material. The
look-ahead limiter in your Optimod uses sophisticated techniques to re-
duce such IM distortion without compromising loudness capability.
Distortion in Processing
In a competently designed processor, distortion occurs only when the processor is
controlling peaks to prevent the audio from exceeding the peak modulation limits
of the transmission channel. The less peak control that occurs, the less likely that the
listener will hear distortion. However, to reduce the amount of peak control, you
must decrease the drive level to the peak limiter, which causes the average level
(and thus, the loudness) to decrease proportionally.
Loudness and Distortion
In FM processing, there is a direct trade-off between loudness, brightness, and dis-
tortion. You can improve one only at the expense of one or both of the others.
Thanks to Orban’s psychoacoustically optimized designs, this is less true of Orban
processors than of others.
In the 8600Si, the tradeoff between brightness and the other two parameters has
been considerably improved (by 2.5 – 3 dB above 6 kHz) when an “MX” preset is ac-
tive compared to when an “8500-style” preset is active. Nevertheless, all intelligent
processor designers must acknowledge and work within the laws of physics as they
apply to this trade-off.
Perhaps the most difficult part of adjusting a processor is determining the best
trade-off for a given situation. We feel that it is usually wiser to give up ultimate
loudness to achieve low distortion. A listener can compensate for loudness by simply
adjusting the volume control. However, there is nothing the listener can do to make
an excessively compressed or peak-limited signal sound clean again.
If processing for high quality is done carefully, the sound will also be excellent on
small radios. Although such a signal might fall slightly short of ultimate loudness, it
will tend to compensate with an openness, depth, and punch (even on small radios)
that cannot be obtained when the signal is excessively squashed.
If women form a significant portion of the station’s audience, bear in mind that
women are more sensitive to distortion and listening fatigue than men are. In any
format requiring long-term listening to achieve market share, great care should be
taken not to alienate women by excessive stridency, harshness, or distortion.
OPTIMOD-FM—from Bach to Rock
You can adjust OPTIMOD-FM so that the output sounds:
•
As close as possible to the input at all times (using the Two-Band structure), or