Optimod-AM 9400 V1.2 Operating Manual - Orban

5-6
TROUBLESHOOTING ORBAN MODEL 9400
duce loudness reduces peak limiting simultaneously, minimizing potential codec artifacts.
Only turn down the output level control to correct codec clipping.
Loudness Decreases Momentarily When the Radio Crossfades between Analog
and Digital Channels
The analog and digital channels may be in reverse polarity (“out of phase”) from
each other. Try both settings of the POLARITY control associated with the output driving
the digital channel to determine which polarity causes a smoother crossfade. Do
not adjust the POLARITY control of the analog channel output because this will swap
positive and negative peak modulation.
Excessive Sibilance (“ess” sounds) in the Digital Radio Channel
The Band 5 compressor/limiter is mainly useful as a de-esser and to prevent high frequency
artifacts when driving low bit rate codecs like the 36 kbps HDC codec used in
the HD AM system. To use the Band 5 compressor/limiter as a de-esser, set the B5
MAXDELTGR to OFF (to allow the channels to be de-essed independently), set the B5
DELTA RELEASE control to +6 (to achieve the fastest possible release), and set the
B4>B5 COUPLING control to 100% (to prevent high frequency energy from building
up excessively).
“Swishing,” “Phasing,” or “Underwater” Artifacts in the Digital Radio
Channel
Excessive high frequency energy can cause this and can also cause gritty high frequency
distortion in digital channels that use a codec employing “spectral band replication”
technology, such as the HDC (used in HD AM) and aacPlus (used in DRM)
codecs. To use the B5 compressor in the 9400’s digital radio processing channel to
control these artifacts, set the B5 MAXDELTGR to 0 (to minimize the amount of L–R
energy that the processing adds at high frequencies), set the B5 DELTA RELEASE control
to 0 (to achieve a smooth integration with the Band 4 compressor), and set the
B4>B5 COUPLING control to 100% (to minimize high frequency energy build-up).
Then adjust the B5 THRESHOLD control to set the maximum amount of high frequency
energy that the processing can produce with bright program material. It is
wise to experiment with this control while listening to the output of the codec you
are using so you can hear the effect that the Band 5 compression has on codec artifacts.
General Dissatisfaction with Subjective Sound Quality
The 9400 is a complex processor that can be adjusted for many different tastes. For
most users, the factory presets, as augmented by the gamut offered by the LESS-
MORE control for each preset, are sufficient to find a satisfactory “sound.” However,
some users will not be satisfied until they have accessed other Modify Processing
controls and have adjusted the subjective setup controls in detail to their satisfaction.
Such users must fully understand the material in Section 3 of this manual to
achieve the best results from this exercise.
Compared to competitive processors, the 9400 offers a uniquely favorable set of
trade-offs between loudness, brightness, distortion, and buildup of program density.
If your radio station does not seem to be competitive with others in your market,
the cause is usually problems with the source material, overshoot in the transmission
link (particularly the transmitter/antenna system) following the 9400, or an inaccu-