Orban Optimod-AM 9400 Operating Manual Download

Page: 144 / 295

3-10

OPERATION ORBAN

MODEL

9400

Starting with one of our suggested presets will help keep you out of trouble when
you edit them to create user presets.

We have supplied several presets tuned for the Microsoft WMA (V9) at 32 kbps. This
codec has severe artifacts at this bitrate and no preprocessing can mask them com-
pletely. The 1100’s WMA presets strictly limit the amount of high frequency energy
applied to the codec. To prevent the processing from adding L–R energy, these pre-
sets operate with full stereo coupling and without stereo enhancement.

OPTIMOD-PC’s ability to maintain source-to-source spectral consistency is also an im-
portant advantage. Once you have set up the processing to minimize codec artifacts
caused by a given piece of program material, OPTIMOD-PC’s will automatically
minimize codec artifacts with any program material.

Fundamental Requirements:
High-Quality Source Material and Accurate Monitoring

Very clean audio can be processed harder without producing objectionable distor-
tion. If the source material is even slightly distorted, OPTIMOD-AM can greatly ex-
aggerate this distortion, particularly if a large amount of gain reduction is used. Po-
tential causes for distortion are poor-quality source material, including the effects of
the station's playback machines, electronics, and studio-transmitter link, as well as
excessive clipping settings in the OPTIMOD-AM processing. See

Maintaining

Audio

Quality in the Broadcast Facility

(an Orban publication downloadable from

ftp.orban.com) for a discussion of how to improve source quality.

A high-quality monitor system is essential. To modify your air sound effectively, you
must be able to

hear

the results of your adjustments.

Maintaining

Audio Quality in

the Broadcast Facility

also contains a detailed discussion of how to efficiently create

an accurate monitoring environment.

Low-Delay Monitoring for Headphones

In live operations, highly processed audio often causes a problem with the DJ or pre-
senter’s headphones. Some talent moving from an analog processing chain will re-
quire a learning period to become accustomed to the voice coloration caused by
“bone-conduction” comb filtering. This is caused by the delayed headphone sound’s
mixing with the live voice sound and introducing notches in the spectrum that the
talent hears as a “hollow” sound when he or she talks. All digital processors induce
this coloration to a greater or lesser extent. Fortunately, it does not cause confusion
or hesitation in the talent’s performance unless the delay is above the psychoacous-
tic “echo fusion” (Haas) threshold of approximately 20 ms and the talent starts to
hear slap echo in addition to frequency response colorations.

The normal delay through the 9400’s analog channel processing is about 22 ms and
the delay through the digital channel processing is about 15 ms. A 15 ms delay is
comfortable for most talent because they do not hear echoes of their own voices in
their headphones. However, a better solution to the monitoring conundrum is this:
Any of the 9400’s outputs can be switched to provide a low-delay monitoring feed,
which is the same as the HD-processed output except that no peak limiting is ap-
plied. The monitor feed’s 5 ms delay is likely to be more comfortable to talent than