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| Section 3
There is no precise recipe for setting up audio processing. While there are some basic fundamentals which
can be used to get started toward the desired sound, it may require a concerted effort with extended listen-
ing and subtle processing changes over time to achieve the ultimate goal. It’s very helpful to know the goals,
take time, and adjust methodically.
It’s perfectly acceptable for the final mix to be loud. In the past, loudness was a problem due to the limita-
tions of the processors of the day. In the quest for ultimate loudness, older processors were probably either
adjusted (or modified) well outside of their “safe” range. Another method was to push the 0dBfs ceiling
level in the signal chain and accept the by-products of the interactions and conflicts among them.
ProSTREAM can change that. The Omnia processing is designed to look at the incoming audio and make
the final mix consistently loud without the artifacts or grunge created by older processors. ProSTREAM
makes loudness an effortless exercise.
The trade-off between quality and loudness is primarily determined by the limiting and clipping sections.
While each function alone will generate added loudness, each has its strength as well as side effects.
When excessive limiting is used, inter-modulation distortion is increased, making the audio sound “mushy”,
and “smeared.” The added short term density can also cause the audio to be “tight”, “squashed”, or “dense.”
The “dynamics” artifacts caused by excessive limiting might sound like “pumping,” or “breathing.” The
suggestion for limiting is “a little goes a long way.”
When excessive clipping is used, harmonic distortion is increased. The audio level is in effect “running into the
brick wall.” Too much clipping can cause the audio to sound “broken-up,” “torn,” “rough,” or “edgy.” The
harder the limiters and clippers are driven, the louder the audio perception. However, increased inter-
modulation and/or harmonic distortion is likely to occur.
Resist the temptation to crank up the aggressive processing sections, like the limiters. Those will add loud-
ness, but usually at the cost of quality. Many times, building a little more RMS level in the AGC sections will
do the trick instead, and with no obvious sonic penalties. Here in order are the best places to start:
1.
Alter the following parameters in the AGC sections:
♦
Increase the AGC Drive to the WB (wideband) AGC section.
♦
Increase the Drive to each band of the multiband AGC screen.
♦
Decrease the Release time settings in each band to make it operate faster.
2.
Drive the final limiter section harder.
3.
Use combinations of the above steps, but in small increments. When multiple changes occur, it
becomes difficult to determine why the result of an adjustment did or did not make sense. Focus on
one specific area the processed sound at a time. Once that area is satisfactory, then move the focus to
the next area, as needed.
It may be desirable to have the processing be perceptibly loud, but dynamic. This may give the
illusion of loudness, retaining detail and clarity, but reduce listener fatigue. This can be achieved by
centering efforts in the multiband section and avoiding heavy use of the final limiter. One trick is to
use fast release times in the multiband limiters, but do not let them produce more than 5 dB - 7 dB
of gain reduction. This keeps the IM distortion of the limiters to a minimum, and doesn’t “over-
squash” the audio. When adjusted in this manner, the limiter sections are relied upon to generate
higher long-term RMS levels, which translates into increases in perceived loudness.
If a “loud and proud” signature is desired, then use more from the limiters. Loudness at all costs is usually the
reason for utilizing more aggressive limiting. Using larger amounts of drive to the multiband limiters, along
with faster release times will generate a signal of high short-term density. The effect of this type of process-
ing is that the audio is consistently loud at all times, or a “wall of sound.” The drawback, however, is the
