Introduction To Processing; Some Audio Processing Concepts; Distortion In Processing - Orban OPTIMOD 6300 Operating Manual

3-4
OPERATION

Introduction to Processing

Some Audio Processing Concepts

Distortion in Processing

See also Figure 1-1: Simplified Block Diagram of Dialnorm Control on
page 1-2.
To avoid
we recommend using PC Remote for doing serious setup and tuning.
Reducing the peak-to-average ratio of the audio increases loudness. If peaks are re-
duced, the average level can be increased within the permitted modulation limits.
The effectiveness with which this can be accomplished without introducing objec-
tionable side effects (such as pumping or intermodulation distortion) is the single
best measure of audio processing effectiveness.
Compression reduces the difference in level between the soft and loud sounds to
make more efficient use of permitted peak level limits, resulting in a subjective in-
crease in the loudness of soft sounds. It cannot make loud sounds seem louder.
Compression reduces dynamic range relatively slowly in a manner similar to riding
the gain. Limiting and clipping, on the other hand, reduce the short-term peak-to-
average ratio of the audio.
Limiting increases audio density. Increasing density can make loud sounds seem
louder, but can also result in an unattractive busier, flatter, or denser sound. It is im-
portant to be aware of the many negative subjective side effects of excessive density
when setting controls that affect the density of the processed sound.
Clipping sharp peaks does not produce any audible side effects when done moder-
ately. Excessive clipping will be perceived as audible distortion.
Look-ahead limiting is limiting that prevents overshoots by examining a few milli-
seconds of the unprocessed sound before it is limited. This way the limiter can an-
ticipate and control peaks that are coming up.
In Dolby Digital transmission channels, appropriate setting of the
D
metadata parameter will allow enough headroom to keep peak
IALNORM
levels below the threshold of the 6300's look-ahead peak limiters. The
best sounding limiting is no limiting at all.
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.
having to toggle the
ORBAN MODEL 6300
meters between functions,