Omnia Audio Omnia 8x - Manual (Page 31)

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Drive: The sets the audio level that enters the WB-
AGC. Increasing the Drive will produce more
compression. This control is calibrated between –6dB
and +6dB, and adjusts the signal level into the
Wideband AGC. It should be adjusted to net
approximately 12dB of gain reduction with typical
programming. Too little gain reduction can defeat the
“leveling” function of the Wideband AGC. Too much
gain reduction has little additional benefit. Nominal
gain reduction values for the Wideband AGC are
between 10 and 15dB.
Release: Controls the speed of recovery for any given amount of gain reduction. Faster action yields less dynamic
range and the presence of more density to the audio. The Release control sets the time constants in relative terms
using Slow, Medium, and Fast. Because the time constants are program-dependent, calibrating these controls in
absolute time values (ms/dB) would be useless—therefore we use simple terminology.
GATE: When set to ON, it will freeze the gain at the last level of processing action that occurred before the audio
signal fell below the threshold of operation. Correct adjustment of this control helps to minimize “pumping”, and
the increase of background noise during pauses in programming.
MIX
This is where the three multiband processors are
mixed together. Use care in adjusting this section, as
too much level from one particular band may cause an
excessive amount of emphasis to that range of
frequencies. Such adjustment may also drive the final
limiter bands in that range of frequencies too hard,
causing the sound to become unnatural, dense, and
squashed. As explained earlier, if your desire is to
“EQ” the sound, you should perform that function
using the drive levels in the multiband section. The
mixer is primarily intended for minor “EQ” changes
to the overall sound. There is a +/-6dB range
adjustment for each band.
of
Final Limiter
Omnia 8x employs a lookahead limiter to provide absolute and precision peak control. This limiter has been
designed to minimize processing side-affects like IMD, which are usually associated with limiters of this type.
Using an innovative design that cancels intermodulation products before they develop, allows this limiter to sound
extremely transparent. The limiting function is derived using numerous control signals that monitor oneanother.
This type of peak controller is used instead of a clipper because it does not generate the same high levels of THD as
a Clipper does. THD causes added difficulties in a coded audio system, as the harmonics generated from the
clipping action, create added artifacts in the encoder. These are especially annoying at high frequencies.
On the other hand, a lookahead limiter yields extremely low levels of THD, although it will create some IMD
component, and this allows the audio coder to operate with minimal sonic artifacts.
There are tradeoffs in how each of these peak controllers sound when they are set to produce added loudness. When
a clipper is pushed, the audio may appear edgier. This is from the added harmonic content. In contrast, the
lookahead limiter will appear busier, or dense as the action of the control signal may be heard, when more limiting
is applied.