Advertisement
Chapter 3: Processing Overview
This chapter presents an overview of the processor using the block diagram from the Omnia-3fm Turbo to
provide a guide to the various processing sections. Not all processing sections discussed in this section are
found in each style. Refer to the chapter on your specific style for additional processing information including a
style-specific block diagram and a Parameter Worksheet.
Note: More detailed technical information about the audio processing employed in Omnia-3 can be found in the
Technical Papers section on the Omnia web site (www.omniaaudio.com).
The Omnia-3 and Audio Processing
There are thirteen possible processing blocks depending on which style of Omnia-3 is being discussed.
Common to all styles are an input AGC circuit for initial level control, bass and warmth EQ adjustment
sections, a multiband crossover section, a multiband limiter, a mixer circuit and a final limiter at the output. The
following block diagram presents the order of these processing blocks as used in the Omnia-3fm Turbo.
Wideband AGC: A very flexible wideband leveler section to provide transparent and smooth control of the
input program. This is achieved through two significant innovations: a dual referenced gate and an intelligent
"makeup" gain algorithm. The dual gate reference is a unique process that references the input dynamics to a
"rolling" reference level.
A user-adjustable Make-Up Gain feature uses an algorithm incorporating a hidden control signal that knows
when a sustained softer portion of program is occurring. It then "fills in" the softer section so that the average
level is increased. This allows the overall AGC function to operate with a slower time constant, yielding lower
intermodulation distortion without losing loudness in the softer passages.
As an example, with classical music, the orchestra might be playing along at a fairly robust level, then enter into
a quiet passage. A conventional AGC would hold the softer passage down until it was able to slowly recover,
keeping the soft passage much too quiet! With Omnia-3's makeup gain function, the hidden, faster time
constant will allow a quick recovery, but only during the softer passage. As soon as the orchestra starts to play
louder, the "makeup" time constant yields control to the primary AGC circuit, hence returning gain to the
previous platform level. This sophistication better preserves the dynamic integrity of the signal.
Typically the wideband AGC should be adjusted to give 10-12 dB of gain reduction on moderately loud
passages.
A built-in phase rotator ensures symmetrical clipping of positive and negative peaks. But, for a more musically
transparent sound (or if phase rotation is built-in to your mic processing) this feature can be defeated.
A third-order (18dB/Octave) high pass filter with five selectable cutoff frequencies from 60 Hz down to 20 Hz
allows removal of subsonic frequencies that may cause problems in processing and further along the airchain.
Bass EQ: For those who demand thunderous bass, the Omnia-3's got it! Up to 12 dB of "thunder" can be added
to shake your listener's walls! This is not some simple bass EQ, but rather a sophisticated concept that takes
into consideration the time alignment of the low frequencies as they pass through the entire system. This allows
30
Advertisement
