The Fbx & True Mobility® Advantage; Fbx Fixed & Dynamic Filters - SABINE SWM7000 Operating Manual

15.3.1. The FBX & True Mobility® Advantage
After inventing FBX technology and refining it for over
a decade, Sabine has brought our patented automatic
feedback control to its fullest realization with the Sabine
SWM True Mobility® wireless systems. Our latest advance
in maintaining the highest quality audio signal is due to
the placement of the signal processing in the input chain
of the microphone signal. Many times signal processing
(compression and equalization) is placed after the output
stage of a mixer, meaning it is applied to a combination of
inputs mixed together into one output and passed through
the processor. Particularly in the case of equalization and
feedback control, one consequence of such placement is
that filtering appropriate to only one microphone may be
applied to all mics in the same mix bus. In other words,
unnecessary filtering may be applied to microphones that,
due to variations in position and microphone characteristics, will feedback at
a different set of frequencies. Although the filters are very transparent, why
add filtering if you can avoid it? And why divide your processing power among
multiple signals?
Placing the filtering and other signal processing in the input signal path is
a concept called Targeted Input Processing. It means each microphone so
equipped will have customized, unique signal processing applied — and no
unnecessary processing.
With FBX technology, your microphone will finally sound loud enough, every-
one in the audience will understand each word, and feedback will be far less
likely to make an unwelcome and unexpected visit—and you'll be comfortable
knowing that protection is extended to anywhere a wireless microphone might
be taken.
14.3.2. FBX Fixed & Dynamic Filters
FBX filters come in two flavors, fixed and dynamic. Both operate automatically.
There is no audible difference between fixed and dynamic filters in terms of
sonic purity; the difference arises in their application.
14.3.2.1. Fixed FBX Filters
Once they set automatically (see Section 7 for information on setting fil-
ters), fixed FBX filters will NOT change frequency. You can think of fixed
filters as cures for problem frequencies (the "first-to-feedback" frequencies
encountered during normal system operation), common to most locations
in the room.
14.3.2.2. Dynamic FBX Filters
Dynamic FBX filters also set automatically, but can change frequency,
on a rotating basis, as the need arises. To help distinguish dynamic from
fixed filters, consider the example of a speaker using a wireless lavalier
microphone, who walks under a ceiling speaker for the first time. In so
doing, he enters a location-specific feedback zone, where it's possible
that a problem frequency may have escaped detection and notching by
a fixed filter. If all fixed filters have been deployed, a dynamic filter will
be set automatically as soon as feedback appears, solving the problem.
Great! But what happens when the speaker then moves away from the
ceiling speaker, and close to a floor monitor? Feedback from the ceiling
speaker is no longer a problem, but a new frequency starts to squeal.
If all fixed and dynamic FBX filters are already set, a dynamic filter will
change, to adjust to the new location. An FBX dynamic filter thus stands
guard if new problem feedback arises after all available filters have been
set, providing a deeper and more flexible level of protection against the
dreaded surprise of feedback.
Other than the ability to change frequency, a dynamic filter is equivalent
to a fixed filter.
FBX Theory & Practice
Fig. 15d - FBX at Work: What FBX Gives Back to your Program
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