SABINE FBX 1210 User Manual

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2014 Sabine, Inc.

7.3. Parametric Filters and FBX

Of course, many savvy sound engineers, realizing the limitations of

graphic equalizers in removing problem feedback, prefer to use a

different type of equalizer, called a parametric EQ, for such applica-

tions. If you’re one such audio engineer, you’ll be comforted to know

that FBX filters share much in common with parametrics.

Compared to graphic filters, parametrics allow more precise adjust-

ments — specifically, control of filter width, the amount of boost or

cut, and the mid-band frequency of the filter. This greater precision,

however, comes at a price, as parametric filters are not nearly as

intuitive or simple to use as graphic equalizers.

Nothing, however, is easier to use than an FBX filter, which enjoys

the precision of a parametric filter, yet deploys instantly and auto-

matically whenever feedback is detected. Effectively, an FBX filter is

a parametric filter set to a tenth-octave width, restricted to cut-only

activity, and automatic in its choice of frequency band.

7.3.1. 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.

7.3.2. Balancing Fixed & Dynamic Filters

Your FBX1210 offers a total of 12 FBX filters (combined fixed and dynamic), which can

be used as needed to exterminate feedback. After years of experience and experimenta-

tion, Sabine has settled upon a default balance of 9 fixed and 3 dynamic filters, set at the

factory. This default condition can be changed to any combination you require.
If you follow setup instructions for setting FBX filters, your FBX1210 will automatically

exit SETUP mode (enter READY status) after all fixed filters, and the first dynamic filter,

have set. In the default condition, this means you will have set ten filters (nine fixed and

one dynamic), with two dynamic filters still not set and remaining on standby alert. If you

wish to set fewer filters, press the READY button before SETUP automatically exits, after

you have set enough filters to safely achieve your desired gain level. In that case, in the

factory default condition, you will reserve three available dynamic filters for standby.

7.3.3. FBX Filter width

Sabine’s experience and testing with filters and sound quality alone led us to decide

upon a default FBX filter width of .10 (one-tenth) octave as the optimal notch width, able

to eliminate feedback without affecting music programs. If, with all filters properly set,

feedback is still a problem, FBX filters may be set to .20 (one-fifth) octave width. This

wider filter setting will help to better eliminate feedback trouble areas, but may also af-

fect music programs slightly. Therefore, the wider setting is generally considered to be

appropriate where speech (less demanding than music) is the primary application. You

can globally change FBX filter width by pressing the FIFTH button on the front panel.

The width of any set filter will always be determined by the position of the switch at the

time the filter is created.

7.3.4. who Benefits from FBX?

Virtually every sound system will be improved with the Sabine feedback control. Singers

and speakers who do not have sound technicians can now increase their monitor or house

system volume so they can hear themselves clearly and with full fidelity, without worrying

if their microphones will suddenly squeal if they move to the wrong place.
Auditoriums and churches of all sizes will enjoy reliable feedback control. Hotels and

conference centers around the world can offer meeting rooms with microphones that won’t

howl during programs. Sabine FBX systems can be installed in theaters, schools, sports

arenas, courtrooms, teleconferencing rooms, intercoms or interactive remote classrooms

— anywhere one or multiple microphones are used.

Fig. 7b.