SABINE FBX-2020 Operations Instructions download pdf (Page 7)

Before You Begin

The FBX automatic feedback controller will improve any sound

reinforcement system. By following these suggestions, you will

be assured of the most benefit from your FBX enhanced sound

system. The instructions presume that you are familiar with the

fundamentals of sound reinforcement.

Where the FBX fits in your sound system:

Place the FBX anywhere in the sound system that a graphic

equalizer might be used to control feedback. The most common

place is between the output of the mixer and the input of a power

amp. In this position, the FBX can sense and eliminate feedback

occurring in any channel of the mixer. The FBX can also be used

on a mixer insert point for a single channel, or a sub-group (see

diagrams on pages 5-6).

Note: If you’re using a mixer with unbalanced 1/4" outputs, you

must use standard unbalanced cables and connectors when

connecting it to the FBX. Similarly, if your mixer is wired for

balanced 1/4" (Tip/Ring/Sleeve) outputs, you must use that

type of connector. If you don’t, you may experience a loss of

gain when using the FBX.

The FBX is designed for balanced output. If either side of the

balanced output is grounded at any point, a 6 dB loss in

dynamic range may occur (+21dBV max. signal level unbal-

anced; +27dBV max. signal level balanced).

A note about graphic equalizers:

The FBX is designed to replace the graphic

equalizer’s function for eliminating feedback. In

many applications, such as churches, auditoriums

or small acoustic ensembles, the mixing board provides all the

tonal control that is necessary. The FBX can replace the graphic

EQ altogether in some applications, however, a graphic equilizer

may be beneficial to shape a system's total performance.

If you do want to use an equalizer, place the FBX after the EQ in

the signal path. Use the EQ’s controls to shape the tonal

response of the sound system, but DO NOT NOTCH FOR

FEEDBACK.

Understanding FIXED and DYNAMIC filters:

Before operating the FBX, you need to under-

stand the two types of FBX filters: FIXED and

DYNAMIC. FIXED FILTERS retain their frequency

center-points until the unit is reset by the user. The system’s

gain before feedback is limited primarily by the number of fixed

filters; i.e., increasing the number of fixed filters increases the

system’s gain before feedback. The FBX's DYNAMIC FIL-

TERS control intermittent feedback that comes and goes

throughout the program. They are continually reset automati-

cally to different frequencies as new feedback occurs during

the program. For most applications, the optimal setting is

nine FIXED and three DYNAMIC FILTERS. This is the

factory default.

ClipGuard™ Adaptive Clip Level Control:

Your FBX-2020Plus has a powerful new feature: Sabine's

patented ClipGuard™ adaptive clip level control. Until Sabine

invented ClipGuard™, engineers had to set audio equipment

OPERATING INSTRUCTIONS

input and output lev-

els to a compromised

setting that allowed

too much noise in

quiet programs and

risked clipping during

high-level programs.

With ClipGuard™, no

front panel program

level control is

needed. It automati-

cally matches the

FBX-2020Plus inter-

nal dynamic range to

the constantly chang-

ing program level and

maintains unity gain.

ClipGuard™ extends

the effective dynamic

range of your FBX-

2020Plus from 100dB

to 105dB!

ClipGuard™ incorpo-

rates TURBO mode

setup, another new

feature. It cuts the

time for FBX filter ini-

tialization to just a few seconds, and it greatly reduces the

volume level of the feedback during setup. The FBX-2020Plus

is set in TURBO mode at the factory and automatically

engages every time you press RESET or SET TOTAL NO.

(to reset filters or set total number of filters). The FBX-

2020Plus automatically returns to normal program mode

when the first dynamic filter is set or when you press the

front panel LOCK FIXED button. ALL FILTER LEDS WILL

CYCLE TO INDICATE THE FBX IS ABOUT TO EXIT TURBO

MODE.

NOTE:

If you press LOCK FIXED to turn off TURBO mode

before all the fixed filters have been set, and you want to use

the rest of the fixed filters, press LOCK FIXED again right away

-- before a dynamic filter sets. Once a dynamic filter sets, you

will not be able to use the rest of the fixed filters unless you reset

and reinitialize the unit.

WARNING: Follow the setup procedure outlined in the

next section, and do not play program during TURBO set-

up mode. Otherwise, the FBX-2020Plus will clip and may

set FBX filters improperly. (Clip level is set to the lowest level

so the feedback clips quickly; therefore, your program will also

be clipped in TURBO mode. Be sure a dynamic filter is set, and

if one isn't, press the LOCK FIXED button before your program

begins.) You'll know the 2020Plus is in TURBO mode if the red

CLIP LED flashes when no other signal level LEDs are on.

NOTE: Any loud sounds picked up by open micrphones while

TURBO is engaged may cause FBX filters to set. For this

reason we recommend maintaining silence as much as pos-

sible during the short time TURBO is engaged.

ClipGuard TURBO Mode Guide™

Question

Answer

What is

TURBO mode?

How do I know

TURBO is on?

How do I turn

off TURBO?

Why won't all

the fixed filters

set?

Can the

1020Plus

work during

the program

with TURBO

on?

TURBO mode speeds up the

FBX filter initialization process

so that it takes only a few

seconds, and it greatly reduces

the volume level of the feed-

back during set-up.

If the red CLIP LED flashes

when no other signal level

LEDs are on, TURBO is on.

TURBO turns off automatic-

ally after the first dynamic fil-

ter is set, or you can turn it

off manually by pressing the

LOCK FIXED button. (Press it

again to unlock the filters.)

NO! TURBO mode should be

turned off either automatically

or manually before your pro-

gram begins. If left on, the

1020Plus will clip,may set FBX

filters improperly.

If you press LOCK FIXED to

turn off TURBO mode before

all the fixed filters have been

set, and you want to use the

rest of the fixed filters, press

LOCK FIXED again right away -

a dynamic filter sets.

un-

less you reset and start the

initialization again.

before

Once a dynamic filter sets,

you will not be able to use

the rest of the fixed filters

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SABINE FBX-2020 Operations Instructions Page 7

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