SABINE FBX 1210 User Manual

Page 4

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4.1. Before You Begin

These instructions apply to the FBX1210. Your FBX Feedback Exterminator will

improve any sound reinforcement system. The instructions presume that you

are familiar with the fundamentals of sound reinforcement.

4.1.1. where the FBX fits in your sound system:

The most common patch point 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. An even better solution is on a mixer insert point for

a single channel, or a subgroup (see application diagrams in

Section Two — Ap-

plications). This targets the feedback control to the mics that need it.
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 (TRS) outputs, you must use that

type of connector. If you don’t, you may experience a loss of gain (up to 6 dB) when

using the FBX. This can occur if either side of the balanced output is grounded at

any point (or when mixing balanced and unbalanced inputs and outputs).

4.1.2. A note about graphic equalizers:


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 equalizer 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


4.1.3. Understanding FIXeD and DYnAMIC filters

Before operating the FBX, you need to understand 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. In addition, you can LOCK the fixed filters so

they do not get any deeper. Locked fixed filters are no longer adaptive. The


DYNAMIC FILTERS control intermittent feedback that comes and goes throughout

the program. They are continually reset automatically 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.

4.1.4. Setup & ready

Your FBX Feedback Exterminator is either in Setup mode or in Ready mode.

Setup Mode: It’s quick and quiet, but use this mode for setup only – do not use

the FBX for your program while in Setup mode. Think of Setup mode as your

key to achieving one of the main benefits of the FBX: getting more gain before

feedback. In Setup mode you will be raising the gain of your system so the FBX

can place transparent filters (Fixed Filters) that will allow you to get all the gain

you need for a loud and clear show. In Setup the FBX is very sensitive so

do not

talk into the mics during setup, and try to keep room noise to a minimum. If the

room is noisy, then go into Ready mode and raise your gain while the fixed filters

are still unlocked (flashing Ready LED).

Ready Mode: Let the show begin. Your fixed filters are eliminating feedback

and giving you extra gain, and your dynamic filters are ready to jump on any new

feedback during the show. In this mode your fixed filters are either locked (red

LEDs) or unlocked (amber LEDs). We recommend locking your fixed filters for

the show. But if you don’t have time for the Setup mode, or if the room is just too

noisy during setup, then you can start off by unlocking the fixed filters. Leaving

the fixed filters unlocked allows them to get deeper if needed, which can be handy

if you need to get more gain before feedback. But once your system stabilizes we

recommend you lock the fixed filters for the duration of the show!

SeCtIon FoUr — oPerAtInG InStrUCtIonS