Section Five - How To Use Fbx Features; Setup Mode; Input / Output Level Switches; Fbx Filter Control - SABINE FBX1220 Operating Instructions Manual

SeCtIon FIVe — How to USe FBX FeatUreS

5.1. Input / output level Switches

Use the two-position switches on the back panel of your FBX1220 / FBX2420 to compensate for input level or output level
requirements. NOTE: For unity gain (recommended), set the channel's input & output level switches to the same setting.
5.1.1. Setting levels: Set both Input & output switches the same for Unity
Gain
pOsitiOn input level switches
Accepts low level input up to +6 dBU
OUT
Accepts high level input up to +24 dBU
IN

5.2. FBX Filter Control

5.2.1. Selecting Filter width
If you're using the FBX for a music application, the standard 1/10-octave constant "Q" filter is most effective. However, in spo-
ken word applications, such as lectures or teleconferencing, we recommend using the wider 1/5-octave filter for more robust
feedback control. You may enable the 1/5-octave filters by pressing the FIFTH OCTAVE button, and the built-in LED will light.
Only filters set after pressing the button in will be 1/5-octave. Press the button again to set subsequent filters to standard
1/10-octave filters. You can mix filter widths: start with a few filters at 1/5 for the worst feedback points, then switch to 1/10.
5.2.2. Setting number of Fixed vs. Dynamic Filters
To change the number of Fixed filters from the factory default of 9 Fixed and 3 Dynamic per channel, push the READY button
for 4 seconds. The filters LEDs will flash 4 times and then go out. Release the READY button, and the LEDs will begin to light
in sequence. When the LED corresponding to the desired number of Fixed filters lights, press the READY button again.
IMPORTANT TIP: You can mix 1/10- and 1/5-octave filters in the same channel. If you have an especially bad feedback prob-
lem, try making the first few filters 1/5-octave filters.
5.2.3. resetting FBX Filters
All FBX filters: To reset all FBX filters, follow the directions in Section 4.2.
Dynamic FBX filters only: To reset only Dynamic filters, press RESET DY-
NAMICS until the current Dynamic filter LEDs flash and then turn off. Release
the button.
5.2.4. Dynamic Filter timer
The Dynamic Filter Timer, when enabled, automatically resets Dynamic filters after a user-selected time has passed (refer to
Timer Settings chart at right).
5.2.4.1. Set the Dynamic Filter timer
1. Press and hold the RESET DYNAMICS button. The Dynamic LEDs flash twice and reset. Continue holding the
button and the current Dynamic Filter Timer setting will flash twice (filter LEDs 1-5, see
Filter Timer Chart at right).
2. Release the RESET DYNAMICS
button and filter LEDs 1-5 will
cycle through the possible timer
settings.
3. Press RESET DYNAMICS again
at the desired timer setting. LEDs
indicating the current timer setting). Your Dynamic Filter Timer is now set. The timer starts
individually for each Dynamic filter.

5.3. Important operating Considerations

5.3.1. Power-off Memory
The FBX stores the positions and depths of the filters in nonvolatile internal memory when the unit is turned off or during a
power failure. The unit will return all filters to their previous frequencies and depths when it is turned back on.
5.3.2. Bypass Mode
The FBX has a true power-off bypass. The signal is unaffected in Bypass mode even if the unit is turned off. Note that if a com-
bination of balanced and unbalanced inputs and outputs is used, the signal may be disconnected or attenuated in Bypass.

5.3.3. Setup Mode

NOTE: Setup mode is for pre-performance audio setup only, and will cause distortion in your audio program if left on
during performance. You must follow the setup procedure outlined in the previous section, and do not play program or talk
into the mics during Setup. Otherwise the FBX will clip and filters may be set improperly (Clip level is set to the lowest level
6
Output level switches
Outputs at low level, for sending signal to low-level devices or some insert
points. See Section 2 for more information on applications.
Outputs at high level, for most line-level devices. See Section 2 for more
information on applications.
will flash twice (including filter LEDs