6
SECTION FIVE — HOW TO USE FBX FEATURES
5.1. Input / Output Level Switches
Use the two-position switches on the back panel of your FBX1200 / FBX2400 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.
NOTE:
Mixing balanced and unbalanced connections may result in a 6 dB loss of gain.
5.1.1. Setting Levels: Set both Input & Output switches the same for Unity Gain
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
spoken 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.
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 NUMBER FIXED
button for 4 seconds. The filters LEDs will flash 4 times and then go out. Release the NUMBER FIXED button, and the LEDs
will begin to light in sequence. When the LED corresponding to the desired number of Fixed filters lights, press the NUMBER
FIXED 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
problem, 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. Re-
lease 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 DY-
NAMICS button. The Dynamic
LEDs flash twice and reset. Con-
tinue holding the button and the
current Dynamic Filter Timer set-
ting 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 will flash twice
(including filter 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
5.31. 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
combination of balanced and unbalanced inputs and outputs is used, the signal may be disconnected or attenuated in Bypass.
Dynamic FBX filters: Factory default of 3 Dynamic
filters flashing just before reset.
Off
1 min.
5 min.
30 min.
60 min.
TIMER
SETTINGS
Current Dynamic Timer (disabled) setting being indicated on third flash.
OUT
IN
Accepts low level input up to +6 dBU
Accepts high level input up to +24 dBU
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.
POSITION
OUTPUT
LEVEL
SWITCHES
INPUT
LEVEL
SWITCHES