Understanding Fixed & Dynamic Filters - SABINE FBX SOLO 620 SL-620 Operating Manual

BEFORE YOU BEGIN
The FBX automatic feedback controller improves any sound reinforcement system. By
following these simple instructions, you will be assured of the most benefit from your FBX
and sound system. The instructions presume that you are familiar with the fundamentals of
sound reinforcement. If any of the terms are not clear, or if the system does not perform as
expected, contact your local Sabine dealer for further information. Read on for a basic
explanation of FBX features you should understand before using your FBX.
POWERING UP
When connecting the power supply to the FBX-SOLO, angle the connector down,
then push the connector up into the input gently, with the lip facing up as shown. Do
not force the connector into or out of the FBX.
UNDERSTANDING FIXED & DYNAMIC FILTERS
The FBX has two types of constant "Q" filters: FIXED and DYNAMIC. Both filters are placed
the same way: Feedback is detected, and the filter is placed just deep enough to eliminate it.
The difference comes after the filter is placed. FIXED FILTERS are set automatically during
the initial setup and remain on the initially detected feedback tone -- they do not move. The
system's gain before feedback is provided by the FIXED FILTERS; i.e., increasing the
number of FIXED FILTERS increases the system's gain before feedback. The FBX's DY-
NAMIC FILTERS control intermittent feedback that occurs during the program; they can
release and move to new feedback frequencies and are for adaptive feedback control during
the performance. For many applications, the optimal setting is the one which gives
maximum gain - i.e., four FIXED and two DYNAMIC filters (default setting). However,
in some applications, such as use of wireless microphones, mobility is more impor-
tant than maximum gain. In this case, you may wish to have more dynamic than fixed
filters. Any combination is possible.
The filters can be reconfigured easily from the factory default setting (four fixed and two
dynamic) to any combination of fixed and dynamic filters. For example, the following
procedure will set three filters fixed and three dynamic:
1. Place the unit in BYPASS mode.
2. Power down the SOLO.
3. While depressing the RESET button, power up the unit.
4. Release the RESET button. The FILTER INDICATOR LEDs will now light in sequence.
5. When the third LED is lit, press the RESET button.
6. Notice that the first three LEDs flash three times to verify that they are now the fixed
filters.
Note: The fixed filters flash three times whenever the FBX is powered up.
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