Section Six - Troubleshooting Tips - SABINE FBX1220 Operating Instructions Manual

so the feedback clips quickly; therefore, your program will also be clipped in setup mode). Be sure the blue Ready light is
on (either flashing or steady) and if it isn't, press the READY button before your program begins. You'll know the FBX1220
/ FBX2420 is in setup mode when the SETUP button is lit. NOTE: You can manually override Setup mode if necessary.
That's right -- press the Ready button!
5.3.4. Mobile vs. Stationary Microphones
One significant advantage offered by the Sabine family of FBX Feedback Exterminator products is their ability to adapt to
changing acoustical relationships involving sound system components in various applications. One major source of potential
feedback problems arises in situations with wireless microphones, when the user of the wireless mic is moving around the
performance area. As a microphone moves in a sound space, with varying degrees of proximity to the speakers and varying
acoustic responses, feedback frequencies may shift. In such a situation, feedback-free mobility may be more important a
concern than maximum system gain.
For this reason we recommend setting FBX filters for mobile microphones by moving to the various possible microphone
locations and setting filters for those locations. As the Setup instructions show, raise the system gain and set the FBX filters
in each predictable location.
In some situations, increasing the number of dynamic filters (versus fixed FBX filters) may allow a second layer of defense
against new feedback from new locations. This technique is recommended if you cannot predict where the performer may roam.
But fixed FBX filters placed in the setup procedure are still your best bet because the feedback filters are already set.
SeCtIon SIX — troUBleSHootInG tIPS
Q. Can I place the FBX in the mixer's EQ loop?
A. Yes.
Q. Can I place the unit in the mixer effects loop?
A. Avoid this configuration. You can configure the system this
way only if each effects send of each mixer channel is set so
that all of the signal is routed completely through the effects
loop. You cannot mix dry signal with effects signal and still
control feedback.
Q. The signal input LEDs do not light. The unit will not catch
feedback. Why?
A. The unit is not in the signal path. Check the connections.
Be sure that the program is interrupted when the input is
disconnected from the back of the unit.
Q. Can I mix balanced and unbalanced inputs and out-
puts?
A. Yes. An unbalanced input and balanced output is compat-
ible.
Q. Why does one of the FILTER ACTIVITY LEDs blink?
A. The last filter to be automatically updated blinks. During
normal operation, the blinking will move from filter to filter as
they are reset. This gives the user a visual confirmation that
the unit is responding to new feedback and is functioning
properly.
Q. Sometimes during the initial setup, the first filter LED
will blink before any feedback has been introduced into
the system. Why?
A. The FBX will set a filter if the system has a hum. Check for
bad grounds. Try resetting the filters with the unit in Bypass.
If the venue is noisy press the Ready button once before
taking the unit out of Bypass. Then take it out of Bypass and
proceed with the normal initiation procedure.
Q. Why does my system sound thin and muffled?
A. Place the FBX in BYPASS MODE. If the system still sounds
thin, your problem is probably improper use of a graphic EQ.
If the problem is really the FBX, re-initialize the system and
make sure the READY button LED is on steadily.
Q. Why does my program sound clipped and distorted?
A. Make sure you are not in Setup mode. Setup mode turns off
automatically after the first dynamic filter is set, or you can
turn it off manually by pressing the READY button. See Sec-
tion 5.3.3. for information on Setup mode.
Q. Can I patch two FBX channels together for twice the
filters?
A. Yes; connect the output of one FBX channel to the input of
the other channel. Patch the FBX between the output of the
mixer and the input of a power amp, and set up the channels
sequentially. When combining channel A with channel B on an
FBX2420, set all channel A filters fo fixed (see section 5.2.2)
and bypass channel B. Follow normal setup procedure on
channel A, and lock the fixed filters (see section 4.2). Then
follow the standard setup procedure channel B, which should
have a few dynamic filters available.
Q. Why doesn't the FBX1220 & FBX2420 Series filter feed-
back immediately?
A. Four possible reasons:
1. Lower frequencies may take longer than higher ones.
2. Check input level of signal at the unit and set gain so the
signal level LED's on the unit light up.
3. It may be patched in an "effects loop", not directly in the
signal path. This WILL NOT WORK.
4. You may have used all 12 filters. Dynamic filters will con-
tinue to operate by notching feedback frequencies as they
occur, but ultimately, gain will exceed filter capacity.
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