LIT-FBX1220-1224-OP-EN-080208.pmd - ks
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© 2008 Sabine, Inc.
SECTION SIX — TROUBLESHOOTING TIPS
Q. Why does my system sound thin and muffled?
A. PlacetheFBXinBYPASSMODE.Ifthesystemstillsounds
thin,yourproblemisprobablyimproperuseofagraphicEQ.
IftheproblemisreallytheFBX,re-initializethesystemand
makesuretheREADYbuttonLEDisonsteadily.
Q. Why does my program sound clipped and distorted?
A. MakesureyouarenotinSetupmode.Setupmodeturnsoff
automaticallyaftertherstdynamiclterisset,oryoucan
turnitoffmanuallybypressingtheREADYbutton.SeeSec-
tion5.3.3.forinformationonSetupmode.
Q. Can I patch two FBX channels together for twice the
filters?
A. Yes;connecttheoutputofoneFBXchanneltotheinputof
theotherchannel.PatchtheFBXbetweentheoutputofthe
mixerandtheinputofapoweramp,andsetupthechannels
sequentially.WhencombiningchannelAwithchannelBonan
FBX2420,setallchannelAltersfoxed(seesection5.2.2)
andbypasschannelB.Follownormalsetupprocedureon
channelA,andlockthexedlters(seesection4.2).Then
followthestandardsetupprocedurechannelB,whichshould
haveafewdynamicltersavailable.
Q. Why doesn't the FBX1220 & FBX2420 Series filter feed-
back immediately?
A. Fourpossiblereasons:
1. Lowerfrequenciesmaytakelongerthanhigherones.
2.Checkinputlevelofsignalattheunitandsetgainsothe
signallevelLED'sontheunitlightup.
3. Itmaybepatchedinan"effectsloop",notdirectlyinthe
signalpath.ThisWILLNOTWORK.
4. Youmayhaveusedall12lters.Dynamiclterswillcon-
tinuetooperatebynotchingfeedbackfrequenciesasthey
occur,butultimately,gainwillexceedltercapacity.
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. Avoidthisconguration.Youcancongurethesystemthis
wayonlyifeacheffectssendofeachmixerchannelissetso
thatallofthesignalisroutedcompletelythroughtheeffects
loop.Youcannotmixdrysignalwitheffectssignalandstill
controlfeedback.
Q. The signal input LEDs do not light. The unit will not catch
feedback. Why?
A. Theunitisnotinthesignalpath.Checktheconnections.
Besurethattheprogramisinterruptedwhentheinputis
disconnectedfromthebackoftheunit.
Q. Can I mix balanced and unbalanced inputs and out-
puts?
A. Yes.Anunbalancedinputandbalancedoutputiscompat-
ible.
Q. Why does one of the FILTER ACTIVITY LEDs blink?
A. Thelast lter to be automatically updated blinks. During
normaloperation,theblinkingwillmovefromltertolteras
theyarereset.Thisgivestheuseravisualconrmationthat
theunitisrespondingtonewfeedbackandisfunctioning
properly.
Q. Sometimes during the initial setup, the first filter LED
will blink before any feedback has been introduced into
the system. Why?
A. TheFBXwillsetalterifthesystemhasahum.Checkfor
badgrounds.TryresettingthelterswiththeunitinBypass.
IfthevenueisnoisypresstheReadybuttononcebefore
takingtheunitoutofBypass.ThentakeitoutofBypassand
proceedwiththenormalinitiationprocedure.
so the feedback clips quickly; therefore, your program will also be clipped in setup mode). Be sure the blue Ready light is
on (either ashing or steady) and if it isn’t, press the READY button before your program begins. You’llknowtheFBX1220
/FBX2420isinsetupmodewhentheSETUPbuttonislit.NOTE: You can manually override Setup mode if necessary.
That's right -- press the Ready button!
5.3.4. Mobile vs. Stationary Microphones
One signicant 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 lters for mobile microphones by moving to the various possible microphone
locations and setting lters for those locations. As the Setup instructions show, raise the system gain and set the FBX lters
in each predictable location.
In some situations, increasing the number of dynamic lters (versus xed FBX lters) 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 xed FBX lters placed in the setup procedure are still your best bet because the feedback lters are already set.
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