Mackie SRM750 Speaker User Manual


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SRM550 • SRM650 • SRM750 Powered Loudspeakers
18
SRM550 • SRM650 • SRM750 Powered Loudspeakers
Appendix A: Service Information
Poor bass performance
• Checkthepolarityoftheconnectionsbetweenthe
mixerandtheloudspeakers.Youmayhaveyour
positiveandnegativeconnectionsreversedatone
endofonecable,causingoneloudspeakertobe
out-of-phasewiththeother.
• Poorbassperformancemaybetheresultofbad
ACpower.Seethesectiontitled‘ACPower’on
page13forfurtherdetails.
Poor sound
• Isitloudanddistorted?Makesurethatyou’renot
overdrivingastageinthesignalchain.Verifythat
alllevelcontrolsaresetproperly.
• Istheinputconnectorpluggedcompletelyinto
thejack?Besureallconnectionsaresecure.
Noise
• Whatisthepositionofthegainknob?Itshould
beat(ornear)“mic”whenamicisconnected
andat(ornear)“line”whenaline-levelsignal
isconnected.Itshouldbe“off”forallunused
inputs.
• Makesureallconnectionstotheactive
loudspeakersaregoodandsound.
• Makesurenoneofthesignalcablesarerouted
nearACcables,powertransformers,orother
EMI-inducingdevices.
• IstherealightdimmerorotherSCR-baseddevice
onthesameACcircuitastheSRMloudspeaker?
UseanAClinelterorplugtheloudspeakerinto
adifferentACcircuit.
IfyouthinktheSRMloudspeakerhasaproblem,
pleasecheckoutthefollowingtroubleshootingtipsand
doyourbesttoconrmtheproblem.VisittheSupport
sectionofourwebsite(www.720trees.com)whereyou
willndlotsofusefulinformationsuchasFAQsand
otherdocumentation.Youmayndtheanswertothe
problemwithouthavingtopartwithyourloudspeaker.
Troubleshooting
No power
• Ourfavoritequestion:Isitpluggedin?Makesure
theACoutletislive[checkwithatesterorlamp].
• Ournextfavoritequestion:Isthepowerswitch
on?Ifnot,tryturningiton.
• IstheRunningManlogoonthefrontpanel
illuminated?Ifnot,makesuretheACoutlet
islive.Ifso,referto“Nosound”below.
• TheinternalAClinefusemaybeblown.Thisis
notauserserviceablepart.Ifyoususpectthe
AClinefuseisblown,pleaseseethe"Repair"
sectionnext.
No sound
• Istheinputgainknobfortheinputsource
turnedallthewaydown?Verifythatallthegain
knobsinthesystemareproperlyadjusted.Look
atthelevelmetertoensurethatthemixeris
receivingasignal.
• Isthesignalsourceworking?Makesurethe 
connectingcablesareingoodrepairandsecurely
connectedatbothends.Makesuretheoutput
levelcontrolonthemixingconsoleisturnedup
sufcientlytodrivetheinputsofthespeaker.
• Makesurethemixerdoesnothaveamuteonora
processorloopengaged.Ifyoundsomethinglike
this,makesurethelevelisturneddownbefore
disengagingtheoffendingswitch.
• Hasitshutdown?Makesurethereisatleast
sixinchesoffreespacebehindeachSRM
loudspeaker.
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