Mackie HD 1801 Car Speaker User Manual


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The Ins and Outs of Polarity
Mackie’sHD-SeriesPoweredSubwoofersincludea
switchthatallowsyoutoquicklyinvertthepolarityof
thesubwoofer’soutputrelativetotheinputsignalitis
receivingfromthemixerorothersoundsource.But
whatexactlydoesthatmean?Asubwooferworksbylit-
erallypumpingairasthewooferconemovesinandout
withrespecttothecabinetinwhichitishoused.Itdoes
soaccordingtothelow-frequencyportionofthesignalit
receivesfromthesoundsource.
Thewooferconeissimplyfollowingthewaveform
asseeninthesinewaveinFigure1.Asthesinewave
rises,thewooferconepushesout.Likewise,asthesine
wavefalls,thewooferconepullsintothecabinet.A
musicalsignalismuchmorecomplex,ofcourse,butthe
sameprincipleapplies.Movementofthewoofercone
causesairpressurechangesthatweperceiveassound.
WhenthePolarityInvertswitch[6]isengaged,the
originalwaveformissimplyreversed180º(seeFigure
2).Again,thesubwooferconefollowsthewaveform.
However,thistimethewooferconestartsbypullinginto
thecabinetfollowedbythewooferconepushingout.If
youhaveeverexperimentedwithasubwooferpolarity
switch,youmaynothavenoticedanychangestothe
soundregardlessofitsposition,especiallyifyouare
listeningtojustthesubwoofer.Thisisnormal,asour
earsperceivethembothasthesame.
Thepolarityinvertswitchcomesintoplaywhenthe
HD1801subwooferispairedwithaloudspeaker.Ideally,
thewooferconesofthesubwooferandfull-rangeloud-
speakerwouldworktogetherbypushingandpullingin
unison.HD-Seriessubwoofersaredesignedtobeused
inabroadrangeofapplications,andwithawidevariety
offull-rangeloudspeakers.Theexibilityprovidedby
thepolarityswitchisnecessarytoensurethatyouare
receivingthebestpossiblesoundfromyoursystem,
regardlessofyoursetup.
Listedbelowaresomerecommendedcongurations
forpairingaMackieHD-Seriessubwoofer(usingthe
High-Passoutput)withaMackiefull-range
loudspeaker.Thesesettingsareagoodstart,butbesure
toexperimenttondthebestsoundforyourvenue.The
loudspeakersmaybestacked,pole-mounted,orown.
•HD-Series full-range loudspeakers-Engagethe
PolarityInvertswitchontheHD1801.
•SRM450v2 full-range loudspeakers-Disengagethe
PolarityInvertswitchontheHD1801.Engagethe
LowCutFilterswitchontheSRM450v2loudspeaker.
Inalternatesetupswherethefull-rangeloudspeakers
arenotco-locatedwiththesubwoofersorarenot
connectedtotheHD-Seriessubwoofer’sHigh-Pass
outputs,youwillneedtoexperimentwiththePolarity
Invertswitchtodeterminewhichsettinggivesyouthe
desiredbassresponseforyourapplication.
Figure 1 Figure 2
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Owner’s Manual
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