Mackie DLM12S - Placement; Cabinet Mounting Limitations; The Ins and Outs of Polarity; Polarity Waveform Explanation

DLM12S Powered Subwoofer
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DLM12S Powered Subwoofer
Placement
TheDLM12Ssubwooferisdesignedtositonthe
oororstage.Itisnotdesignedtobepole-mounted
orsuspended.
Whenpole-mountingloudspeakers,besurethatthe
DLM12Ssubwoofersarestabilizedandsecuredfrom
fallingoverorbeingaccidentallypushedover.For
stackedscenarios,itishighlysuggestedthatstrapsare
utilized.Failuretofollowtheseprecautionsmayresult
indamagetotheequipment,personalinjury,ordeath.
Thecabinethasnoriggingpointsandis
notsuitableforrigging.NEVERattemptto
suspendaDLM12Ssubwooferbyitshandles.
Aswithanypoweredcomponents,protectthemfrom
moistureandextremecoldandfollowtheotherCare
andMaintenancesuggestionsbelow.
The Ins and Outs of Polarity
TheMackieDLM12Ssubwooferincludes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literally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normal/invert[polarity]switch[5]is
engaged,theoriginalwaveformissimplyreversed180˚
[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atthe
sametime.
Thenormal/invert[polarity]switchcomesinto 
playwhentheDLM12Ssubwooferispairedwitha
loudspeaker.Ideally,thewooferconesofthesubwoofer
andfullrangeloudspeakerwouldworktogetherby
pushingandpullinginunison.DLM12Ssubwoofersare
designedtobeusedinabroadrangeofapplications.
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.
Care and Maintenance
YourMackiesubwooferswillprovidemanyyearsof
reliableserviceifyoufollowtheseguidelines:
• Avoidexposingthesubwooferstomoisture.
Iftheyaresetupoutdoors,besuretheyare
undercoverifrainisexpected.
• Avoidexposuretoextremecold(below
freezingtemperatures).Ifyoumustoperate
thesubwoofersinacoldenvironment,warm
upthevoicecoilsslowlybysendingalow-level
signalthroughthemforabout15minutesprior
tohigh-poweroperation.
• Useadryclothtocleanthecabinets.Onlydo
thiswhenthepoweristurnedoff.Avoidgetting
moistureintoanyoftheopeningsofthe
cabinet,particularlywherethedriversare
located.
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Figure 1: Normal [0˚]
Amplitude Amplitude
Figure 2: Invert [180˚]
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Polarity Waveforms