Mackie 18S Headphones User Manual


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Thump18S Powered Subwoofer
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Thump18S Powered Subwoofer
Placement
TheThump18S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
Thump18S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anThump18S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.
Care and Maintenance
YourThump18S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.
The Ins and Outs of Polarity
Thump18S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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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Thump18S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.Thump18S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.
<–– Time ––>
Figure 1: Normal [0˚]
Amplitude
Amplitude
Figure 2: Invert [180˚]
<–– Time ––>
Polarity Waveforms
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