Mackie Thump18S - Placement; Care and Maintenance; The ins and Outs of Polarity

Thump18S Powered Subwoofer
12
Thump18S Powered Subwoofer
Placement
4HE4HUMP3SUBWOOFERISDESIGNEDTOSITONTHE
mOORORSTAGE)TISNOTDESIGNEDTOBEPOLEMOUNTED
ORSUSPENDED
7HENPOLEMOUNTINGLOUDSPEAKERSBESURETHATTHE
4HUMP3SUBWOOFERSARESTABILIZEDANDSECUREDFROM
FALLINGOVERORBEINGACCIDENTALLYPUSHEDOVER&OR
STACKEDSCENARIOSITISHIGHLYSUGGESTEDTHATSTRAPSARE
UTILIZED&AILURETOFOLLOWTHESEPRECAUTIONSMAYRESULT
INDAMAGETOTHEEQUIPMENTPERSONALINJURYORDEATH
4HECABINETHASNORIGGINGPOINTSANDIS
NOTSUITABLEFORRIGGING.%6%2ATTEMPT
TOSUSPENDAN4HUMP3SUBWOOFERBYITS
HANDLES
!SWITHANYPOWEREDCOMPONENTSPROTECTTHEMFROM
MOISTUREANDEXTREMECOLDANDFOLLOWTHEOTHER#ARE
AND-AINTENANCESUGGESTIONSBELOW
Care and Maintenance
9OUR4HUMP3SUBWOOFERSWILLPROVIDEMANYYEARSOF
RELIABLESERVICEIFYOUFOLLOWTHESEGUIDELINES
s !VOIDEXPOSINGTHESUBWOOFERSTOMOISTURE
)FTHEYARESETUPOUTDOORSBESURETHEYARE
UNDERCOVERIFRAINISEXPECTED
s !VOIDEXPOSURETOEXTREMECOLDBELOW
FREEZINGTEMPERATURES)F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MINUTESPRIOR
TOHIGHPOWEROPERATION
s 5SEADRYCLOTHTOCLEANTHECABINETS/NLYDO
THISWHENTHEPOWERISTURNEDOFF!VOIDGETTING
MOISTUREINTOANYOFTHEOPENINGSOFTHE
CABINETPARTICULARLYWHERETHEDRIVERSARE
LOCATED
The Ins and Outs of Polarity
4HUMP3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"UTWHATEXACTLYDOES
THATMEAN!SUBWOOFERWORKSBYLITERALLYPUMPINGAIR
ASTHEWOOFERCONEMOVESINANDOUTWITHRESPECTTOTHE
CABINETINWHICHITISHOUSED)TDOESSOACCORDINGTOTHE
LOWFREQUENCYPORTIONOFTHESIGNALITRECEIVESFROMTHE
SOUNDSOURCE
4HEWOOFERCONEISSIMPLYFOLLOWINGTHEWAVEFORMAS
SEENINTHESINEWAVEIN&IGURE!STHESINEWAVERISES
THEWOOFERCONEPUSHESOUT,IKEWISEASTHESINEWAVE
FALLSTHEWOOFERCONEPULLSINTOTHECABINET!MUSICAL
SIGNALISMUCHMORECOMPLEXOFCOURSEBUTTHESAME
PRINCIPLEAPPLIES-OVEMENTOFTHEWOOFERCONECAUSES
AIRPRESSURECHANGESTHATWEPERCEIVEASSOUND
7HENTHENORMALINVERT;POLARITY=SWITCHIS
ENGAGEDTHEORIGINALWAVEFORMISSIMPLYREVERSED
;SEE&IGURE=!GAINTHESUBWOOFERCONE
FOLLOWSTHEWAVEFORM(OWEVERTHISTIMETHEWOOFER
CONESTARTSBYPULLINGINTOTHECABINETFOLLOWEDBYTHE
WOOFERCONEPUSHINGOUT)F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4HISISNORMALASOUREARSPERCEIVETHEM
BOTHATTHESAMETIME
4HENORMALINVERT;POLARITY=SWITCHCOMESINTO 
PLAYWHENTHE4HUMP3SUBWOOFERISPAIREDWITHA
LOUDSPEAKER)DEALLYTHEWOOFERCONESOFTHESUBWOOFER
ANDFULLRANGELOUDSPEAKERWOULDWORKTOGETHERBY
PUSHINGANDPULLINGINUNISON4HUMP3SUBWOOFERS
AREDESIGNEDTOBEUSEDINABROADRANGEOFAPPLICATIONS
4HEmEXIBILITY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