Mackie 18S Headphones User Manual


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Owner’s Manual
13
Owner’s Manual
Protection Circuitry
TheThump18Ssubwooferemploysabuilt-inlimiter
forlessdistortionatpeaklevels.Additionalprotection
includesautomaticthermalshutdownshouldtheamp
overheat.However,withClass-Damptechnology,which
ishighly-efcient,thisshouldneverbeaproblem.
Theprotectioncircuitsaredesignedto
protectthesubwoofersunderreasonable
andsensibleconditions.Shouldyouchoose
toignorethewarningsigns[e.g.excessivedistortion],
youcanstilldamagethespeakerintheThump18Sby
overdrivingitpastthepointofamplierclipping.
Suchdamageisbeyondthescopeofthewarranty.
Limiting
Thedriverhasitsowncompressioncircuitwhich
helpsprotectitfromdamagingtransientpeaks. 
Thecompressorisdesignedtobetransparentand
isnotnoticeableundernormaloperatingconditions.
Overexcursion Protection
Asubsonicltercircuitjustpriortothepower
amplierpreventsultra-lowfrequenciesfrombeing
amplied.Excessivelow-frequencyenergycandamage
thewooferbycausingitto“bottomout,”alsoknow
asoverexcursion,whichisequivalenttoamechanical
formofclipping.
Thermal Protection
Allampliersproduceheat.TheThump18Sis
designedtobeefcientbothelectricallyandthermally.
Intheunlikelyeventoftheamplieroverheating,
abuilt-inthermalswitchwillactivate,mutingthe
signal.
Whentheamplierhascooleddowntoasafe
operatingtemperature,thethermalswitchresets
itself,andtheThump18Ssubwooferresumesnormal
operation.
Ifthethermalswitchactivates,tryturningdown
thelevelcontrolanotchortwoonthemixingconsole
(orthebackofthesubwoofer)toavoidoverheatingthe
amplier.Beawarethatdirectsunlightand/orhotstage
lightsmaybetheculpritofanamplieroverheating.
AC Power
BesuretheThump18Ssubwooferispluggedinto
anoutletthatisabletosupplythecorrectvoltage
speciedforyourmodel.Itwillcontinuetooperate
atlowervoltages,butwillnotreachfullpower.
Besuretheelectricalservicecansupplyenough
amperageforallthecomponentsconnectedtoit.
Werecommendthatastiff(robust)supplyofAC
powerbeusedbecausetheampliersplacehigh
currentdemandsontheACline.Themorepowerthatis
availableontheline,thelouderthespeakerswillplay
andthemorepeakoutputpowerwillbeavailablefora
cleaner,punchierbass.Asuspectedproblemof“poor
bassperformance”isoftencausedbyaweakACsupply
totheampliers.
Neverremovethegroundpinonthe
powercordoranyothercomponentofthe
Thump18Ssubwoofer.Thisisverydangerous.
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