Mackie SRM550 - Smart Protect; Limiting; Overexcursion Protection; Thermal Protection

Owner’s Manual
13
Owner’s Manual
Smart Protect
ThereareadvancedDSPprotectionmechanisms
designedtosafeguardtheloudspeakersandampliers
frominadvertentdamage.
Theprotectioncircuitsaredesignedto 
protecttheloudspeakersunderreasonable
andsensibleconditions.Shouldyouchoose
toignorethewarningsigns[e.g.excessivedistortion],
youcanstilldamagethespeaker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
TheSRM550andSRM650usean18dB/octavehigh-
passlter,whiletheSRM750usesan24dB/octaveBut-
terworthhigh-passlterjustpriortothelow-frequency
amplier.Thispreventsvery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.SRMloudspeakersare
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SRMloudspeaker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loudspeaker)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SRMloudspeaker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SRM
loudspeaker.Thisisverydangerous.
Care and Maintenance
Theseloudspeakerswillprovidemanyyears
ofreliableserviceifyoufollowtheseguidelines:
• Avoidexposingtheloudspeakers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loudspeakers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.