7
5. Wiring and connections
iscontinuallyclipping.Ahigh-poweredamplierrunningatlessthan90%ofoutputpowergenerallysounds
superiortoalowerpoweramplierrunningat100%.Anamplierwithinsufcientdrivecapabilitywillnot
allowthefullperformanceortheloudspeakertoberealised.(Seetechnicalspecicationssectionfor
recommendedamplierpower.)
Whenusingampliersfromdifferentmanufacturersinasingleinstallation,makecertainthatallampliershave
closelymatchedgains.(Variationshouldbelessthan+/-0.5dB.)Thisprecautionisimportanttotheoverall
systembalancewhenonlyasingleactivecrossoverisbeingusedwithmultiplecabinets.Whenpossible,itis
recommendedthatthesameampliersbeusedthroughout.
Series/parallel connections-Whenrunninglow-impedanceloudspeakersinparallel,caremustbe
takennottoallowtheimpedancetodroptoolow,asdamagemaybesustainedbytheamplier.Mostlow
impedanceamplierswillbeabletohandleloadsof2ohmsto8ohms.Thismeansforexamplethatwhen
usinganamplierwith2ohmloadrating,uptothreeVLS30orsixVLS7/15maybeconnectedinparallel
peroutput,althoughcareshouldbetakenasimpedancevarieswithfrequencyandatsomefrequenciesthe
impedancewilldroptobelow2ohms.
5.3 Constant voltage (70 /100 V) Mode
Inconstantvoltagedistributedsystems,normallyanumberofloudspeakersareconnectedinparalleltoasingle
amplieroutput.Connectthepositive(+)conductorfromtheamplierorpriorloudspeakerinthesystemtoa
positive(+)barrierstripterminalandthenegative(-)conductortoanegative(-)terminal.Theotherparallel
barrierstripisavailableforconnectingadditionalloudspeakers.
Amulti-positionrotaryswitchontherearinputpanelselectseitherthelow-impedanceoperatingmodeorthe
high-impedancemodes(70Vor100V)withavailabletransformertaps.WhenusingVLSSeriesloudspeakersin
distributedlinesystems,thetransformercanbetappedwithavailablepowerlevelsshowninthetablebelow:
70 V 100 V
5W 9.5W
9.5W 19W
19W 37.5W
37.5W 75W
75W 150W
150W -