8
E
1.3OperatingPrecautions
Makesurethe ACmainsvoltageiscorrectandisthesameasthatprintedontherearoftheamplifier.Damagecaused
byconnectingtheamplifiertoimproper ACvoltageisnotcoveredbythewarranty.Makesurethepowerswitchisoff
beforemakinganyinputoroutputconnections.
Itisalwaysagoodideatohavethegaincontrolsmutedduringpower-uptopreventspeakerdamageifthereisahigh
signallevelattheinputs.
Whetheryoubuythemormakethem,usegood-qualityinputandspeakercables.Mostintermittentproblemsare
causedbyfaultycables.Usegood-qualityconnectorsandwire,alongwithgoodsolderingtechnique,toensure
troublefreereliability.
1.4 ACMainsconnection
The ACMainconnectionismadeviatheCPCtypeconnector(IEC20A forK3andK2)ontherearsideofthepanel.
Thefigurebelowshowstheconnectiontotheamplifier.Besurethatyour ACmainspowersourcehasthe
requirementsindicatedinthismanual.
Isimportanttoconnectthegroundforsafety,donotuseadaptersthatdisablethe
ground.
TheDIGAMamplifierhasanautomaticpowerfactorcorrectionsystemfora
perfectmainsnetworkinterface. Theamplifierisaresistiveloadforthemainsnetwork,minimizingthereactivepower
andtheharmonicdistortiononthecurrent. Thesystemallowsperformancetobemaintainedevenincircumstancesof
varyingthemainsvoltage.
figure1.4.1
1.2Mounting
AllDIGAMamplifiersarepreviewedforthestandard19"rackmounting;therearefourfrontpanelsholesandfoutrear
lateralholes. Theamplifiersmustbefixedintorackinbothsides,backandfrontal,toavoidmechanicaldamages. Your
DIGAMamplifierusesaforced-aircoolingsystemtomaintainalow,evenoperatingtemperature.Drawnbyaninternal
fan,airentersthroughtheslotsinthefrontpanelandcoursesoverandthroughcomponents. TheDIGAMseries
amplifiersfeaturean"intelligent"variable-speedDCfanwhichiscontrolledbyheatsinktemperaturesensingcircuits:
thefanspeedwillincreaseonlywhenthetemperatureofeitherheatsinkrequiresit,whichkeepsfannoisetoa
minimumandhelpscutdustaccumulationinside.Underextremethermalload,thefanwillforceaverylargevolumeof
airthroughtheheatsinks.Ifeitherheatsinkgetstoohot,itssensingcircuitwillreducetheoutputpower.Ifthe
amplifieroverheats,anothersensingcircuitshutsdownitscircuittocutoffpoweruntilitcoolstoasafetemperature.
Theexhaustcoolingairisforcedoutthroughtherearofthechassis(seefigure1.2.1),somakesurethereisenough
spacearoundthesidesoftheamplifiertoallowtheairtoescape.Ifitisrackmounted,makesuretheexhaustaircan
flowwithoutresistance.Ifyouareusingarackwithclosedbacks,theremustbeatleastonestandardrackspaceof
openinginthefrontoftherackforeveryfouramplifiers. Amplifiersmaybestackeddirectlyontopofeachother(no
spaceneededbetweenunits),startingfromthebottomoftherack.
figure1.2.1
MAINS
T
U
R
N
T
O
L
O
C
K
CAUTION!RISKOFELECTRICSHOCK:DONOTOPEN
Vac GND
otherKmodels
DigamK3,K2only
openthelock
andinserttheplug
locktheplug
MAINS
GROUND
airflow