INPUT
STEREOORTWINAMPLIFIEROPERATION
Useshieldedcablestoconnectthesignalfromthepre-
amplifierorsignalsourcetothepoweramplifierinput.To
minimizethepossibilityofhumtheshieldedcablesshould
berunparalleltoeachotherorlooselytwistedtogether.
LocatethecablesawayfromspeakerleadsandACpower
cords.Allconnectionsaremadeonthebackpanelofthe
MC
2120.
Forstereooperation,theleftoutputofthepreamplifier
shouldbepluggedintotheLeftinputjackofthepower
amplifier.Therightoutputofthepreamplifiershouldbe
pluggedintotheRight(MONO)inputjackofthepower
amplifier.
Fortwinamplifieroperationa separatesignalsource
canbeconnectedtoeachinput.Instereoortwinamplifier
operationtheMODESWITCHmustbeintheSTEREOposi-
tion.
MONOPHONICORSINGLECHANNELOPERATION
Ashieldedcablefromthesignalsourceispluggedinto
theRight(MONO)inputlackoftheMC2120only.The
MODESWITCHonthebackpaneloftheamplifiermustbe
placedintheMONOposition.IntheMONOpositionthe
rightchannelinputjackconnectstobothleftandright
poweramplifiers.TheLeftINPUTisdisconnected.Onlythe
signalfedintotheRight(MONO)inputwillbeamplified.
Monooutputisobtainedbystrappingbothoutputsin
parallel.ShouldtheMODESWITCHbeleftintheSTEREO
positionandtheoutputtransformersremainstrappedfor
amonophonicload,onechannelwillattempttodrivethe
otherwhichcauseshighcirculatingcurrentsandover-
heating.BecertainthattheMC2120isneveroperatedin
thestereomodewiththeoutputsconnectedformono-
phonicoperation.
OUTPUT
BecertaintheloudspeakersconnectedtotheMC2120
arecapableofhandlingthepoweroutputoftheampli-
fier.
Formultiplespeakeroperation,runseparateleadsfrom
eachspeakertotheamplifier.Becauseofthehighpower
availablefromtheMC2120,besuretouselargediameter
speakerleads.Inallcases,theleadstoandfromthe
speakershouldbetwinconductorortwistedtogether.Use
lampcord,bellwire,orwirewithsimilartypeofinsulation
toconnectthespeakerstotheamplifier.Whenusing8 ohm
speakersandforthenormallyshortdistancesofunder30
feetbetweentheamplifierandspeaker,#18wireor
largercanbeused.Fordistancesover30feetbetweenthe
amplifierandspeakeruselargerdiameterwire.Selectthe
correctsizewireforthewiredistancefromthechart.Itis
recommendedthattheDCresistanceofthespeakerleads
notbeover5%ofthespeakerimpedance.Upto10%can
betolerated.Resistanceoftheleadsshouldbecomputedfor
thelengthofwirebothtoandfromthespeakerorspeakers.
Wirelengthsaboverepresentthewireresistanceequalto
5%ofthespeakersimpedance.Useofsmallerwiresizes
willproducemoreresistancewhichcausesmorepower
lossandlessloudspeakerdamping.
STEREOORTWINAMPLIFIEROPERATION
Checktheimpedanceofthespeakerwhichisusually
identifiedonthespeakeritselforinthespeakerowner's
manual.Connecta leadfromthecommonterminalofthe
leftspeakertotheamplifierLEFTOUTPUTterminalstrip
COMmonscrewConnectanotherleadfromtheothertermi-
naloftheleftspeakertothescrewwiththenumbercor-
respondingtothespeakerimpedanceontheLEFTOUTPUT
terminalstrip.Therightchannelspeakerisconnectedin
thesamemannerontheRIGHTOUTPUTterminalstrip.For
stereoortwinchanneloperationitisnotnecessarytouse
thesameimpedanceloudspeakeroneachoutput.Connect
eachchannelfortheimpedancedesired.Fullpowerwill
bedeliveredtoeachproperlyconnectedspeaker.
4
Wire
Gauge
22
20
18
16
14
12
10
For4
Feet
6
10
15
25
40
60
100
MAXIMUM
OhmLoad
Meters
183
3.05
4.57
7.62
12.19
18.29
30.48
WIRE
For8
Feel
12
20
30
50
80
120
200
LENGTHS
OhmLoad
Meters
3.66
6.10
914
15.24
24.38
36.58
60.96
For16
Feel
24
40
60
100
160
240
400
OhmLoad
Meters
7.32
12.20
18.30
30.50
48.80
73.20
122.00
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