McIntosh C33 User manual

THEMclNTOSHC 33SOLIDSTATESTEREOPREAMPLIFIER
ReadingTime:43MinutesPrice$2.00

VARIOUSREGULATORYAGENCIESREQUIRETHATWEBRINGTHEFOLLOWING
INFORMATIONTOYOURATTENTION.PLEASEREADITCAREFULLY.
WARNING:TOPREVENTFIREORSHOCK
HAZARD,DONOTEXPOSETHISUNITTO
RAINORMOISTURE.
TheMclntoshyouhavepurchasedisa ModelC 33.It
hasa serialnumberlocatedontherearpanelofthe
chassis.Recordthatserialnumberhere:
SerialNumber
Themodel,serialnumberandpurchasedateareim-
portanttoyouforanyfutureservice.Recordthepur-
chasedatehere:
Purchasedate
Uponapplication,MclntoshLaboratoryprovidesa
Three-YearServiceContract.YourMclntoshAuthorized
ServiceAgencycanexpediterepairswhenyouprovide
theServiceContractwiththeinstrumentforrepair.To
assist,recordyourServiceContractnumberhere:
ServiceContractNumber

YourC 33StereoPreamplifierisdesigned
toperformtoitsspecifications
formanyyears.Ifyou
haveanyquestions,pleasecontact:
CUSTOMERSERVICE
MclntoshLaboratoryInc.
2ChambersStreet
Binghamton,NewYork13903-9990
Phone:[phone]
TakeAdvantageof3 years
ofContractService...
FillintheApplicationNOW.
Contents
INTRODUCTION2
SIMPLIFIEDBLOCKDIAGRAM3
INSTALLATION4
SIMPLIFIEDCONNECTINGDIAGRAM6
HOWTOCONNECT7
USINGTHEFRONTPANELCONTROLS12
USINGTHEPUSHBUTTONS15
TOPPANELINFORMATIONAND
SECONDARYCONTROLS17
PERFORMANCELIMITSANDRATINGS18
PERFORMANCECHARTS19
TECHNICALDESCRIPTION22
BLOCKDIAGRAM24
MclNTOSHTHREEYEARSERVICECONTRACT
AnapplicationforA THREEYEARSERVICECONTRACTisincludedwiththismanual.
Thetermsofthecontractare:
1.Mclntoshwillprovideallparts,materials
andlaborneededtoreturnthemeasured
performanceoftheinstrumenttothe
originalperformancelimits.TheSER-
VICECONTRACTdoesnotcoverany
shippingcoststoandfromtheauthoriz-
edserviceagencyorthefactory.
2.AnyMclntoshauthorizedserviceagency
willrepairMclntoshinstrumentsatnor-
malservicerates.Toreceiveservice
underthetermsoftheSERVICECON-
TRACT,theSERVICECONTRACTCER-
TIFICATEmustbepresentedwhenthe
instrumentistakentotheserviceagency.
3.Alwayshaveservicedonebya
Mclntoshauthorizedserviceagency.If
theinstrumentismodifiedordamaged
asa resultofunauthorizedrepair,the
SERVICECONTRACTwillbecancelled.
Damagebyimproperuseormishandl-
ingisnotcoveredbytheSERVICE
CONTRACT.
4.TheSERVICECONTRACTisissuedto
youastheoriginalpurchaser.Topro-
tectyoufrommisrepresentation,this
contractcannotbetransferredtoa se-
condowner.
5.ToreceivetheSERVICECONTRACT,
yourpurchasemustbemadefroma
Mclntoshfranchiseddealer.
6.Yourcompletelyfilledinapplicationfor
theSERVICECONTRACTmustbepost-
markedwithin30daysofthedateof
purchaseoftheinstrument.
7.ToreceivetheSERVICECONTRACT,all
informationontheapplicationmustbe
filledin.TheSERVICECONTRACTwill
beissuedwhenthecompletelyfilledin
applicationisreceivedbyMclntosh
LaboratoryIncorporatedinBinghamton,
NewYork.
8.UnitsinoperationoutsidetheUnited
StatesandCanadaarenotcoveredby
theMclntoshSERVICECONTRACT,re-
gardlessoftheplaceofpurchase.Nor
areunitsacquiredoutsidetheU.S.A.
andCanada,thepurchasersofwhich
shouldconsultwiththeirdealerto
ascertainwhat,ifany,servicecontract
orwarrantymaybeavailablelocally.
Copyright1982© byMclntoshLaboratoryInc.
-1-

Introduction
TheMclntoshC 33isa superquality,highperfor-
manceStereoPreamplifier.Itsdesignhasbeen
governedbyinsistenceongreatflexibility,versatili-
ty,lowdistortionandhighperformancewithlong
life.
TheC 33providesmanyfeaturesforyourlistening
enjoyment.Theyinclude:
1.a dualpreamplifiersystemwithseparatelisten
andrecordprogramlines,whichallowslistening
tooneprogramsourcewhilerecordingfroma dif-
ferentindependentprogramsource.
2.a lownoiseelectronicinputswitchingsystem,
whichusesdualfieldeffecttransistors(FETs)and
shortsignalleadstogivegreatsourcetosource
isolation,lowdistortion,andfreedomfromnoise
andhumpickup.
3.two,sevensource,inputselectorswitchesfor3
tapedecks,2 turntables,1 tuner,and1 auxiliary,
whichallowindependentsourceselectionfor
listeningandrecording.
4.anelectronicrecordmonitorswitch,which
allowstherecordprogramlinetobeheard
throughthemainlistenoutput.
5.a fivebandprogramequalizer,whichpermits
theadjustmentandimprovementoftheloudness
contrastofthefivemostimportantfrequency
ranges.Eachbandcanbeemphasizedorde-
emphasizedtosatisfyyourlisteningtaste.The
programequalizercanbeswitchedtoeitherthe
listenorrecordprogramlines.Thisallows
equalizingtherecordoutputsignaltotape
recordersorequalizingthemainlisteningoutput.
6.a precisionvolumecontrol,whichiselectroni-
callytrimmedduringmanufacturetomaintain
channeltochannelaccuracytobetterthan1
decibel(dB).Thishighorderofaccuracyassures
continuingprogrambalanceasthelistening
volumeischanged.
7.anactivecircuitloudnesscontrol,whichis
electricallyindependentofthevolumecontrol.
CloseconformitytotheFletcher-Munsonequal
loudnesscurvescanbeattainedregardlessofthe
volumecontrolposition.
8.highandlowfrequencyfilters,whichreduce
highfrequencynoiseandlowfrequencyrumbleat
a12dBperoctaverolloffrate.
9.a compandor,whichpermitsexpansionorcom-
pressionofthedynamicrangeofprogrammater-
ialfromeithertherecordtapeoutputorthemain
listenoutput.Compressedrecordingsandbroad-
castscanbeexpandedonplaybacktorestore
theirdynamicrange.Tapescanberecordedusing
compressionandreplayedusingexpansiontoin-
creasesignal-to-noiseratio.
10.frontpaneltaperecorderjacks,whichallow
simpleplug-inofanadditionaltaperecorder
withoutdisconnectingyourregularsystem.This
makestapecopyingtoa portablerecordervery
convenient.
11.a taperecordingprogramline,whichmakesit
veryeasytorecordphono,tuner,orauxiliaryon
upto3 recordersatthesametime(4recorders
whenusingthefrontpaneltaperecorderjacks)or
tocopyfromrecordertorecorder.Recording
operationsdonotinterferewiththeseparate
listenprogramline.
12.anautomaticACpowercontrolcircuit,which
canconvenientlyturnofftheentirestereosystem
whentheturntableturnsoff.
13.a built-inmonitoramplifier,whichprovides20
wattsperchannelpoweroutputandincludesthe
MclntoshpatentedPowerGuardprotectioncir-
cuit.Themonitoramplifiercanbeoperatedfrom
thelistenprogramline,therecordprogramline,or
independentlyfroma separateexternalsource.
14.twofrontpanelheadphonejacks,whichare
poweredbytheinternalmonitoramplifier.
15.twospeakeroutputpushbuttons,whichcontrol
theoperationoftwosetsofloudspeakers(when
usedwiththeoptionalSCR-2speakercontrol
relay)ortwosetsofpoweramplifiers.
16.electronicallyregulatedpowersupplies,which
maintainstableoperationevenduringperiodsof
lowlinevoltage.
Thisoutstandingpreamplifierwillserveyoubest
whenyouunderstanditsfunctionsandwhatitisde-
signedtodo.Sometimeinvestedwiththismanual
willbevaluableinyourknowledgeofhowitworks.
Thesimplifiedblockdiagramonpage3 showshow
theC 33'sinternalcircuitsarearranged.Thesimpli-
fiedconnectingdiagramonpage6 showshowother
componentsareconnectedtotheC 33.
-2-

Simplified
Block
Diagram
One
Channel
Shown,OtherChannel
Identical
MclNTOSH
C 33
STEREOPREAMPLIFIER
-3-

ThePANLOCsystemofinstallingequipmentcon-
venientlyandsecurelyisa directresultofMclntosh
research.BydepressingthetwoPANLOCbuttons
onthefrontpanel,theinstrumentcanbeeitherlock-
edfirmlyinplaceoritcanbeunlockedsothatthe
chassiscanslideforward,givingyoueasyaccessto
thetopandrearpanels.
Thetrouble-freelifeofanelectronicinstrumentis
greatlyextendedbyprovidingsufficientventilation
topreventthebuild-upofhighinternaltemperatures
thatcausedeteriorationofcomponentparts.You
shouldallowenoughclearancesothatcoolaircan
enteratthebottomofthecabinetandbevented
fromthetop.Withadequateventilationtheinstru-
mentcanbemountedinanyposition.Therecom-
mendedminimumspaceforinstallationis15inches
(38.1cm)deep,17inches(43.2cm)wide,and6 in-
ches(15.2cm)high.
Toinstalltheinstrumentina Mclntoshcabinet,
followtheinstructionsthatareenclosedwiththe
cabinet.Foranyothertypeofinstallation,follow
theseinstructions:
1.UnpackfromCarton
OpenthecartonandremovethePANLOCbrackets,
hardwarepackage,andmountingtemplate.Remove
theC 33fromitsplasticbagandplaceitupside
downontheshippingpallet,thenunscrewthefour
plasticfeetfromthebottomofthechassis.
2.MarktheCabinetPanel
Placethemountingtemplateinthepositiononthe
cabinetpanelwheretheinstrumentistobeinstall-
ed,andtapeitinplace.Thebrokenlinesthatrepre-
senttheoutlineoftherectangularcutoutalsorepre-
senttheoutsidedimensionsofthechassis.Make
suretheselinesclearshelves,paritions,orany
equipment.Withthetemplateinplace,firstmarkthe
sixA andB holesandthefoursmallholesthat
locatethecornersofthecutout.Then,jointhefour
cornermarkingswithpencillinesusingtheedgeof
thetemplateasa straightedge.
3.DrillHoles
Usea drillwitha 3/16inch(5mm)bitheldperpen-
diculartothepanelanddrillthesixA andB holes.
Then,usinga drillbitslightlylargerthanthetipof
yoursawblade,drilloneholeateachoftwodiago-
nallyoppositecorners.Theholesshouldbarely
touchtheinsideedgeofthepenciledoutline.Before
takingthenextstep,makesurethatthesixA andB
holeshavebeendrilled.
4.SawthePanelCutout
Sawcarefullyontheinsideofthepenciledlines.
Firstmakethetwolongcutsandthenthetwoshort
cuts.Aftertherectangularopeninghasbeencutout,
-4-

usea filetosquarethecornersandsmoothanyir-
regularitiesinthecutedges,
5.InstalltheMountingStrips
Inthehardwarepackageyouwillfindtwomounting
stripsandtwosetsofmachinescrews.Forpanels
thatarelessthan½ inch(12.7mm)thick,usethe¾
inch(19.1mm)screws;forpanelsthataremorethan
½inch(12.7mm)thick,usethe1¼inch(31.8mm)
screws.
Startingattheright-handsideofthepanel,insert
ascrewofproperlengthintothecenterholeinthe
panel,markedB onthetemplate.Onthebackofthe
panel,aligna mountingstripwiththeholesinthe
panelandtightenthescrewinthecenterholeuntil
thescrewheadispulledslightlyintothewood.
Repeatthisproceduretoattachthemounting
striptotheleftsideofthepanel.
6.AttachthePANLOCBrackets
Usingtwoscrewsofproperlengthinthe A holeson
eachside,attachthePANLOCbracketstothecabi-
netpanel;theshortflangeismountedagainstthe
front(face)ofthecabinetpanel.Thescrewspass
throughthePANLOCbracketflange,thecabinet
panel,andthenthroughthemountingstrips
previouslymounted.
7.InstalltheInstrument
GuidetheACpowercordthroughthepanelopening
tothebackofthecabinet;then,slidetheinstrument
intotheopeningcarefullysothattherailsonthe
bottomofeachsideofthechassisengagethe
tracksonthemountingbrackets.Continuetoslide
theinstrumentintothecabinetuntilitisstoppedby
theadjustpositionlatches.Pressthelatchesin-
ward,thispermitstheinstrumenttoslideintothe
cabinetuntilitsfrontpanelisflushwiththecabinet
panel.DepressthePANLOCbuttonsatthelowerleft
andrightcornersoftheinstrumentpaneltolockthe
unitfirmlyinthecabinet.DepressingthePANLOC
buttonsagainwillunlocktheinstrumentsothatit
canslideforwardtotheadjustposition;ifyoupress
inwardontheadjustpositionlatchesthenyoucan
removetheinstrumentfromthecabinet.
-5-

-6-
SimplifiedConnectingDiagram

HowtoConnect
Rearpanelinputjacksareprovidedfor2 stereo
turntables,PHONO1 andPHONO2;a stereotuner,
TUNER;3 stereotaperecorders,TAPE1,TAPE2,
andTAPE3;andanauxiliaryhighlevelsource,AUX.
Rearpaneloutputjacksareprovidedtofeed3
stereotaperecorders,TAPE1,TAPE2,andTAPE3;
and3 stereo2.5voltlistenprogramlineoutputs,
MAIN,OUTPUT1,andOUTPUT2.Twosetsofjacks,
EXTERNALPROCESSORS;LISTENandRECORD,
areprovidedtoconnectnoisereductionunitsor
othersignalprocessingdevices.Monitoramplifier
EXTINPUTjacks,OUTPUTjacksandspeakerter-
minalsallowconnectingtoandfromthemonitor
amplifier.
CONNECTINGTURNTABLES
Connectthecablefromtheleftchannelofthe
turntableintotheLeftPHONO1 INPUTjack.Con-
nectthecablefromtherightchanneloftheturn-
tableintotheRightPHONO1 INPUTjack.Fora se-
condturntable,connectPHONO2 inthesameway.
TheC 33usesautomaticshortingjacksforthe
PHONOinputs.Iftheinputsarenotconnected,
shortingplugsarenotneeded.
CONNECTINGA STEREOTUNER
Connectthecablefromthetunerleftchannelout-
puttotheLeftTUNERINPUTjack.
Connectthecablefromthetunerrightchannel
outputtotheRightTUNERINPUTjack.
CONNECTINGTAPERECORDERS
ToRecord:
Connecta cablefromtheLeftTAPE1 OUTPUTjack
tothelefthighlevelinputofthetaperecorder.Con-
necta cablefromtheRightTAPE1 OUTPUTjackto
therighthighlevelinputofthetaperecorder.Con-
necta secondandthirdrecorderinthesamemanner
totheTAPE2 OUTPUTandTAPE3 OUTPUTjacks.
ToPlayback/Monitor:
Connecta cablefromthetaperecorderleftchan-
neloutputtotheLeftTAPE1 INPUTjack.Connecta
cablefromthetaperecorderrightchanneloutputto
theRightTAPE1 INPUTjack.Connecta secondand
thirdrecorderinthesamemannertotheTAPE2 IN-
PUTandTAPE3 INPUTjacks.
FrontPanelTapeRecorderJacks:
TAPE3 recorderinputandoutputconnectionsare
alsoavailableattheTAPE3 IN-OUTjacksonthe
frontpanel.Whena plugisinsertedinthefrontpan-
elTAPEINjackthecircuittotherearpanelTAPE3
INPUTjackswillbedisconnected.Insertinga plugin
thefrontpanelTAPEOUTjacksdoesnotdisconnect
therearpanelTAPE3 OUTPUT.Thusitispossibleto
recordfromthefrontpanelTAPEOUTjackandthe
rearpanelTAPE3 OUTPUTjackatthesametimebut
itisnotpossibletolistenfromthecorresponding
jacksatthesametime.Metalshielded¼ inch
stereophoneplugsmaybeused.Connectionsare
tip:leftsignal,ring:rightsignal,andsleeve:com-
monground.
CONNECTINGAUX
Connecttheleftchannelcablefromanyhighlevel
source(tuner,TVset,taperecorder,etc.)totheLeft
AUXINPUTjack.Connecttherightchannelcableto
theRightAUXINPUTjack.
CONNECTINGEXTERNALPROCESSORS
TherearetwosetsofEXTERNALPROCESSOR
jacks.OnesetisforLISTENprogramlinesandone
setisforRECORDprogramlines.Thesejacksare
usedtoconnecttoandfroma noisereductionunit
ortoandfromanyothersignalprocessingdevice.
Besuretomatchlefttoleftandrighttorightchan-
nelswhenconnectingexternalprocessors.
WhenconnectionsaremadetotheEXTERNAL
PROCESSORfromjacks,thesignalpathisbroken
withintheC 33.THEPROCESSORMUSTBETURN-
EDONFORTHEPROGRAMTOPASSTHROUGH
THESYSTEM.
CONNECTINGTOPOWERAMPLIFIERS
ConnecttheMAINOUTPUTjackstotheinputofa
stereopoweramplifier.TheLeftMAINjackconnects
totheamplifierleftinputjack.TheRightMAINjack
connectstotheamplifierrightinputjack.
-7-

Twostereopoweramplifiersortwodelayunits
maybeconnectedinthesamefashiontotheOUT-
PUT1 andOUTPUT2 jacks.Audiooutputsignalis
suppliedtothesejacksonlywhenthefrontpanel
pushbuttonSPEAKER/OUTPUT1 and/or2 pushbut-
tonsarepushed.Thisarrangementisusefulfor
largesystemswhereseparateamplifiersand
loudspeakersareusedatdistantlocations.
SPEAKERCONTROLRELAY(anoptionalaccessory)
TheSPEAKERCONTROLRELAY,orSCR,isde-
signedtoprovidebothspeakercontrolswitching
andhighpowerswitchedACoutlets.Tocontrol
loudspeakers,SPEAKERS1 and2 pushbuttonson
thefrontpanelmustbeused.Whenthisisdone,
OUTPUTjacks1 and2arenormallynotused.Theop-
erationofoutputjacksandspeaker controlwill
otherwiseinterferewitheachother.
PlugthecablefromtheSCRintotheC 33back
panelSPEAKERCONTROLRELAYreceptacle.Con-
nectthepoweramplifieroutputtotheFROM
POWERAMPLIFIERterminalsontheSCR.Observe
correctchannelidentificationaswellascorrect
polarity.TheMAINspeakers(controlledbySPEAK-
ER1 pushbutton)areconnectedattheTOMAIN
SPEAKERterminals.TheREMOTEspeakers(con-
trolledby SPEAKER2 pushbutton)areconnectedat
theTOREMOTESPEAKERSterminals.Again
observecorrectchannelidentificationandpolarity.
TheSCRalsohastwoACpoweroutletsthatpro-
videadditionalcapacityof2400wattsswitchedby
theC 33.UsetheseoutletstosupplyACpowerto
amplifiersorothercomponentswheneverthetotal
loadtobeswitchedbytheC 33exceedstheratingof
1200watts.Forproperoperation,thecablefromthe
SCRmustremainconnectedtotheSCRreceptacle
atthebackoftheC 33.PlugtheSCRheavylinecord
directlyintoawalloutlet.DonotplugitintotheC33.
WhentheC 33isturnedon,powerfromtheC 33will
energizea relayintheSCRwhichconnectsthetwo
SCRACoutletsdirectlytothewalloutlet.
MONITORAMPLIFIER
Althoughitsprimarypurposeistodrivehead-
phones,themonitoramplifiercanalsobeusedto
drivespeakers.Thiseliminatestheneedfora separ-
atestereomonitoramplifier.Themonitoramplifier
willfurnish20wattsperchannelinto8 ohmsor12.6
voltsRMSintoa 600ohmline.Foroperationsee
MONITORAMPLIFIERpage17.Thespeakerscanbe
connectedtotheredandblackoutputterminalsat
therearoftheC 33.Connecttheleftspeakerminus
leadtotheblackOUTPUTCOMterminalclosestto
thecenteroftheC 33.Connecttheleftplusspeaker
leadtotheredOUTPUTL terminal.Connecttheright
speakerminusleadtotheblackOUTPUTCOMter-
minalclosesttotheC 33groundterminal.Connect
theright plusleadtotheredOUTPUTR terminal.
Resistanceofthespeaker hookupwireshouldbe
keptlessthan0.5ohmstoavoidlossesand
responsechanges.
ThemonitorOUTPUTjackscanbeconnectedto
drivea lowimpedanceunbalancedline.
TheINPUTjacksareusedwhenanexternalsource
isfedtothemonitoramplifier.
CONNNECTINGACPOWER
ThepreamplifierACpowercordistobeplugged
intoa 120volt60Hzwalloutlet.
TwotypesofACpoweroutletsareontheback
paneloftheC 33.Fourareblackandtwoaregreen.
Theblackoutletsareswitchedonandoffwhen
theC 33isturnedonandoff.Theseareintendedfor
poweramplifiers,equalizers,andothersaccessor-
iestotalingupto1200wattscapacity.
ThegreenACpoweroutletsareonatalltimesand
areforuseonlywithturntables.Donotusethemfor
anyotherpurpose.Theturntablecanbeusedasa
powerswitchasdescribedinthefollowingsection.
USINGTHETURNTABLEASA POWERSWITCH
Ifa turntableisusedwiththeC 33,itcanoftenbe
usedtoturnyourentiresystemonandoff.Theturn-
tablemustbepluggedintooneofthegreenACout-
letsattherearoftheC 33.TheAUTO/MANUAL
switchalsoattherearmustbeintheAUTOposition.
Whenyouswitchonthepowertotheturntable,a
specialsensorcircuitwilldetectthecurrentdrainof
theturntableandwillturnontheC 33thesameway
theredPOWERpushbuttondoes.Theredpushbut-
tonmustbeintheOFForoutpositiontodothis.
ReadthesectiononAUTO-ONSENSIVITYonpage
17beforeusingthisfeature.
CONNECTINGPROGRAMSOURCEGROUNDS
AGROUNDpostisprovidedtoconnectthegrounds
fromrecordchangers,tapedecks,etc.Toprevent
humpick-up,theleftandrightprogramcablesand
thegroundwirefromthatsourceshouldbewound
ortwistedtogether.Makesurethegroundwiredoes
notmakeanyconnectiontotheshieldsoftheleft
andrightprogramcablesastheyrunbetweenthe
sourceandtheinputofthepreamplifier.
FUSE
A1.0AMPfastactingfuseprotectstheC 33turn-
tablecurrentsensingcircuitsandthegreenACturn-
tableoutlets.Thefusedoesnotprotectequipment
connectedtotheblackACoutlets.Thisfusemust
bereplacedwiththesametypeandrating.Donot
useSLOBLOfuses.
-8-

FMANTENNA
ACPOWERTO
TAPERECORDERS,
TUNERS,POWER
AMPLIFIERS.
TOTALOF1200WATTS.
FORMOREACPOWER
USETHESCRSPEAKER
CONTROLRELAY
ACPOWER
TURNTABLE#2
-9-
ACPOWER
TURNTABLE#1
CONNECTIONSFORTUNERS,TURNTABLES,ANDTAPERECORDERS
TAPE
RECORDER
I
TAPE
RECORDER
2
TUNER
T
APE
RECORDER3

MAINSPEAKERS
REMOTEAREA2
(CONTROLLEDBY
SPEAKER2
PUSHBUTTON)
REMOTEAREA1
(CONTROLLEDBY
SPEAKER1
PUSHBUTTON)
CONNECTIONSFORPOWER
AMPLIFIERSANDLOUDSPEAKERS
USINGMAINSPEAKERSANDENVIRONMENTAL
EQUALIZER.ALSOSHOWNFORREMOTE
SPEAKERSUSINGSEPARATEPOWERAMPLIFI-
ERSANDCONNECTIONSFORANEXTERNAL
NOISEREDUCTIONSIGNALPROCESSOR.
CUSTOM
ENVIRONMENTAL
EQUALIZER
(FORMAINSPEAKERS)
PLAYBACK
NOISEREDUCTIONPROCESSOR
RECORD
-10-

CONNECTIONSFORPOWERAMPLIFIERSANDLOUDSPEAKERS
USINGOPTIONALSCR-2SPEAKERCONTROLRELAY.CONNECTIONSALSO
SHOWNFORTIMEDELAYUNITANDMONITORAMPLIFIERLOUDSPEAKERS.
THE SPEAKER/OUTPUT1 PUSHBUTTONWILLTURNONANDOFFTHEMAIN
SPEAKERSANDTHETIMEDELAYEDPROGRAM.IFTHESCR2 ISNOTUSED
THEPUSHBUTTONWILLTURNONANDOFFONLYTHETIMEDELAYEDPROGRAM.
MONITORAMPLIFIERSPEAKERS
TOREPRODUCE
TIMEDELAYED
PROGRAM
-11-
REMOTE
SPEAKERS
(CONTROLLEDBY
SPEAKER2
PUSHBUTTON)
MAINSPEAKERS
(CONTROLLEDBY
SPEAKER1 PUSHBUTTON)
TOACLINE
TIME
DELAY
UNIT

UsingtheFrontPanelControls
LISTENANDRECORD
SELECTORSWITCHES
TheLISTENinputse-
lectorswitchislocated
attheupperleftonthe
frontpanel.Thisisused
toselecttheinputfor
theLISTENprogram
line.TheLISTENprogramlinefeedsthemainoutput
forthesystempoweramplifierandloudspeakers.
TheRECORDinputselectorswitchislocatedat
thelowerleftonthefrontpanel.Thiscontrolisused
toselecttheinputfortheRECORDprogramline.
TheRECORDprogramlinefeedstherecordoutput
fortaperecorders.Tomakea taperecording,turn
theRECORDselectortotheinputprogramtobere-
corded.Tocopya tape,turnthiscontroltoselectthe
recorderonwhichthetapeistobeplayed.Thiscan
beTAPE1,2,or3.Copiescanthenbemadeonthe
otherrecordersconnectedtotheC 33.TheCOM-
PANDOR,RECordEQUALizer,andRECordMONI-
TORpushbuttonscanbeusedwhenmakingrecord-
ings.Refertothedescriptionofthesecontrolson
Page15fortheiroperation.
MODESELECTOR
TheMODESELEC-
TORallowsyouto
identifyeachstereo
channel,createmono-
phonicprogramma-
terial,anddirectpro-
grammaterialtoone
channelortheother.Thisselectorisusedonlyinthe
LISTENprogramline.
Itcontrolstheprograminsevenways:
LTOL&R:Connectstheleftinputtobothleftand
rightoutputcircuits.
RTOL&R:Connectstherightinputtobothleft
andrightoutputcircuits.
STEREOREV:Connectstheleftinputtotheright
outputcircuitandtherightinputto theleftoutput
circuit.
STEREO:Connectstheleftinputtotheleftoutput
circuitandtherightinputtotherightoutputcir-
cuit.UsethisSTEREOpositionfornormallistening.
MONO(L+ R):Addstheleftandrightinputs
togetherandconnectstobothoutputcircuits.
L+ R TOL:Connectstheleftplusrightprogram
totheleftoutputcircuitonly.
L+ R TOR:Connectstheleftplusrightprogram
totherightoutputcircuitonly.
EQUALIZERFREQUENCYCONTROLS
EachoffiveEQUALIZERFREQUENCYcontrols
raisesorlowerstheamplitudeofa bandoffrequen-
ciescenteredonthefrequencymarkedabovethe
control.Bothleftandrightchannelsareaffected.
Thecenter,orflatpositionofthecontrolhasa de-
tentforeasyreference.
UsetheEQUALIZERFREQUENCYcontrolsto
modifythesoundandbalanceofprogrammaterial.
Herearesomesuggestionsfromwhichtostart.
-12-

Problem
Deepbasstoweak
Allbassweak
Voicereinforcement
Humonprogram
Violins,trumpetsdull
Cymballsnotaudible
EqualizerCorrection
Raise30
Raise30and150
Lower150andraise500
Reduce30and150
Raise1500
Raise10K
TheEQUALIZERFREQUENCYcontrolscanbe
switchedtoeithertheLISTENorRECORDprogram
linesbytheRECORDEQUALizerpushbutton.The
equalizercircuitislocatedaftertheCOMPANDOR
circuit.Usingtheequalizerwillnotinfluencethebe-
havioroftheCOMPANDOR.
BALANCEANDLOUDNESS
TheBALANCEand
LOUDNESScontrolsare
concentric.TheBALANCE
control(largeouterknob)
adjuststhevolumeofthe
channelsrelativetoeach
other.
L-LEFT...turningthecon-
troltotheleftaccentsthe
leftchannelbyreducing
therightchanneloutput.
R-RIGHT...turningthecontroltotherightaccents
therightchannelbyreducingtheleftchanneloutput.
LOUDNESS
TheLOUDNESScontrol(smallcenterknob)pro-
videsa frequencyresponsecontourwhichcompen-
satesforthebehaviorofthehumanearatlowerlis-
teninglevels.Thiscontourisaccuratelymodeled
afterthefamilyof"equalloudness"curvesidenti-
fiedbyFletcherandMunson.Atthefullycounter-
clockwisedetentedFLATposition,theloudness
contouriselectricallyflat.Asthecontrolisturned
clockwise,bothbassandtreblefrequenciesin-
creaseinthecorrectproportion.Thecontourisnot
affectedbydifferentsettingsoftheVOLUMEcon-
trol.AftersettingtheVOLUMEcontrolforthede-
siredlisteninglevel,adjusttheloudnesscontrolfor
thepreferredcompensation.
COMPANDORSYSTEM
TheMclntoshCompan-
dorSystemcanbeusedto
controlthedynamicrange
ofprogrammaterial.Itcan
beusedintwodifferent
ways.Thecircuitscanby
switchedtofunctionasan
expanderorasa compres-
sor.Expansionincreases
thedynamicrangeofpro-
grammaterial.Thiscanbeusedtorestorecompres-
sedmaterialfromtaperecordings,records,orradio
broadcasts.Compressiondecreasesthedynamic
range.Itcanbeusedformakingtaperecordingsor
forlisteningtobackgroundmusic.TheCompandor
canbeswitchedtoeithertherecordorlistenlines.
Inthiswayyoucanmakeyourownrecordingsusing
compressionandthenplaythembackusingexpan-
sion.
TheCompandorSystemhasa totaloffourcon-
trols.TheconcentricCOMPANDORandRATIOcon-
trolsarelocatedonthefrontpanel.TheLEVEL
MATCHandSPEEDselectorarelocatedontheC 33
toppanel.
COMPANDORSELECTOR
TheouterCOMPANDORknobcanbesettoEX-
PAND,OFF,orCOMPRESS.WhentheCOMPAN-
DORswitchisinEXPANDorCOMPRESS,a redlight
willappearaboveListenorRECordattheCOMPAN-
DORpushbutton.InthecenterOFFposition,the
CompandorSystemisswitchedoutofthecircuit
andthelightswillbeout.WhentheCompandoris
notused,theselectorshouldbeplacedintheOFF
position.
RATIOCONTROL
TheinnerRATIOknobisusedtocontrol
amountofexpansionorcompression.
the
LEVELMATCH
TheLEVELMATCHcontrolonthetoppanelisus-
edtorestorethelisteninglevelwhentheexpander
orcompressorisswitchedintothecircuit.
SPEED
TheSPEEDselectoronthetoppanelisusedto
controlhowfasttheCompandorSystemresponds
tosignals.ByswitchingfromFASTtoNORMALto
SLOW,a moregradualrateofchangeinvolumecan
beheard.Selectthepositionthatsoundsbestto
you.Ifmusicwithpercussiveinstrumentsisused,
NORMALorFASTcanprovideveryattractivesound.
AttheFASTspeedtheCompandorSystemfollows
changesquicklybutwilltracklowfrequenciesless
accurately.Non-percussivemusicandvoicerequire
slowerspeed.AtSLOWspeedthelowfrequency
trackingisaccuratebutthesystemwillrespond
moreslowly.TheNORMALpositionisbestsuited
formostprogrammaterial.
USINGTHECOMPANDORASANEXPANDER
WhentheCOMPANDORselectorisintheEX-
PANDposition,theRATIOcontrolisusedtoselect
theamountofexpansion.Fullcounterclockwise
rotationcorrespondstoa ratioof1.0.Thismeans
thatthedynamicrangeoftheexpanderoutputisthe
sameasthedynamicrangeofitsinput.Setthe
VOLUMEcontroltoa normallisteninglevel.No
changeindynamicrangewillbeheard.Asthe
RATIOcontrolisincreasedclockwise,however,the
outputdynamicrangebecomesgreaterthanthein-
put.SettheRATIOcontroltothedesiredexpansion
-13-

(usuallybetween1.2and1.5).Nowswitchtheex-
panderonandoff.A changeintheaveragelistening
levelwillusuallybeheardatthistime.Adjustthe
LEVELMATCHcontroluntiltheaveragelistening
levelmatchesascloselyaspossiblewhentheex-
panderisonandoff.Afterthisadjustmentyouwill
noticethatwiththeexpanderon,loudpassageswill
belouderandsoftpassagesincludingnoisewillbe
softer.
WhentheRATIOcontrolisatthefullyclockwise
positionitcorrespondstoa ratioof2.0.Theoutput
dynamicrangeisthentwicetheinputdynamicrange.
Thissettingisusuallytoohighformostprogram
material.
Twoexamplesforusingtheexpanderareas
follows.
1.Toreducebackgroundnoise(hum,hissor
scratch):
a.Selectthedesiredprogramsourcewiththe
LISTENinputselector.
b.IncreasetheVOLUMEcontrolduringa quiet
passageoftheprogramuntilnoiseisclearlyaudi-
ble.
c.TurntheCOMPANDORselectorknobtoEX-
PAND.TheListen indicatorwilllightoverthe
COMPANDORpushbutton.
d.RotatetheRATIOcontrolclockwiseuntilthe
noiseisacceptablyreduced.
e.AdjusttheLEVELMATCHcontrolasdescribed
previously.
2.Toimprovethe"live"soundofrecordedor
transmittedprogrammaterial:
a.SelecttheLISTENinput.
b.IncreasetheVOLUMEtoa satisfactorylevel.
c.TurntheCOMPANDORselectortoEXPAND.
d. RotatetheRATIOcontrolclockwiseuntilthe
dynamicrangeofthemusic,theratioofloudto
soft,iscorrectforyou.Theusualpositionwillbe
between1.2and1.5
e.AdjusttheLEVELMATCHcontrolasdescribed
previously.
USINGTHECOMPANDORASA COMPRESSOR
WhentheCOMPANDORselectorisintheCOM-
PRESSposition,theRATIOcontrolisusedtoselect
theamountof compression.Fullcounterclockwise
rotationcorrespondstoa ratioof1.0.Thecompress-
oroutputandinputdynamicrangewillbethesame.
SettheVOLUMEcontroltoa normallisteninglevel.
AstheRATIOcontrolisincreasedclockwisetheout-
putdynamicrangebecomeslessthantheinput
range.SettheRATIOcontroltothedesiredcom-
pression.Switchthecompressoronandoff.A
changeintheaveragelisteninglevelwillusuallybe
heard.AdjusttheLEVELMATCHcontroluntilthe
averagelisteninglevelmatchesascloselyaspossi-
blewhenthecompressorisswitchedonandoff.
Afterthisadjustmentyouwillnoticethatwiththe
compressoron,loudpassageswillbesofterand
softpassagesincludingnoisewillbelouder.
WhentheRATIOcontrolisatthefullyclockwise
positionitcorrespondstoa ratioof2.0.Theoutput
dynamicrangeisthenonehalfoftheinputrange.
Thissettingcanbeusefultocreatehighlycom-
pressedbackgroundmusic.
-14-

UsingthePushbuttons
COMPANDOR
TheCOMPANDORpushbuttonconnectsthecom-
pandortoeitherthelistenortherecordprogram
line.Theredindicatorlightsabovethepushbutton
willshowthatthecompandorisconnectedtothe
LIS(listen)programline(pushbuttonout)ortothe
REC(record)programline(pushbuttonin).These
lightswilllightonlywhentheCOMPANDORknobis
turnedtotheEXPANDorCOMPRESSpositions.
RECEQUAL
ThispushbuttonconnectstheEQUALIZERFRE-
QUENCYcontrolstothelistenortherecordprogram
lines.Whenthepushbuttonisout,theequalizersare
connectedtothelistenline.Theredindicatorlight
abovethebuttonwillbeoff.Whenthepushbuttonis
in,theequalizersareconnectedtotherecordline.
Theredlightwillbeon.
RECMONITOR
ThispushbuttonconnectstheC 33mainoutputto
eitherthelistenlineortherecordline.Thispushbut-
tondoesnotstayinafteritispushedastheothers
do.Tochangetheswitchingstatus,pushitagain.
Normaloperationoccurswhentheredindicatorlight
isoff.ThelistenlineisthenconnectedtotheC 33
output.Whenthelightison,therecordlineiscon-
nectedtotheC 33output.Thisswitchenablesyou
tomonitorwhatisbeingfedtothetaperecorder.
Tomonitortheprogramfroma taperecorder,turn
theLISTENinputselectortoTAPE1,TAPE2,or
TAPE3 asappropriate.Tocomparethisprogram
withthesignalbeingfedintotherecorder,pressthe
RECMONITORpushbuttonsothattheredindicator
lightison.PresstheRECMONITORbuttona se-
condtimetolistentotherecorderoutputagain.The
redindicatorwillthenbeoff.
LFFILTER
TheLowFrequencyFILTERcanbeusedonlyin
thelistenprogramline.Whenthepushbuttonisout,
thefilterisoutofthecircuitandtheredindicator
lightwillbeoff.Whenthepushbuttonisin,theLF
FILTERisinthecircuitandtheredlightwillbeon.
Thefilteriseffectiveforallfrequenciesbelow50Hz
andattenuatesattherateof12dBperoctave.Useit
toreduceundesirablelowfrequencynoisesuchas
rumbleormechanicalfeedback.
HFFILTER
TheHighFrequencyFILTERaffectsonlythelis-
tenprogramline.Whenthepushbuttonisoutthefil-
terisoutofthecircuitandtheredindicatorlightis
off.Whenthepushbuttonisin,theHFFILTERisin
thecircuitandtheredlightwillbeon.Thefilterisef-
fectiveforallfrequenciesabove7,000Hzandattenu-
atesattherateof12dBperoctave.Useittoreduce
undesirablehighfrequencynoisesuchasrecord
surfacenoiseortapehiss.
SPEAKER/OUTPUT1 and2
TheSPEAKER/OUTPUT1 and2 pushbuttonscan
beusedtocontroleithertheoutputjacks1 and2 or
themainandremotespeakerswhentheoptional
SPEAKERCONTROLRELAY(SCR)isconnected.
TheSPEAKER/OUTPUTpushbuttonsarenotnormal-
lyusedtocontrolconnectionstotheOUTPUT1 and
2jacksanda SCRforspeakerswitchingatthesame
time.Theoperationoftheoutputjacksandspeaker
controlwillinterferewitheachother.
OUTPUT1 AND2
Theoutputjacks1 and2 arelocatedontherear
paneloftheC 33.Signalsfromoutput1 and2 arethe
sameasthemainoutput.Whenthefrontpushbut-
tonsareout,thelistenprogramlineisnotconnect-
edtooutputjacks1 and2 andtheredindicator
lightsareoff.WhenoneorbothpushbuttonsareIN,
thelistenlineisconnectedtothecorresponding
pairofoutputjacksandtheappropriateindicator
lightwillbeon.TheC 33outputcanthenbeswitch-
edtoadditionalamplifiersorotherdevices.
Additionalamplifierscanserveremoteareassuch
asselectedlivingareas,workshop,oroutdoor
recreationalfacilities.Otherdevicescanbecontroll-
-15-

edsuchasrearchannelreverberationunits,color
displays,etc.ForexampleOutput1 or2 canbecon-
nectedtoa reverberationdeviceandthentotheC33
monitoramplifieranda setofrearloudspeakers.
(ThemonitoramplifierswitchmustbeintheEXTER-
NALposition.)Rearchannelreverberationcanthen
beswitchedinandoutwithouttheneedforanextra
amplifier.
SPEAKER1 AND2 USINGTHESCR
Whenpushbutton1 isinandpushbutton2 isout,
theMAINspeakerswillbeconnectedtothepower
amplifierviatherelaysintheSCR.Theredlight
above1 willbeon.Whenpushbutton1 isoutand
pushbutton2 isin,theremotespeakerswillbecon-
nectedinstead.Theredlightabove2 willbeon.
Whenbothpushbuttons1 and2 arein,bothsetsof
speakerswillbeconnectedandlights1 and2 willbe
on.CAUTION:Whenbothsetsofspeakersarecon-
nectedatthesametime,theircombinedparallelim-
pedancemustnotbetoolowforthepoweramplifier
tohandle.Forexample:Ifbothsetsofspeakersare
8ohms,connectionstothepoweramplifiermustbe
tothe4 ohmtap.Iftheamplifierdoesnothavedif-
ferentimpedancetaps,itmustbeabletodeliver
powertoa 4 ohmloadaswellasan8 ohmload.
POWERON
TheredpushbuttonturnstheC 33onandoff.
Whenthepowerison,thepanelilluminatesandthe
redlightabovethispushbuttonwillgoon.Theturn-
tablecanalsobeusedasa powerswitch.Seepage8.
-16-

TopPanelInformationand
SecondaryControls
COMPANDOR
OperationoftheLEVELMATCHandSPEEDcon-
trolsisexplainedonpage13undertheCompandor
Systemdescription.
AUTO-ONSENSITIVITY
TheSENSITIVITYcontrolislocatedattherightof
theC 33toppanel.Fornormaloperationwithmost
turntables,thecontrolcanbeleftatmid-position.
Someturntables,however,haveelectroniccircuits
thatdrawcurrentwhethertheyareturned"off"or
not.TheC 33AUTO-ONSENSITIVITYcontrolcanbe
usedto"finetune"forthesmallerdifferencebe-
tweenonand"off"currents.
IfyourturntabledoesnotcontroltheAUTO-ON
featureoftheC 33correctly,useoneofthefollow-
ingprocedures:
1.Switchontheturntable.IftheC 33doesnotgoon,
orgoesonbutdoesnotstayon,rotatetheAUTO-
ONSENSITIVITYcontrolclockwisetowardsMAX
untiltheC 33goesonandstayson.Thencheck
forproperoperation.
2.Switchofftheturntable.IftheC 33doesnotgo
off,rotatetheAUTO-ONSENSITIVITYcontrol
counterclockwisetowardsMINuntilitdoesgo
off.Checkforproperoperation.
Ifthisdoesn'tcorrecttheproblem,yourturntable
probablyhaselectroniccircuitsthatdrawthesame
ornearlythesamecurrentwhetheronoroff.AUTO-
ONcontrolisnotpossiblewhenusingthisturntable.
ThegreenACoutletcanstillbeusedbuttheAUTO/
MANUALswitchmustbesetintheMANUALposi-
tion.TheredPOWERpushbuttonmustbeusedin-
stead.
Intheeventyouareusingtworecordplayers,ad-
justtheSENSITIVITYcontrolasdescribedabove
withbothturntablesconnectedtotheC 33green
outlets.Startwithbothturntablesswitchedoff,and
thenoneata timeswitchedon.
MONITORAMPLIFIER
HEADPHONES
Thebuilt-inMonitorAmplifiercandrivehead-
phones,loudspeakers,orprovidea lowimpedance
lineoutput.TheinputtotheMonitorAmplifierisse-
lectedbytheINPUTswitchlocatednearthecenter
oftheC 33toppanel.ThisswitchselectstheLISTEN
program,RECORDprogram,orseparateEXTERNAL
input.FornormallisteningusetheLISTENposition.
TheMonitorAmplifierLEFTandRIGHTGAINcon-
trolsarelocatedtotheleftoftheINPUTswitch.
WhentheswitchisintheLISTENposition,theLEFT
andRIGHTGAINcontrolsregulatethemonitorvol-
umealongwiththemainfrontpanelVOLUMEcon-
trol.WhentheINPUTswitchisintheRECORDorEX-
TERNALposition,onlytheLEFTandRIGHTGAIN
controlsregulatethemonitorvolume.
Themonitoramplifiercanbeusedwithanylow
impedancedynamicheadphones.Highimpedance
headphoneswillworkbutata reducedlistening
level.
-17-

PerformanceLimitsandRatings
PERFORMANCELIMITS
Performancelimitsarethemaximumdeviation
fromperfectionpermittedfora Mclntoshinstru-
ment.Wepromiseyouthatwhenyoupurchasea
newC 33froma Mclntoshfranchiseddealer,itwill
becapableoforcanbemadecapableofperfor-
manceatorexceedingtheselimitsoryoucanreturn
theunitandgetyourmoneyback.Mclntoshisthe
onlymanufacturerthatmakesthisstatement.
PREAMPLIFIERSECTION
FREQUENCYRESPONSE
+0,-0.5dBfrom20Hzto20,000Hz
MAXIMUMVOLTAGEOUTPUT
10voltsfrom20Hzto20,000Hz
TOTALHARMONICDISTORTION
0.01%maximumfrom20Hzto20,000Hz
atratedoutput
SENSITIVITY
Phono-2mVfor2.5Vratedoutput
(0.4mVIHF)
HighLevel-250mVfor2.5Vratedoutput
(50mVIHF)
SIGNALTONOISERATIO,A-WEIGHTED
Phono-90dBbelow10mVinput
(84dBIHF)
HighLevel-100dBbelowratedoutput
(86dBIHF)
MAXIMUMINPUTSIGNAL
Phono-100mV
HighLevel-10volts
INPUTIMPEDANCE
Phono-47kohmsand65pfcapacitance
HighLevel-50kohms
EQUALIZATIONCONTROLS
Variable12dBboostto12dBcutatcenterfre-
quenciesof30,150,500,1500,10kHz
COMPANDORRATIOS
From1:2compressionto2:1expansion
LFFILTER
Flatorroll-offat12dBperoctavebelow50Hz.
HFFILTER
Flatorroll-offat12dBperoctaveabove7,000Hz.
MONITORAMPLIFIERSECTION
CONTINUOUSAVERAGEPOWEROUTPUT
20wattsperchannelinto8 ohms,from20Hzto
20kHz,at0.01%maximumharmonicdistortion
FREQUENCYRESPONSE
+0 -0.2dBfrom20Hzto20,000Hz
SENSITIVITY
750mVforratedoutput(170mVIHF),inputim-
pedanceis27Kohms
SIGNALTONOISERATIO,A-WEIGHTED
100dBbelowratedoutput(87dBIHF)
GENERALINFORMATION
SEMICONDUCTORCOMPLEMENT
31BipolarTransistors
76FieldEffectTransistors
35IntegratedCircuits
107Diodes
1SiliconControlledRectifier(SCR)
ACPOWEROUTLETS
2turntablecurrent-sensing,100watts,green
4switched,1200wattstotal,black
POWERREQUIREMENTS
120volts,50/60Hz,25to85watts
MECHANICALINFORMATION
SIZE:
Frontpanelmeasures16incheswide(40.6cm)
by5-7/16incheshigh(13.8cm).Chassismeasures
15incheswide(38.1cm)by5 incheshigh(12.7cm)
by13inchesdeep(33.0cm),includingPANLOC
shelfandbackpanelconnectors.Knobclearance
requiredis1-1/2inches(3.81cm)infrontonthe
mountingpanel.
FINISH:
Frontpanelisanodizedgoldandblackwith
specialgold/tealnomenclatureillumination.
Chassisisblack.
MOUNTING:
ExclusiveMclntoshdevelopedprofessional
PANLOC
WEIGHT:
26pounds(11.8kg)net,38pounds(17.2kg)in
shippingcarton
-18-