McIntosh MA 5100 User manual

THEMclNTOSHMA5100STEREOPREAMPLIFIER/POWERAMPLIFIER
$1.25

YourMA5100stereopreamplifier/power
amplifierwillgiveyoumanyyearsof
pleasantandsatisfactoryperformance.
Ifyouhaveanyquestionsconcerning
theoperationormaintenanceofthis
instrument,pleasecontact:
CUSTOMERSERVICE
MclntoshLaboratoryInc.
2ChambersStreet
Binghamton,NewYork13903
Phone:[phone]
TakeAdvantageof3 years
ofFREEFactoryService. . .
FillintheApplicationNOW.
CONTENTS
Guarantee1
Installation2,3
HowtoConnect3,4,5
WhattheControlsDo
AndHowtoUseThem5,6,7
BalancingYourStereo7
ListeningtoYourStereo8
PerformanceLimits8,9
TypicalPerformanceCharts10
TechnicalDescription11
BlockDiagrams12
MclntoshLaboratoryIncorporatedguaranteesthis
Instrumenttobecapableofperformanceasadver-
tised.Wealsoguaranteethemechanicalandelec-
tricalworkmanshipandcomponentstobefreeof
defectsfora periodof90daysfromdateofpur-
chase.Ifsuchdefectsoccur,MclntoshLaboratory
Oroneofitsauthorizedagencieswillrepairthe
defectatnocosttothepurchaser.Thisguarantee
doesnotextendtocomponentsdamagedbyim-
properusenordoesitextendtotransportationto
andfromthefactoryorserviceagency.
THREEYEARFACTORYSERVICECONTRACT
Anapplicationfora FREETHREEYEARFACTORY
SERVICECONTRACTisincludedwiththismanual.
Thetermsofthecontractare:
1.Mclntoshwillprovideallparts,materialsand
laborneededtoreturnthemeasuredperformance
oftheinstrumenttotheoriginalperformance
limitsfreeofany charge.TheSERVICECON-
TRACTdoesnotcoverany shippingcoststoand
fromtheauthorizedserviceagencyorthefactory.
2.AnyMclntoshauthorizedserviceagencywillre-
pairallMclntoshinstrumentsatnormalservice
rates.Toreceivethefreeserviceundertheterms
oftheSERVICECONTRACT,theSERVICECON-
TRACTCERTIFICATEmustaccompanytheinstru-
mentwhentakentotheserviceagency.
3.Alwayshaveservicedonebya Mclntoshauthor-
izedserviceagency.Iftheinstrumentismodified
ordamaged,asa resultofunauthorizedrepairthe
SERVICECONTRACTwillbecancelled.Damage
byimproperuseormishandlingisnotcoveredby
theSERVICECONTRACT.
4.TheSERVICECONTRACTisissuedtoyouasthe
originalpurchaser.Toprotectyoufrommisrepre-
sentationthiscontractcannotbetransferredtoa
secondowner.
5.TheSERVICECONTRACTisgiventopurchasers
wholiveInthe50UnitedStatesorCanadaonly,
6.ForyourprotectionMclntoshselectsItsdealers
carefully.Onlyonedealerintenqualifiesfora
Mclntoshfranchise.ToreceivetheSERVICE
CONTRACTyourpurchasemustbemadefroma
Mclntoshfranchiseddealer.
7.Yourcompletelyfilledinapplicationfora SERV-
ICECONTRACTmustbepostmarkedwithin30
daysofthedateofpurchaseoftheinstrument.
8.ToreceivetheSERVICECONTRACTallinforma-
tionontheapplicationmustbefilledin.The
SERVICECONTRACTwillbeissuedwhenthe
completelyfilledinapplicationisreceivedat
MclntoshLaboratoryIncorporatedinBinghamton,
NewYork.Iftheapplicationisnotreceivedat
MclntoshLaboratory,onlytheserviceoffered
underthe90-dayguaranteewillapply.
Copyright© 1972ByMclntoshLaboratoryInc.
1
GUARANTEE

Adequateventilationextendsthetrouble-freelife
ofelectronicinstruments.Itisgenerallyfoundthat
each10°centigrade(18°F)riseintemperature
reducesthelifeofelectricalinsulationbyonehalf.
Adequateventilationisaninexpensiveandeffective
meansofpreventinginsulationbreakdownthatre-
sultsfromunnecessarilyhighoperatingtempera-
tures.Thedirectbenefitofadequateventilationis
longer,trouble-freelife.
Allowatleast15inchesdeepx 17½incheswide
x6 incheshighformountingtheMA5100.Always
allowforairflowbyeitherventilationholesorspace
nexttothebottomoftheequipmentanda means
fora warmairtoescapeatthetop.
Itisrecommendedthatitbemountedina normal
orhorizontalposition.However,withadequateventi-
lationtheinstrumentcanbemountedinanyposition.
TopreparetheMA5100forinstallationremovethe
plasticprotectivecovering.TurntheMA5100upside
downsothatitrestsonitstopontheshippingpallet.
Removethefourplasticfeetfastenedtothebottom
ofthechassis.
Theprofessionalmountingdesigneliminatesthe
needforanyshelforbrackettosupporttheMA5100.
Itiscompletelysupportedbyitsownmounting
brackets.
Positiontheplasticmountingtemplateoverthe
areaofthecabinettobecutoutforinstallation.
Thedesignofthemountingtemplateallowsthe
cutouttobepositionedorlocatedfromthefront
orrearofthepaneltowhichtheinstrumentistobe
mounted.
Ifthecutoutistobelocatedfromtherearofthe
panel,thefollowingstepswillhelpyou.
Onthebackofthecabinetpanel,scribea vertical
centerlinethroughtheexactcenteroftheareain
whichthecutoutistobemade.
Placethetemplateagainstthebackofthepanel
andmatchthetemplatecenterlinewiththecenter-
lineonthecabinetpanel.
Makesurethatthereisatleast¼ inchclearance
betweenthebottomofthedashedlineofthecutout
areaonthetemplateandanyshelforbracebelow
theproposedcutout.
Markthetwolocatingholes("C"holesonthe
mountingtemplate).
Drillthetwolocatingholes.Becertainthedrillis
perpendiculartothepanel.
Nowpositionthetemplateonthefrontofthepanel
byaligningthe"C"locatingholesonthetemplate
withthedrillholes.
Withtemplateinplaceagainstthecabinetpanel,
markthe"A"and"B"drillholesandthefoursmall
holesthatidentifycornersofthecutout.Jointhe
cornermarkswitha pencil.Theedgeofthetemplate
canbeusedasa straightedge.
IMPORTANT:DRILLTHE6 HOLESBEFOREMAK-
INGTHECUTOUT.
Accuratelydrillthethreeholesoneachsideof
thecutoutareawitha 3/16inchdrill.
WiththesawontheINSIDEOFTHEPENCIL
LINEScarefullycutouttherectangularopening.
2

Securethemountingstripstotherearofthe
cabinetpanelusingtwoscrewsfromthehardware
package.
Insertthescrewsinthecenterholesofthecabinet
pane!("B"holesonthetemplate)andtighten.The
screwheadshouldpullintothewoodslightly.(Use
thetwo% inchlongscrewsforpanelsunder½
inch,ortwo1¼inchlongscrewsforpanels½ inch
thickorlarger.)
Attachthemountingbracketstothecabinetpanel
usingfourscrews.
Placethetemplateoverthemountingscrews.The
mountingscrewsshouldbecenteredinthe"A"and
"B"holesonthetemplate.Thesidesofthemount-
ingbracketsshouldmatchtheverticaldashlines
onthetemplate.Ifnecessary,loosenthescrewsand
pushthebracketsintoalignmentandretighten.
Insertthepowercordthroughtheopening.Care-
fullyslidetheMA5100intotheopeningsotherails
onthebottomoftheequipmentslideinthetrackof
themountingbrackets.Continuetoslidetheinstru-
mentinuntilthefrontpanelisagainstthecabinet
panel.
Securetheinstrumenttothemountingbrackets
byinsertingthetwoknurledheadedscrews(fromthe
hardwarepackage)intothebackoftheMA5100
chassis,Thesescrewspassthroughholesinthe
backflangesofthemountingbrackets.
Howtoconnect
CONNECTINGA LOUDSPEAKER
TheMA5100isdesignedforstereooperationonly.
DonotconnecttheMA5100formonophonicopera-
tion.Damagetotheloudspeakermayresult.
SpeakersareconnectedattheOUTPUTbarrier
stripsonthebackpaneloftheMA5100.
Connecttheleadsfromtheleftloudspeakerto
theLEFTOUTPUTbarrierstrip.Connecttheleads
fromtherightloudspeakertotheRIGHTOUTPUT
barrierstrip.Uselampcord,bellwire,orwirewith
similartypeofinsulationtoconnectthespeakers
totheamplifier.Forthenormallyshortdistancesof
under50feetbetweentheamplifierandspeaker,#18
wireshouldbeused.Fordistancesover50feetbe-
tweentheamplifierandspeakerusewireofa larger
diameter(#16or#14.)
CONNECTINGTOTHEAUXILIARY
Anyhighlevelprogramsourcesuchasanother
tunerora TVsetcanbeconnectedtotheAuxiliary
inputjacks.
CONNECTINGA TAPERECORDER
ToRecord:
Connecta cablefromtheL TAPEOUTPUTtothe
lefthighlevelinputonthetaperecorder.
Connecta cablefromtheR TAPEOUTPUTtothe
righthighlevelinputofthetaperecorder.
ToPlayback/Monitor:
Connectthecablefromtheleftchanneloutputof
3

HowtoConnect
RECORDPLAYER
TAPERECORDER
TUNER
LEFTLOUDSPEAKER
4
RIGHTLOUDSPEAKER

ataperecordertotheL TAPEMONitorinput.
Connectthecablefromtherightchanneloutput
ofa taperecordertotheR TAPEMONitorinput.
CONNECTINGA STEREOTUNER
Connectthecablefromtheleftchanneltunerout-
puttotheL TUNERinput.
Connectthecablefromtherightchanneltuner
outputtotheR TUNERinput.
CONNECTINGA RECORDPLAYERTOPHONO1
Connectthecablefromtheleftchannelofthe
recordplayerintotheL PHONO1 input.
Connectthecablefromtherightchannelofthe
recordplayerintotheR PHONO1.
PHONO2 isprovidedfortheuseofa second
recordplayer.
Connectthecablefromtheleftchannelofthe
recordplayerintotheL PHONO2 input.
Connectthecablefromtherightchannelofthe
recordplayerintotheR PHONO2 input.
CONNECTINGA TAPEDECKFORPLAYBACK
Connectthecablefromthelefttaperecorder
headonthetapedeck(onewithoutitsownelec-
tronics)totheL TAPEHEADinput.Connectthe
cablefromtherighttaperecorderheadtotheR
TAPEHEADinput.
GROUNDCONNECTION
AsingleGROUNDpostisprovided.Groundsfor
turntables,recordchangers,tapedecks,etc.,should
beconnectedtothispost.Theleftandrightprogram
cablesandthegroundwirefromthatsourceshould
bewoundortwistedtogether.Toavoidhum,make
surethegroundwiredoesnotmakeanycontactto
theshieldsoftheleftandrightprogramcablesbe-
tweentheprogramsourceandtheMA51000.The
onlygroundshouldbeattheGROUNDpostonthe
rearoftheMA5100.
ACPOWEROUTLETS
Thereare3 blackACpoweroutletsandonered
outlet.ThepowertotheblackACpoweroutletsis
controlledbythefrontpanelpowerswitch.Use
theseoutletsfora tuner,taperecorder,etc.The
redreceptacleisonatalltimes.Usetheredoutlet
fora turntableorrecordchanger.Theturntableor
recordchangerisprotectedbythisarrangement.
Itisnecessarytoturnofftheturntableorrecord
changerwithitsownACpowerswitch.
WhattheControlsDoandHowtoUseThem
INPUTSELECTOR
AUX:Connectstheoutputfromanyhighlevel
programsourcerequiringflatamplificationtothe
highlevelinputstages.Sucha sourcecouldbea
televisionsetorothersourcethathasoutputof
0.25voltsormore.IntheAUXpositionthegainis
0dBtotheTAPEoutputs.Theinputimpedance
is250,000ohms.
TAPE:Connectstheoutputfroma completetape
recordertothehighlevelinputstages.Inthe
TAPEpositionthegaintotheTAPEOUTPUTSis
0dB.Theinputimpedanceis250,000ohms.
TUNER:ConnectstheoutputfromanyAM,FMor
FMSTEREOtunertothehighlevelinputstages.
IntheTUNERpositionthegaintotheTAPEout-
putis0 dB.Theinputimpedanceis250,000ohms.
PHONE1:Connectstheoutputofanymagnetic
phonocartridgetothelowlevelinputstages.The
responsehasbeenshapedtocompensateforthe
characteristicsofmagneticphonocartridges.The
gainat1000Hzis42dBtotheTAPEoutputs.The
inputimpedanceis47,000ohms.
PHONE2:SameasPHONO1.
TapeHd:Connectstheoutputofanytapehead
(atapedeckwithoutitsownelectronics)tothelow
levelinputstages.Theresponsehasbeenshaped
tocompensateforthecharacteristicsofthetape
head.Thegainat500Hzis44dBtotheTAPEout-
puts.Theinputimpedanceis500,000ohms.
BASS
TheBASSisa concentriccontrol.Theouterknob
controlsthelowfrequencyresponseintheright
channel.Thecenterknobcontrolsthelowfrequency
responseintheleftchannel.Thetwoknobsarefric-
tioncoupled.Thispermitsthemtobeadjusted
togetherorindependently.Clockwiserotationin-
creaseslowsandcounterclockwisedecreaseslows.
Turncontroltothecenterpositionforflatresponse.
TREBLE
TheTREBLEisa concentriccontrol.Theouter
knobcontrolsthehighfrequencyresponseinthe
leftchannel.Thecenterknobcontrolsthehighfre-
quencyresponseintherightchannel.Thetwoknobs
arefrictioncoupled.Thispermitsthemtobead-
justedtogetherorindependently.Clockwiserotation
increaseshighsandcounterclockwisedecreases
highs.Turnthecontroltothecenterpositionforflat
response.
VOLUME
TheVOLUMEcontrolregulatestheloudnessin
bothchannels.TheVOLUMEcontrolhasbeenpre-
5

cisiontrackedthroughoutthelisteningrange(0to
—65dB)foraccuratestereobalance.
MODESELECTOR:Connectstheinputprogramto
theloudspeakerinanyofthefollowingsevenways:
LtoL & R:Connectstheleftinputtobothloud-
speakers.
RtoL & R:Connectstherightinputtobothloud-
speakers.
STEREOREV:Connectstheleftinputtotheright
loudspeakerandtherightinputtotheleftloud-
speaker.
STEREO:Connectstheleftinputtotheleftloud-
speakerandtherightinputtotherightloud-
speaker.
MONO(L+ R):addstheleftinputandtheright
inputandthenconnectstheL + R programto
bothloudspeakers.
L+ R toL:Connectstheleftplusrightprogram
totheleftloudspeakeronly.
L+ R toR:Connectstheleftplusrightprogram
totherightloudspeakeronly.
COMPensation
UsetheCOMPswitchtocorrectforphonoequali-
zationintroducedintherecordingprocess.Allcur-
rentstereorecordingsuseRIAAequalization.Some
earlystereoandmonorecordingsuseLPequaliza-
tion.
TAPE:TheTAPEswitchmakesitpossibletoinstan-
taneouslycomparerecordedmaterialwiththesignal
source.Tapejacksonthebackpanelaredesigned
toaccepta signalfroma taperecorderwitha moni-
torheadandpreamplifier.
NORMAL. . . theprogramsourceisfedthrough
thepoweramplifiersandtheloudspeakers.
MONITOR. . . thesignalsourcebecomesthere-
cordedtapeandisfedthroughthepowerpre-
amplifiersandloudspeakers.
WhentheswitchisintheMONITORpositiona tri-
angleislightedabovetheswitch.Whenthelightis
ononlythetapecanbeheard.Tolistennormally
thelightmustbeoff.
PHASE:Electronicallyreversesphaseintheleft
channeltocorrect"outofphase"programsources.
SPEAKER:Forprivatelisteningonheadphonesthe
loudspeakerscanbeturnedoff.Whentheswitchis
intheOFFpositiona triangleislightedabovethe
switch.Whenthelightisonsoundwillnotbeheard
fromthespeakers.Onlytheheadphoneswillbe
heard.
POWER:ThePOWERswitchcontrolstheACinput
power.ItturnstheMA5100onandoff.Theswitch
alsocontrolsthethreeblackACoutletsontheback
panel.
L.F.(LOWFREQUENCYFILTER):UsetheL.F.filter
switchtoreduceobjectionablelow-frequencynoise
6

createdbya turntableorrecordchangerandacous-
ticallycoupledfeedback.
FLAT
filterdisconnected.
FILTER. . . lowfrequencyrumbleandnoisebelow
50HzarereducedwhentheswitchisintheFILTER
position.
H.F.(HIGH-FREQUENCYFILTER):UsetheH.F.
filterswitchtoreduceobjectionablehigh-frequency
noisesuchasrecordscratch.
FLAT. . . filterdisconnected.
FILTER. . . highfrequencynoisesabove5000Hz
arereducedwhentheswitchisintheFILTERposi-
tion.
LOUDNESS
Whenthevolumeisreduced,themusicwillseem
tolosemuchofitsbassandsomeofitstreble.
Thiseffectisduetothesensitivitycharacteristic
ofhumanhearing.Theresponseofthehumanearto
basstonesdecreasesmorerapidlythanitsresponse
tonotescenteredinthemid-tonalrange.TheLOUD-
NESScontrolautomaticallyprovidesthecorrect
amountofbassrequiredtocompensateforthis
changeinresponseofthehumanearatlow-loudness
levels.IntheCOMPENSATEDpositionthevolume
controlisconvertedtoa loudnesscompensatedcon-
trol.Usethispositiontolistenatlowvolumeand
stillhearfull-bassresponse.
BALANCE
TheBALANCECONTROLadjustsforunequalvol-
umeineithertheleftorrightchannels.Thevolume
ofeachchannelcanbevariedrelativetoeachother
withoutaffectingtheircombinedloudness.
LEFT. . . turningthecontroltotheleftaccents
theleftchannelbyreducingtherightchannel
output.
RIGHT. . . turningthecontroltotherightaccents
therightchannelbyreducingtheleftchannel
output.
BalancingyourStereo
Theperformanceandenjoymentofa stereosys-
temisgreatlyincreasedwhenthesoundisproperly
balanced.Thebalanceofthestereosystemisaf-
fectedbymanythingsincludingroomacoustics,fur-
nitureplacement,roomshape,smalldifferencesin
loudspeakers,etc.Toassistyouinbalancingyour
stereosysteminyourroomhereistheprocedure
todeterminecorrectphaseandprogramloudness.
TOADJUSTPHASE
1.Playa familiarrecord.
2.PresstheMODEpushbuttontotheMONOposi-
tion.
3.TurnBALANCEcontrolto12o'clockposition.
4.Standabout10feetinfrontofandmidwaybe-
tweentheloudspeakers.Thesoundshouldappear
tocomefromdirectlyinfrontofyou.Ifthesound
isnotdirectlyinfrontofyouwiththePHASE
switchintheNORMALposition,reversetheleads
ononeloudspeaker.Whenthesoundcomesfrom
directlyinfrontofyouthespeakersareinPHASE.
UsethePHASEswitchtocorrectforoutofphase
programsources.
TOBALANCELOUDNESS
1.PresstheMODEpushbuttontotheMONOposi-
tion.
2.Playa familiarrecord.
3.TurntheBALANCEcontroltothe12o'clockposi-
tion.
4.Whiletheprogramisplaying,standbetweenthe
twoloudspeakers.Listenfora differenceinloud-
nessbetweenspeakers.Next,settheMODEse-
lectortoSTEREO.Ifthereisthena differencein
loudnessturntheBALANCEcontroltowardthe
speakerthatisnotasloud.AdjusttheBALANCE
controluntilthesoundissatisfactorybetween
bothspeakers.
7

ListeningtoYourStereo
PerformanceLimits
LISTENINGTOA STEREORECORD
TurntheINPUTSELECTORtoPHONO1 and
PHONO2,whicheverisconnectedtotherecord
playeryouwishtohear.
MakecertaintheMODESELECTORisinthe
STEREOorSTEREOREVERSEposition.
AdjusttheVOLUMEcontroltodesiredvolume.
LISTENINGTOA MONOPHONICRECORD
TurntheINPUTSELECTORtoPHONO1 or
PHONO2,whicheverisconnectedtotherecord
playeryouwishtohear.
TurntheMODESELECTORtoMONO(L+ R).
AdjusttheVOLUMEcontroltodesiredvolume
LISTENINGTOA STEREOTAPERECORDER
TurntheINPUTSELECTORtoTAPE.
SettheMODESELECTORtoSTEREOorMONO,
dependingontheprogramonthetape.
AdjusttheVOLUMEcontroltodesiredvolume.
TORECORDONA STEREOTAPERECORDER
AllprogramsourcesareavailableattheTAPE
OUTPUTjacks.Theprogrammaterialisunaffected
byallfrontpanelcontrolsexcepttheINPUTSELEC-
TOR.
Tomonitorwhilerecording,thetaperecordermust
haveseparaterecordandplaybackormonitorheads.
TheTAPEswitchpermitsmonitoringthetapere-
cordingswhileintheprocessofrecording.When
theTAPEswitchisatattheMONITORpositionit
willplaythesoundfromthetapeasitpassesthe
playbackhead,a momentafteritisrecorded.The
recordingprocesscontinuesasusual.Whenthe
TAPEswitchisattheNORMALpositiontheprogram
beingrecordedisheard.
LISTENINGTOTAPEDECKS
Tolistentotapefroma tapedeck,proceedas
follows:
TurntheINPUTSELECTORtoTAPEHD.
TurntheMODESELECTORtoMONO(L+ R)or
STEREO,dependingontheprogramonthetape.
AdjusttheVOLUMEcontroltothedesiredvolume.
LISTENINGTOHEADPHONES
TheHEADPHONEjackshavebeendesignedto
feedlowimpedancedynamicheadphones.Electro-
staticheadphonesgenerallyrequirehigherpower
thandynamicheadphones.Theymustbeconnected
totheLEFTandRIGHTOUTPUTbarrierstripson
thebackoftheMA5100.
PerformanceLimitsarethemaximumdeviation
fromperfectionpermittedfora Mclntoshinstrument.
WepromiseyouthatyourMA5100mustbecapable
ofperformanceatorexceedingtheselimitsoryou
getyourmoneyback.Mclntoshistheonlymanufac-
turerthatmakesthisguarantee.
POWEROUTPUT
45RMSwattscontinuousperchannelinto4 or8
ohmsbothchannelsoperating20Hzto20,000Hz.
30RMSwattscontinuousperchannelinto16ohms
bothchannelsoperating20Hzto20,000Hz.
HARMONICDISTORTION
Doesnotexceed0.25%atratedpoweroutput
from20Hzto20,000Hzwithbothchannelsoper-
ating.Typicalperformanceislessthan0.1%at
ratedpower.Distortiondecreasesasoutputpower
isreduced.
INTERMODULATIONDISTORTION
Doesnotexceed0.25%ifinstantaneouspeak
poweroutputistwiceratedpowerorlessper
channelwithbothchannelsoperatingforany
combinationoffrequencies20Hzto20,000Hz.
OUTPUTIMPEDANCE
4,8,or16ohms
DAMPINGFACTOR
50with4 ohmsload,100with8 ohmsload,200
with16ohmsload
FREQUENCYRESPONSE
10Hzto20,000Hz+0—0.5dbatratedpower
8Hzto50,000Hz+0—3.0dBatratedpower
INPUTIMPEDANCE
Auxiliary,TAPE,TUNER,andTAPEMONITOR:
250,000ohms
PHONO1 andPHONO2:47.000ohms
TAPEHEAD:500,000ohms
INPUTSENSITIVITY
Auxiliary,TAPE,TUNER,andTAPEMONITOR:
0.3volts
PHONO1 andPHONO2:2 mV
TAPEHEAD:2 mV
TOTALNOISE
TOTALNOISE(INCLUDINGPOWERAMPLIFIER)
Auxiliary,TAPE,TUNER,andTAPEMONITOR:75
dBbelowratedoutput
PHONO1,PHONO2 andTAPEHEAD:70dBbe-
8

low10mVinput;equivalenttolessthan3 micro-
voltsatinput.
TAPEOUTPUT
0.3voltswithratedinput,lessthan150ohms
sourceimpedance,tooperatein47,000ohmsor
greater.
VOLTAGEAMPLIFICATIONINDECIBELS
Auxiliary,TUNER,andTAPEtoTAPEOUTPUT;0
dB
PHONO1 andPHONO2 at1000HztoTAPEOUT-
PUT: 42dB
TAPEHEADat500HztoTAPEOUTPUT;44dB
LEFTPLUSRIGHTOUTPUT
Adjustable0 to6 voltsfromgeneratorimpedance
of5,000ohms.
BASSCONTROLS
±18dBat20Hz,withfrictionclutchforindepend-
entadjustmentofeachchannel.
TREBLECONTROLS
±18dBat20,000Hzwithfrictionclutchforin-
dependentadjustmentofeachchannel.
HFFILTER
Flat,or5,000Hzcutoff,12dBperoctave.
LFFILTER
Flat,or5,000Hzcutoff12dBperoctave.
SEMICONDUCTORCOMPLEMENT
23SiliconRectifiersandDiodes
34SiliconTransistors
2SiliconBilateralSwitches
2TRIAC
POWERREQUIREMENTS
120volts,5060Hz,70wattsatzerosignaloutput,
200wattsatratedoutput
MECHANICALINFORMATION
SIZE;Frontpanel,16incheswideby5 7/16inches
high;chassis,15incheswideby4½highby14½
deep,includingconnectors.Clearanceinfrontof
mountingpanelincludingknobs,1½inches.
WEIGHT:25poundsnet,41poundsinshippingcar-
ton.
FINISH:FrontPanel:Anodizedgoldandblack:
Chassis:Chromeandblack.
TREBLE:Thehighfrequencyprogrammaterialis
modifiedtosuityourtaste.Rightchannelistheouter
knob,theleftchannelistheinnerknob.
VOLUME:Precisiontrackedatalllisteninglevels.
(0to—65dB.)Doesnotchangestereobalanceas
loudnessischanged.
MODESELECTOR:Sevenpositions:Leftchannel
onlytobothspeakers,Rightchannelonlytoboth
speakers,StereoReverse,Stereo,Mono,L + R to
leftspeakeronly,L + R torightspeakeronly.
COMPensation:Selectfromtwocircuitsthattailor
theresponsetocorrectforthecharacteristicsused
intherecordingofphonographrecords.
TAPE:Monitortherecordedprogramfromthetape
orheartheprogramthatisbeingrecorded.
PHASE:Electronicallyreversephaseintheleftchan-
neltocorrect"outofphase"programsources.
SPEAKER:SwitchtheloudspeakersystemONor
OFFwithoutaffectingtheperformanceofheadphone
jacks.
LFFILTER(RumbleFilter):Flatorroll-off12dBper
octaveabove5,000Hz,down12dBat20,000Hz.
LOUDNESS:COMPENSATEDpositionboostslow
frequenciesforlowlevellistening.Operatesasa
functionofvolumecontrolrotationsofullcompensa-
tionisobtainedatlowervolumelevelsandflatre-
sponseisobtainedatfullvolume.
BALANCE:Naturalbalanceatcenterposition,attenu-
ationofleftorrightchannelbyrotatingcontrol.
FACILITIESANDFEATURES
INPUTSELECTOR:Selectfromsixsources—AUX-
ilary,TAPE,TUNER,PHONO1,PHONO2,orTAPE
HD
BASS:Thelowfrequencyprogrammaterialismodi-
fiedtosuityourtaste.RightChannelistheouter
knob,theleftchannelistheinnerknob.
9

Typical
Performance
Charts
100 1000
FREQUENCYINHERTZ
1000020000
POWERVS.FREQUENCY
10 100 1000
FREQUENCYINHERTZ
10K
100K
HARMONICDISTORTIONVS.FREQUENCYINTERMODULATIONDISTORTIONVS.
EQUIVALENTPOWEROUTPUT
10
POWEROUTPUTINWATTSRMS
100
110100
POWEROUTPUTEQUIVALENTWATTSRMS
10
20
20
15
10
5
0
-5
-10
-15
-20
RESPONSE
INDB
50
50
40
30
20
10
0
POWER
OUTPUTWATTS
RMS
.6
.5
A
.3
.2
.1
0
PERCENTINTERMODULATION
DISTORTION
1
.6
.5
.4
.3
.2
.1
0
PERCENTHARMONICDISTORTION

TechnicalDescription
PREAMPLIFIERSECTION
Thephonoandtapeheadpreamplifiercircuitsin
theMA5100havethreetransistorsineachchannel.
Theinputselectorswitchconnectstheinputjacks
tothefirstvoltagegainstageofthepreamplifier.
Theinputstagehashighvoltagegainandverylow
noise.Thenextstage,anemitterfollower,actsas
animpedanceconverterthatmatchestheinputstage
tothesecondvoltageamplifier.Theemitterfollower
isdirectcoupledtothesecondvoltageamplifier.
Negativefeedbackisusedaroundthelowlevel
sectiontoreducenoiseanddistortiontoanabsolute
minimum.Thenegativefeedbackalsoprovidespre-
cisefrequencycompensationformagneticphono
cartridgesandtapeheads.Thefeedbackremainsin
effectthroughtheentireaudiobandwidth,evenat
20Hzwheregainisthehighest.Thiskindofcareful
Mclntoshengineeringassuresyouoflowestdistor-
tionperformance.
Thetapeheadinputimpedanceis500,000ohms.
Hightapeheadimpedancepermitsuniformhigh
frequencyperformancefromtypicaltapetransport
playbackheads.
TheMA5100isidealfortaperecording.Withan
inputsignalfroma phonocartridgeof10millivolts,
thereis1.4voltsavailableatthetapeoutputjacks.
Phonoinputsignaloverloadisvirtuallyimpossible.
At1,000Hzthephonoinputwillacceptgreaterthan
125millivoltswithoutoverloading.Thisismorethan
than4 timestheoutputfrommostphonocartridges
whenplayinga lowdistortionphonographrecord.
Thephonoinputimpedanceis47,000ohms.This
matchestheimpedanceofmagneticcartridges.
Thepreamplifieroutputisconnectedbytheinput
selectorswitchtothetapeoutput,thetapemonitor
switch,thebalancecontrol,theloudnesscompensa-
tionswitch,andthefirstsectionofthevolumecon-
trol.Thisarrangementpermitsrecordingofthepro-
gramwithoutinterruptionandhastheabilitytomoni-
tortherecordedtape.
Theuseofa twosectionvolumecontrolperforms
twoimportantfunctions.First,theinputsectionof
thevolumecontrolincreasesthesignalhandling
capabilityofthetonecontrolamplifier.Useofthis
arrangementmakesoverdrivingthetonecontrolam-
pliferalmostimpossible.Second,theoutputvolume
controlassuresmaximumsignaltonoiseratiore-
gardlessofthevolumecontrolposition.
Thetonecontrolstagesaremadeupofa three
stageamplifier.Thefirsttwotransistorsareemitter
followers.Thefirstemitterfollowerisdrivenfromthe
outputofthevolumecontrol.Thesecondemitter
followerisdirectcoupledtothethirdstage.Thethird
stageisa highgainvoltageamplifier.
Signalspassthroughtheinputemitterfollower
andthencoupletothesecondandthirdtonecontrol
stagesthroughthetonecontrolnetwork.Thetone
controlcontoursareobtainedbycontrollingthelarge
negativefeedbackaroundthesecondandthirdtran-
sistors.Thisnegativefeedbackisusedtoaccurately
shapetheresponse.Thelargeamountofnegative
feedbackalsomakespossiblelowdistortionfromthe
tonecontrolamplifier.
Theoutputofthetoneshapingamplifierdrivesthe
lowfrequencyandhighfrequencyfiltersandthe
secondsectionofthevolumecontrol.Thefiltersare
designedtoremoveunwantednoisessuchasturn-
tablerumbleandrecordscratch.Thefiltersremove
themaximumamountofobjectionablematerialand
stillhavea minimumeffectonthemusicalcontent
oftheprogrammaterial.
Theoutputofthevolumecontrolisfedtoa two
stagevoltageamplifierthathasverylownoise
characteristics.Negativefeedbackisusedtoimprove
thesignaltonoiseratioandassureanabsolute
minimumofdistortion.
Thephaseswitchispartoftheleftchannelcircuit.
Theswitchselectsfromtwosourcesthatareofequal
amplitudebutare"outofphase"toeachother.In
thenormalpositionthephaseisthesameinboth
channels.Whenthephaseswitchisinthe180°posi-
tiontheleftchannelis"outofphase"whencom-
paredtotheright.Outofphaseprogramsourcema-
terialiseasilycorrectedwiththeuseofthisswitch.
11

BlockDiagram

MclNTOSHLABORATORYINC.
2CHAMBERSST.,BINGHAMTON,N.Y.13903
607-723-3512
Designsubjecttochangewithoutnotice.
PrintedinU.S.A.
Be112002
038-605