McIntosh MA5100 - B User manual

PRICE$1.25
STEREO
PREAMPLIFIER- POWERAMPLIFIER
MA51OO

TheMclntosh"willtoperfection"requiresthatweprobe
constantlyintotheunknowntobringtheperformanceofour
electronicequipmentclosertoperfectionthaneverbefore.
Thisrequiresa constantandrelentlesssearchforlownoise,
broadbandconservativedesignwithaneverlowerdistortion
factor.Thisisnotrequiredofordinaryequipmentofaverage
designs.Itis,forus,a costlybutworthwhilescientificand
engineeringeffort.Ourcontinuingresearchbenefitsourcus-
tomerswiththealmostcompletelackofobsolescenceand
themostreliableequipmentevermade.Italsomeansthe
lowestlong-rangecosttoyou.NearlyalloftheMclntosh
equipmentevermadeisstilluseable,orinuse,thoughit
mayhavebeenmadetwentyyearsago.
CONTENTS
GENERALDESCRIPTION
TECHNICALDESCRIPTION
BLOCKDIAGRAM
PERFORMANCECHARTS
SPECIFICATIONS
INSTALLATION
INA HURRY
TYPICALCONNECTION
CONNECTING
BALANCING
LISTENING
FRONTPANELCONTROLS
GUARANTEE
2
3-4
5
6
7
8
9
10
11-12
12
13
14-15
16
Yourpurchaseofa Mclntoshinstrument
showsthatyouarea carefuldiscriminat-
ingbuyer.Onewhoisinterestedinquality
performance,qualityengineering,quality
manufacturing,andlongtrouble-free
equipmentlife.Youcanprotectyourin-
vestmentbyspendinga fewminutesread-
ingthisowner'smanual.
Whenyouboughta Mclntosh,youbought
countlesshoursofmusicalpleasureand
superiorperformance.Enjoyit!
STEREO
PREAMPLIFIER- POWERAMPLIFIER
MA51OO
1

GENERALDESCRIPTION
ConservativeclaimsandspecificationsaretraditionalatMclntosh.
"Ratedwithhonestyandconservatism. . .""impressiveperform-
ancefigures. . .""Highestqualityofcomponentsandconstruc-
tion. . ."arethewordsusedbyindependentexpertswhenwriting
ofMclntosh.Toassureyouofhighestperformanceeveryadvertised
claimisindividuallyanalyzedandverifiedbyengineersusingthe
mostsophisticatedandsensitivetestinstruments.Everyunitisindi-
viduallytestedusinginternationallyrecognizedtestprocedures.To
assureyouofgreatestreliabilityeverycomponentpartiscarefully
testedandevaluatedbyengineersbeforeitisdesignedina Mclntosh.
TheMA5100youhavepurchasedpassedmorethan100testsbefore
itwasreadyforyou.Eachconnection,wire,resistor,capacitoris
checkedandrechecked.Allspecificationsarechecked.Mclntosh
testingtakestime.Theextrainvestmentinthoroughtestingassures
youofgreatermusicalenjoyment.TheperformanceofyourMcln-
toshMA5100isbackedbya moneybackguarantee.OnlyMclntosh
givesyoua moneybackguaranteeofperformance.YourMA5100
mustbecapableofmeetingitspublishedspecificationsoryouget
arefundofyourpurchaseprice.Mclntoshpromisesperformance.
Weeithermeetourpromiseoryougetyourmoneyback.
YourMA5100canbeprotectedbya freethreeyearfactoryservice
contract.Takeadvantageofthisservice.Fillintheapplicationcard
foundintheowner'spacket.Thefreethreeyearfactoryservice
contractcoverspartsandlabor.Underthetermsofthecontractall
partsandlabornecessarytorepairtheMA5100willbesupplied
freeofcharge.Fillintheservicecontractapplicationfoundinthe
owner'spacketnow.
2

TECHNICALDESCRIPTION
PREAMPLIFIERSECTION
ThephonoandtapeheadpreamplifiercircuitsintheMA5100have
threetransistorsineachchannel.Theinputselectorswitchconnects
theinputjackstothefirstvoltagegainstageofthepreamplifier.The
inputstagehashighvoltagegainandverylownoise.Thenextstage,
anemitterfollower,actsasanimpedanceconverterthatmatchesthe
inputstagetothesecondvoltageamplifier.Theemitterfolloweris
directcoupledtothesecondvoltageamplifier.
Negativefeedbackisusedaroundthelowlevelsectiontoreducenoise
anddistortiontoanabsoluteminimum.Thenegativefeedbackalso
providesprecisefrequencycompensationformagneticphonocart-
ridgesandtapeheads.Thefeedbackremainsineffectthroughoutthe
entireaudiobandwidth,evenat20Hzwheregainisthehighest.This
kindofcarefulMclntoshengineeringassuresyouoflowestdistortion
performance.
Thetapeheadinputimpedanceis500,000ohms.Hightapehead
inputimpedancepermitsuniformhighfrequencyperformancefrom
typicaltapetransportplaybackheads.
TheMA5100isidealtortaperecording.Withaninputsignalfroma
phonocartridgeof10millivolts,thereis1.4voltsavailableatthetape
outputjacks.
Phonoinputsignaloverloadisvirtuallyimpossible.At1 KCthephono
inputwillacceptgreaterthan125millivoltswithoutoverloading.This
ismorethan4 timestheoutputfrommostphonocartridgeswhen
playinga lowdistortionphonographrecord.
Thephonoinputimpedanceis47,000ohms.Thismatchestheimped-
anceofmagneticphonocartridges.
Thepreamplifieroutputisconnectedbytheinputselectorswitchto
thetapeoutput,thetapemonitorswitch,thebalancecontrol,andthe
firstsectionofthevolumecontrol.Thisarrangementpermitsrecording
oftheprogramwithoutinterruptionandhastheabilitytomonitorthe
recordedtape.
Thetonecontrolstagesaremadeupofa threestageamplifier.The
firsttwotransistorsareemitterfollowers.Thefirstemitterfolloweris
drivenfromtheoutputofthevolumecontrol.Thesecondemitterfol-
lowerisdirectcoupledtothethirdstage.Thethirdstageisa high
gainvoltageamplifier.
Signalspassthroughtheinputemitterfollowerandthencoupletothe
secondandthirdtonecontrolstagesthroughthetonecontrolnetwork.
Thetonecontrolcontoursareobtainedbycontrollingthelargenega-
tivefeedbackaroundthesecondandthirdtransistors.Thisnegative
feedbackisusedtoaccuratelyshapetheresponse.Thelargeamount
ofnegativefeedbackalsomakespossiblelowdistortionfromthetone
controlamplifier.
Theoutputofthetoneshapingamplifierdrivesthelowfrequencyand
highfrequencyfiltersandthesecondsectionofthevolumecontrol.
Thefiltersaredesignedtoremoveunwantednoisessuchasturntable
rumbleandrecordscratch.Thefiltersremovethemaximumamount
ofobjectionablematerialandstillhavea minimumeffectonthemusi-
calcontentoftheprogrammaterial.
Theuseofa twosectionvolumecontrolperformstwoimportantfunc-
tions.First,theinputsectionofthevolumecontrolincreasesthesignal
handlingcapabilityofthetonecontrolamplifier.Useofthisarrange-
mentmakesoverdrivingthetonecontrolamplifieralmostimpossible.
Second,theoutputvolumecontrolassuresmaximumsignaltonoise
ratioregardlessofthevolumecontrolposition.
Theoutputofthevolumecontrolisfedtoa twostagevoltageamplifier
thathasverylownoisecharacteristics.Negativefeedbackisusedto
improvethesignaltonoiseratioandassureanabsoluteminimumof
distortion.
Thephaseswitchispartoftheleftchannelcircuitry.Theswitch
selectsfromtwosourcesthatare"outofphase"toeachother.
Inthenormalpositionthephaseisthesameinbothchannels.When
thephaseswitchisinthe180°positiontheleftchannelis"outof
phase" whencomparedtotheright.
Theloudnesscompensationswitchisalsoconnectedtothefirstsec-
tionofthevolumecontrol.Outofphaseprogramsourcematerialiseasilycorrectedwiththeuse
ofthisswitch.
3

POWERAMPLIFIERSECTION
Thereare9 transistorsineachpoweramplifier.Theinputstageis
apairofmatchedtransistorsarrangedasanemittercoupledamplifier
withtwoinputsandoneoutput.Theprogramfromthepreamplifier
connectstooneoftheinputs,thesecondinputisfedfromthefeed-
backloopthatisaroundthepoweramplifiersection.BothACandDC
feedbackareusedaroundthepoweramplifiersection.Noiseanddis-
tortionarereducedbytheuseofa largequantityoffeedback.
Thepowertransistorsaremountedonoversizedanodizedheatsinks.
Theheatsinksassurethatundernormaloperationthetransistorswill
operateata lowtemperature.Iftemperaturesincreaseduetoshorted
speaker,orrestrictedventilation,anautomatictemperaturesensing
deviceturnsofftheMA5100.Thedeviceoperatesautomaticallyata
presettemperature.TheMA5100willturnonagainwhenthetempera-
turehasdecreasedtonormaloperation.Thisadditionalfeaturegives
yourMA5100completereliabilityunderthemostextremeoperating
conditions.
Tofurtherinsurereliabilitya specialpoweroutputSENTRYMONITOR-
INGCIRCUITpreventsfailureofthepoweroutputtransistorsdueto
abnormalmismatchoftheoutput.WhenyourMA5100operatesnor-
mallytheSENTRYMONITORINGCIRCUIThasnoeffectonsignals
passingthroughthepoweramplifier.Ifthepowerdissipationshould
riseabovenormaloperation,theSENTRYMONITORINGCIRCUITre-
strictsthedrivetotheoutputtransistors.TheactionoftheSENTRY
MONITORINGCIRCUITisimmediateforanyinputsignalorload
combination.Thisarrangementassurescompletecircuitreliability.
OnlyMclntoshgivesyouthisdegreeofprotection.
POWERSUPPLYSECTION
Therearefourseparatepowersupplysections.Onepositiveandone
negativehighcurrentsupplyisusedfortheoutputstages.Onepositive
andonenegativelowcurrentsupplyisusedforthepreamplifierand
poweramplifierinputstages.Allsuppliesarefullwaveandusesilicon
rectifiers.Adequatefilteringisusedtoassureanabsoluteminimumof
outputhum.Thepoweroutputstagefiltercapacitorshaveveryhigh
capacity,whichallowsfullpoweroutputbelow20Hz.Thepowertrans-
formerisgenerousinsizeandrunscool,evenunderheavyuse.
MA 5100
4

BLOCKDIAGRAM
5

TYPICALPERFORMANCEDATA
1000
FREQUENCYINHERTZ
10
POWEROUTPUTINWATTSRMSPOWEROUTPUTEQUIVALENTWATTSRMS
FREQUENCYINHERTZ
1000020000
1000 100
20
.6
.5
.4
,3
.2
PERCENT
INTERMODULATION
DISTORTION
.1
0
1
100
6
1
0
20
15
10
5
0
-5
-10
-15
-20
RESPONSE
INDB
POWER
OUTPUT
WATTS
RMS
60
50
40
30
20
10
0
10 100
10K 100K
PERCENT
HARMONIC
DISTORTION
.4
.3
.2
.1
100
10
.6
.5

SPECIFICATIONS
ELECTRICALSPECIFICATIONS
POWEROUTPUT:
45RMSwattscontinuousperchannelinto4 ohms
bothchannelsoperating.
45RMSwattscontinuousperchannelinto8 ohms
bothchannelsoperating.
30RMSwattscontinuousperchannelinto16ohms
bothchannelsoperating.
HARMONICDISTORTION:
Lessthan0.25%atratedpoweroutputfrom20Hzto
20kHz,bothchannelsoperating.Typicalperform-
anceislessthan0.1%atratedpower.Distortionde-
creasesasoutputpowerisreduced.
INTERMODULATIONDISTORTION:
Lessthan0.25%ifinstantaneouspeakpoweroutput
istwiceratedpowerorlessperchannelwithboth
channelsoperatingforanycombinationoffrequen-
cies20Hzto20kHz.
FREQUENCYRESPONSE:
10Hzto25kHz+ 0,-0.5dBatratedpower.
8Hzto50kHz+ 0,-3.0dBatratedpower.
TOTALNOISE(INCLUDINGPOWERAMPLIFER):
HighLevelInputs:75dBbelowratedoutput
LowLevelInputs:70dBbelow10mVinput;equiva-
lenttolessthan3 microvoltsatinput.
OUTPUTIMPEDANCE:
4.8,or16ohms.
DAMPINGFACTOR:
50with4 ohmsload
100with8 ohmsload
200with16ohmsload
INPUTIMPEDANCE:
AUXILIARY,TAPE.TUNER,andTAPEMONITOR:
250,000ohms
PHONO1 andPHONO2:47,000ohms
TAPEHEAD:500,000ohms
INPUTSENSITIVITY:
AUXILIARY.TAPE,TUNER,andTAPEMONITOR:
300mV
PHONO1 andPHONO2:2 mV
TAPEHEAD:2 mV
TAPEOUTPUT:
300mVwithratedinput,1.4voltswith10mVatphono
input.
LEFTPLUSRIGHTOUTPUT:
Adjustable0 to6 voltsfromgeneratorimpedanceof
5,000ohms.
BASSCONTROLS:
±18dBat20Hz,withfrictionclutchforindependent
adjustmentofeachchannel.
TREBLECONTROLS:
±18dBat20,000Hzwithfrictionclutchforinde-
pendentadjustmentofeachchannel.
HFFILTER:
Flat,or5,000Hzcutoff.12dBperoctave.
LFFILTER:
Flat,or50Hzcutoff.12dBperoctave.
POWERREQUIREMENTS:
117volts.AC.50-60Hz.70wattsatzerosignalout-
put,200wattsatratedoutput.
SPECIALFEATURES
COMP(COMPENSATOR)SWITCH:
RIAAorLPphonoequalization.
TAPEMONITORSWITCH:
NORMALorTapeMONITORindicatorlamplightsin
MONITORposition.
PHASESWITCH:
Electronicphaseinverter.Normal(0°)orreverse
(180°).
SPEAKERSWITCH:
SpeakersONorOFFforheadphonelistening,indi-
catorlamplightsinSPEAKEROFFposition.
LOUDNESSSWITCH:
NORMALorCOMPENSATED.
HEADPHONEJACKS:
Two.fortwopairsoflowimpedanceheadphones.
INPUTSELECTOR:
6positions:AUX.TAPE.TUNER,PHONO1,PHONO
2,TAPEHD.
MODESELECTOR:
7positions:L toL andR,R toL andR.STEREORE-
VERSE,STEREO,MONO(L+R),L+R toL,L+RtoR.
SEMICONDUCTORCOMPLEMENT:
23SiliconRectifiersandDiodes
34SiliconTransistors
2SiliconBilateralSwitches
2TRIAC
MECHANICALSPECIFICATIONS
SIZE:
Frontpanel.16incheswideby57/16incheshigh;
chassis.15incheswideby4½incheshighby14½
inchesdeep,includingconnectors.Clearanceinfront
ofmountingpanelincludingknobs,1½inches.
WEIGHT:
25poundsnet,41poundsinshippingcarton.
FINISH:
FrontPanel:Anodizedgoldandblack.
Chassis:Chromeandblack.
7

INSTALLATIONINA CABINET
TopreparetheMA5100forinstallationremovethe
plasticprotectivecovering.TurntheMA5100upside
downsothatitrestsonitstopontheshippingpallet.
Removethefourplasticfeetfastenedtothebottom
ofthechassis.
Nextplacethemountingbrackets,thepartsbagand
themountingtemplateforeasyaccessibility.
Theprofessionalmountingdesigneliminatestheneed
foranyshelforbrackettosupporttheMA5100.Itis
completelysupportedbyitsownmountingbrackets.
Positiontheplasticmountingtemplateoverthearea
ofthecabinetpaneltobecutoutforinstallation.
Thedesignofthemountingtemplateallowsyouto
positionorlocatethecutoutfromthefrontorrearof
thepaneltowhichtheinstrumentistobemounted.
Ifthecutoutistobelocatedfromtherearofthepanel,
thefollowingstepswillhelpyou.
Onthebackofthecabinetpanel, scribea vertical
centerlinethroughtheexactcenteroftheareainwhich
thecutoutistobemade.
Placethetemplateagainstthebackofthepaneland
matchthetemplatecenterlinewiththecenterlineonthe
cabinetpanel.
Makesurethatthereisatleast¼ inchclearancebe-
tweenthebottomofthedashedlineofthecutoutarea
onthetemplateandanyshelforbracebelowthepro-
posedcutout.
Markthetwolocatingholes("C"holesonthemount-
ingtemplate).
Drillthetwolocatingholes.Becertainthedrillisper-
pendiculartothepanel.
Nowpositionthetemplateonthefrontofthepanelby
aligningthe"C"locatingholesonthetemplatewith
thedrillholes.
Insertthescrewsinthecenterholesofthecabinet
panel("B"holesonthetemplate)andtighten.The
screwheadshouldpullintothewoodslightly.(Usetwo
¾inchlongscrewsforpanelsunder½ inch,ortwo1¼
inchlongscrewsforpanels½ inchthickandlarger.)
Attachthemountingbracketstothecabinetpanelus-
ingfourscrews.
Securethemountingstripstotherearofthecabinet
panelusingtwoscrewsfromthehardwarepackage.
Placethetemplateoverthemountingscrews.The
mountingscrewsshouldbecenteredinthe"A"and
'B"holesonthetemplate.Thesidesofthemounting
bracketsshouldmatchtheverticaldashlinesonthe
template.Ifnecessary,loosenthescrewsandpushthe
bracketsintoalignmentandretighten.
Insertthepowercordthroughtheopening.Carefully
slidetheMA5100intotheopeningsotherailson
thebottomoftheequipmentslideinthetrackofthe
mountingbrackets.Continuetoslidetheinstrumentin
untilthefrontpanelisagainstthecabinetpanel.
Securetheinstrumenttothemountingbracketsbyin-
sertingthetwoknurledheadedscrews(fromthehard-
warepackage)intothebackoftheMA5100chassis.
Thesescrewspassthroughholesinthebackflanges
ofthemountingbrackets.
8
Withthetemplateinplaceagainstthecabinetpanel,
markthe"A"and"B"drillholesandthefoursmall
holesthatidentifycornersofthecutout.Jointhecorner
markswitha pencil.Theedgeofthetemplatecanbe
usedasa straightedge.
IMPORTANT:DRILLTHE6 HOLESBEFOREMAKING
THECUTOUT
Accuratelydrillthethreeholesoneachsideofthecut-
outareawitha 3/16inchdrill.
WiththesawontheINSIDEOFTHEPENCILLINES
carefullycutouttherectangularopening.