McIntosh MX 110 User manual

STEREOTUNER
PREAMPLIFIER
MX11O
CONTENTS
GENERALDESCRIPTION1
TECHNICALDESCRIPTION1
FRONTPANELFACILITIES5
INSTALLATION10
CONNECTING10
ACConnections10
ACPowerConnection10
InputConnections11
OutputConnections12
AntennaConnections12
OPERATINGINSTRUCTIONS13
Balancinga StereoSystem13
AdjustingPhase14
BalancingLoudnessBetween
ProgramSources14
AdjustingtheBalanceControlAfterthe
SystemhasbeenBalanced15
AdjustingforSpecialEffects15
ListeningtoMonophonicFMProgram15
ListeningtoMPXStereo16
Listeningtoa StereoRecord16
ListeningtoMonophonicRecords16
ListeningtoTapeDecks16
ListeningtoStereoTapeMachine17
OperatingCurves18
GUARANTEE20
OWNER'SMANUAL
MX11O

MX110TUNERPREAMPLIFIER
GENERALDESCRIPTION
TheMX110combinesinoneunitanex-
tremelylow-distortionpreamplifierwitha
highlysensitiveFMmultiplexstereotuner.
Everydesirablefeatureofa tuneranda pre-
amplifierisincludedinthisdesign.Inter-
stationnoisesuppression,tuningindicator,
FMmultiplexindicator,individualchannel
basscontrols,individualchanneltreblecon-
trols,electronicphaseswitchhaveallbeen
engineeredintotheMX110.TheINPUT
SELECTORgivesyoua choiceofsixdifferent
programsources.TheMODESELECTORisa
newlydevelopedcontrolwhichmakesitvery
easytobalancea stereosystem.Itisde-
signedtoaddlefttorightformonophonic
operation,tocontrolthelefttorightstereo
perspectiveortocomparetheleftandright
channelsofa stereoprogram.Theloudness
ofthephonochannelsandtheauxiliary
channelmaybebalancedtothetunerloud-
ness.Theseadjustingcontrolsarelocatedon
thetopoftheMX110behindthefrontpanel.
ByreleasingthePANLOCbuttonsonthe
frontpanel,youcanslidetheMX110outof
itsmountinguntilthesecondlatchengages.
ThetopmountedLEVELsetcontrolsare
nowavailable.
TheMclntoshdesignedPANLOCsystem
isthefirstprofessionalinstallationtechnique
tobeusedonstereoinstruments.The
PANLOCsystemgivesyouabsoluteeaseof
installation,operation,andmaintenance.
TheMclntoshMX110isa beautifully
engineeredcontrolcenterforthefinest
stereosoundsystems.Theextremecarein
manufacturing,inlayoutdesignandinther-
malengineeringpromisestheusualMclntosh
extravaluesofreliability,performance,and
longlife.
TECHNICALDESCRIPTION
Theradio-frequencyamplifierofthe
MX110isa "cascode"typecircuit.Thecir-
cuitisspeciallydesignedtoamplifyweak
signalswithlessnoiseanddistortion.By
carefullytuningthisRFamplifierduring
manufacturingandcontrollingothercircuit
constants,spuriousresponserejectionis
improved.Thehigh-frequencyoscillatorme-
chanicallayoutisengineeredforminimum
responsetotemperaturevariations.Infact
thecombinationofmechanicalandelec-
tronicdesignissounusuallygoodinthis
circuitthatautomaticfrequencycontrolis
notneededintheMX110.Themixeroutput
isamplifiedbyfourflat-toppedintermediate
frequencyamplifiers.Thetransformersused
intheLF.amplifiersaredesignedformaxi-
mumadjacentchannelrejection, forelectri-
calstability,andforelectricalandmechanical
resistancetoshockandvibration.
TheR.F.andI.F.circuitsoftheMX110are
completelyshieldedandexceedtheFCC
requirementsforsuppressionofoscillator
radiation.Eithera 300ohmor75ohman-
tennamaybeusedwiththeMX110.A VHF
televisionantennawhichissuitableforFM
receptioncanbeconnectedtotheMX110.
IntheMX110,a newtypeofmechani-
caltuningassemblygivessmoothflywheel
tuning.Bycontrollingtherelationsbetween
massandmechanicalresistance,anddivid-
ingworkloadsinthedialdrivesystem,it
becomesnearlyimpossibletodetectany
backlash.Yettheentiredialdriveisa model
ofmechanicalstability.Forsmooth,quiet
actionandextendedlifewithvirtuallyno
wear,a teflonlineddialpointercarriageand
nylonpulleysareusedinthedialcordas-
sembly.
1

MULTIPLEXDECODER
Themultiplexdecoderusesa special
Mclntoshdevelopeddetectingcircuit.Oneof
theadvantagesofthiscircuitistheelimina-
tionofthecriticaladjustmentsnecessary
withcommonlyusedmatrixingmethods.This
circuitdetectstheL+Rsidebandsandauto-
maticallymatrixestherecoveredinforma-
tionwiththeL+Rmaincarriersignal.This
circuitthenyieldstheleftandtheright
programwithmaximumseparation.
Atemperaturestabilized19KCamplifier
locks-ina highlystablepush-pullsynchro-
nousoscillator.Apartfromotheradvantages,
thismethodprovidesgreatestnoiseimmu-
nity.Balanceddetectorscancel19KCand
38KCcomponentsintheoutputandinsure
lowdistortion.
Athree-sectionsharpcutofffilterrejects
SCAinterferenceandreducessusceptibility
tospurioussignals.
TheMX110hasanMPXstereoindicator
thatlightswhenthedialpointercrossesa
stationbroadcastingMPXstereo.A unique
circuitusinga transistoroperatestheMPX
stereoindicator.Thetransistoriscontrolled
bya differentialdetectingcircuitthatam-
plifiesthe19KCpilotsignal.Thiscircuitauto-
maticallydiscriminatesbetweenthe19KC
signalandnoise.
AUDIO
TheMX110audioamplifierconsistsof
threenegative-feedbackamplifyingsections
induplicatefortheleftandrightstereochan-
nelsanda separateL+Rmonophonicampli-
fier.Thefirstsectionineachchannelisa
feedbackpreamplifierusedtoamplifyand
compensatefortheinputsignalscoming
fromphonographpickupsortapeheads.
Levelsetcontrolsareconnectedintotheout-
putcircuitofthispreamplifiersectionwhen
theINPUTSELECTORisswitchedtoPHONO
1orPHONO2.Thesecontrolsmaybeused
tomaintainuniformloudnessbetweenphono
andtunerinputs.Skillfullayout,grounding,
andshieldingforlow-humpickup,metalfilm
resistors,low-noisetubesandextremecare
inmanufacturingcombinetoreducenoise
andhumintheinputamplifiers.
Thesecondamplifiersectionineachchan-
nelisa cathodefollower.Thesharpcut-off
(18dbperoctave)rumbleandhigh-frequency
filtersareassociatedwiththissection.Input-
levelsetcontrolsfortheauxiliaryinputsare
associatedwiththissection.Allthelevelset
controlsareconvenientlyaccessible
Thethirdamplifiersectionisa twostage
negativefeedbackamplifier.Thevariable
bassandtreblecontrolsareincludedinthe
feedbacklooptomaintainthelowestpossible
distortion.Forexamplea wavemeteranaly-
sisofthethreeamplifiersectionsofthe
MX110showslessthan1/10of1%dis-
tortionat3 voltsoutput.TheMODESELEC-
TOR,balancecontrolsandleftandrightout-
putsareassociatedwiththethirdamplifier
section.
TheL+Rmonophonicamplifyingsection
isa feedbacksummingamplifier.Itsupplies
monophonicoutputaswellasL+Routput.
POWERSUPPLY
ThepowersupplyoftheMX110hasre-
ceivedveryspecialdesignattention.Three
separaterectifiercircuitsareused.
First,a full-waverectifiersuppliesD.C.to
theheatersofallaudiostages.
AsecondbridgerectifiersuppliesD.C.to
theanodesoftheaudiostages.
Thena thirdfull-waverectifiersupplies
D.C.tothetunerstages.
Thiselaboratepowersupplydesignin-
suresthelowestpossiblebackgroundhum
levelandalsothemaximumstability.In
additiontothiscarefulworkthepowertrans-
formerusesspecialmagneticshieldingto
minimizepossiblehumpickupintheMX110
aswellasinanyotherequipmentusedwithit.
2

3
MECHANICALSPECIFICATIONS
Dimensions
Chassis:16incheswide;57/16incheshigh;
13inchesdeepincludingconnectors.
FrontPanel:16incheswide;57/16incheshigh.
KnobClearance:1½inches.
Weight
Chassis:27½pounds.
ShippingWeight:36pounds.
TUNERSPECIFICATIONS
Sensitivity
Betterthan2.5microvoltsat100%modula-
tion.
R.F.Amplifier
Cascode.
LF.Amplifiers
Four.
Limiters
Two.
LF.Bandwidth
200KCflattop.
LF.Transformers
Mechanicallycaptive.
Muting
LF.injected.
TuningIndicator
Tuningisindicatedbyanelectronraytube.
MULTIPLEXDECODERSPECIFICATIONS
MPXDecoder
HumLevel:Betterthan60dbbelow100%
stereomodulation.
Distortion:Lessthan0.3%(MultiplexDe-
coderonly).
ChannelSeparation:Betterthan30dbat
1000cps.
AUDIOSPECIFICATIONS
Inputs
Total5 eachchannel:
AUX.;
PHONO1 MAG.orXTAL;
PHONO2 MAG.;
TAPEHEAD;
TAPEMONITOR.
Outputs
MainStereoOutputs,1 TapeStereoOutput,
1L+ROutput.
ACAUX Outlets
1unswitched,2 switched.
SuppressionofPilot(19KC),andCarrier
(38KC):Greaterthan40dbbelow100%
modulation.
FrontPanelStereoIndicatorLight:Acti-
vatedby19KCpilotcarrieronly.
FrequencyResponse
Within± 1db20to20,000cycles.(Including
75microsecondsdeemphasis.)
Hum
Greaterthan70dbormorebelow100%
mod.(AudiotubeshaveD.C.onthefila-
ments.)
Drift
Lessthan25KC.
Ant.InputImpedance
300balanced,75ohmsunbalanced.
Radiation
SubstantiallybelowF.C.C.requirements.
Distortion
Lessthan0.6%distortionat100%modula-
tion,± 75KCdeviationabove2.5micro-
voltsatantenna.
Finish
Anodizedgoldandblack(frontpanel).
Installation
Convenient,professionalPANLOC.

Controls
InputSelector:Total6 positions:AUX,
MPX,FM,PHONO1,PHONO2,TAPE
HEADS.
ModeSelector:Total7 positions:L TOL&R,
RTOL&R,STEREOREV.,STEREO,MONO,
L+RTOL,L+RTOR.
Tone:Dualtrebleandbassnegative-feed-
backcontrolswithslipclutchforindepend-
entadjustmentofeachchannel.Bass
Boost:15dbat50cycles.BassCut:18db
at50cycles.TrebleBoost:15dbat10,000
cycles.TrebleCut:15dbat10,000cycles.
Balance:Turntorighttoemphasizethe
rightchannel.Turntothelefttoemphasize
theleftchannel.
Phase:2 positions:NORMALorREVERSED:
Changingphasedoesnotincreasedistor-
ELECTRICAL
FrequencyResponse
±½db20to20,000cycles.
Distortion
Lessthan0.2%atratedoutput.
HumandNoise
High-levelinputs:80dbbelowratedoutput.
Low-levelinputs:lessthan3 microvoltsat
inputterminals.
InputSensitivity
AUX:0.3voltat200K.
PHONO1:3millivoltsat47K.
PHONO2:3 millivoltsat47K.
tion.H.F.CutoffFilter:2 positions:Flat,or
5KCcutoff.(20dbperoctave.)L.F.Cutoff
Filter:2 positions:Flat,or50cyclescutoff.
(20dbperoctave.)
Loudness:FletcherMunsoncompensation.
TapeMonitor:2 positions:INandOUT.For
comparisonofrecordedtapewithprogram
sourceafterrecording.
Tuning:Flywheeltuning—nobacklash.
Muting:2 positions:INorOUTforintersta-
tionnoisesuppression.
LevelSet:Threeleftandthreerightcontrols.
2forAUX,2 forPHONO1,and2 for
PHONO2.Thesecontrolsarelocatedback
ofthefrontpanelonthetopoftheMX110.
ACPower—ConcentricwithBALANCEcon-
trol:ON-OFF.
SPECIFICATIONS
TAPEHEAD:3 millivoltsat220K.
TAPEMONITOR:0.3voltat100K.
Outputs
MAIN:3 volts2 inparalleleachchannel.
L+R:3 volts.
TAPE:FromFMat100%modulation0.9
voltfromPHONOwhencartridgeoutput
is9.0millivolts—0.9volt;withratedinput
—0.3volt.
POWERREQUIREMENTS:105-125voltsAC
50/60cycles;75watts.
FUSE:1 amp.Slo-Blo.
TUBECOMPLEMENT
16DS4R.F.-1amplifier(nuvistor)
112AT7R.F.-2mixer
16AB4Oscillator
16AU6IF-1
16AU6IF-2
16AU6lF-3/Limiter1
16CS6IF-4/Limiter2
112AT7Muting/L+RAmplifier
16HU6/EM87TuningIndicator
16D10FMAUDIO/LeftandRight
1stAudioAmplifier
16U8MPXAmplifierand19KC
Separator/Indicatorcontrol
112AU7
112AX7
112AX7
112AX7
16U8
16U8
2Diodes
1Diode
1Diode
4Diodes
2Diodes
MPX38KCOscillator
PhonoPreamplifierLeft
PhonoPreamplifierRight
LeftandRight2ndAudio
Amplifier
Left3rdAudioAmplifier
Right3rdAudioAmplifier
Discriminator
MutingandTuningEye
Detectors
AGCClamp
BalancedMPXDetectors
BalancedDet.forIndicator
Light
4

2Silicon
Diodes
1 MA113
DCFilamentSupply
Transistor-IndicatorLight
Switch
4Selenium
Rectifiers HighandLowVoltageSupply
FRONTPANELINFORMATION
DIALSCALES
TheMX110hastwoscales.The88to108
scaleismarkedinmegacycles.The0 to100
scaleistheloggingscale.Theloggingscale
canbeusedtoaccuratelyretuneanystation.
Youmayfinditeasiertokeepa recordof
yourfavoritestationsbyuseofthelogging
scale.
INDICATORS
TheMX110hastwoindicators.Theyare
justbeloweachendoftheloggingscale.On
therightendistheMPXSTEREOindicator.
Ontheleftendisthetuningindicator.
Figure1.MX110FrontPanel.
signalwhilerejectingnoisepulsesofequal
intensity.ForlisteningtoMPXstereo,referto
OPERATINGINSTRUCTIONSonpage00.
Thetuningindicatorofftune.
Figure2.MPXStereoIndicator.
TheMPXSTEREOindicatorwilllightupif
thedialpointercrossesa stationbroadcast-
ingMPXstereo.A specialcircuitisusedto
operatethispanelindicator.Thiscircuit
automaticallydetectsthe19KCMPXstereo
Thetuningindicatorontune.
Figure3.TuningIndicator.
Thetuningindicatorusesthemovement
oftwoelectronbeamsinsidea vacuumtube
toshowwhena stationispreciselytuned.
Thebeamsmovetowardeachotherasthe
stationcomesintotune.Thestationispre-
ciselytunedwhenthebeamscomeclosest
together.Theactionofthisindicatorissub-
stantiallyindependentofthesignalstrength
ofthestation.Onlytheveryweakestsignals
willnotclosethebeams.
5

VOLUME
Figure4.VOLUMEControl.
TheVOLUMEcontrolisthelargeknob
locatedtotheleftsideofthedialface.The
volumecontroladjuststheloudnessofboth
stereochannelsandalsotheL+Rmono-
phonicchannel.
INPUTSELECTOR
Figure5.INPUTSELECTOR.
1.AUX—TheAUXpositionoftheINPUT
SELECTORconnectsthebackpaneljacks
markedAUXthroughtheMX110.Usethese
jackstoconnectanyhighlevelprogram
sourcethroughtheMX110.Connectionsare
madefollowingtheinstructionsonpage11in
thesectiontitledCONNECTING.Operating
procedureisonpage13inthesection
titledOPERATINGINSTRUCTIONS.
2.MPX—TheMPXpositionoftheINPUT
SELECTORconnectsthemultiplexdecoder
totheoutputjacksoftheMX110.Listento
MPXstereobroadcastsinthisposition.To
properlyconnectandoperatetheMX110,
consultthesectionstitledCONNECTINGon
page11andOPERATINGINSTRUCTIONS
onpage13.
3.FM—TheFMpositionoftheINPUTSELEC-
TORconnectsFMmonophonicprogramsto
theoutputjackoftheMX110.Toproperly
operatetheMX110,consultthesection
titledOPERATINGINSTRUCTIONSonpage
13,
4.PHONO1—ThePHONO1 positionofthe
INPUTSELECTORconnectsthejacksonthe
backpanelmarkedPH-1MAG.andPH-1
XTALthroughtheMX110.Anystereophonic
ormonophonicmagneticphonocartridge
pluggedintothePH-1MAG.jacksisfed
throughtheMX110.Anyconstantampli-
tudecartridgesuchasa crystalorceramic
devicepluggedintothePH-1XTALjacksis
fedthroughtheMX110.Toproperlyconnect
andoperatetheMX110forusewithphono
cartridges,seethesectionstitledCON-
NECTINGonpage11andOPERATING
INSTRUCTIONSonpage13.
5.PHONO2—ThePHONO2 positionofthe
INPUTSELECTORconnectsthejacksonthe
backpanelmarkedPH-2throughtheMX110.
Anymagneticphonocartridgepluggedinto
thePH-2jacksisfedthroughtheMX110.To
properlyconnectandoperatetheMX110for
usewithphonocartridges,seethesections
titledCONNECTINGonpage11andOPER-
ATINGINSTRUCTIONSonpage13.
6.TAPEHD—TheTAPEHDpositionofthe
INPUTSELECTORconnectsthejacksonthe
backpanelmarkedTAPEHEADthroughthe
MX110.A tapedeckthatdoesnotcontain
itsownplaybackpreamplifierisconnectedto
theMX110throughthisposition.Toproperly
connectandoperatetheMX110forusewith
tapedecks,consultthesectionstitledCON-
NECTINGonpage11andOPERATINGIN-
STRUCTIONSonpage13.
MODESELECTOR
1.L TOL&R—TheMODESELECTORinthe
LTOL&Rpositionconnectstheleftinputto
bothamplifiersandbothloudspeakers.
2.R TOL&R—TheMODESELECTORinthe
RTOL&Rpositionconnectstherightinputto
bothamplifiersandbothloudspeakers.
3.STEREOREV-TheMODESELECTORin
theSTEREOREVpositionconnectstheleft
inputtotherightloudspeakerandrightinput
totheleftloudspeaker.
6

Figure6.MODESELECTOR.
4.STEREO—TheMODESELECTORinthe
STEREOpositionconnectstheleftinputto
theleftloudspeakerandtherightinputto
therightloudspeaker.Thisisthenormal
stereoposition.
5.MONO—TheMODESELECTORinthe
MONOpositionaddstheleftinputtothe
rightinputandconnectstheL+Rprogram
tobothamplifiersandbothloudspeakers.
6.L+RTOL—TheMODESELECTORinthe
L+RTOL positionaddstheleftinputtothe
rightinputandconnectstheL+Rprogramto
theleftloudspeakeronly.
7.L+RTO R-The MODE SELECTOR inthe
L+RTOR positionaddsleftinputtotheright
inputandconnectstheL+Rprogramtothe
rightloudspeakeronly.
BASS
Figure7.BASSControl.
TheBASScontrolisa dualcontrol.The
twopartsofthecontrolareconcentric.The
centerorsmallknobcontrolsthebassloud-
nessintheleftchannel.Theouterringcon-
trolsthebassloudnessintherightchannel.
Thetwoknobsarefrictioncoupled,thisper-
mitsthemtobeadjustedtogetherorinde-
pendently.Turningclockwiseincreasesbass
loudness.Turningthemcounterclockwise
decreasesbassloudness.
TREBLE
Figures.TREBLEControl.
TheTREBLEcontrolisa dualcontrol.The
twopartsareconcentric.Thecenterorsmall
knobcontrolsthetrebleloudnessintheleft
channel.Theouterringcontrolsthetreble
loudnessintherightchannel.Thetwoknobs
arefrictioncoupled.Thispermitsthemtobe
adjustedtogetherorindependently.Turning
clockwiseincreasesthetrebleloudness.
Turningcounterclockwisedecreasestreble
loudness.
MUTING
Figure9.MUTINGControl.
Mutingsuppressesthebackgroundnoise
andhissnormallyheardbetweenstations.
WiththecontrolintheINpositionthemuting
isturnedon.Weakstationsthatmaynot
overridenoiseandinterferencearealso
suppressedbythemuting.
IntheOUTposition,themutingisturned
off.ThisallowsconventionalFMtuningwith
thenoiseandinterferencepresent.Usethis
positiontotuneweakornoisystations.
7

FILTERS
Figure10.LFRumbleFilterSwitch.
Lowfrequencynoisebelow50cpsis
reducedbypushingtheLFrumblefilter
switchtotheINposition.Lowfrequency
acousticallycoupledfeedbackisalsore-
ducedbythisswitch.
Figure11.HFFilterSwitch.
Surfacenoiseabove5000cyclesisre-
ducedwhenreproducingold,badlyworn
recordingsbypushingtheHFfilterswitchto
theINposition.
POWERBALANCE
Figure12.BALANCEControl.
ThePOWERON-OFFswitchisthecenter
orsmallknobofthisdualcontrol.TheMX110
isoffwhenthePOWERswitchisturnedtothe
POWEROFForleftposition(counterclock-
wise).
OnthebackpaneloftheMX110thereare
threeA.C.OUTLETS.Twooftheseareblack
andtheotherisred.Thepowertotheblack
outletsiscontrolledbythePOWERswitch.
TheREDoutletisusedforpowertoa turn-
tableora recordchanger.Theturntableor
recordchangerdrivesystemisprotectedby
thisarrangement.Itisnecessarytoturnoff
theturntableorrecordchangerwithitsown
controlswitch.Thetwoblackoutletsandthe
redoutletarenotfused.Maximumratingfor
theseoutletsis350wattstotal.
TheBALANCEcontrolbalancestheMX110
forunequalprogramsources.Turningthe
controltotheleftaccentstheleftchannelby
reducingtherightchanneloutput.Turning
thecontroltotherightaccentstheright
channelbyreducingtheleftchanneloutput.
LOUD
Figure13.LOUDCompensationSwitch.
Whenyouturndownthevolume,the
musicwillseemtolosemuchofitsbassand
someofitstreble.Thiseffectisduetothe
sensitivitycharacteristicofhumanhearing.
Theresponseofthehumaneartobassand
treblepitchdecreasesmorerapidlythan
itsresponsetonotescenteredinthemid-
tonalrange.TheLOUDcontrolautomatically
providesthecorrectamountofbassand
trebleboostrequiredtocompensateforthis
changeinresponseofthehumanearatlow-
loudnesslevels.Whenthe"LOUD"switchis
movedtotheINposition,itconvertsthe
volumecontroltoa loudnesscompensated
control.UsetheLOUDINtolistenatlow
volumeandstillhearfull-frequencyrange.
8