McIntosh MAC 4100 User manual

ACONSUMER'SGUIDE
Preparationsupervisedby
RobertLong.HaroldA Rodgers.
andEdwardJ.Foster
Laboratorydata(unlessotherwiserioted)
suppliedbyCBSTechnologyCenter
Mclntosh'sNewReceiver:BreedingTells
Mac4100stereoFM/AM receiver, incase with simulated
wood-grain finish, Dimensions: 185/8by53/4inches(front), 14
inchesdeepplus clearance for controls and connections. AC
convenience outlets: 2 switched plus 1 unswitched (600 wafts
total), 2 for auto onturntable switching (100 wattstotal).
Price: $1,499;optional RMA-5 rack-mounting adapter. $29.
Warranty: three-year service contract, free with purchase of
the receiver, has provisions comparable to typical "limited"
warranties but covers normal wear and tear. Manufacturer:
Mclntosh Laboratory, Inc.. 2 Chambers St.,Binghamton.N.Y.
13903.
Mclntoshhasforsomeyearskepta very lowprofilevis-a-vis
thepress.Thishiatusincommunicationshasfostereda po-
larizationofopinionaboutMclntosh:Isthecompanystillde
servingofitsreputationforsuperbengineering,orisittrad-
ingonpastglories?Onereviewcan'tprovidea definitive
answer,ofcourse,buttheMac4100receivercanbetakenas
apositivesignofhealthinBinghamton.
Thepersonalityofthisreceiverislikethatofanaccom-
plishedservantusedtocopingwithpamperedaristocratswho
demandthefinestbutarenotalwaystechnicallyknowl-
edgeableormanuallydexterous.Accordingly,ittakesrespon-
sibilityina mannerthat,paradoxicallyenough,isunassuming
yetquiteintolerantofinterventionbyitsmaster.Butonceit
hastakenover,itperformsvirtuallyimpeccablyandcaneven
wardofftheconsequencesofineptitudewithoutnoticeable
fuss.
REPORTPOLICYEquipmentreportsarebasedonlaboratorymeasure
meritsandcontrolledlisteningtestsUnlessotherwisenoted,testdataand
measurementsareobtainedbyCBSTechnologyCenter,Stamford.Connecticut,
adivisionofColumbiaBroadcastingSystem.Inc. oneofthenation'sleading
researchorganizations.Thechoiceofequipmenttobetestedrestswiththe
editorsofHIGHFIDELITYSamplesnormallyaresuppliedonloanfromthemanu-
tacturerManufacturersarenotpermittedtoreadreportsinadvanceofpub-
hcation,andnoreport,orportionthereof,maybereproducedforanypurpose
orinanyformwithoutwrittenpermissionofthepublisher.Allreportsshould
beconstruedasapplyingtothespecificsamplestested,neitherHIGHFIDELITY
norCBSTechnologyCenterassumesresponsibilityforproductperformanceor
quality
FEBRUARY197933

Verytittleofthereceiver'sspecialqualityisimmediately
apparentfromtheoutside,thoughinhookingitupyougeta
cluefromtheconvenienceoutlets.Inadditiontotheconven-
tionalswitched(black)andunswitched(red)ones,thereare
twogreenonesmarkedTURNTABLE,plusanAUTO/MANUAL
switch.IfyouusetheAUTOsettinganda turntableplugged
intooneofthegreensocketsisturnedon,thereceiverand
anyoutboardedequipmentrunofftheswitchedoutletswill
comeonautomatically,evenwhenthereceiver'spowerswitch
isoff,andallwillturnoffagainwhentheturntableshuts
down.Thusanautomaticmodelcanbemadetoturnoffthe
wholesystemunattended.Sincethefeatureworksbysensing
currentdrainthroughtheturntableoutlets,theswitchserves
tooverrideitshouldtheturntablebeoneofthosethatdraw
somecurrentevenwhentheyareoff.
Thereceiver'sswitchingishandledbyDCcontrolvoltages,
actuatedbythefront-panelcontrolsandfedtoFETsthatac-
tuallydothesignalswitching.Therearetwofundamentalad-
vantagestothisapproach:Switchingtransientsareelimi-
nated,andtheshort,directsignalpathsmadepossible
minimizenoisepickup,RFI,andcrosstalk.Inallofthesere-
spectsthe4100isabovereproach.WeseldomhaveRFIprob-
lemsinourarea,butwedooftenfindthat,forexample,some
audiofromanFMtunersectionwill"'leak"intothetape-moni-
torsignals;nonewasdetectableintheMac.
TheFMsectionisunusualinthat—inadditiontoconventional
automaticstereo/monoswitching—ithasanautomatic-blend
featurethatprogressivelyreducesstereoseparation(and
henceout-of-phasenoise)assignalstrengthdrops.Sincethe
fullaudiobandisblended,theresultingstereoimagemaybe
abitstablerthaninthemoreusualhigh-blendsolution,but
thehissseemsa littlemoreintrusivefora givendegreeofsep-
arationloss.Onweaksignalsitdoeswork,however—and,like
somanyfeaturesoftheMac,withoutdrawingundueatten-
tiontoitself.Similarly,theAutomaticFrequencyLockgently
holdsontoanFMstationthathasbeentunedcorrectly;were
itnotforthefrontpanelAFLLED,whichlightswhenlockoc-
curs,youwouldbeunawareofitsaction.ThisLEDactsasa
tuningaid;whenthemutingison,theLEDannouncesarrival
ata receivablestationbeforetheunmutingaction(whichis
gentleandslightlydelayed)allowsanyaudiotopass.The
34
HIGH FIDELITY MAGAZINE
MclntoshMac4100Receiver
Captureratio
TunerSection
Alternatechannelselectivity
THD + N
80Hz
1kHz
10kHz
IMdistortion
19-kHzpilot
38-kHzsubcarrier
Lch
0.25%
0.17%
1.8%
S/Nratio(at65dBf)
stereo
mono
2dB
76dB
Rch
0.25%
0.22%
1.7%
006%
-63½dB
-66½dB
67dB
71dB
AmplifierSection
Manufacturersratedpower
mono
0.16%
0.15%
0.21%
17¾dBW(75watts)/ch.
Poweroutputatclipping(channelsdrivensimultaneously)
Lch
Rch
20dBW(98watts)
20dBW(98watts)
Dynamicheadroom(at1 kHz)1½idB
Frequencyresponse
RIAAequalization
+V,,-V,dB,20Hzto20kHz
+ V», -3dB,13Hzto35kHz
±1dB,20Hzto20kHz
Inputcharacteristics(re0 dBW(1watt);noiseA-weighted)
phono1,2
aux1,2
tape1,2
Sensitivity
0.27mV
30.0mV
30.0mV
S/Nratio
76½ dB
80dB
80dB
Phonooverload(clippingpoint)88mVat1 kHz
Dampingfactorat50Hz
100

rangeofthesignal-strengthmeteriswellchosenasanaidin
antennaorientationforbestreceptionofproblemstations.
Theamplifiersection,too,exemplifiestheextracarethat
setsthereceiverapart.Whethertheoptionthatenables
switchinginthreespeakerpairssimultaneouslyrequires
them ornot,ithasthreedistinctprotectionsystems.The
mostconventionalistriggeredbya heatsensorandshuts
downtheoutputuntiltheheatsinkhascooledtowithinsafe
operatinglimits.TheSentryMonitorcircuitreactstoabnor-
malcurrentconditionsbyrestrictingthedrivetotheoutput
transistors.AndthePowerGuardcircuitrespondstoover-
drivethatnormallywouldcreatehardclippingbyshavingoff
thepotentiallydangerousharmonics—"softening"theclip
ping,sotospeak.Noneimpingesonnormaloperation;all
minimizetheeffects—aural,thermal,orelectrical—ofabnor-
maloperation.
ThePowerGuard,forexample,limitspeakssosmoothly
thatyouareunlikelyevertohearthisreceiveroverload,as
such.ThetopLEDsinthefront-panelpowerdisplay—theone
possibleconcessiontofashioninthedesign—arePower
Guardpilots;belowthat,thedisplayiscalibratedfrom100
wattsdownto0.1wattin5 dBsteps.Aswe'vesaidbefore,
we'renotconvincedoftheutilityofsuchindicators,butthe
calibrationpointsdoseemrelativelywellchosen.
Twounusualfeaturesofthefrontpanelaretheequalizer/
tonecontrolsandthe"loudness"knob.Thelattermightbet-
terbemarked"contour"sinceitdoesnotadjustmidband
levellikemostloudnesscontrols,butsimplyaddsboostinthe
deepbassplussomeintheuppertrebletocompensatefor
lowlisteninglevels.Likeotherseparate-knobschemes,this
freestheloudnesscompensationfromthevolumecontrol
andmakesitadjustabletotheactuallisteninglevelsthrough
thesystem;unlikesome,theappropriatesettingmustbede-
terminedbyearalone—whichisarguablythemostreasonable
approach.
Theequalizer'sfivebandshavemaximumrangesofap-
proximately± 13dBandaremarkedforcenterfrequencies
of30,150,500,1,500,and10,000Hz—makingthem,re-
spectively,controlsforsubbass,bass,midrange,treble,and
sparkle.The30-Hzcontrolismosteffectiveasa rumble-fil-
ter/boom-boostcontrol;thetoponemightbeusedasa hiss
filter,thoughitsmaximumcutsettingdullstheuppertreblea
gooddeal.Asanensemble,theyoffergenuinelyusefulflex-
ibility;allhavedetentedcenter"flat"positions.
Whilethelabmeasurementsgivelittlecluetothe"extras"
fromwhichthereceiver'sspecialqualitiesderive,theydocu-
mentitsverysolidperformance.Mclntoshappearstobe
thinkingintermsoflisteningqualityratherthanspecsman-
ship(anattitudeweapplaud),sodistortion,forexample,is
onlyvanishinglylow—notinfinitesimallylow.Thefrequency
responsehasbeenintentionallycutoffbeyondtheaudio
bandtohelpmaintaincleansoundbyinhibitinginter-
modulationwithinfrasonicandultrasonic"garbage"(ade-
signcriterionthatappliestothetunersectionaswellasthe
amplifier);thoughthis,similarly,maydismaythosewhojudge
anamplifierbyitssquarewaves,theresultswithmusicseem
allthebetterforit.Tunerdataarelikewisevery good—even
superb—withnooffsettingcauseforcomplaintofanykind.
Itisobvious,too,thatMclntoshhasa clearlyformedideaof
thesortofuseritisdesigningfor:someonewho,whileheis
uninterestedinplayingthe"pro,"caresvery muchabout
qualityandcraftsmanship.Thecosmetics,the"feel,"andthe
soundqualityoftheMac 4100areallsuperb;thecontrolsare
minimalforthedegreeofusefulflexibilitytheyprovide,with
littleifanyconcessiontouserswhosimplyliketoputter.This
truly isa receiverformusiclovers.
CIRCLE136ONPAGE89
FEBRUARY197935
NEWMEASUREMENTSTANDARDS
Inmakingcomparisonsbetweencurrentreportsandthosepublishedin
thepast,readersarecautionedtopayparticularattentiontothereference
levelsandsimilartestcriteriacitedS/Nratiostorelectronics,inpar-
ticular,aremeasuredverydifferentlynowthatwehaveadoptedsalient
featuresofthenewIHFamplifier-measurementstandardWhilewebe-
lievethatthenewtechnique(whichalsoimpliesa sanerapproachto
loadingofallinputsandoutputs)willresultinmeasurementsthatmore
perfectlyreflectaudible,inuseeffects.theycannotbecompareddirectly
tothenumbersresultingfromtheformer,moreconventionallabmeas-
urements