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
