MindPrint-AN/DI PRO
1.Layout of theAN/DI PRO
1.1 Input Section
TheAN/DIPROisequippedwithacompleteinputsectioncomprisingastudio-levelline
input,amicrophoneinputwitha-20dBdampingswitch,andswitchablephantompower
forcondensermicrophones.ThediscretemicrophoneinputstagefeaturesClass-A
engineeringanddeliversthefinesthigh-endqualityforprofessionalapplications.
Withitssensiblyarrayedfrontpanelinputs,theAN/DIPROisahighlyversatileconverter,
auniversaltoolthatenablesyouworkwithanytypeofsignalsourceandistherefore
ideallysuitedtoeveryprojectstudio.
Theinputsectionactuallyconsistsoftwoindependentcircuits,whichallowsyouto
handleandprocessthetwostereochannelsseparately.Withthebenefitofthesedual
circuits,youarefreetousetheAN/DIPROforstereosignalsaswellastwoseparate
monauralchannels.
TheMic/Lineinputselectorswitchesbackandforthbetweenthemicrophoneandline
input.Separategainknobsforthemicrophoneandthelinesignalsallowyoutoseta
suitablelevelforeach.The12-segmentLEDmeterisavisualreferencethatwill makeit
easierforyoutosettheideallevel.Forsomeapplications,youmayfindthatits"hot-
swap"optioncomesinhandywhenyouhavetoswitchbackandforthrepeatedlybetween
thetwoinputswhilethedeviceisinoperation.Withseparateknobsformicandline,you
aresparedthehassleofconstantlyhavingtoreadjustlevels.
Ifyouconnectdynamicorelectretmicrophones,youwon'tneedphantompower.However,
thefirstchoiceinstudiosaregenerallycondensermicrophonesthatrequire48voltsin
accordancewiththeinternationalnormIEC268-15.TheAN/DIPROisdesignedtoprovide
therequiredcurrent.Formicrophonesthatneedit,simplypresstheV48switch.When
you'rerecordingparticularlyloudinstruments,forexampleakickdrumor atrumpetwith
themicpointingdirectlyatitshorn,youmaycomeacrossasituationwhereyouare
unabletoturntheleveldownfarenoughtogetacleansignal.TheAN/DIPRO featuresa
-20dBdampingoptionspecificallyforthissituation.
1.2 Level Meter
Incontrasttoanaloggear,digitaldevicesaren'tdesignedtoaccommodatesaturated
signals.Uptothefinaltenthofadecibelundertheclipthreshold,thesoundremains
unchanged,butassoonasthesignallevelcrossesthisthreshold,thedevicewill
immediatelygenerateextremelyuglydistortion—universallydreaded digitalclipping.
Ontheotherhand,ifyoudialinalevelthatistoolow,thisinevitablycausesthelevelof
quantizationnoisetoincrease.Thistypeofnoiseisgeneratedwhenthesignalisdigitized.
Duringthequantizationprocess,aninfiniteorcontinuousanalogsignalissubdivided into
afinitenumberofdiscretedigitalvalues.Historically,thisproblemhasmadeitrather
difficulttodialinasuitablelevelonaconventionalA/Dconverter.
Itisessentialthatakindofbuffer,orheadroom,bemaintainedtopreventthesignalfrom
crossingtheclippingthreshold.Atthesametime,however,thisheadroomhastobekept
assmallaspossibleinordertoholdquantizationnoisetoalowlevel.
Thesetwocriticalprerequisitesaremucheasiertomeet-withtheAN/DIPRO's24-bit
technologyandsuperiordynamicrangeofupto116dB -becausetheratiooftheclipping
thresholdtoquantizationnoiseisconsiderablygreaterthanisthe case
withconventionalconverters.
Inaddition,thelevelmeterisdesignedtoletyousetlevelsasyoudidinthepaston
standardanaloggear—youaren'tforcedtogrowaccustomedtoanewtechnique.Simply
setyourAN/DIPROtotheusual0dBmark—briefsignalpeaksthatbleedintothe
yellowzoneareOK.Whenyoudialinthistypeofsetting,youautomaticallyhavea
fairlycomfortableheadroomof8decibelsandasignal-to-noiseratioof
awhopping108decibels.
AswonderfulastheAN/DIPROis,itisneverthelesssubjecttothelawsofphysics,so
avoidclippingliketheplague.MakecertainthatthefinalLEDsegment(red)neverlights
up,noteveninresponsetospikesor extremesignalpeaks.
1.3A/D Converter
AftertheAN/DIPRO’spremiumpreampsectionhasworkeditsaudiomagic,thesignalis
convertedsothatitcanbeintroducedintothedigital domain.Theconvertedsignalis
routedoutsimultaneouslyviathethreedigitaloutputslocatedontherearpanelofthe
device—notsurprisingly,thesearelabeledDigitalOut.Ifyouwanttopatchthestereo
channels'signalstoyourotherdigitalequipmentfurtherdowntheline,youcanaccess
theAES/EBUsignalattheXLRportoryoucanaccesstheS/PDIFsignalateitherthe
coaxialportortheopticalinterface.What'smore,thisisnotjustaneither/or
proposition—youarefreetousealloftheoutputsatthesametime.Thewordlengthof
thedigitalsignalis24bitsandthusfullyexploits thetechnicalpotentialoftheAES/EBU
andS/PDIFstandardsrightdowntothelastbit.Foryoursamplingfrequency,youcan
choosefromthestandard44.1and48kHzsettings,plusthestate-of-the-art96kHzformat,
whichiswellonitswaytobecomingthestandardforprofessionalrecording.Usethe
frontpanelselectorbuttonstosetthedevicetothesamesamplingratethattherestof
yourpost-converterdigitalequipmentwillbeusing.Usingexternalsynchronizationthe
AN/DIPROalsoallowsyoutousesamplingfrequenciesof 32and88.2kHz.64kHz
samplingfrequencyisnotpossible.
1.4 Inserts
TheAN/DIPROofferseveryopportunitytotransportanysignalintothedigitaldomain,
totallyunadulteratedandinfirst-ratequality,thusenablingdigitalsignalprocessingof
thehighestorder.Theremaybetimes,however,whenyouwanttodeliberatelycoloran
audiosignalorprocessitviaanaloggear.Forexample,youmaychoosetoroutethe
mastermixthroughahigh-endanalogcompressororaddatouchoftubeenhancementtoa
signalbeforeyousendittoahard-diskrecorder.Thebestplacewithinthesignalchainto
insertthistypeofequipmentisafterthepreamp,butbeforetheanalogsignalis
transformedintoitsdigitalequivalent.
TheAN/DIPROisequippedwithSendandReturnjacksthatenableyouto insertanalog
devicessuchasequalizers,compressorsortubedevices.Connecttheinputoftheexternal
devicewiththeSendjackoftheAN/DIPRO,androutetheprocessedoutputsignalto
AN/DI’sReturnjack.Thismeansyoucanstillfallbackonyourfavoriteanalog
processor—itsimplybecomesacomponentofthesignalchain,thefinalstageofwhich
isdigitalconversioninoutstandingquality.
1.5 Synchronization
Wheneverdigitalaudiodevicesareconnectedtooneanother,theirinternalclock
frequencies(samplingrates)needtoruninsync.Ifthedigitalsignalisbeingtransmitted
betweentwoandonlytwodevices,youwon'thavetoconcernyourselfwiththisnecessity
becausethesignalformatsAES/EBUandS/PDIFtransmitsynchronizationinformation
alongwiththeaudiodata.Herethefirstdevicedictatestheconditionsforcommunication
tothesecond.Thereceivingdeviceautomaticallyadaptsitssamplingratetomatchthat of
thesendingdevicebytrackingitviaacontrolcircuit(PLL,PhaseLockedLoop).
IfyouintendtouseyourAN/DIPROeitherasthefront-enddeviceforcomputer-based
hard-diskrecording,asahigh-qualitypreampforliverecordinginconjunctionwitha
24-bitDATrecorder,orasamasterconverterforyouranalogmixingconsole,youdon't
needtogivesynchronizationanotherthought.
If,however,your setupfeaturesmorethantwodigitaldevices,automaticsynchronization
maybehamperedbytoolongachainofconsecutivedevicesor—incomplexcon-
figurationsinwhichsomedevicessimultaneouslysendandreceivedata—automatic
synchronizationmaybealtogetherimpossible.Synchronizationerrorsaremanifestedas
