Rane PAQRAT Instruction and safety manual

OPERATING/SERVICEMANUAL RC 24A
PAQRATRECORDINGCONVERTER
DESCRIPTION
TheRC24A(or“PAQRAT”)allowsyoutorecordandplaybackstereodigitalaudiosignalswithupto24bitsof
resolutionusingyourAlesisADATmodulardigitalmultitrack.
TheRC24AaccomplishesthistaskbyconvertingtheAES/EBU(orSPDIF)stereo24-bitdigitalaudiosourcesignalto
four16-bitchannelscompatiblewithAlesis’sproprietary“ADATOptical”interface.TheRC24Asimultaneouslywrites
thesesignalsontotheADATand reads them backoffagain.Controlsonthefront panel allow you toassignthesefour
channels to tracks 1-4, 5-8, or 1-8 (two identical groups of four tracks) on the ADAT. The odd tracks carry the upper 16
bitsoftheoriginaldigitalaudio signal, and the eventrackscarrythelowereightbits plus a -20dB reference tone.
Note:Althoughitisnearlyimpossibletoachievebetterthan20-bitperformancefromtoday’sA/Dconverters,werefer
tothehighresolutioninputsandoutputsto/fromthePAQRATas24-bitanyway,justtosimplifythings.Youcaninterface
anyAES/EBUorSPDIFsignaltotheinputandoutputofthePAQRATfrom16to24bits.
SETUP&OPERATION
1.Connectone ofthesuppliedfiber opticcablesbetweenthe digitaloutputconnectoron yourADATand theDIGITAL
INPUTconnectorontheRC-24A.
2.Connectone of thesuppliedfiberoptic cablesbetweenthedigital inputconnectoronyour ADATandtheDIGITAL
OUTPUTconnectorontheRC-24A.
3.Connectastereodigitalaudiosource signal (up to 24-bit) to the AES/EBU (or SPDIF) INPUT on the rear of the RC-24A.
SettheINPUT SELECTswitchtoAES/EBU orSPDIFforthe appropriate input.
4.ConnecttheAES/EBUOUTPUTon therearof theRC-24Ato whateverisreceiving the24-bitdigitalaudiosignalduring
playback(andmonitoring).
5.ConnectthesuppliedRane RS-1 remotepowersupplytothered POWER jack ontherearofRC-24A.
6. Make sure the ADAT is plugged in and turned on.
7.PresstheDIGITALINbuttonontheADATtoselecttheADATOPTICALinterfaceasthe audio signal source.
8.PresstheRECORDTRACKASSIGNandPLAYBACKTRACKASSSIGNbuttonsontheRC-24Atoselecttracks1-4,5-8,
or1-8(record only).Armthecorresponding tracksontheADAT for recording.
9.Recordandplaybacktracks on the ADAT as normal,usingtheAES/EBU(orSPDIF)Inputand Output on the RC-24Aas
thesourceanddestinationforthe24-bitdigitalaudiosignal.
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FRONTPANELDESCRIPTION
1.POWERLED. Whendim,thisLEDindicates that you forgottopluginthe RC-24A.
2.SYNC LED. Indicates that a suitable AES/EBU (or SPDIF) sync source is plugged in. If this LED is not lit, the RC-24A is
notreceivingsignalfrom a source. Check theINPUTSELECTswitchto make sure theproperinputisselected.
3.TRANSPORTPRESENTLED. When lit,thisLED indicatesthatanADATisconnectedtotheRC-24Aviathefiberoptic
interface.
4.RECORDTRACKASSIGNBUTTON.Thispushbutton switchletsyouselectwhichfourtracks oftheADATare
recordedwiththestereo 24-bitdigitalaudiosource signal. An LEDindicateswhetheryou are recordingontotracks1-4 or
5-8.
5.RECORDTRACKASSIGN“BOTH”BUTTON .Thispushbuttonselectsall8tracksforrecording,nomatterwhatthe
stateofthe RECORD TRACKASSIGNBUTTON(previous section)is. Tracks1-4are identicaltotracks5-8. Usethis
optionwhenyouarearchivingastereomaster,andwishtocreatearedundantcopyonthesametape.
6.PLAYBACKTRACKASSIGNBUTTON.Thispushbuttonswitchletsyouselectwhichfour tracksoftheADATare
convertedbackto24-bitdigitalaudio,andtransmittedouttheAES/EBUOUTPUT.AnLEDindicateswhetheryouare
playingtracks1-4or 5-8.
7.SAMPLERATELEDS. TheseLEDsindicatethe samplerateofthe AES/EBU(orSPDIF)source (sync)input(44.1kHzor
48kHz).
8.SOURCEWORDLENGTHLEDS.TheseLEDsindicatethewordlength(inbits)oftheAES/EBU(orSPDIF)source
(sync)input.
9.16-BITDITHEREDOUTPUTENGAGESWITCH. Thisswitchengages16-bitditheringandtruncationontheAES/
EBUOUTPUT. Dithershouldbe engaged whentheAES/EBUOUTPUT is feedingadevicethattruncates the signalto16
bits(e.g.DATrecorder,digitalsignalprocessors,andsoon).
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REARPANELDESCRIPTION
1.AES/EBUOUTPUT. TheAES/EBUOUTPUTtransmitsdigitalaudioconformingtotheAES/EBUstandard.Digitalaudio
exitingthisOutputisidenticalto the original digital audiofedtotheAES/EBU(orSPDIF) INPUT and recorded onto the
ADAT.ThisOutput istypicallyconnectedto aD/Aconverter,hard diskrecorderora CDmasteringsystem. TheAES/EBU
OUTPUTfollowsinternationalconventions,withpin2hot,pin3negative,andpin1tiedtochassisground.
2.AES/EBUINPUT. TheAES/EBUINPUTfollowstheAES/EBUstandard.LiketheAES/EBUOUTPUTconnector,pin2is
hot, and pin 3 is not. This Input is typically connected to a digital audio source, such as an A/D convertor or the output of a
digitalmixer.
3.SPDIFINPUT. TheSPDIFINPUT isjustliketheAES/EBUINPUT,except datareceivedherereceivesdigitalaudio
formattedwiththeconsumer“SonyPhilipsDigitalInterfaceFormat”.
4.INPUTSELECTSWITCH. ThisswitchallowsyoutoselectthedesiredInput(SPDIForAES/EBU).Anotherwayof
puttingitis:youmustselecttheproperInput(theoneyoupluggedacable into).
5.ADATOPTICALINTERFACE. ThisinterfaceconnectstheRC-24AtoadeviceequippedwiththeADATOPTICAL
INTERFACE(e.g.AlesisADATorFostexRD-8).UseonlyRanepart#280-101fiberopticcables.
6.POWERINPUT. Plugtheexternalpowersupplyintothisconnector.Caution:NeverconnectanythingexcepttheRane
RS1ACpowersupply(enclosedwiththeunit)tothethingthatlookslikearedtelephonejackontherearoftheRC-24A.
Thisisa low-voltageACpower input,andconnectingit totelephones,computer keyboards,orotherdevices willresultin
unpredictable,andpotentiallycatastrophic,results.IfyouwanttodestroyyourRC-24A,wesuggestwiringittotheoutput
of a power amplifier, or dropping it out of an airplane.
FCC&VDENOTICE
Thisequipmenthasbeentestedandfoundtocomply
withthelimitsfor a ClassAdigitaldevice, pursuant to
Part15oftheFCCRules,andsimilarrequirementsfound
inEuropeanspecificationsVDE0871/0875.Theselimits
aredesignedtoprovidereasonableprotectionagainst
harmfulinterferencewhentheequipment isoperatedin a
commercialenvironment.Thisequipmentgenerates,uses,
andcan radiate radio frequency energy and, if not
installedandusedinaccordancewiththeinstruction
manual,maycauseharmfulinterferencetoradiocommu-
nications.Operationofthisequipmentinresidentialarea
islikelytocauseharmfulinterferenceinwhichcasethe
user will be required to correct the interference at their
ownexpense.USEOFSHIELDEDDIGITALCABLES
ISREQUIREDFORFCCCOMPLIANCE.
IMPORTANTNOTE
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All features & specifications subject to change without notice. 520-388 MAY95Printed in the U.S.A. on Recycled Paper
©RaneCorporation1080247thAvenueWest,MukilteoWA98275-5098 TEL[phone] FAX[phone]
OPERATINGNOTES
ByRogerNichols
MixingtoPAQRAT.ThefirsttimeI usedthePAQRAT
wastostore 20-bitmixesofWalterBecker’s soloalbum.In
mastering,morethanonce,adrop-outon theopticaldisk
madeusscrambleforthe PAQRAT encoded tapetosavethe
day.Ifyouareprinting your mixes toPAQRATandDAT,
connecttheDAT machineontheoutputof thePAQRATand
engageOUTPUTDITHERonthePAQRATfrontpanel.This
way you will get the benefit of 16-bit dithering for DAT
storage.IftheDATmachineisconnecteddirectly to the 20-
bit data, the 16 bits stored on the DAT will be truncated,
resultinginlowerfidelity.
HardDiskAudio. IfyouperformDSPoperationsonhard
disk(iftheharddiskcontainsdigital audio,shouldthe
spelling of disc end in a “C” instead of a “K”?) files, the
highestfidelitywouldberealizediftheresultantfilewas
storedas a 24-bit file. If multiple DSP operations are tobe
performed,suchasnoisereductionononepass,limitingon
anotherpass,EQonanotherpass,and thenfinallydigitally
mixedwithanother audio file,thenallof theprocessing
shouldbedone inthe24-bit mode.Theresultantaudio file
RC24AANDALESISADATSYSTEMCONNECTION
thenneedstobe convertedto16-bitonlyonce, and thenasty
artifactsarekepttoaminimum.The24-bitfilescanbe
backedupthroughaPAQRATtomaintainthehighestquality
intheaudiodata.
MasteringwithPAQRAT.Whenmasteringaprojectthat
was mixed 16-bit, use the PAQRAT to make an EQ safety.
Theoutputfromdigitalmasteringconsolesisusually24-bit
(the24-bitsis generatedbythemathused toperformdigital
EQ,limiting,compressionandlevelchanges).IftheEQtape
isonly16-bit,the noise floorincreasesbecauseofthe
roundedoffmath.
SelectingBoth.WhenusingthePAQRATtostoretwo
channelmixes,select“BOTH” fortheRECORDTRACK
ASSIGN.Thisprovides youwithan addedlevelofredun-
dancy.Theaudiodataisrecordedtwice.Ifforsomereason
youweretoencounteradropoutontheprimarytracks,then
it may be possible to retrieve the data from the other set of
tracksbyswitchingthePLAYBACKTRACKASSIGNtothe
othersetoftracks.Thismethodlets you think of the eight
trackasagiantDATmachinewithbuilt-inredundancy.
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