System User Guide / Owners Manual

AES and unlock switches

The‘aes’and‘unlock’switchescanbesetto‘‘mute’or‘thru’.Thebehaviorofthe

CC1inthesemodesisdescribedinChapters‘Mastermode’and‘Slavemode’.

Key Lock mode

IfyourCC1isusedinonesettingmostofthetimeyoucanuse“KeyLock”modeto

preventclockingerrorsbyaccidentalpressingofcontrolbuttonsontheCC1’sfront

panel.InthismodetheCC1doesnotrespondtothepushofanybutton.“KeyLock”

modeisengagedbyholdingthe“44.1/48/Slave”buttonduringpowerup.Itwill

thenlockthemodethatwassetbeforethelastpowerdown.Toleave“KeyLock”

mode,holdthe“44.1/48/Slave”buttonduringpowerupagain.

4. Setting up the Studio

Inadigitalstudioallequipmentwillneedtobesynchronised.Ifallthereisaretwo

boxes,onesendingandonetransmitting,allthatisneededisadigitalsignaland

therecipientwilllocktothat.Whenmultiplesourcesarefeedingintoonerecipi-

ent(e.g.adigitaldeskconnectedtoseveraldigitalrecordersandconverters),all

sourceswillneedtobesynchronous.Thisiswhatahousesync(akamasterclock)is

for.Severalformatsareinuse.TheAESpromotesastandardcalledAES11thatuses

anAES3link,butmostequipmenttendstouseawordsyncsignalonaBNCconnec-

tor.TheAES11standardistobeamendedtoincludethispractice.Wethinkthisisa

goodmove,sincethepurityofaclockrecoveredfromanAES3linkisrathersuscep-

tibletoissueslikecablelengthandbandwidthlimitations.TheAES3outputonthe

CC1isprovidedtocaterforthefewequipmentthatneedsAES11overAES3.When

theoutputisnotusedforthispurpose,itdoublesasajitterremovalfunctionfor

anyAES3signal(provideditissynchronouswiththeCC1).

Moststudiosthathaveintroducedahousesynchavenoticedachangeintheoverall

soundqualityoftheirequipment.Usuallyforthebetter,sometimesfortheworse.

Atissueisjitter(akintowowandflutter,butthenappliedtothesamplingclock).

Chapter6“Jitterexplained”willgointomoredetails.Theimportantpointtoremem-

beristhatjitteraffectsaudioqualityonlyatpointsinthechainwhereanactual

time-basedconversionistakingplace,typicallyADandDAconvertersbutalso

increasinglyasynchronoussamplingrateconverters.