Kurzweil PC3K Series - Flanger

Effects
Flanger
9-17
Flanger
Flangingistheprocessofaddingorsubtractingasignalwithatime‐displacedreplicaofitself,
whichresultsinaseriesofnotchesinthefrequencyspectrum,generallyreferredtoasacomb
filter.InthePC3K,theflangerisamulti‐tapdelayline,all(butone)ofwhose
tapscanhavetheir
lengthsmodulatedupanddownbyalowfrequencyoscillator(LFO).TherateoftheLFOis
expressedinTempo(seeChapter4).
StatDlyLvl(StaticDelayLevel)isthelevelofthefirst,non‐movingtap .Negativevaluesinvert
thepolarityofthetap.Therangeis
‐100to100%;0%turnsthetapoff.
DlyCrsandDlyFinarethe coarseandfinelengthcontrolsfortheStaticdelay(StatDly…)and
fortheminimumvalueofthemovingdelays(Dlyn…).Thecoarserangeis0to228ms,andthe
finerangeadjuststhecoarse
rangeinsamples(=1/48,000sec=20.8μsec)from‐127to127.
XcursCrsandXcursFindeterminehowfartheLFO‐modulateddelaytapscanmovefromthe
centeroftheirranges.ThetotalrangeoftheLFOsweepistwicetheexcursion.Iftheexcursionis
setto
0,theLFOdoesnotmoveandthetapbehaveslikeasimpledelaylinesettotheminimum
delay.Thecoarserangeis0to228ms;therange0to5msismosteffectiveforflanging.Thefine
rangeadjuststhecoarserangeinsamplesfrom‐127
to127.
Quantize + Flange
TheQuantizeportionofthisalgorithmproducesdigitaldistortionknownasquantizationnoise,
bylimitingthenumberofbitsavailabletothesignal.
DynamRange(dynamicrange)controlshowmanybitstoremovefromthesignaldatawords.
Thelowerthelevel,thegreaterthe distortion.At0dBthehottestof
signalswilltogglebetween
onlytwoquantizationlevels,therebyproducingasquarewave.Every6dBaddeddoublesthe
numberofquantizationlevels,reducingthenoiseandgettingclosertotheoriginalsignal.Ifthe
signalhasalotofheadroom(availablesignallevelbeforedigitalclipping),thennotall
quantization
levelswillbereached.Rangeis0to144dB.
Headroomsetstheavailablesignallevelbeforedigitalclipping.Settingthisproperlyprevents
thesignalfromgettingridiculouslyloudatlowlevelsofDynamRange.Youwanttohaveit
matchtheamountoflevelstillavailableabovetheinputsignal:this
isdonebyfindingthe
DynamRangelevelatwhichthesignalstartsgettinglouder,andsettingHeadroomtomatchthe
DynamRangevalue.Rangeis0to144dB.
DCOffsetaddsapositiveDCOffsettotheinputsignal,whichallowsyoutoaltertheposition
wheredigitalzeroiswith
respecttoyoursignal.AtlowDynamRangesettings,thiscancause
theoutputto“sputter”.RangeisOff/‐79.0to0.0dB.
LaserVerb
LaserVerbisanewkindofreverbwhichproducesadelayedtrainofclosely spacedreflections,
orimpulses.Astimepasses,thespacingbetweentheimpulsesgetswider,whichcreatesa
discerniblebuzzypitchthatgetslowerasthespacingincreases.Thesignalcanbefedbackinto
itselftoextend
theeffect.
DlyCoarseistheoveralldelaylength,whichcontrolsthedurationordecaytime.0.5secisa
goodstartingpoint.Rangeis0to1.3secondsinthe2Uversionofthealgorithm,and0to2
secondsinthe3Uversion.
DlyFineadjuststhe
delaywitharesolutiondownto0.2ms.Rangeis‐20.0to20.0ms.