Dolby Laboratories DP570 A.3.5 Generating Test Noise, A.3.6 Increasing the System Volume , A.3.7 Measuring SPL, A.3.8 Computing Channel Trims

66 Dolby® DP570 Multichannel Audio Tool User’s Manual
Configuring a Monitor System
A.3.5 Generating Test Noise
TheDP570generatestwokindsoftestnoise:pinkandfiltered.Pinknoiseexertsanequal
soundpressurelevelacrosstheentirespectrum.Filterednoiseispinknoisethathasbeen
highpassfilteredatthepreestablishedLFEcrossoverfrequency.
Clickabuttontogeneratetheappropriatekindoftestnoise.ClickPinkifyourbass
managementsettingisNone.Otherwise,clickFiltered.Thetestnoisebuttonsareshown
inFigureA‐2directlyundertheAnalogOutputscheckbox.
Whenactivated,thetestnoisecyclesaroundthespeakersinorder:Left,Center,Right,
RightSurround,BackSurroundRight,BackSurroundLeft,LeftSurround,andsubwoofer
—remainingtwosecondsateachoutputbeforemovingontothenext.
Thetestnoisefeatureisintelligent.Whenyoubeginanindividualspeakertrimadjustment,
thetestnoiseremainsatthatspeakeruntilyoucompletetheadjustmentandmoveto
anotherspeaker,allowingyoutoadjusttheSPLaccordingtothefollowingprocedure.
A.3.6 Increasing the System Volume
Afterturningonthenoise,raisethemasterVolu mesliderslowlyuntilmeterreadings
reachyourtargetSPL.Whenthesystemisproperlycalibrated,thistargetSPLwillregister
0onthemaster Volu mescale.Ifitdoesnot,adjusttheMa sterTrimslideruntilthetarget
SPLmeasures0onthemaster Volu meslider.Yo uarenowreadytobeginmakingfine
adjustments.
A.3.7 Measuring SPL
ToaccuratelymeasureSPL:
1. Sitinthereferencelisteningposition.SettheSPLmetertoCweightingandSlow
response.
2. Facingthefrontspeakers,holdtheSPLmeteratchestlevel,withthemicrophone
facingupatanangleofapproximately45° totheCenterspeaker.Keepthemeterat
arm’slengthtopreventmeasuringaudiothatmayreflectfromyourbody.
3. KeeptheSPLmeterinthisposition.MakesurethatthemeterisaimedattheCenter
speakerasyoutakereadingsfortheLeftandRightspeakers.
4. TotaketheSPLreadingsfortheLeftSurroundorRightSurroundspeakers,keepthe
meteratthesameangleandpositionasyoudidforthefrontspeakers.Turnyour 
body90°fromtheCenterspeakertowardthewallclosesttothesurroundspeakeryou
aremeasuring.Thisminimizesshadowing(obscuringthemeterwithyourbody).
A.3.8 Computing Channel Trims
Aftermeasuringeachspeaker,computethedifferencebetweenthemeasuredactualSPL
andthetargetSPL.AdjustthetrimforeachspeakerappropriatelyusingtheMultichannel
Trims controlsshowninFigureA‐8.
Warni ng: Beforeyouturnontestnoise,besurethatyourplaybacksystemissetnohigher
thanmoderatevolume.Iftheplaybacklevelishigh,youriskdamagingyour
speakersandpossiblyyourhearing.ThedefaulttestnoiselevelfromtheDP570
is–20dBFStothedigitaloutputs(+4dButotheanalogmonitoroutputs).