- Dolby Multichannel Audio Tool User's Manual

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Figure A‐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Volumesliderslowlyuntilmeterreadings
reachyourtargetSPL.Whenthesystemisproperlycalibrated,thi stargetSPLwillregister
0onthemaster
Volumescale.Ifitdoesnot,adjusttheMasterTrimslideruntilthetarget
SPLmeasures0onthemaster
Volumeslider.You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Figure A‐8.
Warning: 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).