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Dolby Laboratories DP570 Stereo System User Manual

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Configuring a Monitor System Calibrating Speaker Playback Levels

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DP570 Multichannel Audio Tool User’s Manual 69

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degrees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degrees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.

Figure A-8 Multichannel Trims Controls

Whenyouhavesettrimlevelsforallyourspeakers,clickthetestnoisecontrolshownin

Figure A‐2directlyundertheAnalogOutputscheckbox.

A.3.9 Subwoofer Calibration

Subwoofersarecalibratedusingadifferentprocesstha n therestofthespeakers,preferably

withdifferentequipment.Toproperlycalibratethesubwoofer,areal‐timeanalyzer(RTA)

isrequired.IfanRTAisnotavailable,youcanapproximatethesettingswithanSPLmeter.

WhenusinganRTA,propercalibrationrequires

settingtheLFEchannelsignalsenttothe

subwoofer,withinitstypicalbandwidth of25to120Hz,10dBhigherthanthemain

channels.Figure A‐9showsasampleRTAdisplayofaproperlycalibratedsubwoofer.

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