- Dolby Multichannel Audio Tool User's Manual

Calibrating Speaker Playback Levels
Dolby
®
DP570 Multichannel Audio Tool User’s Manual 67
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than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.
FigureA‐9 
Figure A-9 Real-time Analyzer (RTA) Display
IfanRTAisnotavailable,settingtheLFEchannelhigher(forexample,89dBcfortheLFE
channelwhentheCenterchannelmeasures85dBc)cangiveanapproximatelevelwithan
SPLmeter.Thislevelvarieswith thequalityofthemeterbeingused.
Forfuturereference,ifcalibrating
thesubwooferwithanRTA,measurethelevelwithan
SPLmeterandnotethemeterreadingforthepropercalibration.Usethismeasuredvalue
forquickchecksofthesystemcalibrationinthefuture.
+10 dB
LFE Channel
Center channel
0 dB datum
+10 dB datum