Dolby Laboratories Multichannel Audio Tool DP570 - Manual (Page 83)

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