Dolby Laboratories Multichannel Audio Tool DP570 - Manual (Page 82)

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, this 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).