Installation manual

Dolby
®
Model CP650 Installation Manual B-Chain Alignment
4-5
Please Wait...
Calibrating....
Mi
c
L
eve
l
T
oo
L
ow
or Too High
Proceeding
Uncalibrated
The scope should now be receiving sync signals
from the CP650. Set the scope vertical inputs to
100 mV/div. Set the horizontal sweep rate to
1 ms/div. Temporarily switch the inputs to GND
and move the vertical position of each trace to line
up with the bottom screen graticule line. Do not
move the vertical positions after completing
this step. Switch the inputs to DC and adjust the
sync to trigger on the waveform. Adjust the scope
horizontal position offset such that each displayed
burst appears on the left and right-hand sides of
the screen. If necessary, adjust the Mic input-level
pot until the center area of the displayed pink
noise moves to the middle of the scope screen.
OFF
80
70
60
50
40
30
menu
OK
With a sound pressure level meter, measure the
noise level in the room. Rotate the front-panel
knob until the room reading is shown on the front-
panel screen.
Note: Hold the sound pressure level meter near the location of
mic 1. The adjustment range is from 45 to 108.5 dB in 0.5 dB
steps.
Press the OK button.
Wait while the system automatically calibrates to
the room reading.
Note: The calibration is retained in CP650 memory and can be
used in future alignments. However, it is advisable to recalibrate
the system when re-arranging microphones because the sound
pressure level will vary slightly with microphone placement.
The CP650 is shipped from the
factory with the Mic input-level
control set to minimum.
Note: The spectrum analyzer, built into the CP650, has
automatic level control covering a range of mic input levels.
However, if you see an error message reporting mic level too low
or too high:
The microphone(s) may require phantom power. Move DIP
switch 3 up, press and hold the left menu button, and rotate the
main fader counterclockwise one step back to the Calibrate SPL
Menu, and repeat the above steps.
OR
While watching the oscilloscope RTA display, adjust the Mic
gain control to place the flat part of the signal in the approximate
center of the screen. The trimpot is accessible through an
opening in the setup panel. Then press / hold the left menu
button, and rotate the main fader counterclockwise one step back
to the Calibrate SPL menu, and repeat the above steps.