Dolby
®
Model CP650 Installation Manual
Final Adjustments
7-2
Mic Bypass
Video Clamp RTA1 RTA2
1 2 3
7
4 5 6
8
SIGNAL
PRESENT
MAIN
HF
Lt
Rt
Lt
Rt
Sw
L
C
R
Ls
Rs
SERIAL DATA
MIC MUX
OK
+
OK
Normal Bypass
If your CP650 is equipped with a Cat. No. 791
Crossover Card:
Follow the previous steps to set the
Main
bypass
level trimpot for correct low-frequency level
matching.
With the unit in bypass, adjust the
HF
bypass
level trimpot for correct low/high-frequency
balance. A real-time analyzer should be used for
accurate setting.
Verify that the audio level in the auditorium
sounds the same when in normal and bypass
modes by using the OK button to toggle back and
forth between normal and bypass.
When finished, leave the CP650 in normal
operating mode (Power button
not
showing red).
Optical Surround Level Trim
It is recommended that you perform this adjustment. (See Appendix C.)
7.2
Setting Optical Surround Delay
In analog optical formats, the CP650 incorporates a delay line in the surround channel
to ensure that sound from the rear of the theatre arrives at the listeners’ ears
approximately 20 milliseconds after the arrival of sound from the front speakers. The
delay is adjustable from 20 to 150 ms, in 1 ms steps. The setting is stored to CP650
memory using the procedure outlined below. Use the following formula to calculate
the correct delay setting:
1. Estimate the distance between a rear seat and the nearest surround loudspeaker, in
feet. If the metric system is used, multiply the meters by 3 to convert to feet.
2. Estimate the distance from this seat to the front loudspeakers (again, in feet). If
the metric system is used, multiply the distance by 3 to convert distance from
meters to feet.
3. Subtract the distance measured in step 1 above from the distance measured in
step 2, then add 20. The result is the delay time, in milliseconds.
For example:
•
The selected seat is 10 feet (3.3 meters) from the nearest surround speaker.
•
The selected seat is 80 feet (26.7 meters) from the front speakers.
•
The delay is set for (80-10) + 20 = 90 milliseconds.
