Dolby
®
Model CP650 Installation Manual
Final Adjustments
7-3
Optical Surround
Delay
> xxx mSec
menu
OK
Press the left menu button to move to the
Optical
Surround Delay
menu.
OK
Rotate the front-panel knob to show the desired
delay, then push the OK button.
You can verify that the delay setting is acceptable by listening to a familiar Dolby
®
A-type film that ideally contains both center-channel dialogue and some discernible
surround sound. The Dolby Cat. No. 251 SR/Digital film “
Jiffy”
serves this purpose
well. If a stereo film is not available, the delay time can be checked with a mono film
if the film is played in Format 04, Dolby A-type optical with surround. All speakers
should be
on
for this test.
While the film is playing, walk around the theatre and listen carefully to the surround
speakers during center-channel dialogue. The dialogue should appear to be coming
primarily from the screen, and not from the surround speakers.
If you hear discernible dialogue from the surround speakers, the delay time was
probably set too long.
If you hear an objectionable amount of dialogue from the surround speakers that
persists regardless of the delay time setting, there is probably a severe gain or azimuth
error in the system. Re-check both the Dolby level and the A-chain alignment of the
optical system.
In many films, the surround information is intended for subtle effects and may
provide only a low-level ambience. If the surround level and delay time have been
adjusted as previously described, the surround information will be at the level desired
by the film director. Do not be tempted to increase the surround level, because the
effect desired by the film production team may be thwarted.
7.3
Setting Digital Surround Delay
The CP650 automatically calculates a typical digital surround delay based on the
optical surround delay setting performed in the previous section. Actual theatre
geometry affects the amount of surround delay required; you may, therefore, wish to
set the delay manually.
