User`s manual

B-Chain Alignment Procedures
Notes
5-33
You can verify that the delay setting is acceptable by listening to a familiar Dolby
encoded film which ideally contains both center channel dialogue and some
discernible surround sound. The Dolby Cat. No. 251 SR/Digital “Jiffy” film
serves excellently for this purpose. 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.
Make certain all speakers are ON for this test.
JIFFY
TEST FILM
Cat. No. 251 SR•D—A subjective film for testing theatre sound
RECORDED IN
Running Time:
Picture format:
6 minutes
1.85:1 widescreen or
2.35:1 anamorphic
Sound formats:
10
digital
05
analog SR
Dolby Laboratories Inc. • 100 Potrero Avenue
San Francisco, CA 94103-4813
Telephone [phone] • Facsimile 415-863-1373
Dolby, the Double-D symbol and Dolby Stereo are trademarks
of Dolby Laboratories Licensing Corporation
S94/10117
While the film is playing, walk around the theater and carefully listen to the
surround speakers when there is center channel dialogue. The dialogue should
appear to be coming from the screen with no significant dialogue coming 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,
which persists regardless of the delay time setting, there is probably 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 ambiance. 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 impaired or
destroyed.
Connect a cassette deck or CD player to the from non sync terminals on terminal
block TB6 on the backplane of the CP45.
5.5 Setting Optical Surround Delay