Dolby Laboratories CP65 - Manual (Page 44)

B-Chain Alignment Procedures
Action Indication Step
No.
5-10
a. Setting Room Equalization
12
13
→
12 11 REPEAT
Dolby
gain mono
non-sync
gain
points test
mono eq
Ls
R
C
L
Ls
R
C
L
gnd
Ls
R
C
L
R
L
signal present
Cat. No.
242
Dolby
gain mono
non-sync
gain
points test
mono eq
Ls
R
C
L
Ls
R
C
L
gnd
Ls
R
C
L
R
L
signal present
Cat. No.
242
O FF 80 7 0 60 5 0 4 0 30
75-80 dBC
O FF 80 7 0 60 5 0 4 0 30
75-80 dBC
O FF 80 70 6 0 5 0 4 0 3 0
75-80 dBC
Dolby
gain mono
non-sync
gain
points test
mono eq
Ls
R
C
L
Ls
R
C
L
gnd
Ls
R
C
L
R
L
signal present
Cat. No.
242
B-Chain Alignment Procedures
Notes
5-11
a. Setting Room Equalization
With a sound pressure level meter located at the position in the theatre used for step 6,
adjust the center channel gain on the Cat. No. 242 card until the channel produces a
reading of 75-80 dBC. (After room equalization for all channels is set, the sound pressure
level will be set to 85 dBC.) The pink noise should be at least 20 dB above the background
noise level of the theatre. If a level of 75-80 dBC cannot be obtained, adjust the gain of
the amplifiers and and try again. A row of four LEDS, signal present L, C, R and S, is
on the front edge of the Cat. No. 242 card. Each LED indicates the presence of signal for
the appropriate channel and lights intermittently when pink noise is sent through the
system from the Cat. No. 85C or from a film.
Repeat steps 11 and 12 for the left and right channels. Switch on the appropriate pink
noise switch on the Cat. No. 85C pink noise generator, one channel at a time.
Compare the response displayed on the real time analyzer (RTA) for each channel (L, C,
R). All should show a similar shape. Any large differences indicate faulty or misaligned
crossovers or defective speakers. Speaker phasing could also be at fault. See
Appendix A.