Dolby Laboratories CP65 - Manual (Page 51)

B-Chain Alignment Procedures
Action Indication Step
No.
5-24
4
5
6
7
d. Subwoofer Alignment (Cat. No. 441)
Dolby
n-sync surr gain
Q
on
present signal gnd
gain
bass
Q
mid freq
cut
treble
tp
bass
Q
freq mid
cut
treble
gain mag/dig opt gain
off
auto freq
cut
tp present signal
Subwoofer
Left Surround
Right Surround
Cat. No.
441
Dolby
n-sync surr gain
Q
on
present signal gnd
gain
bass
Q
mid freq
cut
treble
tp
bass
Q
freq mid
cut
treble
gain mag/dig opt gain
off
auto freq
cut
tp
present signal
Subwoofer
Left Surround
Right Surround
Cat. No.
441
Dolby
n-sync surr gain
Q
on
present signal gnd
gain
bass
Q
mid freq
cut
treble
tp
bass
Q
freq mid
cut
treble
gain mag/dig opt gain
off
auto freq
cut
tp
present signal
Subwoofer
Left Surround
Right Surround
Cat. No.
441
90 dBC 85 dBC ➝
Dolby
n-sync surr gain
Q
on
present signal gnd
gain
bass
Q
mid freq
cut
treble
tp
bass
Q
freq mid
cut
treble
gain mag/dig opt gain
off auto freq
cut
tp
present signal
Subwoofer
Left Surround
Right Surround
Cat. No.
441
O FF 80 7 0 60 5 0 4 0 30
.05 .1 .2 .4 .8 1.6 3.15 6.3 12.5 kHz
dB
–10
+5
0
–5
+10
B-Chain Alignment Procedures
Notes
5-25
d. Subwoofer Alignment (Cat. No. 441)
Adjust the mag/dig gain control on the Cat. No. 441 card for a 90 dBC SPL (sound
pressure level) in the theatre. (If this level cannot be obtained it may be necessary to
change the J2 jumper setting to increase or decrease the output - - see page 2-5). When
you have obtained this level turn the mag/dig gain control down for an 85 dBC SPL.
Note
This level is only an approximation. Sound pressure level
meters are not appropriate for setting accurate levels of
narrow band signals. The correct final level will be set later
in this procedure using an RTA.
Turn the cut control at the top of the Cat. No. 441 card to the fully clockwise (CW) position
for minimum cut. This disables the subwoofer equalizer circuit.
Note the frequency of the peak in the response. You will need this information in Step
9 following.
Turn the Q control on the Cat. No. 441 card to its mid point (for a moderately wide notch).
Turn the cut control back to the fully counterclockwise (CCW) position for full cut.