OPTIMOD SURROUND PROCESSOR OPERATION
3-19
sired sound before you make further modifications at the Full or Ad-
vanced Modify levels.
Setting Preset Loudness Correctly for Dolby Digital Transmission
In sound for picture applications that use a Dolby Digital transmission channel to the
consumer’s receiver, you can use the 8685’s L
OUDNESS LEVEL meter as a reference for
adjusting a user preset’s loudness. This meter’s calibration tracks the 8685’s active
D
IALNORM value, which is either the DIALNORM value in the active Setup (which ap-
plies to any preset whose D
IALNORM value is set to GLOBAL) or the DIALNORM value in
the active processing preset if this value is not set to G
LOBAL.
The controls to which the following procedure refers are described later in Section 3.
A) Make sure that the input reference level in the active preset is correctly ad-
justed (step 7 on page 2-11).
B) Make sure that the 8685’s active D
IALNORM value is the same as the Dialnorm
value you are transmitting to consumers’ receivers (step 10 on page 2-14).
C) L
OCATE to ADVANCED CONTROL, which is where you can access the controls re-
quired to complete the steps below.
D) If the AGC is turned on in the preset, adjust the AGC
DRIVE control so that the
AGC is producing the desired amount of compression. We recommend 10 dB
or less with normal levels.
E) If the AGC’s idle gain (i.e. the gain reduction produced by the AGC when its si-
lence gate is on) is inappropriate, adjust it with the AGC
IDLE GAIN control.
If you are using a factory processing preset and you have adjusted the
input reference level correctly, there is no need to adjust the AGC
DRIVE
or AGC IDLE GAIN controls.
F) Adjust the MULTIBAND DRIVE or 2-BAND DRIVE control (depending on whether
the five-band or two-band structure is active) to produce the desired amount
of multiband gain reduction. We recommend about 5 dB for dialog at normal
levels.
G) If you wish to use the Loudness Controller: Set the L
OUDNESS THRESHOLD con-
trol to –10 dB, which matches its threshold to the 8685’s active D
IALNORM
value. Then set the MB
LIMIT DRIVE control to make the LOUDNESS GR meter
indicate 3 dB of gain reduction with dialog at normal levels.
You should see the LOUDNESS LEVEL meter peaking around 0 dB when the
L
OUDNESS GR meter shows that gain reduction is occurring
H) If you do not wish to use the Loudness Controller: Set the LOUDNESS
THRESHOLD control to OFF. Then adjust the MB LIMITER DRIVE control to pro-
duce 0 dB peak indications on the L
OUDNESS LEVEL meter with dialog at nor-
mal levels.
Presets with the loudness controller off will produce wider source-to-
source loudness variation (as indicated on the L
OUDNESS LEVEL meter)
than presets with the loudness controller on. When the loudness control-
To Next Page
Loading...
Need help?
General
