Orban Optimod-FM 8300 Operating Manual page 77

OPTIMOD-FM DIGITAL
The 8300 can also truncate its output word length to 20, 18, 16 or 14 bits.
The 8300 can add dither for input material that is insufficiently dithered
for these lower word lengths (see the next step).
F) Adjust D
ITHER
[In] or [Out]
When set to In, the 8300 adds "high-pass" dither before any truncation
of the output word. The amount of dither automatically tracks the set-
ting of the W
considerably reduces added noise in the midrange by comparison to
white PDF dither. However, unlike extreme noise shaping, it adds a
maximum of 3 dB of excess total noise power when compared to white
PDF dither. Thus, it is a good compromise between white PDF dither and
extreme noise shaping.
If the source material has already been correctly dithered (as is true for
virtually all commercially recorded material), you may set this control to
OUT
. However, particularly if you use the Noise Reduction feature, the
processing can sometimes attenuate input dither so that it is insufficient
to dither the output correctly. In this case, you should add dither within
the 8300.
G) Set D
IGITAL
H) Set the O
UT
I) Press the P
REV
J) Set the DO 100% control.
 If the O
UT
analyzer, adjust the DO 100% control to make the modulation monitor
read 100% modulation (usually 75 kHz deviation).
See the notes in step (7.D) on page 2-27
 If the O
UT
modulation of the digital channel does not exceed 0 dB. Note that the
look-ahead limiter may exhibit up to 2 dB of overshoot on certain program
material, so set the level conservatively. You must use a preset without
"UL" in its name to make this adjustment.
This should not cause any problems because matching the loudness of
the FM and digital channels at the HD receiver permits the digital peak
limiting to be much lighter than the analog peak limiting, thanks to the
fact that receiver has 5 dB higher gain on the HD channel than on the
analog channel.
9. End Analog and Digital I/O setup.
If you are using a external AGC and you temporarily set the E
step 1 on page 2-24, set the E
to I or O , as desired.
N UT
control. This is first-order noise shaped dither that
L
ORD EN
F to AES or SPDIF
ORMAT
S to FM or HD.
OURCE
button.
S is set to FM: Using a modulation monitor or modulation
OURCE
S is set to HD: Adjust the DO 100% control so that the peak
OURCE
AGC to Y
XT
.
ES
INSTALLATION
AGC to NO in
XT
2-29