OPTIMOD-FM INSTALLATION
2-35
[Skip steps (D) through (I) if you will not be using the digital output.]
(See the notes immediately above.)
E)
Set the digital output Samp Rate (sample rate).
[32], [44.1], or [48], in kHz
The 8400’s fundamental sample rate is always 32 kHz, but the internal sam-
ple rate converter sets the rate at the 8400’s digital output. This adjustment
sets the 8400 output sample rate to ensure compatibility with equipment re-
quiring a fixed sample rate.
F)
Adjust the SR SYNC control.
[Internal / SYNC IN / INPUT]
You can lock the sample rate of the 8400’s AES/EBU output to the sample rate
of a reference AES/EBU signal that is applied to either the AES/EBU input or
the SYNC input.
The selections are Internal, SYNC IN, and INPUT. INPUT sets the AES/EBU
output sample rate and synchronization to the same sample rate present at
the AES/EBU input. Likewise,
SYNC IN uses the sync input’s sample rate
and synchronization as the source.
Internal sets the AES/EBU output syn-
chronized to the 8400’s internal clock and uses the
Samp Rate setting to de-
termine its output sample rate.
The output sample-rate selector (“
Samp Rate”) has no effect in the INPUT
and SYNC IN modes unless sync is lost. Then the output reverts to internal
sync at the sample rate that is preset by the output sample-rate selector. Oth-
erwise, the output sample rate follows the sample rate present at the selected
input, regardless of the setting of the output sample rate selector.
If no AES/EBU signal is provided to the 8400 Input or Sync In, set
SR Sync
to
Internal and select the desired output sample rate.
G)
Set the desired output Wrd Length (word length).
[14], [16], [18], [20], or [24], in bits
The largest valid word length in the 8400 is 24 bits. The 8400 can also trun-
cate its output word length to 20, 18, 16 or 14 bits. The 8400 can also add
dither, and you should set it to do so if the input material is insufficiently
dithered for these lower word lengths. (See the next step.)
H)
Adjust Dither to In or Out, as desired.
[In] or [Out]
When set to
In, the 8400 adds “high-pass” dither before any truncation of the
output word. The amount of dither automatically tracks the setting of the
Word Length control. This is first-order noise-shaped dither that reduces
added noise in the midrange considerably 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.
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