MOTU PCI-424, User Manual

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M O T U P C I A U D I O C O N S O L E
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As shown above in Figure 6-10, notice that the
AES/EBU output can also directly mirror a pair of
HD192 analog inputs. In effect, this lets you route
any analog input pair directly to the AES/EBU
output.
AES Output Clock
The AES Output Clock menu provides several
clock sources and sample rate options for the AES/
EBU output.
Figure 6-11: Clock sources for the AES/EBU output.
Each clock option is briefly explained below.
System
Choose
System
when you want the AES/EBU
output sample rate to match the HD192’s system
clock, and you don’t need to convert to a different
sample rate or resolve the output to some other
external clock. No sample rate conversion will
occur when this option is chosen.
AES Input
Choose AES Input when you would like the AES/
EBU output sample rate to match — and
continuously resolve to — the sample rate
currently being received by the AES/EBU input. If
necessary, the AES/EBU output signal will be
sample rate converted to match the AES input rate.
☛
Be careful when both the HD192’s AES/EBU
input and output are connected to the same
external device: this option is likely to create a
clock loop.
AES Word In
Choose
AES Word In
when you would like the AES/
EBU output to match — and continuously resolve
to — word clock being received from the HD192’s
‘AES Word In’ BNC jack. If necessary, the AES/EBU
output signal will be sample rate converted to
match the AES Word In rate.
44.1 / 48 / 88.2 / 96 kHz
Choose one of these sample rates when you need to
convert the AES/EBU output to a rate different
than the HD192’s sample rate. When you choose
one of these rates, the additional
Fixed Frequency
option appears, as shown below in Figure 6-12.
Figure 6-12: The Fixed Frequency option.
Check the Fixed Frequency option to generate the
chosen sample rate with AES/EBU output
independently driven by its own clock crystal (not
resolved to the system clock).
Uncheck
the Fixed Frequency option to generate
the chosen sample rate but also resolve to the
System clock. For example, if the system clock is set
to 48 kHz and the AES/EBU output is set to
96 kHz, the AES/EBU output will run at exactly
twice the sample rate of the system clock. This will
be true even if the system clock is running faster or
slower than 48 kHz because the HD192 system is
slaving to an external clock.
Metering options
The HD192 provides several options for the front-
panel input and output meters.