V4Hd Tab Settings; Sample Rate; Clock Source - MOTU V4HD User Manual

V4HD TAB SETTINGS

Sample Rate

Choose the desired Sample Rate for recording and
playback. The V4HD can operate at 44.1 (the
standard rate for compact disc audio), 48, 88.2, 96,
176.4 or 192 kHz. Make absolutely sure that all of
the devices connected digitally to the V4HD match
the V4HD's sample rate.
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Mismatched sample rates cause distortion and
crackling. If you hear this sort of thing, check the
sample rate settings in your hardware and here in
MOTU Audio Setup.
Operation at 4x sample rates (176.4 or 192kHz)
At the 4x sample rates (176.4 or 192kHz),
operation of the V4HD audio features is restricted,
due to the higher audio bandwidth demands, as
follows:
The V4HD provides 8 channels of analog input
■
and 8 channels of analog output, simultaneously.
Only one 8-channel digital input or output bank
■
can be used, with sample rate conversion applied,
because the digital I/O banks only operate up to
96 kHz. With sample rate conversion, you can
either capture or play back digital audio via ADAT
optical, AES/EBU, embedded SDI or embedded
HDMI out at any sample rate from 44.1 kHz to
96 kHz.
The headphone output is disabled.
■

Clock Source

The Clock Source determines what the V4HD will
use as its time base for audio. The following
sections briefly discuss each clock source setting.
Video Clock
When video is enabled (see "Enable Video" on
page 50), the V4HD audio clock slaves to video,
and this is the only choice in the Clock Source
menu.
M O T U A U D I O S E T U P
Internal
When video is disabled (see "Enable Video" on
page 50), use the Internal setting when you want
the V4HD to operate under its own digital audio
clock. For example, you may be in a situation
where all you are doing is playing audio from Final
Cut Pro or audio software on the computer. In a
situation like this, you most often don't need to
reference an external clock of any kind.
ADAT optical
When video is disabled (see "Enable Video" on
page 50), the ADAT optical clock source setting
refers to the clock provided by the V4HD's optical
input, when it is connected to an ADAT optical
device. This setting can be used to slave the V4HD
directly to the optical input connection. In this
scenario, the ADAT Optical clock source setting lets
you slave the V4HD to the other device via its
digital connection to the V4HD.
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The V4HD has two pairs of optical
connectors: a main pair (for 8-channel operation at
44.1 or 48 kHz) and an auxiliary pair (for channels
5-8 at 88.2 or 96 kHz). In ADAT optical clock
mode, the V4HD always resolves to the optical
input in the main pair, even during 88.2 or 96 kHz
operation. So be sure to connect the ADAT optical
clock master to the optical input in the main input
connector.
If the ADAT Optical setting does not appear in the
menu, it means that the V4HD's optical input is
currently disabled. Choose Enabled from the
ADAT input menu (Figure 8-1 on page 72).
For further details about this setting, see "Syncing
digital audio devices" on page 29.
Word Clock In
When video is disabled (see "Enable Video" on
page 50), the Word Clock In clock source setting
refers to the Word Clock In BNC connector on the
V4HD rear panel. Choosing this setting allows the
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