MOTU 24Ai, Руководство пользователя

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H A R D W A R E I N S T A L L A T I O N
40
AUDIO CONNECTIONS
Here are a few things to keep in mind as you are
making audio connections to your 24Ai or 24Ao
interface.
D-Sub connectors
The 24Ai and 24Ao D-Sub connectors accept
standard, female Panasonic/Tascam (AES-59)
D-sub cables. Be sure the screws have standard
4-40 threading (not metric threading). For details
and pin-outs, see Appendix D, “D-sub Connector
Specifications” page (85).
Analog trims
All quarter-inch analog inputs and outputs can be
trimmed. This allows them to support a variety of
standards, including EBU-R68, SMPTE RP-155,
+4dBu, -10dBV, 2vRMS, 1vRMS.
24Ai analog inputs are equipped with high-quality,
digitally controlled analog trim that provides a
range from -96 to +22 dB in 1dB steps.
24Ao outputs can be trimmed in the DAC at 32 bit
resolution. Range is 24 dB.
Trim controls are most easily accessed in the web
app. See “Device tab” on page 14. Trim settings can
also be accessed in the LCD menu.
Optical
Your MOTU interface provides three banks of
ADAT optical (“lightpipe”) connectors. Together,
they provide 24 channels of ADAT optical digital
I/O at 44.1 or 48 kHz. At the high sample rates
(88.2 or 96 kHz), 4-channel SMUX operation
provides 12 channels of I/O and supports two
modes (item #24 on page 15):
■
Standard — for 2x optical connection to
3rd-party SMUX-compatible hardware products.
■
Type II (Legacy) — for 2x optical connection to
legacy MOTU products that are equipped with
optical ports and support 2x operation.
The optical ports are disabled when the interface is
operating at a 176.4 or 192 kHz.
TOSLink (optical S/PDIF)
Alternately, the optical ports can be configured for
stereo TOSLink (optical S/PDIF) in the web app
(item #24 on page 15). The optical IN and OUT
banks can be configured independently.
SYNCHRONIZATION
If you connect devices digitally to your MOTU
device, or if you need to synchronize your MOTU
device with an outside time reference such as word
clock, you must pay careful attention to the
synchronization connections and clock source
issues discussed in the next few sections.
Do you need to sync?
If you will be using only your MOTU device’s
analog inputs or outputs (and none of its digital
I/O), and you don’t need to resolve your system to
external word clock, you don’t need to make any
sync connections. You can skip this section.
Situations that require synchronization
There are two general cases in which you will need
to resolve you MOTU device with other devices:
■
Synchronizing with other digital audio devices
so that their digital audio clocks are phase-locked
(as shown in Figure 4-6)
■
Resolving your MOTU device to an external
clock source
■
Networking multiple MOTU AVB interfaces
Synchronization is critical for clean digital I/O
Synchronization is critical in any audio system, but
it is especially important when you are transferring
audio between digital audio devices. Your success
in using the digital I/O features on your MOTU
device depends almost entirely on proper synchro-
nization. The following sections guide you through
several recommended scenarios.