User Manual

HARDWARE INSTALLATION
37
SETUP FOR MULTIPLE INTERFACES
It is possible to connect multiple MOTU interfaces
directly to your host computer through multiple
USB (and Thunderbolt) ports. Alternately, you can
connect multiple interfaces, operating as AVB
Ethernet audio interfaces, using an AVB switch
connected directly to the Mac. However, there are
several disadvantages to using any of these direct
connection schemes:
■ The audio interfaces will not be clocked to one
another and may be susceptible to drift, unless you
use external word clock connections (if available).
You are better off using the AVB network
connections shown on pages 34-36. In this setup,
the interfaces are very tightly synchronized with
each other (measured in pico seconds) through
their network connections.
■ You will not be able to route audio directly from
one audio interface to another. You are better off
using the AVB network connections shown on
pages 34-36, which allows you to route audio
streams (hundreds at a time) directly among
interfaces with near-zero latency.
Connecting multiple interfaces using
Thunderbolt
If you have other MOTU AVB interfaces with
Thunderbolt connectivity (1248, 8M, 16A or
112D) and your host computer has two or more
Thunderbolt ports, you can connect one interface
to each port, either directly or at the end of a
Thunderbolt daisy chain (on either port or both
ports).
Connecting multiple interfaces using
Thunderbolt and USB
Another way to operate multiple interfaces on the
same host computer is to connect the first interface
to a Thunderbolt port and the second to a USB 2.0
(or 3.0) port.
Multiple interfaces and USB
When connected through USB, your MOTU
interface operates as a USB 2.0 device, even when
connected to a USB 3.0 port. USB 2.0 provides
enough bus speed for several USB 2.0 devices, but
due to your MOTU interface’s high-performance
requirements for real-time operation and low
latency timing, we recommend the following:
■ Do not connect more than two units to your
computer’s USB 2.0 or 3.0 port(s).
■ When two units are connected with USB 2.0,
don’t connect other USB 2.0 or 3. 0 devices, such as
external hard drives.
■ For best results, establish clock synchronization
with other interfaces connected to the same
computer. You can use optical or AVB to achieve
clock synchronization.
Multiple AVB Ethernet audio interfaces
When operating your MOTU interface as an AVB
Ethernet audio interface (“AVB Ethernet audio
interface setup” on page 34), multiple AVB audio
interfaces can be connected using a MOTU AVB
Switch (or any 3rd-party AVB switch), and the Mac
can see all of them through their AVB connection.
For example, you could connect an Avid S3 console
to the Mac, and then connect a MOTU interface to
the S3’s extra network port (which is a built-in
switch). The Mac can see both the MOTU interface
and S3 for audio I/O. However, OS X takes over
each device for exclusive use, so they can only
stream audio to and from the Mac, not each other.
The same is true for all AVB devices connected to
the Mac. See “Syncing multiple AVB audio
interfaces connected to a Mac” on page 43.
Mixing and matching audio interfaces
You can mix and match MOTU audio interfaces.
For example, you could connect a 1248 through
Thunderbolt and another MOTU audio interface,
such as the 24Ao, through USB 2.0.