15. Using more than one Fireface 800
The current driver supports up to three Fireface 800. All units have to be in sync, i.e. have to
receive valid sync information (either via word clock or by using AutoSync and feeding synchronized
signals).
• If one of the Firefaces is set to clock mode Master, all others have to be set to clock mode
AutoSync, and have to be synced from the master, for example by feeding word clock. The
clock modes of all units have to be set up correctly in the Fireface Settings dialog.
• If all units are fed with a synchronous clock, i.e. all units show Sync in their Settings dialog,
all channels can be used at once. This is especially easy to handle under ASIO, as the ASIO
driver presents all units as one.
When using all channels of more than one Fireface 800, a FireWire 800 interface is necessary.
FireWire 400 will usually not suffice for operating more than one Fireface. When using only one
Fireface 800, a FireWire 800 interface does not provide any performance advantages, especially
does not help to achieve lower latency. But connecting a hard drive to the Fireface (hub functionality),
FireWire 800 will immediately increase performance and reliablility.
• The cabling of FireWire 800 units is critical. In real world operation, it is not unusual that all
Firefaces have to be connected directly to the 1394b ports of the computer, using cables of
similar length. A long cable from the computer to the first Fireface, and a short one from the
first to the second Fireface can cause problems.
More information about numbers of channels and bus load can be found in chapter 37.4.
The driver takes care of the numbering of all Firefaces, so that it doesn't change. The unit with
the lowest serial number is always 'Fireface (1)'. Please note:
• If the Fireface (1) is switched off, Fireface (2) logically turns to the first and only Fireface. If
Fireface (1) is switched on later, the numbering changes and the unit becomes Fireface (2)
immediately.
• The driver has no control on the numbering of the WDM devices. Therefore it might happen
that the WDM devices (2) are mapped to unit (1), especially when switching on more Firefaces
during a Windows session. A reboot with all Firefaces already operational should solve
this problem.
Note: TotalMix is part of the hardware of each Fireface. Up to three mixers are available, but
these are separated and can't interchange data. Therefore a global mixer for all units is not
possible.
