Known Problems; Using More Than One Fireface Ucx - RME Audio Fireface UCX User Manual

10.3 Known Problems

If a computer does not provide sufficient CPU-power and/or sufficient USB or PCI* bus transfer
rates, then drop outs, crackling and noise will appear. Raising the buffer size in the Settings
dialog of the Fireface UCX helps in most cases. It is also recommended to deactivate all
PlugIns to verify that these are not the reason for such effects. Further information is found in
chapter 32.3.
*The note on PCI is not an error in this manual: very often FireWire controllers are connected to
the PCI bus. Therefore the same problems known from PCI audio cards can occur with Fire-
Wire audio interfaces as well. Further information is found in chapter 32.4.
Another common source of trouble is incorrect synchronization. ASIO does not support asyn-
chronous operation, which means that the input and output signals not only have to use the
same sample frequency, but also have to be in sync. All devices connected to the Fireface UCX
must be properly configured for Full Duplex operation. As long as SyncCheck (in the Settings
dialog) only displays Lock instead of Sync, the devices have not been set up properly!
The same applies when using more than one Fireface UCX - they all have to be in sync. Else a
periodically repeated noise will be heard.
Fireface UCX supports ASIO Direct Monitoring (ADM). Please note that not all programs sup-
port ADM completely or error-free. The most often reported problem is the wrong behaviour of
panorama in a stereo channel.
In case of a drift between audio and MIDI, or in case of a fixed deviation (MIDI notes placed
close before or behind the correct position), the settings in Cubase/Nuendo have to be
changed. At the time of print the option 'Use System Timestamp' should be activated. The Fire-
face supports both MME MIDI and DirectMusic MIDI. It depends on the used application which
one will work better.

11. Using more than one Fireface UCX

The current driver supports up to three Fireface UCX. 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 synchro-
nized 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.
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 Fire-
faces during a Windows session. A reboot with all Firefaces already operational should
solve this problem.
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User's Guide Fireface UCX © RME