Intel Fireface 800 - Manual (Page 30)

30 User's Guide Fireface 800 © RME
13.3 Known Problems
If a computer does not provide sufficient CPU-power and/or sufficient PCI-bus transfer rates,
then drop outs, crackling and noise will appear. Raising the buffer size in the Settings dialog of
the Fireface 800 helps in most cases. We also recommend to deactivate all PlugIns to verify
that these are not the reason for such effects.
The above note on PCI is not an error in this manual: very often FireWire controllers are con-
nected to the PCI bus. Therefore the same problems known from PCI audio cards can occur
with FireWire audio interfaces as well. Further information is found in chapter 35.3.
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 800
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!
When using more than one Fireface 800, all Firefaces have to be in sync, see chapter 14. Else
a periodically repeated noise will be heard.
Fireface 800 supports ASIO Direct Monitoring (ADM). Please note that not all programs support
ADM completely or error-free. The most often reported problem is the wrong behaviour of pano-
rama 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.
14. 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 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.
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 when a hard drive is connected to the Fireface (hub
functionality), FireWire 800 will immediately increase performance and reliability.
• 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 35.4.