RME Fireface UCX II 40-Channel USB-B Audio/MIDI Interface - Manual (Page 33)

User's Guide Fireface UCX II © RME
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14.2 Clock Modes - Synchronization
In the digital world, all devices must be either Master (clock source) or Slave (clock receiver).
Whenever several devices are linked in a system, there must always be a single master clock.
A digital system can only have one master! If the Fireface’s clock mode is set to 'Master', all
other devices must be set to ‘Slave’.
The Fireface UCX II utilizes a very user-friendly, intelligent clock control, called AutoSync . In
AutoSync mode, the system constantly scans the digital input for a valid signal. If any valid signal
is found, the Fireface switches from the internal quartz (
Clock Mode – Current Internal) to a
clock extracted from the input signal ( Clock Mode – Current SPDIF, ADAT, AES or Word). The
difference to a usual slave mode is that whenever the clock reference fails, the system will au-
tomatically use its internal clock and operate in clock mode Master.
AutoSync guarantees that record and record-while-play will always work correctly. In certain
cases however, AutoSync may cause feedback in the digital carrier, so synchronization breaks
down. To solve this problem switch the Fireface clock mode to
‘Internal’.
RME’s exclusive
SyncCheck technology enables an easy to use check and display of the cur-
rent clock status. SyncCheck indicates whether there is a valid signal (Lock, No Lock) for each
input (Word Clock, SPDIF, ADAT, AES), or if there is a valid and synchronous signal (Sync). In
the field Clock Mode the clock reference is shown. See chapter 40.1.
Via
Clock Source a preferred input can be defined. As long as the Fireface sees a valid signal
there, this input will be designated as the sync source, otherwise the other inputs will be scanned
in turn. If none of the inputs are receiving a valid signal, the Fireface automatically switches
clock mode to ‘Internal’.
In some situations changing the clock mode can not be
avoided. Example: An ADAT recorder is connected to
the ADAT input (ADAT immediately becomes the Au-
toSync source) and a CD player is connected to the
AES input. Try recording a few samples from the CD
and you will be disappointed - few CD players can be
synchronized. The samples will inevitably be corrupted,
because the signal from the CD player is read with the
clock from the ADAT. In this case the Clock Source
should be temporarily set to
AES .
In practice, SyncCheck provides the user with an easy way of checking whether all digital devic-
es connected to the system are properly configured. With SyncCheck, finally anyone can master
this common source of error, previously one of the most complex issues in the digital studio
world.