User Manual

User's Guide Fireface UFX II © RME

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 UFX 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 sig-

nal is found, the Fireface switches from the internal quartz (Clock Mode – Current Internal) to a

clock extracted from the input signal (Clock Mode – Current ADAT, AES or Word). The differ-

ence to a usual slave mode is that whenever the clock reference fails, the system will automati-

cally 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, ADAT, AES), or if there is a valid and synchronous signal (Sync). In the field

Clock Mode the clock reference is shown. See chapter 39.1.

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

AutoSync 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 cor-

rupted, 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 de-

vices 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.