User Manual

User's Guide Fireface UFX II © RME

8.7 Clock Modes - Synchronization

In the digital world, all devices must be either Master (clock source) or Slave (clock receiver).

Whenever several devices are linked within 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 remedy this, 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). See chap-

ter 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’.

Under WDM the Fireface will (has to) set the

sample rate. Therefore the error shown to the

right can occur. An AES, SPDIF or ADAT

signal with a sample rate of 48 kHz is used as sync source, but Windows audio had been set to

44100 Hz before. The red color of the text label signals the error condition, and prompts the

user to set 48000 Hz manually as sample rate.

Under ASIO the audio software sets the sample rate, so that such an error will usually not hap-

pen – but it can too. In slave mode the external sample rate has priority. Feeding 44.1 kHz will

prevent the ASIO software to set 48 kHz – obviously, as the only way to do so would be to enter

a different clock mode (Master/Internal).

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.