RME DSP System Multiface - Manual (Page 15)

User's Guide HDSP System Multiface II © RME
15
8.2 Clock Modes - Synchronization
In the digital world, all devices must be either Master (clock source) or Slave (clock receiver).
Whenever several devices are linked within a system, there must always be a single master
clock.
A digital system can only have one master! If the HDSP’s clock mode is set to 'Master', all
other devices must be set to ‘Slave’.
The HDSP system 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 Multiface switches from the internal quartz (Clock Mode – Current Internal) to a
clock extracted from the input signal (Clock Mode – Current ADAT, SPDIF 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, e.g. when the inputs and outputs of a DAT machine are connected directly to
the Hammerfall DSP
, AutoSync may cause feedback in the digital carrier, so synchronization
breaks down. To solve this problem switch the HDSP clock mode to Master (Clock Mode - In-
ternal).
The HDSP ADAT and SPDIF input operate simultaneously. Because there is no input selector
however, the HDSP has to be told which of the signals is the sync reference (a digital device
can only be clocked from a single source). By selecting a Clock Source a preferred input is de-
fined. As long as the unit sees a valid signal there, this input will be designated as the sync
source.
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 SPDIF 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 SPDIF.
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, SPDIF), or if there is a valid and synchronous signal (Sync). In the
field Clock Mode the clock reference is shown. See chapter 30.1.
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.