User`s guide

16
User's Guide Fireface 400 © RME
7.4 Settings Dialog - LTC
The Fireface 400 can extract position information as APP (ASIO Positioning Protocol) from
Timecode (LTC, SMPTE) received at the analog input 4.
A detected Timecode is shown as time information in the LTC In field. The analog input signal
needs a specific level: slowly reduce the level until the display stumbles or completely fails.
Then increase the level by about 10 dB.
The field Input State will show further details of the Timecode.
Basically Timecode can also be used as clock source. However, the calculation of the position
information is less precise then. Recommended is a clocking of the Fireface 400 with a clock
signal (for example Word) directly from the device that sends the Timecode.
7.5 Clock Modes - Synchronization
In the digital world, all devices must be either Master (clock source) or Slave synchronized to a
master. Whenever several devices are linked, there must always be a single master clock.
Remember that 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 400 uses a very user-friendly, intelligent clock control, called AutoSync. In Auto-
Sync mode, the system constantly scans all digital inputs 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 ADAT etc). The difference to a usual
slave mode is that whenever the clock reference fails, the system will automatically use its in-
ternal clock and operate in Master mode.
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 Fireface 400, AutoSync may cause feedback in the digital carrier, so synchronization breaks
down. Remedy: switch the Fireface clock mode to Master (Clock Source – Internal).
The Fireface 400 ADAT and SPDIF inputs operate simultaneously. Because there is no input
selector, the unit has to be told which one of the signals is the sync reference (a digital device
can only be clocked from a single source). The Clock Source selection is used to define a pre-
ferred input for the automatic clock system. This input will stay active as long as a valid signal is
found.
To cope with some situations which may arise in studio practice, defining a sync reference is
essential. One 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 corrupted, because the signal from the CD player is read with the
(wrong) clock from the ADAT i.e. out of sync. In this case, the Clock Source should be set tem-
porarily to SPDIF.
RME’s exclusive SyncCheck technology (first implemented in the Hammerfall) enables an easy
to use check and display of the current clock status. Input Status indicates whether there is a
valid signal (Lock, No Lock) for each input (Word Clock, ADAT, SPDIF and LTC), or if there is a
valid and synchronous signal (Sync). In the field Clock Mode the clock reference is shown (Cur-
rent…). See chapter 30.1.