RME Audio Fireface 400, Руководство пользователя, Страница: 46 / 100

46
User's Guide Fireface 400
© RME
If several digital devices are to be used simultaneously in a system, they not only have to oper-
ate with the same sample frequency but also be synchronous with each other. This is why digi-
tal systems always need a single device defined as ‘master’, which sends the same clock signal
to all the other (‘slave’) devices.
RME’s exclusive
SyncCheck technol-
ogy enables an easy to use check and
display of the current 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). The AutoSync Ref display
shows the input and frequency of the
current sync source (see chapter
37.1).
In practice, SyncCheck provides the
user with an easy way of checking
whether all digital devices 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.
Thanks to its AutoSync technique and
lightning fast PLLs, the Fireface 400 is
not only capable of handling standard
frequencies, but also any sample rate
between 28 and 200 kHz. Even the
word clock input, most often used in
varispeed operation, allows any fre-
quency between 28 kHz and 200 kHz.
At 88.2 or 96 kHz: If the ADAT input
has been selected in
Pref Sync Ref , the sample frequency shown in the SPDIF Freq. field dif-
fers from the one shown in AutoSync Ref . The unit automatically switches to S/MUX mode
here, because ADAT optical inputs and outputs are only specified up to 48 kHz. Data from/to a
single input/output is spread over two channels, the internal frequency stays at 44.1 or 48 kHz.
In such cases, the ADAT sample frequency is only half the SPDIF frequency.
22.4 Limit Bandwidth
This option allows to reduce the amount of bandwidth used on the FireWire bus. A typical ex-
ample is the use of the Fireface with a laptop. Only in rare cases both ADAT ports are needed,
in many cases even both stay unused. The option
SPDIF will reduce the amount of
constantly (!) transferred data from around 3 MByte (6 in both directions) to only 1.7 MByte (3.4
in both directions). The FireWire connection will be more stable, reliable and robust, leaving
additional bandwidth for other devices. At the same time the CPU and system load is reduced,
as less channels have to be processed and to be transferred. In TotalMix, the deactivated soft-
ware playback channels will be replaced with empty plates. More details are found in chapter
37.4.
Available Settings
All channels (default) activates all 18 input and output channels.
SPDIF activates all 10 analog channels plus SPDIF.
Analog 1-8 activates only the first eight analog channels.