Digital Connections; Adat; Spdif - RME Audio Fireface 400 User Manual

28. Digital Connections

28.1 ADAT

The ADAT optical input of the Fireface 400 is fully compatible with all ADAT optical outputs.
RME's unsurpassed Bitclock PLL prevents clicks and drop outs even in extreme varipitch op-
eration, and guarantees a fast and low jitter lock to the digital input signal. A usual TOSLINK
cable is sufficient for connection. More information on Double Speed (S/MUX) can be found in
chapter 35.5.
ADAT In
Interface for a device sending an ADAT signal to the Fireface 400. Carries the channels 1 to 8.
When receiving a Double Speed signal, this input carries the channels 1 to 4.
ADAT Out
Interface for a device receiving an ADAT signal from the Fireface 400. Transmits channels 1 to
8. When sending a Double Speed signal, this port carries channels 1 to 4.
Note: The optical output can only be used as ADAT output when SPDIF Out – Optical is not
checked in the Settings dialog.

28.2 SPDIF

The SPDIF input is configured in the Settings dialog. The Fireface 400 accepts all commonly
used digital sources as well as SPDIF and AES/EBU.
To receive signals in AES/EBU format,
an adapter cable is required. Pins 2 and
3 of a female XLR plug are connected
individually to the two pins of a phono
plug. The cable shielding is connected
to pin 1 of the XLR and the ground
contact of the phono plug.
In SPDIF mode, identical signals are available at both the optical and the coaxial output. An
obvious use for this would be to connect two devices, i.e. using the Fireface 400 as a splitter
(distribution 1 on 2).
Special Characteristics of the SPDIF Output
Apart from the audio data itself, digital signals in SPDIF or AES/EBU format have a header con-
taining channel status information. False channel status is a common cause of malfunction. The
Fireface 400 ignores the received header and creates a totally new one for the output signal.
Note that in record or monitor modes, set emphasis bits will disappear. Recordings origi-
nally done with emphasis should always be played back with the emphasis bit set!
This can be done by selecting the Emphasis switch in the Settings dialog (SPDIF Out). This
setting is updated immediately, even during playback.
Note: Recordings with (pre-) emphasis show a treble boost (50/15 µs), which has to be com-
pensated at playback. Therefore, when selecting Emphasis all analog outputs will be processed
by a treble filter based on 50/15µs, which sounds like a high cut.
User's Guide Fireface 400 © RME
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