10
User's Guide ADI-648 © RME
7. The ADAT to MADI Converter
7.1 General
This part of the ADI-648 converts ADAT optical to MADI. ADAT optical carries 8 channels of 24
bit audio at up to 48 kHz sample rate, and 4 channels at up to 96 kHz. Transmission is done via
a single optical line (TOSLINK). The length of the optical cable is limited to about 10 m.
Because the
Sample Split
(S/MUX) format doesn't contain a coding, the ADI-648 cannot distin-
guish it from normal (44.1/48 kHz) material. Whether the MADI output is supposed to work in
96K Frame mode has to be set explicitly by the user.
The inputs can be used in any combination, e. g. it is sufficient to connect an input signal only
to input 3. In slave mode, this input is automatically being used as clock source. If more than
one signal is present, the one furthest left is being used as clock source, i. e. the active input
with the lowest number.
The 8 ADAT optical inputs are transferred to a 64-channel MADI output. Furthermore, the ADI-
648 contains an easy-configurable 8-channel 16x16
Matrix Router
. Any of the outputs, which
are divided into 8-channel blocks, can be fed from any 8-channel input block, both on the
ADAT and the MADI side. With this, there is not only free routing within the ADAT to MADI
conversion, but also splitting and routing within the same format.
7.2 Inputs
The ADAT optical inputs of the ADI-648 are 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.
ADAT input 8 is used to switch the MADI output format from 56-channel to 64-channel mode.
When ADAT input 8 does not receive a valid input signal, the ADI-648 generates a 56-
channel MADI signal. When feeding a valid input signal, a 64-channel MADI signal will be
generated.
This rule is also true when 96K Frame mode is active. Then 28 or 32 channels will be available.
7.3 Input State Display
The input state is being displayed by means of 16 LEDs. A missing or invalid input signal is
indicated by flashing of the SYNC LED. When using multiple inputs in clock mode ADAT
INPUT, the input with the lowest number is being used as clock source. In case ADAT is not
chosen as clock reference, SyncCheck takes the chosen clock (internal, external, MADI) as
reference and compares it to the clocks of the inputs. Non synchronous inputs will be indicated
by flashing of the corresponding SYNC LED. A missing or invalid input signal will be displayed
by blinking of the ADAT INPUT CLOCK LED.
Audio data present in the input channels are signalled by a AUDIO LED per input. As the ADI-
648 operates in 8-channel blocks, an AUDIO LED will show audio data from 8 channels simul-
taneously. The green LED is lit as soon as one of the channels of an 8-channel block contains
audio data, that is no longer digital zero.
