RME Audio Hammerfall HDSP 9632 User Manual page 20

Via Pref. Sync Ref (preferred synchronization reference) a preferred input can be defined. As
long as the card sees a valid signal there, this input will be designated as the sync source, oth-
erwise the other inputs will be scanned in turn. If none of the inputs are receiving a valid signal,
the card automatically switches clock mode to 'Master'.
To cope with some situations which may arise in studio practice, setting 'Pref Sync Ref' is es-
sential. One example: An ADAT recorder is connected to the ADAT input (ADAT immediately
becomes the sync 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, 'Pref Sync Ref' should be temporarily
set to SPDIF.
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 technology (first implemented in the Hammerfall) enables an easy
to use check and display of the current clock status. The 'SyncCheck' field indicates whether no
signal ('No Lock'), a valid signal ('Lock') or a valid and synchronous signal ('Sync') is present at
each of the digital clock source inputs. The 'AutoSync Ref' display shows the current sync
source and the measured frequency.
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.
Thanks to its AutoSync technique and lightning fast PLLs, the HDSP is not only capable of han-
dling standard frequencies, but also any sample rate between 28 and 200 kHz. Even the word
clock input, which most users will use in varispeed operation, allows any frequency between 28
kHz and 200 kHz.
At 88.2 or 96 kHz: If one of the ADAT inputs has been selected in Pref Sync Ref, the sample
frequency shown in the field SPDIF Freq. differs from the one shown in AutoSync Ref. The card
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 in-
ternal frequency stays at 44.1 or 48 kHz. In such cases, the ADAT sample frequency is only half
the SPDIF frequency.
User's Guide HDSP System HDSP 9632 © RME
20