User Manual

User's Guide HDSP System HDSP 9652 © 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 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 Reference 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.

An example to illustrate this: The

ADAT1 and ADAT2 inputs are

receiving signals from a digital

mixing desk that has been set to

clock mode 'Internal' or 'Master'.

An ADAT recorder is connected

to the ADAT3 input. The Ham-

merfall DSP is set to AutoSync

mode. As expected, SyncCheck

shows that the ADAT1 and

ADAT2 inputs are in sync (as

they are driven by the same

clock from the mixing desk), but

shows ‘Lock’ instead of 'Sync' for the ADAT3 input. Because the ADAT recorder is not receiving

any signals from HDSP or from the mixer, it will generate its own clock at a rate which is (al-

most) the same as the sample frequency of the mixing desk - but not identical.

Remedy: To drive the ADAT recorder from its digital input, set it to slave mode (DIG), and con-

nect the input to the HDSP’s ADAT3 output. The Hammerfall DSP is already in sync with the

mixing desk, so it will send an identical (synchronous) signal to ADAT3 out. The ADAT recorder

will lock onto this, its output will also be in sync. The signal from the ADAT recorder is now fully

in sync with the signals from the mixing desk.

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 103 kHz. Even the word

clock input, which most users will use in varispeed operation, allows any frequency between 28

kHz and 103 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

internal frequency stays at 44.1 or 48 kHz. In such cases, the ADAT sample frequency is only

half the SPDIF frequency.