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Application examples<br />
DDS allows for a simultaneous change of speed and tune during record and playback. From<br />
alignment to other sources up to creative effects – everything is possible..<br />
DDS allows to intentionally de-tune the complete DAW. This way, the DAW can match instruments<br />
which have a wrong or unchangeable tuning.<br />
DDS allows to define a specific sample rate. This feature can be is useful in case the system<br />
randomly changes the sample rate – for unknown reasons. It also prevents a change from<br />
Double Speed (96 kHz) to Single Speed (48 kHz), which would cause configuration and routing<br />
problems by the changed amount of ADAT channels.<br />
11.3 Clock Modes - Synchronisation<br />
In the digital world, all devices are either the ‘Master’ (clock source) or a ‘Slave’ synchronized<br />
to the master. Whenever several devices are linked within a system, there must always be a<br />
single master clock. The Hammerfall <strong>DSP</strong>’s intelligent clock control is very user-friendly, being<br />
able to switch between clock modes automatically. Selecting AutoSync will activate this mode.<br />
In AutoSync mode, the system<br />
constantly scans all digital inputs<br />
for a valid signal. If this signal<br />
corresponds with the current<br />
playback sample rate, the card<br />
switches from the internal quartz<br />
(AutoSync Ref displays 'Master')<br />
to a clock generated from the<br />
input signal (AutoSync Ref displays<br />
'Slave'). This allows on-thefly<br />
recording, even during playback,<br />
without having to synchronize<br />
the card to the input signal<br />
first. It also allows immediate<br />
playback at any sample rate<br />
without having to reconfigure the<br />
card.<br />
AutoSync guarantees that normal<br />
record and record-while-play will<br />
always work correctly. In certain<br />
cases however, e.g. when the inputs and outputs of a DAT machine are connected directly to<br />
the Hammerfall <strong>DSP</strong>, AutoSync may cause feedback in the digital carrier, so synchronization<br />
breaks down. To remedy this, switch the H<strong>DSP</strong>’s clock mode over to 'Master'.<br />
Remember that a digital system can only have one master! If the H<strong>DSP</strong>’s clock mode is set<br />
to 'Master', all other devices must be set to ‘Slave’.<br />
The Hammerfall <strong>DSP</strong>'s ADAT optical input and the SPDIF input operate simultaneously. Because<br />
there is no input selector however, the H<strong>DSP</strong> has to be told which of the signals is the<br />
sync reference (a digital device can only be clocked from a single source). This is why the system<br />
has been equipped with automatic clock source selection, which adopts the first available<br />
input with a valid digital signal as the clock reference input. The input currently used as sync<br />
reference is shown in the AutoSync Ref status field, together with its sample frequency.<br />
User's Guide H<strong>DSP</strong> <strong>System</strong> H<strong>DSP</strong> <strong>9632</strong> © <strong>RME</strong> 17