Sync Source; Input Channel Selection; Analogue Line-Up Nomenclature With Pro Tools; System Interconnection Examples - Prism Sound ADA-8XR Module Reference

Prism Sound ADA-8XR Multi-channel A/D D/A Converter Module Reference - Revision 1.01
normally set to '=Ext', and automatically follow the rate of their Sync Source (i.e. the Pro
Tools bus). Typically, only the record path (usually Path 1) of the Master converter has its
sample rate set explicitly, with all other Paths in the system being set to follow it with '=Ext'.
If a USD or other external reference sync is in use, even the Master converter may be set to
'=Ext'.

6.8.2 Sync Source

Pro Tools can set the Sync Source of the Master converter to either 'Internal' or 'Digital'. In
ADA-8XR terms, these correspond to 'Local' and 'DI' respectively, where 'DI' is a digital I/O
module (e.g. AES3). If no appropriate digital I/O module is fitted, selection of 'Digital' sync
from Pro Tools will not cause any change. Changes to the Sync Source will only take effect if
the sample rate for that Path is not set to '=Ext', i.e. if the unit is the Master converter.

6.8.3 Input Channel Selection

The Hardware Setup dialogue in Pro Tools can be used to select the source of each input
channel pair as either analogue or digital. Obviously, this feature only applies to ADA-8XRs
that have an appropriate digital I/O module fitted (e.g. AES3). Perhaps not so obvious is that
the DIO slots from which the user wishes to make his selection must all be selected as input
ports in the Source Port menu (see the Firmware Reference). The Hardware Setup dialogue
is essentially changing the settings of the ADA-8XR's Input Channels menu, so remote
control of input channel selection will only work if Input Selection Mode is set to 'Channel'
rather than 'Path'. Also, this remote control feature will not work if the Input Channels menu
has 'All' selected. The Factory Default Stores for Pro Tools, described above, automatically
ensure that these conditions are met.
The ADA-8XR allows greater flexibility in the selection of inputs from its front panel than is
possible from Pro Tools - the front panel may be used to select any number of input modules
of either analogue or digital format provided that the appropriate modules are fitted. The Pro
Tools software only allows selection between one analogue module and one digital module
for each input pair. If more than one of each is selected in the Source Port menu, Pro Tools
can switch each input pair between the first analogue module and the first digital module only.
Also, the ADA-8XR front panel can select the source of all eight inputs to a path individually,
whereas the Pro Tools software can only select by channel pair.

6.9 Analogue Line-Up Nomenclature with Pro Tools

Some confusion may result from the different nomenclatures used in the ADA-8XR and Pro
Tools systems for expressing analogue line-up levels.
Pro Tools sets its analogue line-up by reference to 'headroom' above a nominal operating
level of 0VU (+4dBu). The ADA-8XR's line-up is specified in terms of the dBu equivalent of
full-scale digital (0dBFS). So, for example, to set a line-up on the ADA-8XR equivalent to
'14dB' in Pro Tools nomenclature, it is necessary to set 18dBu on the ADA-8XR (+4dBu +
14dB).

6.10 System Interconnection Examples

Connecting ADA-8XRs to Pro Tools couldn't be simpler, since they generally only require the
data cable to be connected (no Superclock or Wordclock is required). The exception to this is
where a USD is in use, in which case a Wordclock must be run from the USD's Wordclock
output to the Master ADA-8XR's Wordclock input.
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