Digital Clocking Considerations In The Studio; Using The S/Pdif Output To Record Two Signals - Solid State Logic XLogic Alpha Channel Manual

Digital clocking considerations in the studio

Digital clocking considerations in the studio Digital clocking considerations in the studio Digital clocking considerations in the studio
Please note that in order to use the S/PDIF output reliably, all digital devices in your studio should be
synchronised from the same clock source. The Alpha Channel will presume it is the master sync source
unless a S/PDIF signal is connected to it's S/PDIF input. If presented with a S/PDIF signal in this manner
then the Alpha Channel will automatically slave to this clock source.
- If nothing is connected to the S/PDIF input then the Alpha Channel as the master
sync source will output a clock of 44.1kHz. In this case all other devices should be set
to sync from their digital inputs and hence the Alpha Channel should act as the sync
reference for these devices.
If the Alpha Channel receives a sync reference it will lock to the incoming sync fre-
quency* and its sync output will follow the input sync's reference frequency.
* (tested sync freq range 32Khz-108Khz)

Using the S/PDIF output to record two signals

Using the S/PDIF output to record two signals Using the S/PDIF output to record two signals Using the S/PDIF output to record two signals
The Alpha Channel utilises the stereo S/PDIF output in a very useful way. The left hand side of the S/
PDIF output will carry the same signal (after A/D conversion) as appears at the Analogue output. This
means that if you select the left hand side of the S/PDIF input of the audio interface in your DAW then
you will record exactly what you are hearing.
However, if you select the right input of your audio interface, the signal that comes from the Alpha
Channel is taken from the pre-insert, post filters point. This means it will have no EQ, insert or limiter
effects. It is also 12db below the left hand side because that allows enough headroom for the signal to
avoid clipping the converter.
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By creating two mono audio tracks and selecting the left S/PDIF input for one
and the right input for the other you can record both these signals simultane-
ously.
The decision over which track to use can then be made later on in the recording
process.
By taking the right hand side of the S/DPIF signal you are provided with a
slightly cleaner, unprocessed version of the source signal.
This signal is 12db below the left hand side signal, but when recording at 24bit
this is an acceptable recording level with enough headroom for peaks.