Rear Panel Controls
EXT SYNC Switch
Pressing “In” the EXT SYNC switch forces the 8 OctoPre
analogue to digital converters to synchronise to the clock
signal connected to the rear panel BNC style connector.
Note: When using an external clock source always select
the front panel frequency switch to match the sample rate
of the incoming signal. Without this the unit cannot lock to
the external clock signal.
*AES/SPDIF Switch
When the switch is in the “In” position the digital signals
present at the 9 pin D Type connector conform to the
“Professional” AES digital format standard. When the
switch is in the “Out” position the digital signals present at
the 9 pin D Type connector conform to the “Consumer”
SPDIF digital format standard.
Front Panel Controls
When the digital interface card is fitted into the OctoPre,
the Frequency Select and Dither switches and indicators
become active.
Frequency Select
Pressing the SELECT switch increments the converter
sample frequency from 44.1KHz through to 96KHz, when
either 88.2KHz and 96KHz is selected the operation of the
ADAT™ sockets automatically switch to the S/MUX
2
operation.
Dither
Pressing the DITHER switch selects the digital output
word length to either 24, 20 or 16 bit, this is achieved by
dithering the converted signal and truncating the unused
bits.
Lock Indicator
The lock indicator is lit when the rear panel EXT SYNC
switch is pressed in and the unit is synchronised to the
incoming signal connected to the BNC connector.
Note: In case of discontinuity in the external clock
connection or extreme variation in external clock
frequency the OctoPre Lock indicator may switch off
indicating the unit has lost lock. To recover lock in this
situation, re-select the correct sample frequency from the
OctoPre front panel.
Audio Operation
The signal which is converted to digital is taken just before
the analogue output where 0dBfs (the maximum level
before digital overload) is equivalent to a 21dBu level at
the analogue output. The maximum analogue level can be
prevented from exceeding 0dBFs by using the channel
dynamics controls - see the OctoPre user guide for full
instructions.
www.focusrite.com
