Installation guide

Chapter 4: Connecting Your Studio 27
The 882/20 I/O Interface
This section explains all of the connectors and
indicators on the front and back panels of the
882/20 I/O interface, how they are used, and of-
fers suggestions for connecting the 882/20 I/O
to your studio.
882/20 I/O Interface Front Panel
The 882/20 I/O has the following front panel in-
dicators, moving from left to right:
Power
This switch applies power to the 882/20. The “I”
position is on. The “O” position is off.
Sync Mode
The Sync Mode LEDs indicate which sample rate
clock reference is currently used by the analog-
to-digital converters (ADCs) and the digital-to-
analog converters (DACs).
Internal This is the 882/20 I/O standard setting.
In this mode, the 882/20 I/O sample rate is gen-
erated by its internal crystal oscillator (whose
frequency is determined by the Sample Rate set-
ting in the Session Setup window). Internal
mode should be active whenever the 882/20 I/O
is not synchronized to an external clock source.
Digital This setting indicates that a S/PDIF word
clock signal is the source for the 882/20 I/O
sample rate. This is the setting you would use for
inputting material from DAT machines or other
S/PDIF digital devices.
To use the 882/20 I/O digital input and output
as an effects send and return to a digital effects
device, you should set the 882/20 I/O to Inter-
nal mode. You should then set the digital effects
device to accept an external digital clock (from
the 882/20 I/O) so it synchronizes with
Pro Tools.
In an expanded system, the system clock is car-
ried by the audio interface connected to the first
Pro Tools card in your system. This audio inter-
face will act as the master interface in your sys-
tem, and all other audio interfaces will be slaved
to it. Only the master interface allows you to set
the Sync Mode. Slaved interfaces do not allow
this parameter selection.
Slave This LED is lit when the 882/20 I/O sam-
ple rate is synchronized to another Digidesign
audio interface or synchronization peripheral.
In this mode, the sample rate of the slave inter-
face is derived from the frequency of the incom-
ing master clock signal present at the Slave
Clock In (256x) port. The 882/20 I/O automati-
cally switches to this mode when a Slave Clock
Out signal from another Digidesign interface,
Universal Slave Driver, Video Slave Driver, or
SMPTE Slave Driver is connected to its Slave
Clock In port.
Front panel of the Digidesign 882/20 I/O
20
Signal
Present
LEDs
Sync Mode
Power
Sample
Rate
Ch 1–2
Input
Because some digital audio devices do not
output proper clock when they are not play-
ing back, leaving the 882/20 I/O in Digital
mode may cause Pro Tools audio playback
quality to suffer, or to play back at the
wrong pitch. If you are using digital I/O, re-
set the Sync Mode from Digital to Internal
after inputting material.
TDM_Install.book Page 27 Saturday, January 13, 2001 9:35 PM