Installation guide

Chapter 4: Connecting Your Studio 33
Slave This LED is lit when the 1622 I/O is syn-
chronized to another Digidesign audio interface
or synchronization peripheral. In this mode, the
sample rate of the slave interface is derived from
the frequency of the incoming master clock sig-
nal present at the Slave Clock In (256x) port. If
the Sync Mode is set to Internal, connecting a
Slave Clock Out signal from another Digidesign
interface or synchronization peripheral to the
1622 I/O Slave Clock In port will automatically
switch it to Slave mode.
In expanded Pro Tools systems, the Super Clock
output of the master audio interface locks all
other interfaces together with sample accuracy,
keeping all signals phase-synchronous.
Ch 1–2 Input
This LED indicates the format (analog or digital)
of the audio input signal to channels 1–2. In
Pro Tools, you choose analog or digital input for
these two channels in the Session Setup window
or the Hardware Setup dialog. Input channels 3
through 16 of the 1622 I/O are always analog.
Sample Rate
These LEDs display the current sample rate of
the 1622 I/O internal crystal oscillator, which
can be either 44.1 kHz or 48 kHz. In Pro Tools,
this is set in the Session Setup window or in the
Hardware Setup dialog.
The 1622 I/O provides the following sample
rates:
48 kHz This is a standard sampling rate of many
professional audio devices. It is recommended
for use with devices that cannot receive digital
transfers at 44.1 kHz.
44.1 kHz This is the compact disc standard sam-
pling rate and the Pro Tools default sample rate.
To avoid the need for sample rate conversion,
you should use this rate when you are recording
material that will ultimately be published on a
compact disc.
Input Meters
These LEDs indicate whether signal is present at
a given channel’s input. Segment 1 (green) indi-
cates –20.0 dB. Segment 2 (yellow) indicates
–3.0 dB. Segment 3 (red) indicates –0.1 dB.
Output Meters
These LEDs indicate whether signal is present at
one of the two outputs. Segment 1 (green) indi-
cates –20.0 dB. Segment 2 (yellow) indicates
–3.0 dB. Segment 3 (red) indicates –0.1 dB.
Channel 15–16 Direct Inputs
These are balanced, 1/4-inch TRS jacks for con-
venient front panel audio input connections.
Inputs can be individually calibrated from
+4 dBu to –10 dBV line levels and higher in 2 dB
gain steps, using the Other Options dialog
(choose Setups > Hardware and click Other Op-
tions). This allows the 1622 I/O to accommo-
date any standard line-level input, including
When slaving to a Digidesign Universal
Slave Driver, Video Slave Driver, or SMPTE
Slave Driver, set the clock source to Internal.
The audio interface will automatically
switch to Slave mode when it detects the
256x input clock.
When you are using an external digital
source such as a DAT recorder, the front
panel of the 1622 I/O indicates only the in-
ternal oscillator sample rate, not that of the
external digital source.
TDM_Install.book Page 33 Saturday, January 13, 2001 9:35 PM