DigiDesign 192 I User manual

192 I/O
™

Legal Notices
This guide is copyrighted ©2007 by Digidesign, a division of
Avid Technology, Inc. (hereafter “Digidesign”), with all rights
reserved. Under copyright laws, this guide may not be
duplicated in whole or in part without the written consent of
Digidesign.
003, 003 Rack, 96 I/O, 96i I/O, 192 Digital I/O, 192 I/O,
888|24 I/O, 882|20 I/O, 1622 I/O, 24-Bit ADAT Bridge I/O,
AudioSuite, Avid, Avid DNA, Avid Mojo, Avid Unity, Avid Unity
ISIS, Avid Unity MediaNetwork, Avid Xpress, AVoption,
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Audio Engine, Digidesign Intelligent Noise Reduction,
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DigiTranslator, DINR, DV Toolkit, EditPack, Impact, Interplay,
M-Audio, MachineControl, Maxim, Mbox, MediaComposer,
MIDI I/O, MIX, MultiShell, OMF, OMF Interchange, PRE,
ProControl, Pro Tools M-Powered, Pro Tools, Pro Tools|HD,
Pro Tools LE, QuickPunch, Reel Tape, Reso, Reverb One,
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Velvet, and X-Form are trademarks or registered trademarks of
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are the property of their respective owners.
Product features, specifications, system requirements, and
availability are subject to change without notice.
PN 9106-58405-00 REV A 10/07
Comments or suggestions regarding our documentation?
email: [email protected]
Warning
This product contains chemicals, including lead, known to the
State of California to cause cancer and birth defects or other
reproductive harm. Wash hands after handling.
Communications & Safety Regulation Information
Compliance Statement
The model 192 I/O complies with the following standards
regulating interference and EMC:
• FCC Part 15 Class A
• EN55103 – 1, environment E4
• EN55103 – 2, environment E4
• AS/NZS 3548 Class A
Radio and Television Interference
This equipment has been tested and found to comply with the
limits for a Class A digital device, pursuant to Part 15 of the
FCC Rules.
Communications Statement
This equipment has been tested to comply with the limits for a
Class A digital device. Changes or modifications to this
192 I/O not authorized by Digidesign, Inc., could void the
Certification and negate your authority to operate the 192 I/O.
This 192 I/O was tested for CISPR compliance under
conditions that included the use of peripheral devices and
shielded cables and connectors between system components.
Digidesign recommends the use of shielded cables and
connectors between system components to reduce the
possibility of causing interference to radios, television sets,
and other electronic devices.
Safety Statement
This equipment has been tested to comply with USA and
Canadian safety certification in accordance with the
specifications of UL Standards; UL1419 and Canadian CSA
standard; CSA C22.2 No.1-M90. Digidesign Inc., has been
authorized to apply the appropriate UL & CUL mark on its
compliant equipment.

Important Safety Instructions
When using electric or electronic equipment, basic precautions
should always be followed, including the following:
• Read all instructions before using this equipment.
• To avoid the risk of shock, keep this equipment away from
rain water, and other moisture. Do not use this equipment
if it is wet.
• The equipment should only be connected to the correct
rating power supply as indicated on the 192 I/O.
• Do not attempt to service the equipment. There are no
user-serviceable parts inside. Please refer all servicing to
authorized Digidesign personnel.
• Any attempt to service the equipment will expose you to a
risk of electric shock, and will void the manufacturer’s
warranty.
Warning!
• HD audio interfaces need room at their sides to maintain
proper air flow and cooling.
• Do not install these units into a rack or other enclosure that
doesn't leave room on either side for the unit fans.
• Do not block the sides of the units (where fans are), or
disconnect the fan.
• If the units are racked up in a case, remove all lids, doors,
or covers before operating the units.
• Failure to do so can result in the units overheating very
quickly, which can permanently damage them.
Disposal of Waste Equipment by Users in the
European Union
This symbol on the product or its packaging indicates that this
product must not be disposed of with other waste. Instead, it
is your responsibility to dispose of your waste equipment by
handing it over to a designated collection point for the recycling
of waste electrical and electronic equipment. The separate
collection and recycling of your waste equipment at the time of
disposal will help conserve natural resources and ensure that
it is recycled in a manner that protects human health and the
environment. For more information about where you can drop
off your waste equipment for recycling, please contact your
local city recycling office or the dealer from whom you
purchased the produ

Contents v
contents
Chapter 1. Introduction to the 192 I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
What’s Included . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
About This Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
About www.digidesign.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Chapter 2. 192 I/O Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
192 I/O Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
192 I/O Back Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Using Input and Output Trims . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Appendix A. Adding or Removing I/O Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Installing an I/O Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Removing an I/O Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Appendix B. Pinout Diagrams for the DB-25 Connectors . . . . . . . . . . . . . . . . . . . . . . . . 19
Analog Output DB-25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Analog Input (+4 dBu) DB-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Analog Input (–10dB(V)) DB-25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
AES/EBU DB-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
TDIF DB-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Appendix C. 192 I/O Calibration Mode Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
About Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Calibrating the 192 I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

192 I/O Guidevi

Chapter 1: Introduction to the 192 I/O 1
chapter 1
Introduction to the 192 I/O
The Digidesign 192 I/O™ 16-channel digital au-
dio interface is for use in a Pro Tools|HD system
and features 24-bit analog-to-digital (A/D) and
digital-to-analog (D/A) converters. The 192 I/O
supports sample rates of up to 192 kHz for supe-
rior dynamic range and low noise floor.
192 I/O Features
• 16 discrete channels of input and output,
with 4-segment LED Meters to monitor input
and output on each channel. Input and Out-
put channels can include:
• Eight channels of 24-bit D/A and A/D con-
verters for superior analog input and out-
put at sample rates of 44.1 kHz, 48 kHz,
88.2 kHz, 96 kHz, 176.4 kHz, and 192 kHz
• Ten channels of 24-bit-supported AES/EBU
I/O. Eight-channel AES/EBU I/O supports
sample rates of up to 96 kHz on all chan-
nels, and of up to 192 kHz on four chan-
nels simultaneously. Two-channel AES-
EBU I/O supports sample rates of up to
96 kHz.
• Sixteen channels of Optical I/O, through
two pairs of Lightpipe (ADAT) connectors;
one pair of optical ports can be switched to
two channels of optical S/PDIF I/O
• Two 24-bit-capable S/PDIF I/O supporting
sample rates of up to 96 kHz
• Real-time sample rate conversion on inputs of
eight channels of either AES/EBU, Optical, or
TDIF.
• External Clock input and output for synchro-
nizing 192 I/O with external 1x Word Clock
or 256x (Slave Clock) devices.
• Legacy Port for Digidesign-qualified
Pro Tools|24 MIX audio interfaces.
• Optional addition of cards to expand analog
or digital I/O.
• Simultaneous use of multiple Pro Tools|HD
audio interfaces to further expand system in-
put and output. For more information see the
Expanded Systems Guide.
What’s Included
•192I/O
•ACpowercable
• DigiLink cable (1.5ft. [0.46m])
• BNC cable (1.5ft. [0.46m])
• Digidesign Registration Information Card

192 I/O Guide2
System Requirements
The Digidesign 192 I/O requires a Digidesign-
qualified Pro Tools|HD system.
Compatibility Information
Digidesign can only assure compatibility and
provide support for hardware and software it has
tested and approved. For a list of Digidesign-
qualified computers, operating systems, hard
drives, and third-party devices, refer to the
Digidesign Web site (www.digidesign.com).
About This Guide
This guide provides a hardware overview of the
192 I/O.
Complete instructions for connecting and con-
figuring the 192 I/O for your Pro Tools|HD sys-
tem are located in the Pro Tools|HD Getting
Started Guide. For additional information about
using Pro Tools software to route your interface
inputs and outputs to Pro Tools inputs and out-
puts, see the Pro Tools Reference Guide.
Conventions Used in This Guide
Digidesign guides use the following conven-
tions to indicate menu choices and key com-
mands:
:
The following symbols are used to highlight im-
portant information:
Convention Action
File > Save Choose Save from the File
menu
Control+N Hold down the Control key
and press the Nkey
Control-click Hold down the Control key
and click the mouse button
Right-click Click with the right mouse
button
User Tips are helpful hints for getting the
most from your system.
Important Notices include information that
could affect your data or the performance of
your system.
Shortcuts show you useful keyboard or
mouse shortcuts.
Cross References point to related sections in
this guide and other Digidesign guides.

Chapter 1: Introduction to the 192 I/O 3
About www.digidesign.com
The Digidesign website (www.digidesign.com)
is your best source for information to help you
get the most out of your Pro Tools system. The
following are just a few of the services and fea-
tures available.
Product Registration Register your purchase on-
line. See the enclosed Digidesign Registration
Information Card for instructions.
Support and Downloads Contact Digidesign
Technical Support or Customer Service; down-
load software updates and the latest online
manuals; browse the Compatibility documents
for system requirements; search the online An-
swerbase; join the worldwide Pro Tools commu-
nity on the Digidesign User Conference.
Training and Education Become a certified
Pro Tools Operator or Expert; study on your
own using courses available online, or find out
how you can learn in a classroom setting at a
certified Pro Tools Training Center.
Products and Developers Learn about Digidesign
products; download demo software; learn about
our Development Partners and their plug-ins,
applications, and hardware.
News and Events Get the latest news from Digi-
design; sign up for a Pro Tools demo.
To learn more about these and other resources
available from Digidesign, visit the Digidesign
website (www.digidesign.com).

192 I/O Guide4

Chapter 2: 192 I/O Overview 5
chapter 2
192 I/O Overview
This chapter describes the front and back panel features of the 192 I/O.
192 I/O Front Panel
Power Switch and LED Ring
This button turns the 192 I/O on and off.
The LED ring around the power button will light
green to indicate that the unit has powered up
successfully and is connected to an active
Pro Tools|HD system. If the LED ring is orange,
the unit has power, but the computer it is con-
nected to is shut down.
Sample Rate
These LEDs display the current sample rate of
the 192 I/O internal crystal oscillator: 44.1 kHz,
48 kHz, 88.2 kHz, 96 kHz, 176.4 kHz, or
192 kHz. The sample rate can be set in Pro Tools
when you create a new session, or in the Hard-
ware Setup or Playback Engine dialogs if no ses-
sion is open.
See the Pro Tools|HD Getting Started Guide for complete system installation and configuration instruc-
tions. If you are adding the 192 I/O to an existing system, see the Expanded Systems Guide.
192 I/O Front Panel

192 I/O Guide6
Loop Master LED
The LOOP MASTER LED indicates which
Pro Tools|HD audio interface is the master
Pro Tools peripheral. The Loop Master LED will
be continuously lit on the current Loop Master
peripheral only, and unlit on all other peripher-
als. (Only one Pro Tools|HD I/O can be Loop
Master at a time.) The Loop Master LED will al-
ways be lit with a single interface.
Loop Master defaults to the first Pro Tools|HD
peripheral connected to the primary, or “core”
Pro Tools|HD card. On Pro Tools|HD (for PCIe)
this is the Accel Core card. On Pro Tools|HD (for
PCI) this is the HD Core card.
Sync Mode LEDs
The SYNC MODE LEDs indicate the current
Clock Source as set in Pro Tools.
INT (Internal) Indicates the 192 I/O sample clock
is generated by its internal crystal oscillator, as
determined by the session Sample Rate.
DIG (Digital) Indicates that an external AES/EBU,
TDIF, Optical (ADAT), or S/PDIF device is pro-
viding system clock. If no valid clock source is
detected, 192 I/O will switch to INT, the DIG
LED will flash, and an error message will appear
on-screen in Pro Tools.
If at least two channels are not assigned from
the selected digital port in the Main page of the
Hardware Setup dialog, or if no valid clock
source is detected at this port, 192 I/O will
switch to INT and the DIG LED will flash.
LOOP (Loop Master) Indicates that the 192 I/O is
slaving to another Pro Tools|HD I/O through
Loop Sync. You do not set LOOP mode any-
where in the software. This is done automati-
cally when you choose another peripheral as
LOOP MASTER.
EXT (External) Indicates that the 192 I/O is us-
ing the EXT CLOCK IN port for system synchro-
nization.
External Clock input and output do not have to
be at the Word clock rate. EXT CLOCK IN syn-
chronization will typically be 1x the current ses-
sion sample rate. However, for sample rates
higher than 48 kHz, the 192 I/O will generate a
choice of 1x or a base rate of 44.1 kHz or 48 kHz,
depending upon the higher rate, as follows:
Meters
These four-segment LEDs indicate signal level
for each of the sixteen channels. The top row of
meters indicates input levels, and the bottom
row shows output levels. These meters are cali-
brated at –42 dB, –18 dB, –6 dB, and 0 dB, respec-
tively.
Session Sample Rate Word Clock Support
44.1 kHz 44.1 kHz
(or 256x out)
48 kHz 48 kHz
(or 256x out)
88.2 kHz 88.2 kHz
44.1 kHz
96 kHz 96 kHz
48 kHz
176.4 kHz 176.4 kHz
44.1 kHz
192 kHz 192 kHz
48 kHz
Note that 0 dB is not to be confused with
clipping; use the on-screen meters in
Pro Tools to determine whether a signal is
clipping. See the Pro Tools Reference Guide.

Chapter 2: 192 I/O Overview 7
192 I/O Back Panel
Although the 192 I/O is a 16-channel audio in-
terface, it has up to 50 inputs and outputs avail-
able through its various back panel connectors.
Input and Output Cards
The 192 I/O features four bays for I/O cards.
Bays 1–3 contain Analog In, Analog Out, and
Digital I/O cards, respectively. The fourth bay is
an expansion bay, for which you can purchase
an additional audio card of your choice.
Installing an optional A/D, D/A, or D/D card
provides even more I/O (up to a maximum pos-
sible 74 inputs and outputs). See Appendix A,
“Adding or Removing I/O Cards.”
Analog Input
This section contains connectors for analog au-
dio input with 24-bit, 192 kHz A/D converters.
Input is provided through two discrete DB–25
connectors. You can connect sources at both op-
erating levels and choose between them from
within Pro Tools. The two inputs are:
+4 dBu Balanced Provides eight balanced input
channels at +4 dBu nominal operating levels.
–10 dB(V) Balanced Provides eight balanced in-
put channels at –10 dB(V) nominal operating
levels.
For wiring information, see Appendix B, “Pi-
nout Diagrams for the DB-25 Connectors.”
For each channel, you can select input level and
Input Trim settings from within the Hardware
Setup dialog. (For instructions, see the
Pro Tools|HD Getting Started Guide.)
192 I/O back Panel
Bay 2: Analog Out Card
Bay 1: Analog In Card Bay 3: Digital I/O Card
Empty Bay for Optional Card
Enclosure

192 I/O Guide8
Input Trims
Two dedicated Input Trims per analog input
channel provide further calibration options and
flexibility. Depending on how you utilize the
two DB–25 input ports, you can use the A and B
trim settings for numerous applications. See “In-
put Trims” on page 11.
In addition, the soft-clip limiter function helps
avoid digital clipping. See “Input Trims” on
page 8, and “Soft Clip Limiting” on page 12.
Analog Output
This section contains a single DB–25 connector
and Output Trims for eight channels of analog
audio output. These balanced outputs operate at
+4 dBu levels. See Appendix B, “Pinout Dia-
grams for the DB-25 Connectors.”
Output Trims
The Output Trims below the DB–25 connector
are used to individually calibrate each channel’s
output level.
Two sets of Output Trims are provided for each
channel allowing you to store a second set of
headroom values. This allows you to match two
different headroom values for either input con-
nector. For more information, see “About Input
Operating Levels” on page 11.
Digital I/O
This section contains connectors for eight chan-
nels each of AES/EBU I/O, TDIF I/O, and Optical
(ADAT) I/O. Only one digital format can be used
at a time.
AES/EBU DB–25 connectors for eight channels
of AES/EBU input and output. Each of the paired
channels is a balanced three-conductor signal,
and supports 192 kHz sample rates in dual-wire
mode. Dual-wire mode uses two of 192 I/O’s
physical I/O channels of AES/EBU I/O to carry
each single stream of 192 kHz audio. Therefore,
only four simultaneous channels of AES/EBU
I/O are available at 192 kHz.
TDIF DB–25 connectors for eight channels of
TDIF input and output. Conforms to standard
eight-channel TDIF pinouts.
For more information, see Appendix B, “Pinout
Diagrams for the DB-25 Connectors.”
Optical (ADAT) Dedicated, eight-channel 24-bit
capable Optical port. Using real-time sample
rate conversion, these inputs will accept up to
48 kHz sample rates and convert them to a
Pro Tools session running at up to 192 kHz.
These outputs will only output at sample rates of
up to 48 kHz. Unlike the Optical port located on
the enclosure, this Optical (ADAT) port is not
switchable to Optical S/PDIF.
The inputs on the Digital I/O Card feature real-
time sample rate conversion. For example, you
can stream audio with a sample rate of 44.1 kHz
into a 96 kHz session.
For more information, see the Pro Tools|HD Get-
ting Started Guide.
For –10 dB(V) gear, a special DigiSnake ca-
ble (sold separately) is available. If you want
to make your own cable, be sure to use in-line
transformers or resistor networks to properly
pad the +4 dBu output to –10 dB(V) levels.
Most consumer electronics operate at
–10 dB(V) levels, and may not feature bal-
anced inputs and outputs. You can connect
–10 dB(V) signals to the –10 dB(V) inputs,
but you will need to make sure that the neg-
ative terminals are not connected.

Chapter 2: 192 I/O Overview 9
Enclosure Connectors
The right half of the back panel of 192 I/O fea-
tures a set of non-removable connectors that are
mounted to the enclosure.
These connectors feature two additional chan-
nels of AES/EBU I/O and another eight channels
of Optical I/O. These ports appear on-screen in
Pro Tools as AES/EBU [Encl], and
Optical (ADAT) [Encl]. The reference to the en-
closure [Encl] differentiates the chassis-
mounted ports from the I/O of the same types
on the Digital I/O Card.
Also mounted on the enclosure are two chan-
nels of S/PDIF I/O on RCA connectors, Loop
Sync, External Clock, and ports for attaching the
192 I/O to Pro Tools|HD cards and other audio
interfaces.
AES/EBU [Encl]
These are balanced, three-conductor XLR con-
nectors that accept and output a stereo, 24-bit
AES/EBU digital data stream. These two ports
support up to 96 kHz sample rates. The enclo-
sure ports do not support dual-wire mode (re-
quired for 176.4 kHz and higher sample rates),
or provide real-time sample rate conversion (use
the ports on the Digital I/O card for these fea-
tures).
S/PDIF Stereo I/O
These are unbalanced, two-conductor RCA jacks
that accept and output a stereo S/PDIF digital
data stream. S/PDIF supports up to 24-bit audio,
at sample rates up to 96 kHz.
Optical (ADAT) [Encl]
These are Optical ports that accept up to eight
channels of Optical (ADAT) input and output,
or two channels (stereo) optical S/PDIF input
and output. Optical (ADAT) mode supports sam-
ple rates up to 48 kHz. In TOS-Link mode, sup-
ports two-channel Optical input and output at
sample rates up to 96 kHz. This port does not
feature real-time sample rate conversion.
About Lightpipe-Compatible Devices
Lightpipe is an industry standard, eight-channel
optical digital audio connection created by Ale-
sis. Lightpipe is found on many devices, includ-
ing Optical (ADAT) decks, modular digital mul-
titracks (MDMs), sound cards, A/D or D/A
converters, and digital consoles.
LOOP SYNC In and Out
Loop Sync is a dedicated clock loop for synchro-
nizing multiple Pro Tools|HD peripherals to-
gether (multiple audio interfaces, and/or a
Digidesign SYNC I/O and one or more audio in-
terfaces). Loop Sync uses a word clock signal
based on sample rates of either 44.1 kHz or
48 kHz. As sample rate increases in the system,
Loop Sync continues to operate at a base rate of
44.1 kHz or 48 kHz, depending upon the higher
rate.
The Loop Sync In and Out ports are standard
BNC connectors that output a 1x Loop Sync
clock signal. Loop Sync should only be used to
chain multiple Pro Tools|HD peripherals to-
gether.

192 I/O Guide10
EXT. CLOCK In and Out
The External Clock I/O ports are standard BNC
connectors that receive and output a word clock
signal. These ports can be used to synchronize
the 192 I/O to any device that requires (or pro-
vides) word clock.
External Clock In and Out are configured by
your choice for Clock Source in Pro Tools.
AC Power
This connector accepts a standard AC power ca-
ble. The 192 I/O is auto power-selecting (100V
to 240V) and will automatically work with a
standard modular cable to connect to AC power
receptacles in any country.
Primary DigiLink
The Primary port is where the DigiLink cable
connects a Pro Tools|HD card (or other audio in-
terface) to the 192 I/O. The Primary DigiLink
port sends and receives all 32 I/O channels. As
the 192 I/O is a 16-channel only device, chan-
nels 17–32 are passed through to the Expansion
or Legacy port.
DigiLink Length Specifications
There are five different lengths of DigiLink ca-
bles.
•18”(0.46m), included with each interface
•12’(3.6m), included with each
Pro Tools|HD card
•25’(7.62m)
•50’(15.25m), the maximum length sup-
ported for 192 kHz sessions (sold sepa-
rately)
•100’ (30.5m), the maximum length sup-
ported by 96 kHz sessions (sold separately)
Expansion DigiLink
The Expansion port lets you connect an addi-
tional Pro Tools|HD audio interface to the
192 I/O. The Expansion port passes channels
17–32 to the secondary, or expansion I/O.
Legacy Port
This port lets you connect MIX-series Digidesign
audio interfaces to the 192 I/O. You can connect
two eight-channel interfaces (such as the 888|24
or 882|20) or a single sixteen-channel interface
(such as the 1622 I/O, or 24-bit ADAT Bridge
I/O) for expanded input and output options, us-
ing their original cables.
When the Legacy port has been activated from
within Pro Tools, your MIX-series I/O will ap-
pear as channels 17–32 in Pro Tools.
Because crucial timing data is passed
through the Loop Sync and Word Clock
ports, you should use high-quality, 75-ohm
RG–59 cables for making connections.
For more information about DigiLink ca-
bles, refer to the Digidesign Web site
(www.digidesign.com).
For more information on using Expansion
or Legacy audio interfaces, see the
Pro Tools|HD Getting Started Guide, and the
Expanded Systems Guide.

Chapter 2: 192 I/O Overview 11
Legacy and Expansion Peripheral Port
Limitations
Because both the Legacy port and the Expansion
port use channels 17–32, you can only use one
at a time.
The Legacy port is not available in any session in
which the sample rate is set for higher than
48 kHz.
Accessory Port
This port is not supported.
Using Input and Output Trims
Input Trims
The Input Trims below the two DB–25 connec-
tors on the Analog In card are used to store two
different calibration settings (A and B) for each
channel.
These two adjustable Input Trims are for pre-
cisely calibrating and switching between a
choice of independently adjustable headroom
settings for each channel. You can adjust each
Input Trim by hand with a small screwdriver.
For example, you could use the A trims for the
+4 dBu port, and use the B trims for –10. Or, use
A and B to maintain two different trims for any
signal input port (+4 dBu or –10 dB(V)).
If you are not using the –10 dB(V) input connec-
tor, the B trims can be used to store an alternate
set of headroom values for the +4 dBu inputs.
Once set, you can switch between the different
trim headroom values for the same input level
from within Pro Tools.
About Input Operating Levels
Check the owner’s manual for your mixer,
power amplifier or effects processor to see if it
operates more comfortably at line level, in
which case consider setting the 192 I/O to oper-
ate at –10 dB(V) line levels and/or adjusting the
Input Trims.
Consider the following when connecting a
mixer:
If your mixer cannot handle more than 1.5V
(RMS) inputs at +4 dBu, then you should set the
192 I/O to operate at –10 dB(V) line level.
If your mixer can handle up to 15.5V (RMS)
inputs, or has pads or attenuators on its inputs,
then you can use the +4 dBu setting on the
192 I/O.
192 I/O is calibrated for 18 dB headroom at
the +4 dBu setting.
Most manuals contain device input specifica-
tions, including whether or not there are pads or
attenuators. Consult the manufacturer’s docu-
mentation for your mixer or power amplifier for
further information.
Selecting Analog Input Operating
Levels
If you want to switch the input levels of the
192 I/O from +4 dBu to –10 dB(V), you can ac-
cess these parameters on a channel-by-channel
basis in the Hardware Setup dialog. For instruc-
tions, see the Pro Tools|HD Getting Started Guide

192 I/O Guide12
Soft Clip Limiting
The 192 I/O provides an optional “soft” limiter
for each input. The Soft Clip limiter can be used
to attenuate incoming analog signals to provide
extra protection from temporary clipping tran-
sients and digital distortion.
With Soft Clip enabled, 192 I/O supports an ad-
ditional 4 dB of headroom by rounding off the
top 4 dB to the clip point.
Output Trims
18 dB and 20 dB Output Levels
The 192 I/O has two Output Trims for each out-
put signal. You can switch between these Out-
put Trim levels from within Pro Tools.
• Output Trim A is factory calibrated for 18 dB
headroom.
• Output Trim B is calibrated for 20 dB head-
room.
Digital Format Settings and
Sample Rate Conversion
The 192 I/O lets you specify the digital format
for input, and apply sample rate conversion.
To configure digital formats and sample rate
conversion:
1 Launch Pro Tools.
2 Choose Setup > Hardware.
3 Click the Digital tab and select Input Format
(AES/EBU, ADAT, or TDIF).
4 Enable real-time Sample Rate Conversion by
selecting channel pairs (1–2, 3–4, 5–6, 7–8) in
the SR Conversion box on the Digital tab.
For more information, see the Pro Tools|HD Get-
ting Started Guide.
For more information on Soft Clip Limiting
and other 192 I/O settings, see the
Pro Tools|HD Getting Started Guide.
For more information, see Appendix C,
“192 I/O Calibration Mode Instructions.”
At session sample rates above 48 kHz, sam-
ple rate conversion for the TDIF and Optical
(ADAT) inputs on the Digital I/O card is au-
tomatically enabled on all eight inputs of
the selected format.

Appendix A: Adding or Removing I/O Cards 13
appendix a
Adding or Removing I/O Cards
The 192 I/O comes with one available expan-
sion bay on the back of the unit. This bay lets
you add another 192 AD Card, 192 DA Card, or
192 Digital Card (all sold separately) to increase
the amount of available I/O on the unit.
The expansion bay is the only bay that allows
for another card. The other three bays are hard-
wired for the appropriate card (the upper left
bay houses a 192 AD card; the upper right, the
192 Digital card; and the lower left, the 192 DA
card). See “Installing an I/O Card” on page 13.
These factory-installed cards can be removed, if
needed, for servicing, or to swap out cards in the
fourth bay for different studio setups. If you re-
move a single card from the 192 I/O, the unit
will continue to function while the audio card is
being serviced. See “Removing an I/O Card” on
page 16.
Installing an I/O Card
Installing an optional card in the expansion bay
To insert or replace a card:
1 Power off and disconnect the 192 I/O from
your Pro Tools|HD system.
2 Make sure that the equipment is properly
grounded.
3 Remove all 16 of the small Phillips-head
screws around the edges of the top cover. Don’t
lose the screws—put them in a safe place!
Bay
Number
Card
Allowed
1A/D
2D/A
3D/D
4Any
It is important that you follow the guidelines
in this chapter to avoid damaging your
192 I/O or any of your I/O cards.
Removing the top cover screws

192 I/O Guide14
4 Lift off the top of the 192 I/O and set it aside.
5 Remove the five screws on the cover over the
empty bay. Do not misplace these screws; note
that they are a different size and shape from the
top cover screws.
6 Look into the empty bay to locate the guide
rails for the card to slide in on.
7 Slide the edges of the card into the guide rails
on each side of the bay.
8 Gently push the card back into the bay, lifting
slightly to keep components underneath the
card from touching the back panel.
9 Attach the card’s faceplate onto the back
panel surface of the 192 I/O with the same
screws you removed from the empty bay cover.
Removing the cover on the empty bay
Locating guide rails along sides of empty bay
Guide Rails
guide rails
Placing the edge of the card into the guide rails
Lifting slightly while pushing the card back into the bay
Attaching the card faceplate into the back panel
surface of the 192 I/O
guide rails