Avid Technology HD I/O User manual

HD I/O Guide

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Contents iii
Chapter 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
HD I/O Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
What’s Included. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
System Requirements and Compatibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Registration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
About This Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
About www.avid.com . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Chapter 2. HD I/O Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
HD HD I/O GuideI/O Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
HD I/O Back Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 3. Connecting HD I/O. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Connecting HD I/O to HD Native Cards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Connecting HD I/O to Pro Tools|HD Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Chapter 4. Configuring HD I/O in Pro Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Hardware Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Configuring HD I/O. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Using Input Trims. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Chapter 5. Adding or Removing I/O Cards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Removing an I/O Card . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Installing an Expansion I/O Card. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Chapter 6. Pinout Diagrams for the DB-25 Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Analog Output DB-25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Analog Input (+4 dBu) DB-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Analog Input (–10dBV) DB-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
AES/EBU DB-25 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
TDIF DB-25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Contents

HD I/O Guideiv
Chapter 7. HD I/O Calibration Mode Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
About Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Calibrating the HD I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Switching Jumpers on the Analog Output Card. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Appendix A. Compliance Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Environmental Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
EMC (Electromagnetic Compliance). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Safety Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Chapter 1: Introduction 1
Chapter 1: Introduction
Avid®HD I/O is a multi-channel digital audio
interface designed for use with Avid HD Native
and Pro Tools|HD hardware. HD I/O features
24-bit analog-to-digital (A/D) and digital-to-an-
alog (D/A) converters, and supports sample
rates of up to 192 kHz.
HD I/O comes in three standard configurations:
• 8 x 8 x 8 (8 analog in, 8 analog out, and 8
digital in and out)
• 16 x 16 analog in and out
• 16 x 16 digital in and out
You can also add or remove analog (ADC and
DAC) and digital cards for custom configura-
tions.
HD I/O Features
HD I/O provides up to sixteen discrete channels
of audio input and output, each with a 4-seg-
ment LED meter. The total available analog and
digital I/O is dependent on the configuration of
Analog and Digital Expansion I/O cards in-
stalled in HD I/O.
Analog I/O
• Up to 16 channels of 24-bit D/A and A/D con-
verters for superior analog input and output at
sample rates of 44.1 kHz, 48 kHz, 88.2 kHz,
96 kHz, 176.4 kHz, and 192 kHz with Analog
In and Analog Out HD I/O cards
• Soft Clip and Curv limiting circuits to protect
against clipping on analog input
Digital I/O
• Up to 16 channels of 24-bit digital I/O, using
AES/EBU, TDIF DB-25, or Optical at sample
rates of 44.1, 48, 88.2, 96, 176.4, and 192 kHz
with a Digital HD I/O card
• Real-time sample rate conversion on digital
inputs with a Digital I/O card (up to sixteen
channels of AES/EBU, Optical, or TDIF)
• Support for S/MUX Optical for sample rates of
88.2 kHz and higher
• Support for 2 channels of S/PDIF Optical (en-
closed) with sample rates of up to 96 kHz
• 2 channels of AES/EBU I/O (enclosed) with
support for sample rates up to 192 kHz
• 2 channels of 24-bit-capable S/PDIF I/O (en-
closed) with support for sample rates up to
192 kHz
Synchronization
• Loop Sync input and output for connecting ad-
ditional Avid HD audio interfaces and periph-
erals
• External Clock input and output for synchro-
nizing HD I/O with external Word Clock de-
vices
Expandability
• Optional addition of I/O cards to expand ana-
log or digital I/O
• Simultaneous use of multiple Avid HD audio
interfaces to further expand system input and
output

HD I/O Guide2
What’s Included
• Avid HD I/O audio interface
•ACpowercable
• DigiLink Mini cable (18 inches [0.46m])
• DigiLink Mini adapter
• BNC cable (18 inches [0.46m])
•HDI/OGuide
•HealthandSafetyGuide
• Registration Information Card
System Requirements and
Compatibility
Avid can only assure compatibility and provide
support for hardware and software it has tested
and approved.
For complete system requirements and a list of
qualified computers, operating systems, hard
drives, and third-party devices, visit:
www.avid.com/compatibility
Registration
Review the enclosed Registration Information
Card and follow the instructions on it to quickly
register your purchase online. By registering,
you become eligible to receive the following:
• Information regarding technical support
• Software update and upgrade notices
• Limited warranty on hardware
Hardware Warranty
Your warranty can be found on the Registration
Information Card.

Chapter 1: Introduction 3
About This Guide
This guide provides a basic overview of the
HD I/O features and functionality.
For hardware installation instructions for your
HD Native hardware, see the HD Native Install
Guide.
For hardware installation instructions for your
Pro Tools|HD hardware, see the Pro Tools|HD
User Guide.
For Pro Tools installation instructions, see the
Pro Tools Installation Guide.
For additional information about using
Pro Tools software, see the Pro Tools Reference
Guide (in Pro Tools, choose Help > Pro Tools
Reference Guide).
Conventions Used in This Guide
All of our guides use the following conventions
to indicate menu choices and key commands:
:
The names of Commands, Options, and Settings
that appear on-screen are in a different font.
The following symbols are used to highlight
important information:
Convention Action
File > Save Choose Save from the
File menu
Control+N Hold down the Control key
and press the N key
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 Pro Tools guides.

HD I/O Guide4
About www.avid.com
The Avid website (www.avid.com) is your best
online source for information to help you get the
most out of your Pro Tools system. The follow-
ing are just a few of the services and features
available.
Product Registration Register your purchase on-
line.
Support and Downloads Contact Avid Customer
Success (technical support); download software
updates and the latest online manuals; browse
the Compatibility documents for system re-
quirements; search the online Knowledge Base
or join the worldwide Pro Tools community on
the User Conference.
Training and Education 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 Avid
products; download demo software or learn
about our Development Partners and their plug-
ins, applications, and hardware.
News and Events Get the latest news from Avid
or sign up for a Pro Tools demo.

Chapter 2: HD I/O Overview 5
Chapter 2: HD I/O Overview
This chapter describes the front and back panel features of the HD I/O.
HD I/O Front Panel
Power Switch and LED Ring
This button turns HD I/O on and off. The LED
ring around the power button will light green or
orange to indicate the system status:
Green LED Ring Indicates that the unit has pow-
ered up successfully and is connected to an ac-
tive system.
Orange LED Ring Indicates that the unit has
power, but the computer it is connected to is
shut down.
Sample Rate
These LEDs display the current sample rate of
the HD I/O internal clock: 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 Hardware Setup
or Playback Engine dialogs if no session is open.
HD I/O Front Panel

HD I/O Guide6
Loop Master LED
The LOOP MASTER LED indicates which audio
interface is the master peripheral. The Loop
Master LED will be continuously lit on the cur-
rent Loop Master peripheral only, and unlit on
all other peripherals. (Only one Avid HD periph-
eral can be Loop Master at a time.) The Loop
Master LED will always be lit with a single inter-
face.
With HD Native hardware, Loop Master defaults
to the first audio interface connected to Di-
giLink Mini Port 1 on the HD Native card.
For Pro Tools|HD systems, Loop Master defaults
to the first audio interface connected to the pri-
mary, 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 HD I/O sample clock
is generated by its internal clock, as determined
by the session Sample Rate.
DIG (Digital) Indicates that an external
AES/EBU, TDIF, Optical (ADAT), Optical
(ADAT S/MUX), or S/PDIF device is providing
system clock. If no valid clock source is de-
tected, HD I/O will switch to internal clock, the
DIG LED will flash, and an error message will
appear on-screen in Pro Tools.
LOOP Indicates that the HD I/O is slaving to an-
other Avid HD audio interface or SYNC periph-
eral using Loop Sync.
EXT (External) Indicates that the HD I/O is using
the EXT CLOCK IN port for system synchroniza-
tion.
When synchronized to Word Clock, External
Clock input and output do not have to be at the
Word Clock rate. EXT CLOCK IN synchroniza-
tion will typically be 1x the current session sam-
ple rate. However, for sample rates higher than
48 kHz, HD I/O generates a choice of 1x, 2x, or
4x of a base rate of 44.1 kHz or 48 kHz, 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
calibrated at –42 dB, –18 dB, –6 dB, and 0 dB,
respectively.
Session Sample Rate Word Clock Support
44.1 kHz 44.1 kHz
48 kHz 48 kHz
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.

Chapter 2: HD I/O Overview 7
HD I/O Back Panel
Although the HD I/O is a sixteen-channel audio
interface, it has up to 94 inputs and outputs
available through its various back panel connec-
tors.
HD I/O comes in three standard configurations:
• 8 x 8 x 8 analog and digital in and out
• 16 x 16 analog in and out
• 16 x 16 digital in and out
Input and Output Cards
The HD I/O features four bays for HD I/O Ex-
pansion cards. With the standard 8 x 8 x 8 con-
figuration, bays 1–3 contain Analog In, Analog
Out, and Digital I/O cards, respectively. The
fourth bay (as shown in this 8 x 8 x 8 configura-
tion) is an expansion bay, for which you can
purchase an additional Expansion I/O card of
your choice.
By installing an optional AD Expansion card,
DA Expansion card, or Digital Expansion card,
you can add even more I/O capacity (up to a
maximum possible 110 inputs and outputs). See
Chapter 5, “Adding or Removing I/O Cards.”
Analog Input
The HD I/O Analog In card contains connectors
for analog audio input with 24-bit, 192 kHz A/D
converters. Input is provided through two dis-
crete DB–25 connectors (one for +4 dBu
sources, and the other for –10 dBV sources).
You can connect sources at both operating levels
and choose between them from within
Pro Tools.
HD I/O Back Panel, 8 x 8 x 8 configuration shown
964530300294856
WORD CLOCK LOOP SYNC
PRIMARY PORT
EXPANSION PORT
IN
OUT
AC ~ 100-240V;50-60HZ; A
S/PDIF
IN
OUT
AES/EBU
INPUT
AES/EBU
OUTPUT
OPTICAL
IN OUT
ACCESSORY
12345678
ANALOG INPUT
+4 dBu BALANCED -10 dBV BALANCED
12345678
ANALOG OUTPUT
BALANCED
DIGITAL I/O
AES/EBU
ADAT
IN
TDIF I/O
ADAT
OUT
Bay 2: Analog Out card
Bay 1: Analog In card Bay 3: Digital I/O card
Bay 4: Empty for Optional card
Enclosure
Input and Output cards for 192 I/O are not
supported in HD I/O.

HD I/O Guide8
+4 dBu Balanced Provides eight balanced input
channels at +4 dBu nominal operating levels.
–10 dBV Balanced Provides eight balanced input
channels at –10 dBV nominal operating levels.
For wiring information, see Chapter 6, “Pinout
Diagrams for the DB-25 Connectors.”
For each channel, you can select input level from
within the Hardware Setup dialog (see “Hard-
ware Setup” on page 19).
Input Trims
The Input Trims below the DB–25 connectors
are used to individually calibrate each channel’s
input level. See “Input Trims” on page 28.
Additionally, the Limiter function helps avoid
digital clipping (see“Limiter” on page 24).
Analog Output
The HD I/O Analog Out card 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 Chapter 6,
“Pinout Diagrams 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. For more information, see
Chapter 7, “HD I/O Calibration Mode Instruc-
tions.”
Most consumer electronics operate at –10 dBV
levels, and may not feature balanced inputs
and outputs. You can connect –10 dBV
signals to the –10 dBV inputs, but you will
need to make sure that the negative terminals
are not connected.
For –10 dBV gear, you can switch a jumper
on Analog Output cards (on a channel-by-
channel basis) from the default Hi position
to Lo for a –6 dB pad. You can then adjust
the Trim pot for the corresponding output
channels by an additional –4 dB to accom-
modate –10 dBV gear. For more informa-
tion, see Chapter 7, “HD I/O Calibration
Mode Instructions.”

Chapter 2: HD I/O Overview 9
Digital I/O
The Digital I/O card contains connectors for
eight channels 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 single-
wire mode up to eight channels. Dual-wire mode
uses two HD I/O physical I/O channels of
AES/EBU I/O to carry each single stream of
176.4 kHz or 192 kHz audio. Therefore, only
four simultaneous channels of AES/EBU I/O are
available at 176.4 kHz or 192 kHz.
TDIF DB–25 connectors for eight channels of
TDIF input and output. Conforms to standard
eight-channel TDIF pinouts. For more informa-
tion, see Chapter 6, “Pinout Diagrams for the
DB-25 Connectors.”
Optical (ADAT) Dedicated, eight-channel 24-bit
capable Optical ports (up to 48 kHz), with real-
time sample rate conversion on input (only).
Note that Optical S/PDIF is not supported with
the Digital I/O card and is supported with the
enclosed Optical ports only (for more informa-
tion, see “Optical (ADAT) [Encl]” on page 10).
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.
Enclosure Connectors
The right half of the back panel of HD I/O fea-
tures a set of non-removable connectors that are
mounted to the enclosure.
These connectors include two channels of
AES/EBU IO, Optical I/O (for another eight
channels of ADAT format, or two channels of
Optical S/PDIF), and two channels of coaxial
S/PDIF I/O. On-screen, these connectors are
identified as AES/EBU [Encl], Optical (ADAT)
[Encl], Optical (S/PDIF) [Encl], and S/PDIF
[Encl].
Other connectors include Loop Sync, External
Clock, and ports for attaching the HD I/O to
HD Native or Pro Tools|HD cards, or to other
Avid HD audio interfaces.
We recommend using Avid DB-25 TDIF ca-
bles for optimum compatibility.
For more information, see“Hardware Setup”
on page 19.

HD I/O Guide10
AES/EBU [Encl]
These are balanced, three-conductor XLR con-
nectors that accept and output a stereo, 24-bit
AES/EBU audio signal. These two ports support
up to 192 kHz sample rates.
Optical (ADAT) [Encl]
These Optical ports provide up to eight channels
of Optical (ADAT) input and output, or two
channels (stereo) optical S/PDIF input and out-
put. Optical (ADAT) mode supports sample
rates up to 48 kHz. Using S/MUX, these Optical
ports support provide up to four channels of Op-
tical S/MUX input and output at sample rates of
88.2 and 96 kHz, and up to two channels of Op-
tical S/MUX input and output at sample rates of
176.4 and 192 kHz. In TOS-Link mode, the ports
support two channels of Optical input and out-
put at sample rates up to 96 kHz.
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), A/D or D/A converters,
S/MUX, and digital consoles.
S/PDIF Digital In and Out
These are unbalanced RCA jacks that receive
and send two channels of S/PDIF audio. S/PDIF
supports up to 24-bit audio, at sample rates up
to 192 kHz.
DigiLink Mini Ports
PRIMARY PORT
Use the PRIMARY PORT to connect HD I/O to
an HD Native cards using a DigiLink Mini cable,
or to Pro Tools|HD card using a DigiLink cable
with a DigiLink Mini adapter.
The Primary port sends and receives 32 chan-
nels to and from an HD Native or Pro Tools|HD
card. Input and output channels 17–32 (if ac-
tive) are passed through to the EXPANSION
PORT.
EXPANSION PORT
The EXPANSION PORT lets you connect an ad-
ditional Avid HD audio interface to HD I/O. The
EXPANSION PORT passes input and output
channels 17–32 to the expansion (or secondary)
audio interface.
This port is only available when HD I/O is con-
nected directly to an HD Native or Pro Tools|HD
card (it is not available when the HD I/O is con-
nected to the Expansion Port on another audio
interface).
Configure HD I/O for ADAT S/MUX on the
enclosed ADAT port and also on the ADAT
port on the Digital I/O card to get 8 channels
at 88.2/96 kHz or 4 channels at
176.4/192 kHz.
To maintain data integrity and minimize
jitter, use only 75-ohm coaxial cable for
S/PDIF connections.

Chapter 2: HD I/O Overview 11
DigiLink Mini Cables and Adapters
Avid provides various cables and adapters to
connect Avid HD audio interfaces to HD Native
and Pro Tools|HD cards.
DigiLink Mini Cables
Use DigiLink Mini cables to connect HD I/O to
an HD Native card, as well as to other Avid HD
audio interfaces (such as another HD I/O or HD
OMNI).
There are five different lengths of DigiLink Mini
cables:
• 18”(0.46m)
• 12’(3.6m) (sold separately)
• 25’(7.62m) (sold separately)
• 50’(15.25m), the maximum length sup-
ported for 176.4 kHz and 192 kHz sessions
(sold separately)
• 100’ (30.5m), the maximum length sup-
ported by 88.2 kHz and 96 kHz sessions
(sold separately)
DigiLink Mini Adapters
Use a DigiLink cable with a DigiLink Mini
adapter to connect HD I/O to a Pro Tools|HD
card. You can also use a DigiLink Mini adapter
to connect HD I/O to legacy Pro Tools|HD audio
interfaces (such as 192 I/O).
There are two types of DigiLink Mini adapters:
• 12” DigiLink Mini female to DigiLink male
• 12”DigiLink Mini male to DigiLink female
Clock and Synchronization Ports
WD CLOCK IN and OUT
The Word Clock I/O ports are standard BNC
connectors that receive and output word clock
signal. These ports can be used to synchronize
HD I/O with any word clock-capable device.
Word Clock In can be configured by selecting it
as the Clock Source in the Hardware Setup dia-
log in Pro Tools. Word Clock Out can also be
configured in the Hardware Setup dialog using
the External Clock Output selector.
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, or a SYNC HD
and one or more audio interfaces). Loop Sync
technology lets you synchronize to any digital
peripheral connected to any of the Pro Tools|HD
audio interfaces in your Pro Tools system. 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 contin-
ues to operate at a base rate of 44.1 kHz or
48 kHz, depending upon the higher rate.
For more information about DigiLink Mini
cables and adapters, visit the Avid website
(www.avid.com).
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.

HD I/O Guide12
The Loop Sync In and Out ports are standard
BNC connectors that output a 1x Word clock sig-
nal. Loop Sync should only be used to chain mul-
tiple Pro Tools|HD peripherals together (such as
Pro Tools|HD audio interfaces and SYNC HD).
AC Power
This connector accepts a standard AC power ca-
ble. HD I/O is auto power-selecting (100V to
240V) and will automatically work with a stan-
dard modular cable (IEC) to connect to AC
power outlets in any country.
Accessory Port
This port currently has no functionality.

Chapter 3: Connecting HD I/O 13
Chapter 3: Connecting HD I/O
HD I/O provides up to sixteen channels of
analog and digital I/O with HD I/O with Avid
HD Native or Pro Tools|HD hardware.
HD Native With HD Native hardware, HD I/O
can be connected to the HD Native card using a
DigiLink Mini cable. You can add additional HD
audio interfaces to your system using the Expan-
sion port on the back of HD I/O or the second
DigiLink Mini Port on the HD Native card. See
“Connecting HD I/O to HD Native Cards” on
page 14.
Pro Tools|HD With Pro Tools|HD hardware,
HD I/O can be connected to a Pro Tools|HD card
using a DigiLink cable with a DigiLink Mini
adapter. You can add additional HD audio inter-
faces to your system using the Expansion port
on the back of HD I/O or using additional
Pro Tools|HD cards. See “Connecting HD I/O to
Pro Tools|HD Cards” on page 16.
Rack Mounting HD Audio
Interfaces
HD I/O and all Avid HD audio interfaces need
room at their sides to maintain proper air flow
for cooling. Do not block the sides of the unit or
disconnect the internal fan. If the units are rack-
mounted in a case, remove the case lids or doors
before operating the system. Failure to do so can
result in the units overheating very quickly,
which can permanently damage sensitive com-
ponents.
For more information about installing the
HD Native card, see the HD Native Install
Guide.
For more information about installing
Pro Tools|HD cards, see the Pro Tools|HD
User Guide.

HD I/O Guide14
Connecting HD I/O to HD Native Cards
To connect HD I/O to an HD Native card:
Connect HD I/O Primary Port to the DigiLink Mini Port 1 on the HD Native card using the included
DigiLink Mini cable.
To connect two HD I/Os to an HD Native card:
1 Connect the Primary Port to DigiLink Mini Port 1 on the HD Native card using the included DigiLink
Mini cable.
2 Connect the additional HD I/O (or other compatible Pro Tools audio interface) by doing one of the
following:
• Connect the Primary Port of the secondary interface to the Expansion Port of the primary inter-
face with an additional DigiLink Mini (or DigiLink to DigiLink Mini adapter).
– or –
• Connect the Primary Port of the secondary interface to DigiLink Mini Port 2 on the HD Native
card.
3 Make the necessary Loop Sync connections (see “Connecting Loop Sync” on page 15).
Figure 1. HD I/O connected to the DigiLink Mini Port 1 on an HD Native card
PORT 1PORT 2

Chapter 3: Connecting HD I/O 15
Connecting Loop Sync
If you are using two or more HD audio interfaces or a SYNC peripheral, Loop Sync must be connected
to maintain proper clock synchronizations among the devices. For examples that include a SYNC pe-
ripheral, see the SYNC HD Guide. For an example of connecting multiple Avid HD audio interfaces,
see Figure 2 below.
To make Loop Sync connections:
1 Connect the Loop Sync Out of each interface to the Loop Sync In of the next interface with a BNC ca-
ble.
2 Connect the Loop Sync Out of the last interface to the Loop Sync In of the primary interface or SYNC
peripheral with a BNC cable.
Figure 2. DigiLink Mini and Loop Sync connections for two HD I/Os with HD Native
PORT 1PORT 2

HD I/O Guide16
Connecting HD I/O to Pro Tools|HD Cards
To connect HD I/O to a Pro Tools|HD card:
Connect HD I/O Primary Port to the DigiLink Port on the first available Pro Tools|HD card with a
DigiLink cable (included with your Pro Tools|HD hardware) and a DigiLink Mini adapter.
To connect multiple HD I/Os to a Pro Tools|HD system:
1 Connect the Primary Port of the first HD I/O to the DigiLink Port on the Pro Tools|HD Accel Core
card with a DigiLink cable (included with your Pro Tools|HD system) and a DigiLink to DigiLink Mini
adapter.
2 Do one of the following:
• Connect the Primary Port of the second HD I/O to the Expansion Port on the first HD I/O with the
included 18-inch DigiLink Mini cable.
– or –
• Connect the Primary Port of the second HD I/O to the next available Pro Tools|HD card with a Di-
giLink cable and a DigiLink to DigiLink Mini adapter.
3 Connect additional HD I/Os to additional Pro Tools|HD cards.
4 Make the necessary Loop Sync connections.
Figure 3. HD I/O connected to the DigiLink Port on a Pro Tools|HD Accel Core card (16-channel I/O system)
12-foot DigiLink cable
with DigiLink Mini adapter