DigiDesign 888/24 I/O Installation Manual

Digidesign

888|24 I/O Audio Interface

Installation Guide

Digidesign Inc.

3401-A Hillview Avenue

Palo Alto, CA 94304 USA

tel: 650·842·7900

fax: 650·842·7999

Technical Support (USA)

650·842·6699
650·856·4275

Product Information

650·842·6602
800·333·2137

Fax on Demand

1-888-USE-DIGI (873-3444)

World Wide Web

www.digidesign.com

Digidesign FTP Site

ftp.digidesign.com

Copyright

This User’s Guide is copyrighted ©1999 by Digidesign, a
division of Avid Technology, Inc. (hereafter “Digidesign”), with
all rights reserved. Under copyright laws, this manual may not
be duplicated in whole or in part without the written consent of
Digidesign.

DIGIDESIGN, AVID and PRO TOOLS are trademarks or
registered trademarks of Digidesign and/or Avid Technology,
Inc. All other trademarks are the property of their respective
owners.

All features and specifications subject to change without
notice.

PN 932707455-00 REV A 11/99

Communications & Safety Regulation Information

Compliance Statement

The model 888/24 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

• CISPR 22 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 product
not authorized by Digidesign, Inc., could void the Certification
and negate your authority to operate the product. This product
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; UL813 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 product.

• 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.

• The product should be connected only to the correct power
supply as indicated on the product.

contents

Using the 888/24 I/O

The 888/24 I/O Interface
Changing Operating Levels of Individual 888/24 I/O Channels
Making Signal Connections to the 888/24 I/O
Using the 888/24 I/O Interface as Stand-Alone Audio Converter
Changing the Default Sample Rate of the 888/24 I/O in A/D Stand-Alone Mode
Changing the Default Word Clock Lock Port of the 888/24 I/O in D/A Stand-Alone Mode
Muting the DAC Outputs of the 888/24 I/O in A/D Stand-Alone Mode

Appendix A. Technical Specifications

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Appendix B. Calibrating the 888/24 I/O (Pro Tools 5.0)

About Calibration
Calibrating The 888/24 I/O

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. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Appendix C. Calibrating the 888/24 I/O (Pro Tools 4.x)

About Calibration
Calibrating The 888/24 I/O

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Contents

iii

888/24 I/O

iv

Using the 888/24 I/O

The 888/24 I/O™ is an 8-channel digital au­dio interface that features 24-bit analog-to­digital, and 24-bit digital-to-analog con­verters for superior dynamic range, reduced
noise floor, and the capability to work with
the full 24-bit mixing, editing, processing,
and mastering environment of Pro Tools.

The 888/24 I/O can be used in two ways:

As a 24-bit Audio Interface for Pro Tools

◆

As a stand-alone 24-bit audio converter

◆

This User’s Guide explains the indicators
and connectors on the 888/24 I/O. It also
explains how to use it with a Digidesign
Pro Tools
stand-alone 24-bit audio converter in your
studio.

☞

information in this guide is covered in your

Pro Tools TDM Hardware Installation Guide

®

system, or as an independent,

If you own a Pro Tools system, most of the

.

The 888/24 I/O Interface

This section explains each of the connec­tors and indicators on the front and back
panels of the 888/24 I/O Interface, how
they are used, and offers suggestions for
connecting the 888/24 I/O to your studio.

888/24 I/O Front Panel

The 888/24 I/O has the following front
panel indicators, moving from left to right:

Front panel of the 888/24 I/O

1. Power

This switch applies power to the 888/24.
The “I” position is on. The “O” position is
off.

2. 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).

Using the 888/24 I/O

1

Internal

This is the 888/24 I/O standard set­ting. In this mode, the 888/24 I/O sample
rate is generated by its internal crystal oscil­lator (whose frequency is determined by
the Sample Rate setting in the Session
Setup window). Internal mode should be
active whenever the 888/24 I/O is not syn­chronized to an external clock source.

Digital

This setting indicates that an
AES/EBU or S/PDIF word clock signal is cur­rently the source for the 888/24 I/O sample
rate. This is the setting to use for inputting
material from DAT recorders or other digi­tal devices.

To use the 888/24 I/O digital inputs and
outputs as effects sends and returns to dig­ital effects devices, you should set the
888/24 I/O to Internal Sync Mode. You
should then set the digital effects device to
accept an external digital clock (from the
888/24 I/O) so it synchronizes itself to
Pro Tools.

The 888/24 I/O can only synchronize to
and receive word clock lock on channels
1–2 of its digital inputs. To synchronize
your system to an external digital clock
source, it must be connected to digital in­puts 1–2 of the 888/24 I/O. In an expanded
Pro Tools system, the system clock is car­ried by the Audio Interface connected to
the first Pro Tools card in your system. This
Audio Interface will act as the master inter­face in your system. All other Audio Inter­faces will be slaved to it.

▲

Because some digital audio devices do not
output proper clock when they are not playing
back, leaving the 888/24 I/O in Digital Sync
Mode may cause Pro Tools audio playback
quality to suffer, or play back at the wrong
pitch. If you are using digital I/O, reset the
Sync Mode from Digital to Internal after input­ting material.

Slave

This LED is lit when the 888/24 I/O
sample rate is synchronized 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 signal present at the Slave Clock
(256x) port.

The 888/24 I/O automatically 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 the
888/24 I/O Slave Clock In port.

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 phase­synchronous.

✽

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.

888/24 I/O

2

3. Sample Rate and 1–2 Format Indicators

These LEDs indicate the sample rate of the
888/24 I/O internal crystal oscillator and
the digital format (AES/EBU or S/PDIF) of
the audio input signal to channels 1 and 2.

The choice of digital format for these two
channels is made in the Session Setup win­dow or Hardware Setup dialog. Digital in­put pairs 3–4, 5–6, and 7–8 of the
888/24 I/O are always AES/EBU. Sample
Rate is set in the Session Setup window or
Hardware dialog in Pro Tools.

The 888/24 I/O provides the following
sample rates:

48 kHz

many professional audio devices. It is rec­ommended for use with devices that can­not receive digital transfers at 44.1 kHz.

44.1 kHz

sampling 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.

▲

source such as a DAT recorder, the front panel
of the 888/24 I/O indicates only the internal
oscillator sample rate, not that of the external
digital source.

This is a standard sampling rate of

This is the compact disc standard

When you are using an external digital

4. Level Meters

The 888/24 I/O level meters monitor the
channel outputs of Pro Tools. Input levels
are monitored on-screen in the Pro Tools
software.

The 888/24 I/O is factory calibrated so that
a meter reading of –18 dB corresponds to
the 888/24 I/O nominal operating level
(which can be set to either +4 dBu or
–10 dBV). If you sent the output to an ana­log device with a VU meter, this would cor­respond to “0 VU” on the VU meter.

The red LED indicators on the Audio Inter­face indicate both full-code (highest level
before clipping) and clipping of Pro Tools
output signals. The on-screen meters in
Pro Tools software indicate clipping when
at least three consecutive full-code samples
follow each other.

5. Input Level Trims

The 888/24 I/O analog inputs are factory
calibrated at a –18 dB nominal level, refer­enced to a full code signal. This means at
the nominal reference input level (either
+4 dBu or –10 dBV), you have 18 dB of
headroom before clipping. The input level
trim pots allow adjustment of the
888/24 I/O input levels to match the oper­ating level of your external equipment. Ad­justments can be made with a Phillips
screwdriver.

6. Output Level Trims

The 888/24 I/O analog outputs are factory
calibrated at a –18 dB nominal level, refer­enced to a full code signal. This means at
the nominal reference output level (either
+4 dBu or –10 dBV), you have 18 dB of
headroom before clipping. The output
level trim pots allow adjustment of the
888/24 I/O output levels to match the op­erating level of your external equipment.
Adjustments can be made with a Phillips
screwdriver.

Using the 888/24 I/O

3

To calibrate the input and output levels of
the 888/24 I/O to match your mixing con­sole or other devices in your studio, use
Calibration Tool (for Pro Tools 4.3.1 and
earlier) or use Calibration Mode and the
Signal Generator Plug-In (for Pro Tools 5.0
or later).

pair is disabled when digital input format is
chosen for that channel.

The 888/24 I/O analog audio connectors
are balanced XLRs with pin 2 wired hot,
(or “+”); pin 3 cold, (or “–”); and pin 1
ground.

☞

Instructions for calibrating the 888/24 I/O

appear in Appendix B of this Guide.

888/24 I/O Back Panel

The 888/24 I/O has the following back
panel connectors, moving from left to
right:

Back panel of the 888/24 I/O

1. Analog Audio Outputs

These are balanced male XLR connectors
for analog audio output connections. All
eight output channels are continuously ac­tive. The 888/24 I/O analog outputs feature
24-bit digital-to-analog converters.

2. Analog Audio Inputs

These are balanced female XLR connectors
for analog audio input connections. The
888/24 I/O analog inputs feature 24-bit an­alog-to-digital converters. Because input
channels 1–8 of the 888/24 I/O are soft­ware selectable in pairs between analog or
digital format, analog input to a channel

3. AES/EBU Digital Outputs 1–8

The 888/24 I/O AES/EBU output jacks are
balanced, three conductor, XLR connectors
which output a 24-bit digital data stream.
Output is continuously active on both the
AES/EBU and S/PDIF jacks even when the
888/24 I/O input selector is set to analog.

4. AES/EBU Digital Inputs 1–8

The AES/EBU digital format is used in
many professional digital audio devices, in­cluding some DAT recorders. The Inter­face’s AES/EBU input jacks are balanced,
three conductor, XLR connectors which ac­cept a full 24-bit digital data stream.

For AES/EBU connections, 110-ohm cables
are highly recommended for use in profes­sional installations. For best results, cable
lengths should not exceed 30 meters.

Input channels 1–8 of the 888/24 I/O are
software-selectable in pairs between analog
or digital format. Digital input to a channel
pair is disabled when analog input format
is chosen for that channel in the Hardware
Setup dialog. Input to AES/EBU input chan­nels 1–2 is disabled when S/PDIF digital for­mat is chosen for these inputs in the
Pro Tools Session Setup window.

888/24 I/O

4