Alesis HD24 User Manual

Contents

Welcome!..........................................................3

About the ADAT HD24......................................3

Important features of your ADAT HD24 ....3

ADAT HD24 key features:..................................5

How to Use This Manual...........................6

Important Safety Instructions...................................7

Instructions de Sécurité Importantes (French)......8

Beim Benutzen dieses Produktes beachten Sie
bitte die folgenden Sicherheitshinweise:

(German) ..........................................................9

CE Declaration of Conformity........................... 10

Instructions to the User (FCC Notice)................ 10

Quick Start Guide.................................................. 11

If you can't wait to get started:.......................... 11

Front panel tour—left side................................ 14

Front panel tour—right side .............................15

Locate/auto buttons ............................... 15

Special features....................................... 15

About the Display............................................ 16

Rear panel tour................................................ 17

Connections......................................................... 19

Unpacking and Inspection................................ 19

Mounting on a Shelf or Non-Rack

Enclosure ............................................... 19

Installing in a Rack .......................................... 19

Thermal Considerations in Rack

Mounting............................................... 19

Power ............................................................. 20

AC Power Hookup .................................20

AC Grounding ....................................... 20

Analog inputs and outputs...............................21

From the console to the HD24's inputs:..... 22

About Audio Cables ............................... 23

Typical input jack hookups...................... 23

Sync In/Out .................................................... 24

ADAT Optical Digital Inputs and Outputs ........ 25

About 16-bit and 20-bit signal transfers .... 25

High sample rate operation ..................... 25

Footswitches ................................................... 29

The LRC Remote.............................................. 29

Basic Recording and Playback ................................ 31

About the hard drives ...................................... 31

Songs.............................................................. 31

Making A Recording ........................................34

Time Counter..........................................34

Transport Buttons....................................35

Recording ........................................................35

Sample Rate Selection..............................35

Track Selection and Setting Levels ............36

The meters.......................................................37

Peak hold modes.....................................37

Setting the Recording Level......................38

Input Select......................................................39

Digital Input ...........................................39

Clock Source settings when recording

the Digital Input......................................39

Using All Input .......................................39

Input Monitor Controls.....................................40

Auto Input..............................................40

All Input.................................................40

Playback..........................................................41

Scanning.................................................41

Scrubbing ...............................................41

Pitch Control....................................................42

Using Locate Points ...............................................43

Locating ..........................................................43

Special Locate Points ........................................43

Other Locate Commands ..................................45

Creating A Playback/Record Loop....................45

Automated Recording ......................................47

Rehearsing..............................................48

Working with Drives ..............................................49

Mounting and selecting a drive .........................49

How Drives Get Mounted........................50

Dismounting drives.................................50

Adding additional drives..................................51

Disk size and recording time....................51

Backing up your work ......................................54

Editing ................................................................55

Editing Controls...............................................55

Using the Edit Start and Edit End Points ............56

Adjusting the Edit Start and Edit End Points ......57

Using the Cut and Copy Commands..................58

Using the Paste Command................................60

Undo...............................................................62

The Edit Buffer and Levels of Undo..........62

Track Slip ........................................................63

More about editing...........................................64

High resolution operation ...................................... 65

88.2/96 kHz sampling rates.............................. 65

The tradeoffs .......................................... 65

Ensuring sample-rate compatibility.......... 65

How ADAT Optical handles a 96 or

88.2k signal ............................................ 66

Using the HD24 with an external High Sample

Rate-capable A/D or D/A converter................. 66

The optional 96k Analog I/O boards................. 66

Synchronization and MIDI ..................................... 67

Synchronization............................................... 67

MIDI Time Code..................................... 67

SMPTE Time Code.................................. 67

MIDI............................................................... 68

Using the HD24 with tape-based ADATs .......... 69

Synchronizing with ADAT...................... 69

Using the ADAT HD24 with the BRC Master

Remote Control ...............................................70

Matching start times for synchronization.. 70

Compatibility issues ............................... 70

Using the HD24 with the M20........................... 72

Using Ethernet ..................................................... 73

When you'd use Ethernet and the HD24............ 73

What you can do..................................... 73

Limitations............................................. 73

Materials you will need.................................... 74

Cables....................................................74

Hub....................................................... 74

Interface card ......................................... 74

Software................................................. 74

Setting the IP parameters of the ADAT HD24 .... 75

About setting up your computer....................... 76

A word of caution................................... 76

Apple Macintosh configuration instructions.......77

Connection .............................................77

Setting up the AppleTalk, TCP/IP and

Remote Access control panels...................77

Windows 95/98/ME PC configuration

instructions......................................................80

Verifying a PC's connection to the

HD24......................................................83

Transferring files with Explorer.........................84

Tips and tricks about Explorer..................85

About using FTP download software........85

To upload files from the computer to the

HD24...............................................................86

More about IP addresses...................................86

About the subnet mask .....................................87

About the gateway address...............................87

Connecting the HD24 directly to a cable or

DSL modem.....................................................87

To quit FTP server mode...................................88

An Example Network.......................................89

Troubleshooting....................................................91

Troubleshooting Index......................................91

Avoiding ground loop noise ....................93

Line Conditioners and Protectors .............93

Care and Maintenance ......................................94

Cleaning .................................................94

Refer All Servicing to Alesis.....................94

Obtaining Repair Service .........................95

Specifications.......................................................97

Dimensional drawing .......................................98

Index ..................................................................99

Alesis Limited Warranty .......................................101

2 ADAT HD24 Reference Manual

Introduction/Safety Instructions

Welcome!

Thank you for making the Alesis ADAT HD24™ a
part of your studio. Since 1984, we've been
designing and building creative tools for the audio
community. We believe in our products, because
we've heard the results that creative people like you
have achieved with them. One of Alesis' goals is to
make high-quality studio equipment available to
everyone, and this Reference Manual is an important
part of that. After all, there's no point in making
equipment with all kinds of capabilities if no one
explains how to use them. So, we try to write our
manuals as carefully as we build our products.

The goal of this manual is to get you the information
you need as quickly as possible, with a minimum of
hassle. We hope we've achieved that. If not, please
drop us an email and give us your suggestions on
how we could improve future editions of this
manual.

We hope your investment will bring you many years
of creative enjoyment and help you achieve your
goals.

Sincerely,
The people of Alesis Studio Electronics

About the ADAT HD24

Alesis, the company that revolutionized
multitrack recording with the introduction of
the ADAT, now offers the ADAT HD24 hard
disk recorder. The HD24 writes to hard disk in
a special way to provide 24 tracks of 24-bit
audio on low-cost IDE hard drives, and offers
drop-in compatibility with over 150,000 ADAT
systems world wide. The ADAT HD24 shatters
the cost-per-track price barrier for professional
quality audio recording.

Important features of your ADAT
HD24

¾ Uses affordable, hot-swappable hard

drives as removable media:

To allow the use of affordable IDE hard drives
as removable recording media, on a cost and
performance par with tape, Alesis had to
overcome limitations such as data fragmentation
that occurs in traditional hard disk recording
formats. In order to achieve this, Alesis
engineered a new method of writing on hard
drives called ADAT FST™, specifically designed
for music recording. Unlike the writing schemes
employed by computer-based systems, this new
method keeps tracks of a given song in adjacent
sectors of the hard disk, reducing the required
"seek time" for the drive, providing a much
greater level of stability in recording and
playing back data. Using ADAT FST, seek-to­play functions are virtually instantaneous, and
the data fragmentation that can cause hard disk
crashes is greatly diminished. As a result, very
low-cost, widely available, low-RPM IDE hard
drives can be used with exceptional results. For
the first time, at about $4 per gigabyte, the cost
of the hard disk storage medium is less than that
of ADAT tape. Entire 24-track projects can be
stored on a single removable drive. Alesis
engineered custom drive caddies and protective
storage cases to establish today's affordable IDE
drives as the new exchange medium for music
recording. The HD24 ships with two drive
caddies, one loaded with a 10-gigabyte hard
drive which will yield approximately 45 minutes
of 24-track recording time at 24-bit/48 kHz, and
the other ready for you to install your own drive
in.

ADAT HD24 Reference Manual 3

Introduction/Safety Instructions

¾ Everything you need is built-in:

The HD24 comes complete with 24 channels of
analog and digital inputs and outputs—there are no
cards or extras to buy to get audio in or out of the
recorder. Superb sonic performance was a base-line
objective for Alesis. The HD24 provides 24 tracks of
high-resolution 24-bit uncompressed linear
recording at standard sample rates of 44.1kHz or 48
kHz. It supports 12 tracks at sample rates of

88.2kHz and 96kHz when slaved to external digital
products such as A/D, D/A converters, and a
forthcoming 96 kHz option will allow high-sample
rate analog I/O right from the back panel. An
external BNC word clock input is provided for
slaving to external clock sources. The HD24 also
provides powerful editing capabilities with CUT,
COPY, PASTE and multiple UNDO functions across
any or all tracks simultaneously.

¾ Connects easily to over 150,000 ADAT

systems worldwide:

The rear panel of HD24 includes 24 channels of
ADAT Optical inputs and outputs and ADAT Sync
IN and OUT connectors to allow HD24 to sample­accurately synchronize with other ADATs, a BRC
remote controller, and products from over 100
manufacturers. When connected to a BRC, the
HD24 emulates three traditional ADATs. Up to five
ADAT HD24 units can be synchronized to make up
to 120-track systems, simply by chaining 9-pin
cables from the Sync Out of one HD24 to the Sync In
of another.

¾ Provides multiple methods of file

transfer:

The HD24 allows you to move data to and from
the recorder in THREE convenient ways:

• The hard drives used by the HD24 are so
affordable that drive caddies can be stored
on the shelf just like tape, and instantly hot­plugged into the front panel when you want
to change projects. The ADAT FST drive
format establishes removable hard drives as
the most reliable, easiest-to-use multitrack
media for pro applications. Two front-panel
drive bays allow quick retrieval and fast
back up of projects. Drives are hot­swappable, and fast back-up (a few minutes
for an entire drive) is possible between two
front-panel drive bays.

• Industry-standard ADAT Optical I/O
allows transfer of up to 24 tracks of 24-bit
audio simultaneously in real-time using
inexpensive fiber-optic cables. The HD24
can easily send digital audio to and from
devices such as tape-based ADATs, digital
mixing consoles, and computer cards or
interfaces.

• A rear-panel Ethernet port allows the HD24
to be connected as a stand-alone FTP server
with its own IP address that can be accessed
from a computer network, even over the
Internet! Songs appear as folders on any
Web browser, containing individual .WAV
or AIFF files for each track. You can
download and upload files from any HD24
connected to a network. Files can then be
processed using computer-based editing
applications and moved back to the HD24.

4 ADAT HD24 Reference Manual

Introduction/Safety Instructions

ADAT HD24 key features:

1. 24 Track simultaneous recording at 44.1/48 kHz
(12 tracks @ 88.2/96 kHz)

2. Storage media: Standard IDE hard drive
(minimum 5,400 RPM)

3. Recording time per each 10 gigabytes @ 48kHz:
45 minutes x 24 tracks; @ 96kHz: 45 minutes x 12
tracks

4. Number of drive bays: Two front-panel, hot­swappable

5. Recording Modes:

44.1/48 kHz
24 track, 16 track, 8 track, 4 track, 2 track

88.2/96 kHz
12 track, 8 track, 6 track, 2 track

6. Resolution: 24 bit linear PCM encoding

7. Internal clock Fs: 44.1kHz, 48kHz, 88.2kHz,
96kHz; External clock; Varispeed -16%/+6%
@48kHz

8. A/D converters: Twenty-four channels of 24 bit,
128x oversampling (standard)

9. D/A converters: Twenty-four channels of 24-bit
128x oversampling (standard)

10. OPTION: 96 kHz-capable A/D/D/A board
(Dealer-installed circuit board, replaces standard
A/D/D/A circuit board)

11. Analog I/O spec: +4 dBu nominal level (for –15
dBFS digital level) on balanced 1/4" TRS
connectors x 48 (standard)

12. Digital I/O: 24 channels (3 each, 8 channels) ­ADAT Optical format IN, 24 channels ADAT

Optical OUT, on standard fiber-optic 1mm
Toslink-style connectors

13. Synchronization: ADAT Sync. Up to five
HD24 units can be synchronized for up to
120 sample-accurate tracks. Control and
slaving is possible from any ADAT Sync
device.

14. Remote control: Ships with ADAT LRC
remote control. HD24 can be also be
controlled via ADAT Sync port, or MIDI
Machine Control. Optional full-function
remote control (available soon).

15. Editing: Cut, Copy, Paste, Move, Insert
across any or all tracks. Multiple levels of
undo

16. MIDI: IN, OUT. MIDI Time Code transmit;
MMC and SYSEX transmit and receive

17. Software update method: Via MIDI or
Ethernet

18. Data transfer via Ethernet FTP, 10Base-T,
using standard Cat 5 cable (RJ-45 connector)

SONIC PERFORMANCE:

Frequency response: 22Hz - 22kHz ±0.5 dB
Total Harmonic Distortion: <.003%
Signal To Noise: > 103dB, A-weighted
Dynamic Range: 144dB, digital IN to digital
OUT; > 103 dB analog IN to analog OUT A­weighted

COMPARING MEDIA COST @48kHz:

Recording

UNIT
PRICE

ADAT Tape
(unformatted)

Standard IDE
Hard Drive
5400 rpm

ADAT HD24 Reference Manual 5

$15.00 ea. 42 min. x 8

$99.00/ 30
GB
Average

time per
media unit

tracks x 20 bit)

135 min. x 24
track, 24 bit

Qty. req'd
for 24 track,
45 min.
project

3 tapes 4 cents $1.00 $45.00

1/3 of a drive
(10 GB)

Per track
minute

3 cents 73 cents $33.00

Recording CostMEDIA

Per 24-track
minute

Per
project

Introduction/Safety Instructions

How to Use This Manual

This manual is divided into the following sections
describing the various functions and applications for
the ADAT HD24. While it's a good idea to read
through the entire manual once carefully, those
having general knowledge about studio equipment
should use the table of contents to look up specific
functions.

Chapter 1: Quick Start. If you're already
experienced with recording, this will get you started
using the ADAT HD24 right away. It's a short guide
to the essential elements of hooking it up and using
it for the first time. A brief tour of the front and
back panels also directs you to the chapters focused
on individual features.

Chapter 2: Connection and Chapter 3:
Basic Recording and Playback give detailed

instructions for connecting the ADAT HD24 to a
variety of typical audio systems and guides you
through your first recordings step-by-step. The
middle chapters focus on features you don't have to
know about, but that make recording and mixing
easier: Using Locate Points, Editing.

Chapters 6-9 cover deep background
information that will help you use your ADAT
HD24 to its greatest capability by synchronizing it to
other ADATs, communicating with sequencers
using MIDI, connecting it to a computer using
Ethernet, and adding 88.2/96 kHz sampling.

Near the end of the manual are troubleshooting
tips, specifications, and an Index to
help you find what you're looking for.

Helpful tips and advice are highlighted in a shaded

box like this.

In text, the names of specific controls or connectors
on the hardware of the HD24 are printed in a special
font, i.e., the RECORD button.

✪ When something important appears in the

manual, an icon (like the one on the left) will
appear in the left margin. This symbol
indicates that this information is vital when
operating the ADAT HD24.

6 ADAT HD24 Reference Manual

Important Safety Instructions

Safety symbols used in this
product

This symbol alerts the user that there are
important operating and maintenance instructions
in the literature accompanying this unit.

This symbol warns the user of uninsulated
voltage within the unit that can cause dangerous
electric shocks.

This symbol warns the user that output
connectors contain voltages that can cause
dangerous electrical shock.

Please follow these precautions
when using this product:

1. Read these instructions.

2. Keep these instructions.

3. Heed all warnings.

4. Follow all instructions.

5. Do not use this apparatus near water.

6. Clean only with a damp cloth. Do not spray any
liquid cleaner onto the faceplate, as this may damage
the front panel controls or cause a dangerous
condition.

7. Install in accordance with the manufacturer's
instructions.

8. Do not install near any heat sources such as radiators,
heat registers, stoves, or other apparatus (including
amplifiers) that produce heat.

blades with one wider than the other. A grounding­type plug has two blades and a third grounding
prong. The wide blade or the third prong are
provided for your safety. When the provided plug
does not fit into your outlet, consult an electrician for
replacement of the obsolete outlet.

10. Protect the power cord from being walked on or
pinched, particularly at plugs, convenience
receptacles, and the point where they exit from the
apparatus.

11. Use only attachments or accessories specified by the
manufacturer.

12. Use only with a cart, stand,
bracket, or table designed for use with
professional audio or music equipment.
In any installation, make sure that injury
or damage will not result from cables

pulling on the apparatus and its
mounting. If a cart is used, use caution when moving
the cart/apparatus combination to avoid injury from
tip-over.

13. Unplug this apparatus during lightning storms or
when unused for long periods of time.

14. Refer all servicing to qualified service personnel.
Servicing is required when the apparatus has been
damaged in any way, such as when the power­supply cord or plug is damaged, liquid has been
spilled or objects have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does
not operate normally, or has been dropped.

15. This unit produces heat when operated normally.
Operate in a well-ventilated area with at least six
inches of clearance from peripheral equipment.

16. This product, in combination with an amplifier and
headphones or speakers, may be capable of
producing sound levels that could cause permanent
hearing loss. Do not operate for a long period of time
at a high volume level or at a level that is
uncomfortable. If you experience any hearing loss or
ringing in the ears, you should consult an
audiologist.

17. Do not expose the apparatus to dripping or
splashing. Do not place objects filled with liquids
(flower vases, softdrink cans, coffee cups) on the
apparatus.

18. WARNING: To reduce the risk of fire or electric

9. Do not defeat the safety purpose of the polarized
or grounding-type plug. A polarized plug has two

ADAT HD24 Reference Manual 7

shock, do not expose this apparatus to rain or
moisture.

Introduction/Safety Instructions

Instructions de Sécurité Importantes (French)
Symboles utilisés dans ce produit

Ce symbole alèrte l’utilisateur qu’il existe
des instructions de fonctionnement et de
maintenance dans la documentation jointe avec ce
produit.

Ce symbole avertit l’utilisateur de la
présence d’une tension non isolée à l’intérieur de
l’appareil pouvant engendrer des chocs électriques.

Ce symbole prévient l'utilisateur de la
présence de tensions sur les raccordements de
sorties, représentant un risque d'électrocution.

Veuillez suivre ces précautions lors de
l’utilisation de l’appareil:

1. Lisez ces instructions.

2. Gardez ces instructions.

3. Tenez compte de tous les avertissements.

4. Suivez toutes les instructions.

5. N’utilisez pas cet allareil à proximité de l’eau.

6. Ne nettoyez qu’avec un chiffon humide. Il est

potentiellement dangereux d'utiliser des
pulvérisateurs ou nettoyants liquides sur cet
appareil.

7. Installez selon les recommandations du

constructeur.

8. Ne pas installer à proximilé de sources de

chaleur comme radiateurs, cuisinière ou autre
appareils (don’t les amplificateurs) produisant
de la chaleur.

9. Ne pas enlever la prise de terre du cordon

secteur. Une prise murale avec terre deux
broches et une troisièrme reliée à la terre. Cette

dernière est présente pour votre sécurité. Si
le cordon secteur ne rentre pas dans la prise
de courant, demandez à un électricien
qualifié de remplacer la prise.

10. Evitez de marcher sur le cordon secteur ou
de le pincer, en particulier au niveau de la
prise, et aux endroits où il sor de l’appareil.

11. N’utilisez que des accessoires spécifiés par le

constructeur.

12. N’utilisez qu’avec un stand,
ou table conçus pour
l’utilisation d’audio

professionnel ou instruments de musique.
Dans toute installation, veillez de ne rien
endommager à cause de câbles qui tirent sur
des appareils et leur support.

13. Débranchez l’appareil lors d’un orage ou
lorsqu’il n’est pas utilisé pendant
longtemps.

14. Faites réparer par un personnel
qualifié. Une réparation est nécessaire
lorsque l’appareil a été endommagé de
quelque sorte que ce soit, par exemple
losrque le cordon secteur ou la prise sont
endommagés, si du liquide a coulé ou des
objets se sont introduits dans l’appareil, si
celui-ci a été exposé à la pluie ou à
l’humidité, ne fonctionne pas normalement
ou est tombé.

15. Puisque son fonctionement normale génère
de la chaleur, placez cet appareil au moins
15cm. des équipments péripheriques et
assurez que l’emplacement permet la
circulation de l’air.

16. Ce produit, utilisé avec un amplificateur et
un casque ou des enceintes, est capable de
produite des niveaux sonores pouvant
engendrer une perte permanente de l’ouïe.
Ne l’utilisez pas pendant longtemps à un
niveau sonore élevé ou à un niveau non
confortable. Si vous remarquez une perte de
l’ouïe ou un bourdonnement dans les
oreilles, consultez un spécialiste.

8 ADAT HD24 Reference Manual

Introduction/Safety Instructions

Beim Benutzen dieses Produktes beachten Sie bitte die folgenden
Sicherheitshinweise: (German)

sind, um Schäden und Verletzungen zu
vermeiden. Wenn Sie einen Rollwagen

1. Lesen Sie die Hinweise.

2. Halten Sie sich an die Anleitung.

3. Beachten Sie alle Warnungen.

4. Beachten Sie alle Hinweise.

5. Bringen Sie das Gerät nie mit Wasser in
Berührung.

6. Verwenden Sie zur Reinigung nur ein
weiches Tuch. Verwenden Sie keine
flüssigen Reinigungsmittel. Dies kann
gefährliche Folgen haben.

7. Halten Sie sich beim Aufbau des Gerätes an
die Angaben des Herstellers.

8. Stellen Sie das Gerät nich in der Nähe von
Heizkörpern, Heizungsklappen oder
anderen Wärmequellen (einschließlich
Verstärkern) auf.

9. Verlegen Sie das Netzkabel des Gerätes
niemals so, daß man darüber stolpern kann
oder daß es gequetscht wird.

10. Benutzen Sie nur das vom Hersteller
empfohlene Zubehör.

11. Verwenden Sie ausschließlich Wagen,

Ständer, oder Tische, die speziell
für professionelle Audio- und
Musikinstrumente geeignet sind.
Achten Sie immer darauf, daß die
jeweiligen Geräte sicher installiert

benutzen, achten Sie darauf, das dieser
nicht umkippt, um Verletzungen
auszuschließen.

12. Ziehen Sie während eines Gewitters
oder wenn Sie das Gerät über einen
längeren Zeitraum nicht benutzen den
Netzstecher aus der Steckdose.

13. Die Wartung sollte nur durch
qualifiziertes Fachpersonal erfolgen.
Die Wartung wird notwendig, wenn das
Gerät beschädigt wurde oder aber das
Stromkabel oder der Stecker,
Gegenstände oder Flüssigkeit in das
Gerät gelangt sind, das Gerät dem
Regen oder Feuchtigkeit ausgesetzt war
und deshalb nicht mehr normal arbeitet
oder heruntergefallen ist.

14. Dieses Gerät produziert auch im
normalen Betrieb Wärme. Achten Sie
deshalb auf ausreichende Lüftung mit
mindestens 15 cm Abstand von anderen
Geräten.

15. Dieses Produkt kann in Verbindung mit
einem Verstärker und Kopfhörern oder
Lautsprechern Lautstärkepegel
erzeugen, die anhaltende Gehörschäden
verursachen. Betreiben Sie es nicht über
längere Zeit mit hoher Lautstärke oder
einem Pegel, der Ihnen unangenehm is.
Wenn Sie ein Nachlassen des Gehörs
oder ein Klingeln in den Ohren
feststellen, sollten Sie einen Ohrenarzt
aufsuchen.

ADAT HD24 Reference Manual 9

Introduction/Safety Instructions

CE Declaration of Conformity

Manufacturer’s Name: Alesis Corporation
Manufacturer’s Address: 12509 Beatrice Street

declares, that the product:

Product Name: ADAT HD24
Model Type: Digital audio recording device

conforms to the Standards for Safety and EMC for this product listed on the Internet site:

Instructions to the User (FCC Notice)

Los Angeles, CA 90066
USA

www.alesis.com

This equipment has been tested and found to
comply with the limits for a class B digital device,
pursuant to Part 15 of the FCC Rules. These limits
are designed to provide reasonable protection
against harmful interference in a residential
installation. This equipment generates, uses, and
can radiate radio frequency energy and, if not
installed and used in accordance with the
instructions, may cause harmful interference to
radio communications. However, there is no
guarantee that interference will not occur in a
particular installation. If this equipment does cause
harmful interference to radio or television reception,
which can be determined by turning the equipment
off and on, the user is encouraged to try and correct
the interference by one or more of the following
measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between the equipment

and receiver.

• Connect the equipment into an outlet on a
circuit different from that to which the receiver
is connected.

• Consult the dealer or an experienced radio/TV
technician for help.

This equipment has been verified to comply with
the limits for a class B computing device, pursuant
to FCC Rules. In order to maintain compliance with
FCC regulations, shielded cables must be used with
this equipment. Operation with non-approved
equipment or unshielded cables is likely to result in
interference to radio and TV reception. The user is
cautioned that changes and modifications made to
the equipment without the approval of
manufacturer could void the user’s authority to
operate this equipment.

10 ADAT HD24 Reference Manual

chapter 1

Quick Start Guide

If you can't wait to get started:

If you're experienced with multitrack recording, this
chapter is a "shorthand" guide for those who want
to start using the HD24 right away. The basic
hookup and operation of the Alesis ADAT HD24™
is similar to that of previous ADATs in most
respects. If you have questions about any of the
features, don’t worry – later chapters will unveil the
mysteries of the HD24's unique and special features.

✪ If you're new to multitrack recording, start

with the more detailed instructions for
hookup and operation starting in the next
chapter.

Step 1: Hook it up to a mixer

1. Pull the ADAT HD24 out of the package.

2. Make sure the POWER switch on the back of the

HD24 is OFF, and plug it into a grounded AC
power source with the supplied power cable.

2. Connect the outputs of a mixer to the INPUTS on

the back of the ADAT HD24.

3. Connect the OUTPUTS of the ADAT HD24 to the

LINE IN or TAPE IN jacks of the mixing
console.

If you're using a digital mixer:

Instead of steps 2 and 3 above, use optical
cables to connect the three sets of ADAT OPTICAL

DIGITAL inputs and the three sets of outputs to

the mixer.

You'll need six long optical cables for this.

4. Turn the POWER switch on the back of the HD24

ON.

Once you have done this, in the future you should

press the POWER switch on the front of the
HD24 to turn it on or off.

For more information on connecting the
HD24, see chapter 2: Connections.

ADAT HD24 Reference Manual 11

quick start guide • chapter 1

Step 2: Get the drive ready

Mount and select the hard drive

When you first turn on the power, the HD24 will
automatically mount the last drive that was selected
in the system. (Mounting means that the system
recognizes the disk, has powered it up, and can
communicate with it.) If you have two hard drives
installed, only one will be mounted. Since this is the
first time you are powering up the unit, the HD24
will mount the drive that you installed in Drive bay

1.

• If there were no drives inserted, they will be
mounted automatically when you push
them in.

• If you have two drives inserted, one drive
may be selected for use at a time, even
though both are mounted. A selected drive
is the one that will be used for recording or
playback. The drive that was most recently
selected will be selected automatically at
power-up. (See the icons next to the HD
FREE SPACE display to find out which one
is selected.

To select a disk if it's not mounted:

1. Press the DRIVE button of the disk you want to
use.

The display will read:

Selecting HD2

with a progress bar underneath for a few seconds,
until the drive has mounted.

Initialize or select the song

2. On a new, empty drive the display will read:

No songs on disk
(press NEW SONG)

Or, if the drive already has songs on it, it will
show the last song used.

S0 1 : "Song Name "
00:03:55:10 24t

Press YES (▲) (under the display) if you want to
change to a different song.

In any case, there has to be at least one valid drive
inserted and mounted, with its green DRIVE LED lit
before you can proceed.

NOTE: Never pull a drive caddy out unless the DRIVE

LED is OFF! Dismount the drive first by
pressing its DRIVE button and then the YES
(▲) button.

✪ If the HD24 is in a menu or mode you don't

understand, STOP. Look through the manual
to learn more about the situation before
proceeding.

12 ADAT HD24 Reference Manual

chapter 1 • quick start guide

Step 3: Try a test recording

Now we’re ready to try some basic recording. In
this exercise, we’ll simply record some audio into a
new song, then play it back to hear the results.

1. First, press the NEW SONG button on the top
right corner of the unit. The display should
look like this:

Create New Song?
(Press Y /N)

2. Press the YES (▲) button. The display should
then look like this:

SampleRate?48. 0 k
(Press New Song)

3. Press the YES (▲) or NO (▼) buttons to select a
sample rate–either 44.1kHz, 48kHz, 88.2kHz, or
96kHz.

If you aren’t sure which one to use, choose 48kHz.

4. When you’ve made a choice, press the NEW

SONG button. The display will prompt you for

the number of tracks:

# of Tracks? 2 4
(Press New Song)

5. Choose the number of tracks you want in your
session. Press the NO (▼) button a few times to
choose 8 tracks for this example, then press NEW

SONG.

The reason that you would choose a smaller number
of tracks is that larger sessions use much more disk
space.

The display will now show the default “Song
Name” and you are ready to record.

6. The next step is to choose an input format.

• If you are using an analog mixer, make sure that
“Input” is set to “Analog” on the bottom left
corner of the display. If it isn’t, press the INPUT

SELECT button.

• If you are using a digital mixer, press the INPUT

SELECT button so that the “Input” indicator in

the bottom left corner of the display reads
“Digital”. Then press the CLOCK SOURCE button
until the “Clock Source” indicator in the display
reads “Optical”. If you hear ticks and pops
when you arm a track, see page 25, “ADAT
Optical Digital Inputs and Outputs”.

7. Next, arm a track. Press the numbered buttons
below the meters of the tracks you want to arm,
also known as Track Record Enable buttons.

The red Record light will flash under the tracks
selected for record, and the blue Input light will also
turn on.

8. Send some signal to the HD24. This can be from
the Tape or Group outputs of your mixer, or
you can simply use a line level source (CD
player, drum machine, etc.). Plug this source
into the Input of the track you are recording to
(1,2, etc.)

9. Set the level of the source so that the loudest
peaks do not light the red “Clip” lights on the
HD24’s meters, but light the meter segments
just below that point.

10. Press PLAY and RECORD. Begin playing the
source.

11. Press STOP once you’ve recorded a few bars.

12. Press the REW or LOCATE 0 button to go to the
beginning of the song, then press PLAY to hear
what you recorded.

You can now arm other tracks and record more
layers to your song. When you’re finished, give the
song a name by pressing the NAME button and using

the oval-shaped cursor keys (YES (▲), NO (▼), <
and >).

ADAT HD24 Reference Manual 13

quick start guide • chapter 1

Front panel tour—left side

Meters

Each track has its own 10-segment, peak-reading meter.
When it turns yellow, you have 6 dB or less of
headroom left. At the top, the red CLIP warns you of
the onset of clipping.

If a track's meter is surrounded by a lit rectangle, that

track is currently selected for editing. See page

55.

REC INDICATORS: These indicate when a track is

"armed" for recording (flashing) or in record (solid),
as controlled by TRACK BUTTONS 1-24.

INPUT INDICATORS: These indicate when a track

is monitoring its input (indicator ON), as
controlled by the AUTO INPUT, ALL INPUT buttons
in combination with whether the track is armed.

See page 40 for details.

DRIVE 1, DRIVE 2: Use these buttons to select or

unmount (power down) a drive. The LED beneath
it indicates the state of
the drive:

• If the LED is
off, the drive is
unmounted (or
empty) and
may be
removed.

• LED green: the
drive is
mounted.

• LED red: the
drive is currently
being accessed for
recording or
playback.

Ö To see which drive is

selected, look at the icons
next to the HD Free Space
display. See page 49.

POWER (SOFT): Once the

"hard" POWER switch on the
rear panel is ON, push this to
turn the unit on and off.

TRACK BUTTONS 1-24: these are most often

used to arm a track for recording, but they
are also used to select tracks for editing.

TRACK EDIT: Hold this while pressing a TRACK

button to select a track for editing.

PEAK MODE: This sets how the

meter will display peaks:
continuously holding them until

PEAK CLEAR is pressed, holding

peaks on the meter for a few
moments, or not hold them at all.

For more about the meters and
level setting, see Chapter 3: Basic

Recording and Playback.

Drive
caddies:

The ADAT
HD24 records
on removable,

affordable IDE
hard drives. It
comes sup­plied with a 10­gigabyte drive
in the DRIVE 1
slot, which
gives you 45
minutes of 24­track recording
time (1080 total
track minutes).

The DRIVE 2
slot comes with an empty caddy, which you can fill
with an IDE drive of any size, from almost any
manufacturer (see your Alesis dealer for details).
Additional drive caddies are available from your
Alesis dealer, so you can instantly swap out
projects, just as conveniently as tape.

Never pull a drive caddy out unless its LED is
off! Doing so could physically damage the
drive or corrupt data on it.

For more information about drive caddies, see Chapter 5:

Working with Drives.

14 ADAT HD24 Reference Manual

Front panel tour—right side

chapter 1 • quick start guide

Editing buttons

The EDIT START and EDIT END
buttons define a region of a
track (or tracks, as determined
by the TRACK EDIT button) that
can be selected for editing.
Press CUT to remove the region
(leaving silence on the track),
and COPY to copy it without
removing it. PASTE pastes the
audio that was cut or copied
starting at the EDIT IN point,
overwriting data on the
selected track(s). If you decide
the edit you made was a
mistake, press UNDO to go back
to the way it was.

You can UNDO only
edit operations.
Recordings and
overdubs can't be
undone.

See Chapter 6: Editing for
detailed information on editing
in the ADAT HD24.

Locate/auto buttons

allow you to instantly access
seven different locations in
the current Song: LOCATE 0
returns to the zero point,
while LOCATE 1-6 instantly
locate to those points stored
in memory. SET LOCATE records
the current location in the next
locate point (above that shown
in the display). When AUTO

PLAY is on, the HD24 will

automatically start playing
when a locate point is reached.
The LOCATE key sends the HD24
to the location currently shown
in the bottom of the display.

See Chapter 4: Using Locate Points for
details.

Display buttons

These buttons relate to the icons
at the bottom of the display.

INPUT SELECT toggles between

analog or digital input. CLOCK

SOURCE selects whether the

HD24's sample rate will be set
by the INTernal clock, the

WORD IN jack on the back

panel, or the OPTICAL input.

If the clock is internal, SAMPLE

RATE allows you to select the

sample rate (44.1, 48, 88.2, or 96
kHz). LOCATE SELECT, along
with the cursor keys below,
allows you to select which of
the current Song's 24 locations
will be accessed when you
press the LOCATE key.

CURSOR buttons: YES (▲), NO

(▼), < and > control whatever
is currently shown the middle
of the display—selecting songs,
naming them, answering
questions. See the next page for
examples of how these are
used.

STOP, PLAY, RECORD work as

they do on any recorder. Tap

REW or FFWD to jump 5 seconds

in either direction, or hold them
to continue scanning.

Song buttons

Press SONG SEL to select any of
64 song locations to record or
play back. NEW SONG
initializes a blank song,
allowing you to choose how
many tracks it will have, etc.
Use DEL SONG to delete a song
from the hard drive, and NAME
to name a song or locate point.

Special features

As long as the clock source
display shows INT, PITCH allows
you to speed up or slow down
the playback or recording
speed.

UTILITY is used for important

housekeeping tasks such as

setting the ISP address,
etc.

TRACK SLIP is an editing

function that allows you
to time-delay or advance
any tracks up to 170 ms.

Press MIDI when you want
to see the menus that
control MIDI Time Code
generation, MIDI
Machine Control input,
etc.

See Chapter 8: Synchronization

and MIDI.

The AUTO RETURN and

AUTO RECORD buttons allow

you to set up a "loop" so you
can record a section over and
over, until you get it right.

REHEARSE allows you to hear a

punch in as if it were being
recorded, without erasing it.

Details are covered in Chapter 4:

Using Locate Points.

ADAT HD24 Reference Manual 15

quick start guide • chapter 1

A

A

About the Display

Time counter

shows the current location (from
the Song Start point, zero in ABS
time) in hours, minutes, seconds,
and frames.

The alphanumeric
display:

This does different things,
depending on what's
going on at the time. In
this example, it shows the
current Song (number 01,
titled "HD24".) On the
second line, it's showing
the length of the song: six
minutes, 13 seconds, and
20 frames. It's also
showing that this song has
24 tracks. As shown, the
cursor (underline) is
beneath the Song number,

and pressing the YES (▲) button would change to
Song 02. If a screen is asking a question (like,
Delete Song?), you press YES (▲) or NO (▼) as
you wish.

Status icons

show the current settings
controlled by the INPUT,

CLOCK SOURCE AND SAMPLE
RATE (switches underneath

the display) and the

MONITOR icon shows the

status of ALL INPUT AND

AUTO INPUT (switches to

the left of the display).

uto Icons

light whenever the

UTO RECORD, AUTO

PLAY, AUTO RETURN, or
REHEARSE functions are

engaged.

Locate point
display:

Each Song has its own
set of 24 Locate points.
This shows you which
one the HD24 will
access if the LOCATE
button is pressed. It
also shows you if the
point is being used as
the START, END, punch
IN or OUT point of one
of the AUTO features.

See Chapter 4: Using Locate

Points for details.

HD FREE SPACE indicator
shows how much
recording time is available
on the selected disk at the
current track width and
sample rate. The small
yellow indicator to the left
shows whether Drive 1 or
Drive 2 is selected (it's 2 in
this display)

Tracks
available

(Not in all
displays.) Shows
how many tracks
are available in the
current Song—in
this case, all 24.
Tracks take up
disk space even if
they're not
recorded, so don't
initialize a song
with more than
you need.
See page 30 for
information on
setting the track
count of a song.

Write-protect
status

(Not in all
displays.) An icon
of a locked
padlock will
appear in songs
that have been
protected from
changes. An
unlocked padlock
icon will appear in
songs that are
NOT write­protected.

16 ADAT HD24 Reference Manual

Rear panel tour

AC connector

This is where a standard IEC
detachable power cord plugs
in.

Analog I/O

These INPUT and OUTPUT jacks
may be connected to balanced
or unbalanced mixers, since
they're 3-conductor balanced
1/4” phone jacks (also called
TRS for “tip-ring-sleeve”). See

Chapter 2: Connections.

chapter 1 • quick start guide

ADAT Optical (Digital
I/O)

Each of these connectors carries
8 channels of digital audio
information (or, 4 channels at
the 88.2/96 kHz sampling rate).

See Chapter 2: Connections.

POWER switch (hard)

Normally, you'll leave this
switch on, controlling power
from the front panel switch.

Always turn off the unit using the

front panel POWER
switch first. The "soft"
power-off procedure
parks the drive heads,
so they may be removed
safely.

Ethernet

Connect this jack to a computer
to transfer audio to any
workstation. Each Song will
appear as a folder containing
each track as a separate .WAV
or .AIFF file. Since the HD24
uses FTP, you can even connect
this jack to a cable modem to
transfer files over the Internet.

See Chapter 9: Ethernet.

Word clock input

Connect the word clock output
of a digital mixer or master
clock source to this jack, to
ensure that everything in the
studio samples at exactly the
same time, avoiding ticks and
clicks.

LRC and PUNCH

Connect the LRC remote
control (supplied) to the LRC
jack, and any momentary
footswitch (optional) to the
PUNCH jack for hands-free
recording.

MIDI

MIDI IN allows the HD24 to
follow MMC commands from a
sequencer, and MIDI OUT can
transmit MMC and MTC (MIDI

Time Code). See Chapter 8:

Synchronization and MIDI.

ADAT Sync

Connect a remote control (such
as the BRC™) to the SYNC IN
jack. Or, connect a 9-pin cable
from the SYNC OUT jack of
another ADAT unit here to
expand a system to as many as
120 simultaneous tracks. See

Chapter 8: Synchronization and MIDI
and Chapter 2: Connections.

ADAT HD24 Reference Manual 17

quick start guide • chapter 1

18 ADAT HD24 Reference Manual

chapter 2

Connections

Unpacking and Inspection

Your ADAT HD24 was packed carefully at the
factory. The shipping carton was designed to
protect the unit during shipping. Please retain this
container in the highly unlikely event that you need
to return the HD24 for servicing.

The shipping carton should contain the following
items:

• ADAT HD24 with the same serial number as
shown on shipping carton

• Power cable

• LRC remote control unit

• This reference manual

• Two drive caddies, one with an installed hard
drive

• Stick-on rubber feet for table top installation

• Alesis warranty card

✪ It is important to register your purchase; if

you have not already filled out your
warranty card and mailed it back to Alesis,
please take the time to do so now.

Mounting on a Shelf or Non-Rack
Enclosure

To mount the HD24 on a shelf or other flat surface,
Alesis recommends attaching the included stick-on
feet to the deck’s bottom to avoid scratching the
shelf’s surface.

Installing in a Rack

The ADAT HD24 may be simply set on a table, or
installed in a standard 19” audio equipment rack.
The rack ears are integral to the unit.

✪ The ADAT HD24 has a small cooling fan that

vents towards the rear of the unit. Make sure
this outlet is not blocked. Make sure the rack
itself has ventilation of the rear area.

Thermal Considerations in Rack
Mounting

The HD24 can be mounted in an equipment rack
(taking up 3 rack spaces) or placed on a table or
shelf. When you install it, keep in mind that heat is
the major enemy of electronic equipment. Please
observe the following:

• The HD24 is designed to perform properly over
a range of ambient temperatures from 10° C to
+40° C (50° F to 104° F), in up to 80% non­condensing humidity. These are not absolute
limits, but Alesis cannot guarantee that the
HD24 will meet its published specs or remain
reliable if operated outside of these ranges.

• Always allow adequate ventilation behind the
HD24. Do not seal any enclosure that holds the
HD24. It is not necessary to leave an empty
rack space above or below the HD24 unless it
runs hot enough to affect equipment above or
below it. If your environment is unusually
warm and not air conditioned, space between
units will help the units run cooler.

Please observe the general comments on thermal
considerations given under “Thermal
Considerations in Rack Mounting” no matter where
or how the deck is mounted.

ADAT HD24 Reference Manual 19

• Do not attach the stick-on feet to the bottom of
the HD24 if it will be rack-mounted.

connections • chapter 2

Power

Make sure you read the initial Important

Safety Instructions chapter at the front of this
manual.

AC Power Hookup

With the POWER switch on the REAR
PANEL of the ADAT HD24 turned OFF, plug

the female end of the power cord into the HD24’s

POWER INPUT socket and the male (plug) end into a

good quality, noise-free AC power source of the
proper rating.

It’s good practice to not turn on the HD24 until all

other audio cables are hooked up as well.
Make sure your amplifier or powered
speakers are switched off when turning the
HD24 on or off to avoid damage.

The ADAT HD24 works with any standard line
voltage from 90 to 240 volts and comes with a
detachable AC line cord suitable for the country to
which the unit is shipped.

Do not operate any electrical equipment with
ungrounded outlets. Plugging the ADAT
HD24 into an ungrounded outlet, or “lifting”
the unit off ground with a three-to-two wire
adapter, can create a hazardous condition.
Alesis cannot be responsible for problems
caused by using the ADAT HD24 or any
associated equipment with improper AC
wiring.

To use the ADAT in another country:

The ADAT HD24 has what's called a "switching
power supply". That means it works with any AC
voltage from 90 to 250 volts, 50 to 60 Hz. This
eliminates the need for transformers or voltage
switches when you travel from country to country.
Your HD24 was supplied with the correct power
cord for your country or local area. If you plan to
travel with it to another country, obtain an IEC-spec
AC power cable compatible with the outlets used in
the other country and use it in place of the supplied
cable. The following alternative power cords are
approved for use with it:

AC Grounding

The line cable is an IEC-spec AC power cable
designed to be connected to a grounded 3-pin
outlet, with the third, round pin connected to
ground. Do not substitute any other type of AC
cord; IEC-spec cables of various lengths may be
purchased from electronics stores or your Alesis
dealer.

The ground connection is an important safety
feature designed to keep the chassis of electronic
devices such as the ADAT HD24 at ground
potential. Unfortunately, the presence of a third pin
does not always indicate that an outlet is properly
grounded. You may use an AC line tester to
determine this. If the outlet is not grounded, consult
with a licensed electrician. When AC currents are
suspected of being highly unstable in VAC and Hz,
a professional power conditioner should be used.

• For 90-120 VAC 50/60 Hz operation in the US,
Canada and/or Japan, use Alesis UL/CSA
power cord #7-41-0001.

• For 240 VAC 50 Hz operation in England, use
Alesis Power cord #7-41-0004.

• For 220 VAC 50 Hz operation in Europe and
Scandinavia, use Alesis EU power cord #7-41-

0002.

• For 240 VAC 50 Hz operation in Australia, use
Alesis AS power cord #7-41-0003.

Do you hear an AC hum in your system?

For detailed tips on how to get rid of "ground
loops" that cause hum, see page 92.

20 ADAT HD24 Reference Manual

chapter 2 • connections

Analog inputs and outputs

✪ When connecting audio cables and/or

turning power on and off, make sure that all
devices in your system are turned off and the
volume controls are turned down.

Outputs from the HD24 to a mixing
console:

Balanced outputs

The ADAT HD24's 24 analog OUTPUTS should be
connected to the balanced line inputs or "tape
inputs" of a recording console.

The line inputs of most modern consoles are
designed to accommodate a three-conductor TRS
(tip-ring-sleeve) 1/4" phone jack, (non-military
type) as shown below:

Unbalanced Line Input

Signal

Ground

Tip

Sleeve

Balanced Line Input

Hot

Cold

Ground

Tip

Ring

Sleeve

Unbalanced outputs

You may use two-conductor 1/4" phone cables if
your mixer doesn't have balanced inputs. In some
cases, the mixer may have "RCA/Phono" inputs. In
this case, obtain adapter cables.

Tip: Label or color-code cables wherever

possible. With 48 different I/O connections,
you don't want to guess. "Snakes" (multipair
cables) are a good idea; you can get them in
8, 16, and 24-channel versions. Some have
numbers written on the wire so you can tell
one cable from another.

Others use different colors of wire. If so, use an

acronym to keep the colors in order (like "Roy
G. Biv" stands for red-orange-yellow-green­blue-indigo-violet in the order 1-2-3-4-5-6-7-

8). Use the same color order for the inputs
and the outputs.

If you're using snakes, make sure you label (with a

marking pen on tape, or with a commercial
label machine) which are the inputs, which are
the outputs, and which tracks they go to.
Someday, you'll be glad you took the time.

Tip

Sleeve

Ring

Tip

Sleeve

If the mixer has XLR line inputs:

First of all, make sure that the XLR inputs are for
“tape returns”. XLR inputs on most consoles are
intended for microphone-level signals, not line-level
inputs. However, if the line or tape inputs of the

This is the same connector used in the ADAT HD24.
Obtain 24 channels of 3-conductor TRS 1/4"-to-1/4"
cable, and connect the outputs of the HD24 to the

console use XLR connectors, you'll need to obtain an
XLR-to-TRS (1/4") cable assembly. These are wired
as shown below:

inputs of the console.

Pin 1 (Ground)

Pin 2 (+)

Sleeve (Ground)

Ring (-)

Tip (+)

Pin 3 (-)

Don't use line transformers: Many XLR-to-1/4" adapters sold at electronics stores are NOT adapters,

but transformers (and very low quality transformers at that). Don't use these on the output of the ADAT
HD24—they're unnecessary and generally sound awful because they don't have the headroom to handle the
ADAT HD24's output. Get a hard-wired adapter or cable from your professional audio dealer, or make one
yourself from components.

ADAT HD24 Reference Manual 21

connections • chapter 2

From the console to the
HD24's inputs:

What's INPUT NORMALLING?

Most affordable analog consoles don't
have 24 outputs. Even those with 24 or
32 tape inputs usually have only eight
busses or group outputs. Luckily, the
HD24 is designed so it can still be used
with eight, four, or even two-bus
consoles, thanks to a feature called
input normalling that allows signal
from the console plugged into one
track to appear at others. For example,
if you have an 8-bus console, simply
connect from the bus/group outputs to
the first 8 tracks of the ADAT HD24.
Signal from the first input will appear
at tracks 1, 9, and 17 without forcing
you to repatch any cables, once you set
the INPUT NORMALLING feature.

To connect from the group
outs of a mixer:

You can choose between five different Input Modes:
2-Input Mode, 4-Input Mode, 8-Input Mode, 12­Input Mode, and 24-Input Mode. These can provide
five different analog audio input hookup options:

• 2 Bus Mixer: Connect the mixer’s two bus
outputs to the HD24’s INPUTS [1] and [2]. Select
2-Input Mode on the HD24 by holding down
the INPUT SELECT button until the display reads:

Select Audio
Input Tracks

Then press either Track Select buttons [1] or [2];
notice that the INPUT LEDs for tracks 1 and 2
remain lit until you release the INPUT SELECT
button.

• 4 Bus Mixer: Connect the mixer’s four bus
outputs to the HD24’s INPUTS [1] through [4].
Select 4-Input Mode by holding down the INPUT

SELECT button until you’re prompted to select

the tracks; press either Track Select buttons [3]
or [4]. The INPUT LEDs for tracks 1 through 4
remain lit until you release the INPUT SELECT
button.

• 8 Bus Mixer/Direct Outputs: Connect
the mixer’s eight bus outputs (or 8 direct
outputs) to the HD24’s INPUTS [1] through [8].
Select 8-Input Mode by holding the INPUT

SELECT button and pressing any Track Select

button from [5] - [8]. The INPUT LEDs for tracks
1 through 8 remain lit until you release the

INPUT SELECT button.

• 12 Bus Mixer: You’ve got the drill by now,
right? When the display reads “Select
Audio Input Tracks”, press a Track
Select button between 9 and 12, and the lower
inputs will “normal” to the higher tracks (1 to 1
and 13, 2 to 2 and 14, etc.)

• 24 Bus Mixer (or Direct Outs): Same
deal—press INPUT SELECT and press a track 13 or
above to have the “normal” setup with each
track “hearing” its own separate input.

In the first four modes, the HD24 internally
connects the inputs to the higher tracks (for
example, Input 1 goes to tracks 1, 9 and 17 in 8­Input mode).

22 ADAT HD24 Reference Manual

chapter 2 • connections

About Audio Cables

The connections between the ADAT HD24 and your
studio are your music’s lifeline, so use only high
quality cables. These should be low-capacitance
shielded cables with a stranded (not solid) internal
conductor and a low-resistance shield. Although
quality cables cost more, they do make a difference.

¾ Route cables to the HD24 correctly by

observing the following precautions:

• Do not bundle audio cables with AC power
cords.

• Avoid running audio cables near sources of
electromagnetic interference such as
transformers, monitors, computers, etc.

• Do not place cables where they can be stepped
on. Stepping on a cable may not cause
immediate damage, but it can compress the
insulation between the center conductor and
shield (degrading performance) or reduce the
cable’s reliability.

• Avoid twisting the cable or having it make
sharp, right angle turns.

• Never unplug a cable by pulling on the wire
itself. Always unplug by firmly grasping the
body of the plug and pulling directly outward.

Typical input jack hookups

The inputs of a multitrack recorder are typically
hooked up in one of three ways:

• From the console’s "direct outs"

(sometimes labeled "tape outs".

This patches one channel of the mixer directly
to one track of the recorder, bypassing most
mixer circuitry. This is preferred when the
signals going to tape require none of the mixer’s
features (effects, grouping, routing, etc.).

• From the mixer's "bus" or "group"
outputs. You can use the mixer for grouping,
premixing, effects, etc. This puts more circuitry
between the sources and the HD24, although
since most routing can be done at the mixer,
you’ll seldom need to do any repatching.

• From a combination of direct
outputs and bus outputs. Some
situations require a combination of the two
approaches, especially if you're recording a lot
of tracks at once and your mixer has only 8
group outputs:

¾ Example:

Here's a typical arrangement that might be used on
a live tracking session, cutting basics for a full band
plus two "guide vocals":

And most importantly, keep connectors

clean. Every few months, unplug them and

wipe off oxidation with a clean cloth soaked in
alcohol or contact cleaner. Insert the plugs in
the jacks a few times, to clean the internal jack
contacts. Although Alesis does not endorse
any specific product, certain chemicals, when
applied to electrical connectors, are claimed to
improve the electrical contact between
connectors. Avoid oily products that actually
attract more dirt.

The ADAT HD24 is wired according to the modern

standard of “Pin 2 (tip) = Hot”. Some older
equipment was wired with Pin 3 hot; check to
make sure correct polarity is maintained
throughout your system.

Mic Mixer out Track

Kick Direct out 1

Snare " 2

Snare bottom " 3

Hi-hat " 4

Tom 1 Group 1-2 5-6 (pan left)

Tom 2 " 5-6 (left-center)

Tom 3 " 5-6 (right-center)

Tom 4 " 5-6 (pan right)

Overhead left Direct out 7

Overhead right Direct out 8

Bass " 9

Guitar " 10

Piano Group 3-4 11-12 (stereo)

Digital synth " "

Analog synth " "

Vocal 1 Direct out 13

Vocal 2 " 14

ADAT HD24 Reference Manual 23

connections • chapter 2

Even a 4-bus mixer could be used to record these 14
tracks.

Sync In/Out

The two DB 9 connectors on the back panel marked

SYNC IN and SYNC OUT are used for synchronizing

two or more HD24s together, or a combination of
HD24s and other ADATs, or a computer
workstation using the ADAT/EDIT card or similar
device. Up to five HD24s can be linked, making a
120-track system. This requires a male-to-male, 9­pin D connector cable for each additional machine
in the chain.

Use only Alesis-approved Sync cables, available in

various lengths from your dealer. Improper

cables (such as those used for
computers) may not function
correctly.

In such a system, you are basically treating all
connected machines as though they were a large
multitrack unit. The first ADAT in the chain is
called the “master”, and all other connected units
are referred to as “slaves”. However, each slave can
also be used independently when the master
machine is stopped.

The Sync In and Out connections can also be used
for synchronizing to SMPTE Time Code. See
Chapter 8 for more information.

To synchronize multiple HD24s
and/or ADATs:

1. Locate the SYNC IN and SYNC OUT connectors.

2. Connect one end of a male-to-male, 9-pin
connector cable to the master’s SYNC OUT jack.

3. Connect the other end of the cable to the first
slave’s SYNC IN jack.

4. For additional slaves, connect one end of a
male-to-male, 9-pin D connector cable to the
first slave’s SYNC OUT jack, and the other end to
the second slave’s SYNC IN jack. Its SYNC OUT
jack then connects to the third slave’s SYNC IN
jack, and so on.

The moment the SYNC connection is made, the
slave machine(s) will automatically switch to
external clock and follow transport commands from
the master (unless taken offline by dismounting all
drives, or ejecting tapes). For more

information about using multiple HD24s
and/or ADATs, refer to chapter 8.

The illustration below depicts an ADAT HD24
being used as the master machine to another HD24
so they can be synchronized together, making a 48­track recorder.

24 ADAT HD24 Reference Manual

chapter 2 • connections

ADAT Optical Digital Inputs and
Outputs

Each of the digital inputs and outputs of the ADAT
HD24 carries eight tracks or channels (up to 48 kHz)
on a single fiber optic cable in the industry-standard
ADAT Optical format. To cover the 24 tracks of the
HD24, there are three sets of inputs and three sets of
outputs. Connect these outputs if you want to:

• copy audio between ADATs within the
digital domain

• connect to a digital mixing console

• transfer audio to and from a computer

workstation with ADAT Optical ports

• receive digital signals from many Alesis
keyboards and effect devices

Digital copying requires three fiber optic cables for
each HD24 in the system (or any other ADAT­compatible product). Additional cables are available
from your dealer in various lengths up to 16 feet.
When connecting a digital mixer, you'll need six
cables per HD24 in the system. Digital audio
connections can be made while power is on or off.
Note: To bounce tracks within a single HD24, it is
not necessary to connect the optical network.

To transfer audio from the HD24 to
non-24-bit systems you have two
options:

1. Transmit at 24 bit, and the receiving unit will
ignore the bits it can't read, essentially cutting
them off. This option provides the lowest noise
when tracks are going to be processed and
mixed.

2. Connect the machines via analog inputs and
outputs. This will effectively dither the 24-bit
signal of the HD24 to whatever the receiver is
using. While a digital transfer is theoretically
best, today’s converters are of such high quality
that the difference is usually not audible.

High sample rate operation

At the 88.2 and 96 kHz sample rates, the ADAT
Optical format becomes essentially a 4-channel
interface. See Chapter 7, "High Resolution
Operation".

About 16-bit and 20-bit signal
transfers

All data on the ADAT Optical cable has always
been in a 24-bit word length; in earlier 16-bit
ADATs the eight least significant bits are filled with
zeroes, in 20-bit ADATs the last four bits are zeroes.
If 24-bit data is sent to a 20-bit machine, the four
“extra” bits are simply ignored, much as fractions of
a penny don't matter when you actually pay your
bill at the gas station. ADAT Type II machines
(such as the M20, XT20, and LX20) can receive a full
20-bit transfer via the optical cables (if the tapes in
those machines were formatted in 20-bit mode).
The ADAT/EDIT system can receive a full 24-bit
transfer, as can many other computer workstations.

If you have a digital mixer, you may need to

upgrade its software or hardware to receive or
generate true 24-bit signals via the ADAT
Optical interface.

ADAT HD24 Reference Manual 25

connections • chapter 2

To connect the digital inputs and
outputs

1. Locate the DIGITAL IN and DIGITAL OUT
connectors for Tracks 1-8.

Remove the connectors’ plugs (if present) and store
for later use.

2. Remove the clear, plastic tube covering each
end of the optical cable (if present). Connect
one end of the fiber optic cable into the DIGITAL

OUT 1-8 jack of the HD24.

The cable is non-polarized, so either end can be
inserted into the optical output.

3. Connect the other end of the fiber optic cable to
the ADAT Optical™ input for the first eight
tracks of the receiver (mixer, computer
interface, or ADAT).

Tip: if the machines are on, the cable from the source
machine will show a red light at the end.

4. Repeat steps 2 and 3 for the DIGITAL OUT 9-16
and DIGITAL OUT 17-24 jacks.

At this point, you should be able to PLAY a song on
the HD24 and hear it (or see the meters move) on the
other unit.

5. Now, connect the outputs of the other device to
the DIGITAL IN 1-8, DIGITAL IN 9-16 and DIGITAL

OUT 17-24 of the HD24.

Only eight outputs on the other device?

In some cases, such as an 8-bus digital mixer
without direct outputs, you may not need to
connect to the DIGITAL IN 9-16 and DIGITAL IN

17-24 of the HD24. The HD24 can

electronically "patch" a digital input from its
first eight inputs to higher tracks if needed.
See page 22.

The illustration below shows an HD24 connected to
an 8-bus digital mixer. The mixer’s ADAT Optical
outputs are connected to the HD24 Digital Inputs
and the HD24’s Digital Outputs are connected to
the mixer’s ADAT Optical Inputs.

26 ADAT HD24 Reference Manual

chapter 2 • connections

Copying between ADATs

If you combine an ADAT HD24 with several
ADATs in a system and aren't using a digital mixer,
you may connect them directly so you can copy the
HD24 to tape and the tapes to the HD24.

To digitally copy between an HD24 and tape-based
ADATs, simply connect the DIGITAL OUTS of the
HD24 machine to the DIGITAL INS of three different
ADATs, and then the inputs to the outputs, as
shown below. Connect the SYNC OUTS so the
HD24 is last in the chain.

ADAT Optical hookups between two HD24s aren’t

usually necessary—it’s faster to simply swap
hard drives and make copies in a single
machine.

Don’t loop the opticals: Unlike tape-based

ADATs, the HD24 is not designed to be
connected in a digital loop; there is no “digital

through” mode where one HD24 will simply
“pass along” the digital signal at its input. The
digital output of each HD24 simply represents
whatever is on that particular machine.

ADAT HD24 Reference Manual 27

connections • chapter 2

Connecting to a computer interface
card

This illustration shows an HD24 connected to an
ADAT-compatible computer interface card. The
card’s ADAT outputs are connected to the HD24
Digital Inputs and the HD24’s Digital Outputs are
connected to the card’s ADAT Inputs. In this
particular case the ADAT SYNC is connected so that
the card (computer) is the master or controller of the
ADAT HD24. Check with the manual for your
computer interface for complete instructions.

28 ADAT HD24 Reference Manual

chapter 2 • connections

Footswitches

The HD24 provides two footswitch connectors on
its rear panel using 1/4" mono (T/S) jacks. One,
labeled LRC, allows locate and play commands when
used with a standard footswitch, or more elaborate
control when used with the LRC Remote control;
the other, labeled PUNCH, is for punch in/out
control.

The two footswitch jack functions are designed to
be used with any momentary single-pole/single­throw footswitch (either normally open or normally
closed*). These should be plugged in prior to
power-up so that the HD24 can configure itself for
the type of footswitch being used.

✪ When using a normally open footswitch, the

footswitch can be plugged in without
restarting the HD24 (powering down and
powering up). However, if using a normally

closed footswitch, the HD24 should be
restarted after plugging it in. Don’t step on

the footswitch while the HD24 is being
powered on, or the switch will operate
“backwards”.

The LRC Remote

You can connect the compact “LRC” HD24 remote
control unit to the LRC jack only to provide remote
access of transport functions. Using the punch jack
for an LRC does not work on the HD24. An ADAT
LRC can also be used, but double-check the labeling
of the buttons as these have changed for the HD24.

The Punch In/Out footswitch and HD24 Remote

both work in conjunction with the Rehearse
and Auto Record features. See Chapter 4,
"Using Locate Points".

ADAT HD24 Reference Manual 29