ALESIS ADAT "BLACK FACE" Reference Manual
TABLE OF CONTENTS CHAPTER 1: INTRODUCTION
1.0 ABOUT ADAT...5 1.2 IMPORTANT NOTE ABOUT THIS MANUAL..9 1.3 OVERVIEW OF MAIN FUNCTIONS..10 1.3A Transport...10 1.3B Record/Monitor functions..10 1.3C Punching...10 1.3D Autolocation...11 1.3E LED Indicators...11 1.4 ENGAGED VS. DISENGAGED TAPES..11 1.5 A WORD ON ADAT's S-VHS CASSETTE TAPE.12 1.6 OPERATING ENVIRONMENT...13 1.6A Thermal Considerations in Rack Mounting.13 1.6B Mounting on a Shelf or Non-Rack Enclosure..13 1.6C Avoiding Electromagnetic Interference.13

CHAPTER 2: HOOKUP

2.0 POWER...15 2.0A The AC Cord..15 2.0B Avoiding Ground Loops..16 2.1 AUDIO CABLE TIPS..17 2.2 AUDIOUNBALANCED INPUTS..18 2.2A Input Jack Characteristics..18 2.2B Typical Input Jack Hookups..19 2.2C Special Unbalanced Input Jack Wiring.19 2.3 AUDIOUNBALANCED OUTPUTS...20 2.4 AUDIOBALANCED INPUTS AND OUTPUTS..21 2.5 DIGITAL I/O...21 2.6 SYNC....21 2.7 METER BRIDGE...22 2.8 FOOTSWITCHES....22
CHAPTER 3: GETTING READY TO RECORD
3.0 POWER-UP AND TAPE INSERTION..23 3.1 FORMATTING A TAPE...23 3.1A To Format A New Tape, or Reformat/Erase an Old Tape...24 3.1B To Extend a Format...25 3.1A Additional Format Considerations..26 3.1B Record A Benchmark Tape...27 3.2 TRACK RECORD/MONITOR CONTROLS.27 3.2A Record Enable Buttons..27 3.2B Auto Input Monitor...27 3.2C All Input Monitor..29 3.2D Digital Input...29 3.3 SETTING LEVELS...29 3.4 TRANSPORT CONTROL OPERATION...31 3.4A Eject...31 3.4B Rewind...31
3.4C Fast Forward...31 3.4D Stop...32 3.4E Play...32 3.4F Record/Punch In or Out..33 3.5 FOOTSWITCH-CONTROLLED PUNCHING..34
CHAPTER 4: PITCH, AUTOLOCATION, AND REMOTE CONTROLS
4.0 PITCH CONTROLS...35 4.1 AUTOLOCATION CONTROLS..36 4.1A Setting Locations...36 4.1B Autolocating to One of the Three Location Points..37 4.1C Shuttling Between Locate 1 and 2..37 4.1D The Auto Play Function...38 4.1E Record, Then Audition Your Part..38 4.2 FOOTSWITCH CONTROLLED AUTOLOCATION..38 4.3 USING THE LRC REMOTE CONTROL...39
CHAPTER 5: MULTIPLE ADAT OPERATION
5.0 MULTIPLE ADAT BASICS41 5.1 SYNCHRONIZING MULTIPLE ADATS..42 5.1A Hooking Up Multiple ADATs..42 5.1B ADAT ID (Identification) Numbers..42 5.1C How the Master and Slave Decks Interact..43 5.1D Achieving Lock...44 5.1E Independent Slave Mode..44 5.2 FORMATTING WITH MULTIPLE ADAT SYSTEMS..44 5.2A Master Format Enabled and Performing a Complete, Start-to-Finish Format.44 5.2B Master Format Enabled and Extending the Format...45 5.2C Master Format Disabled..45 5.3 AUTO-LOCATION/LOOPING WITH MULTIPLE ADATS...47

CHAPTER 6: BACKUP

6.0 BACKUP BASICS...49 6.1 BACKING UP VIA DIGITAL I/O..49 6.1A Normal Method...50 6.1B Optical-Only Method..52 6.2 BACKING UP VIA ANALOG I/O...53

CHAPTER 7: APPLICATIONS

7.0 7.1 7.2 7.3 7.4 COMBINED MULTITRACK/ MASTERING DECK..55 ARCHIVING...55 BOUNCING....56 LIVE RECORDING...56 USING ADAT WITH MIDI SEQUENCERS VIRTUAL TRACKING...56 7.6 VIDEO LOCATION RECORDING...57 7.7 MODULAR RECORDING 57
CHAPTER 8: ADAT ADVANCED FEATURES
8.0 ABOUT THE ADVANCED FEATURES..59 8.1 ADVANCED FEATURES 59 8.1A Eject the tape in the Master ADAT of a Multi ADAT System...60 8.1B Device Id....60 8.1C Auto Input Monitor Option Select..60 8.1D Software Version...60 8.1E Tape Write Protect Status..60 8.1F Monitor/Audio Path Select..61 8.1G Crossfade Select...61 8.1H Digital 48k Master Clock Enable/Disable..62 8.1I Total Running Time of Drum Motor..62
CHAPTER 9: MAINTENANCE/SERVICE
9.0 GENERAL INFORMATION63 9.0A Cleaning...63 9.0B Maintenance...63 9.0C Refer All Servicing to Alesis..63 9.1 ADAT HEAD LIFE...64 9.2 ADAT HEAD MAINTENANCE...64 9.3 TAPE MAINTENANCE - SAFE TAPE..66 9.4 ERROR MESSAGES...67 9.4A ADAT Messages and Explanation..68 9.4B Errors 1 to 9..69 9.4C Steps to Take Before Calling for Help..71

CHAPTER 10: APPENDICES..

10.0 APPENDIX 1 DIGITAL RECORDINGA QUICK TOUR..73 10.0A Analog Tape Recording Basics..73 10.0B Digital Tape Recording Basics..74 10.0C Why Does ADAT Use S-VHS Cassettes?..74 10.1 APPENDIX 2 GLOSSARY....76 10.2 APPENDIX 3 SPECIFICATIONS...80 10.3 APPENDIX 4 SCHEMATICS...83

To sync together two or more ADATs, connect the Sync Out from the master to the next ADATs Sync In. Its Sync Out can in turn feed a third ADATs Sync In, etc. This requires a shielded dual male, 9-pin D connector cable available at your Alesis dealer. For more information on syncing ADATs together, see Chapter 5.

METER BRIDGE

To connect ADAT to the Alesis RMB Remote Meter Bridge, run a dual male, 9-pin D connector cable from the ADAT Meter Bridge out connector to the RMB input connector.

FOOTSWITCHES

Any momentary single-pole/single-throw footswitch, normally open or normally closed, will work for the two footswitch functions. These should be plugged in prior to power-up so that ADAT can configure itself for the type of footswitch being used.
3.0 POWER-UP AND TAPE INSERTION
After all connections are made, turn on power. ADAT first checks whether a tape has been inserted.
If a formatted tape is present, the counter shows the elapsed time since the beginning of the tape. If an unformatted tape is present, the counter will show noFO, and the FORMAT LED will flash to indicate that the tape needs formatting. At this point you should format the tape (see next section). If there is no tape, the counter shows "----" to indicate no tape is present.
Insert the end with the hinged door first, label side up, until you encounter a slight bit of resistance. Push gently on the center of the cassette until ADAT draws the tape inward. Once ADAT has started to pull in the tape, do not keep pushing the tape in. Note: to record on a S-VHS cassette, the write protect tab (located on the spine of the cassette) must be intact. If you try to record on a tape that has had the write protect tab broken off, the display will read "Prot" and the ADAT will not record on the tape. This allows you to prevent accidental erasure of valuable recordings. To record on a tape that has had the tab broken off, simply use a piece of scotch tape, label, etc. in place of the write protect tab to completely cover the hole in the cassette's spine.

FORMATTING A TAPE

Just as formatting a floppy disk lets a computer know where to place data, formatting an ADAT tape time-stamps the tape to single-sample accuracy so that audio is referenced to an accurate time base. This allows for simplified synchronization, accurate tape counter readings, and intelligent autolocation with the BRC Remote Control. When formatting begins, ADAT writes some setup data during the first two minutes and 15 seconds of tape, then at time -00:05, writes the time in minutes and seconds onto a special sync track. This does not use up any of the eight audio tracks. Please note: The display shows timings with a period separating the hours and minutes (00.00), but this manual shows a colon instead of a period for clarity (00:00).

Audio can be recorded while formatting, just in case you have a hot musical idea but no formatted tapes. Simply press record enable for the tracks to be recorded before pressing the Format button. Tracks not enabled prior to pressing Format will be recorded with silence, and cannot be enabled once formatting begins. It is a good practice to "exercise" the tape before formatting it by fast forwarding it to the end, then rewinding it back to the lead. This evens out the tape pack and relieves any stresses and strains that may have occurred during tape manufacture and storage. Blank tapes must be rewound to the very beginning in order to be formatted. Caution: Do not re-format over a previously formatted tape, then stop reformatting. When the tape transitions from the newly-formatted part to the previously formatted part, there will be timing discontinuities and the audio will do unpleasant things. Also, during that transition the tape will be non-functional and you will not be able to record anything over it. When in doubt, either re-format the tape all the way to the end, or back up a bit and do a format extension (see previous section and next section) when you need to re-format over the transition zone. For safety, label your tape. You dont want your ADAT tape confused with a standard video tape. The only way to stop formatting is to press Stoppunching out is not sufficient. Tapes can be bulk-erased with a bulk tape eraser. In a multiple-ADAT setup where one is the master and other ADATs are slaves, there are several other considerations. See Chapter 5.
3.1D Record a "Benchmark" Tape
We recommend that you format and record a new tape with any signal, such as a test tone, in a single pass with no overdubs during the first week of operation. Store this tape in a safe, dry location and don't use it for any other purpose. Such a "benchmark" tape is useful to determine if the error correction rate is increasing over time because the heads need to be cleaned, or if a tape is defective. See Section 9.2.
TRACK RECORD/MONITOR CONTROLS
These controls determine which tracks will be recorded on in record mode, and whether tracks will monitor the input or taped signal.

3.2D Digital Input

This switch determines whether ADAT will record from its analog inputs (balanced or unbalanced) or digital input. To record from the digital input, press the switch; its LED will light. All eight channels will be received via the fiber optic connection (section 6.1) and the analog inputs will be ignored. DIGITAL IN can be turned on or off only when the ADAT is in STOP mode. When recording while DIGITAL IN is on, the ADAT's speed is slaved to the clock of the incoming digital signal. The PITCH controls will have no effect when recording from the digital inputs, although they will remain lit. Do not turn on DIGITAL IN if nothing is connected to the digital input, since the ADAT will "hunt" for a clock that isn't there, causing long sync times. (For the one exception to this rule, see Section 6.1A.)

SETTING LEVELS

Unlike analog tape recorders, whose meters indicate 0 VU at the ideal nominal recording level, with 10 to 15dB headroom above the point, 0dB on ADAT represents
the maximum possible signal level. Signals above 0dB will be clipped and lead to digital distortionan ugly, splattering sort of sound. As on most digital recorders, O dB on the ADAT meter is referenced to full scale, the maximum signal that can be recorded in 16 bits. Reference-level signals plugged into ADAT are recorded 15 dB below full scale. For example, if your mixer has +4 dBu balanced outputs that are connected to ADAT's +4 dBu multipin ELCO connector (or it has -10 dBV unbalanced outputs connected to ADAT's 1/4" phone jacks), when your mixer's meter reads 0 VU, the ADAT meter will read -15 dB. Therefore, you can run your mixer levels "into the red" over 0 VU and still not distort the ADAT until the mixer's meter reads "+15". Just remember that no matter what, if ADAT's meters indicate 0 dB (highest red LED lit), distortion is on the verge of occurring. Theoretically, the lowest noise and distortion in an ADAT recording occurs just as the highest input peaks barely reach 0 dB full scale. Unlike analog recorders (which get more and more distorted with higher levels), an ADAT tape that is recorded "in the yellow" will sound great. However, in setting levels you must strike a balance between what you gain by recording at high levels, and what you might lose if the incoming signal hits the "digital brick wall" above 0 dB and distorts on a peak. This is especially true in live recording, where peak levels are hard to predict. You must also be careful when setting levels to make sure that the mixer isn't distorting. In critical situations, consider limiting the input signal using the Alesis 3630 Compressor/Limiter to ensure against overload and get a maximum level without distortion. The ADAT meters are the instantaneous peak reading type: any voltage, no matter how short, will be registered, because the peak level is all that matters to ADAT. Other meters (as on most mixing consoles) may have different ballistic characteristics or show average level instead of peak. It is normal for them not to match the ADAT meters exactly. The RMB Remote Meter Bridge provides peak metering for four ADATs in a rack-mountable package, and can be mounted above the console or the BRC Master Remote Control. The RMB also features peak-hold features that make it easier to avoid distortion.

TRANSPORT CONTROL OPERATION
The transport controls resemble those of a conventional tape recorder, although there are several extra features.

3.4A Eject

Press to eject the tape from ADAT. If the tape is moving, it will stop before ejecting. Note: This control does not operate while recording or formatting to avoid interrupting these processes.

3.4B Rewind

Press to rewind the tape, as confirmed by the REW LED. When fully rewound, the REW LED turns off and the STOP LED lights.
Pressing Rewind while recording punches out before rewinding. Engaged tapes rewind at about ten times normal speed. Disengaged tapes rewind at about twenty times normal speed. For the fastest rewind, press the Stop button twice, or until the Stop LED flashes, before pressing REW. Pressing Rewind while holding the Play button initiates review mode. The tape rewinds at about three times normal speed, and you can hear chunks of attenuated audio so you know where you are in the tape. The PLAY LED will be lit, and the REW LED will flash. Releasing the Rewind button returns to normal Play mode.

3.4C Fast Forward

Press to fast forward the tape, as confirmed by the FFW LED. Upon reaching the end, the FFW LED turns off and the STOP LED lights.
Pressing Fast Forward while recording punches out before fast forwarding. Engaged tapes fast forward at about ten times normal speed. Disengaged tapes fast forward much faster. For the fastest rewind, press the Stop button twice, or until the Stop LED flashes, before pressing REW. Pressing Fast Forward while holding the Play button initiates cue mode. The tape fast forwards at about three times normal speed, and you can hear chunks of attenuated audio so you know where you are in the tape. The PLAY LED will be lit, and the FFW LED will flash. Releasing the Fast Forward button returns to normal Play mode.

3.4D Stop

This button performs three functions.
Stop the transport. Push to stop any function involving tape motion. A lit STOP LED indicates that the tape is not moving and is engaged. A flashing STOP LED indicates that the tape is not moving and is disengaged. Disengage/engage the tape. While the STOP LED is lit, press STOP again to disengage the tape (STOP LED flashes). While the STOP LED is flashing, press

There are two cases where you want the slave(s) to act independently. Formatting is initiated independently on the slave for a number of reasons, as detailed in section 3.1. Digital in can also be set independently for the slave(s) since you may want to record via the analog ins on some machines and via the digital ins on others.

5.1D Achieving Lock

In a multi-ADAT system, the ADATs will "chase" the master and can only enter record once they are in perfect sample-lock. Audio will not appear at the outputs of an ADAT until sample-lock sync is achieved. When an ADAT is in lock, the PLAY LED will light solid, and the center decimal point in the display will appear. To achieve the fastest chase-lock performance from a multi-ADAT system, use the Locate points whenever possible.
5.1E Independent Slave Mode
If the master ADAT is stopped, then each of the slaves will function independently. For example, you can press Play on one of the slaves (or change the auto input monitor, etc.) and it will go into play; the other slaves will not respond. However, any time you press Play on the master or initiate any transport function, it will take over and control the slaves.
FORMATTING WITH MULTIPLE ADAT SYSTEMS
Formatting works similarly to formatting on a single ADAT. However, it is necessary to consider what the slave does when formatting is initiated on the master.
5.2A Master Format Enabled and Performing a Complete, Start-toFinish Format
If the master format is enabled, performing a complete start-to-finish format, and the slave tape is not formatted:
If the slave format function is on, the slave rewinds to the start of the tape and does a complete format. If the slave format function is off, the slave rewinds to the start of the tape and plays, but displays noFO (no format) while flashing the format LED.
If the master format is enabled, performing a complete start-to-finish format, and the slave tape is formatted:
If the slave format function is off, the slave rewinds to the start of the tape and plays in sync with the master.
If the slave format function is on, the slave rewinds to the start of the tape and does a complete format.

1. The two ADATs should be connected in the normal manner:
Connect the SYNC OUT of the master to the SYNC IN of the slave using an Alesis 9-pin sync cable. Connect the DIGITAL OUT of the slave to the DIGITAL IN of the master using the fiber optic cable that came with your ADAT.
2. Put the original tape to be copied into the slave ("id 2") ADAT, which will be the source. 3. Put a blank or preformatted new tape into the master ("id 1") ADAT, which will be the target. (If the tape is blank, press Record Enable on all tracks of the master, and then press FORMAT on the master). 4. Set the master ADAT's clock source to internal by holding SET LOCATE and pressing DIGITAL IN until the display says "Int". 5. Press the DIGITAL IN switch on the master and slave machine. Both DIGITAL IN LEDs should be lit. 6. Record enable all tracks on the master (target) ADAT. Make sure all tracks on the slave are in SAFE mode (red LEDs not on or blinking). 7. Press PLAY and RECORD on the master ADAT. 8. Press STOP on the master after backing-up is complete. The result is a new "clone" of the original master that will synchronize sampleaccurately as if it were the original. It is also possible to make a "clone" from the master machine to the slave machine, although this isn't the preferred method if the source tape has shown any signs of deterioration. Simply connect the DIGITAL OUT of the master to the DIGITAL IN of the slave, and press the Record Enable switches on the slave machine instead of the master. Note: Even though the master machine is the source and may not have anything plugged into its optical digital input, you still need to press Digital In on the master and set its clock to internal (hold Set Locate and press Digital In so the display reads "int"). The reason that the master's DIGITAL IN LED must be lit during backup is so the master "knows" that it is making a digital transfer, and uses the proper time settings for a digital transfer. This assures sample-accurate timing precision. If some of this is hard to remember, an explanation of how Digital In affects synchronization may help. Consider a situation where you have two ADATs, and want to back up the slave ADATs tape to the master ADAT. So, you connect the

7.0 COMBINED MULTITRACK/ MASTERING DECK
ADAT can serve as a combination 6-track multitrack recorder and 2-track mastering deck. Record your audio into tracks 1-6, then run them through a mixer into tracks 7 and 8. Tracks 7 and 8 then contain the stereo master recording. An alternative is to record 5 tracks of audio, and dedicate one track to SMPTE time code or some other synchronization protocol. MIDI sequencers can be synched to the tape, and used to drive virtual instruments that also feed the mixer.

ARCHIVING

ADAT is superb for archiving applications.
Archive speeches and broadcasts. ADAT can record over five hours of mono material by recording 40 minutes on each track. Record over 2-1/2 hours of stereo mixes. Archive them by mixing down to four sets of stereo pairs. Record libraries of stereo samples into ADAT. Again, this gives over 2-1/2 hours of recording time.

BOUNCING

Although ADAT requires the BRC to do digital bouncing, standard bouncing using the analog outputs results in virtually imperceptible loss of fidelity. Tracks can be bounced within ADAT, as well as to other machines.

LIVE RECORDING

ADAT is excellent for live recording because of its compact size and easy operation. Eight tracks allow for recording audience sounds, ambience, and individual soloists as well as a stereo mix off the PA.
USING ADAT WITH MIDI SEQUENCERS:VIRTUAL TRACKING
There is a trend for hard disk recording and playback to occur within a software MIDI sequencer environment, however ADAT can offer much of the same flexibility without the added expense of a new program or hard disk recording system.
Stripe one ADAT track with SMPTE, and sync your sequencer to this SMPTE signal by whatever means you normally use. As you control ADATs tape motion with the transport controls, the sequencer will automatically follow along, letting you mix digital recording with any sequencer.

VIDEO LOCATION RECORDING

With ADAT, there are enough tracks to stripe SMPTE and record seven tracks of dialog/sound effects on location. ADAT also makes an excellent mixdown deck for new multichannel formats (such as surround sound) that require more than two tracks.

MODULAR RECORDING

Collaborations work particularly well with dual-ADAT systems. You can record your tracks into one machine, then do a premix into two tracks of the second machine, which is of course synchronized to the first. Send this tape to your partner, who adds parts in the other tracks. When the tape comes back, just pop it in the second deck, and your partners parts will be in sync with what you laid down originally.

Periodically check the AC cord for signs of fraying or damage. Unplug ADAT when not in use for extended periods of time. Place a dust cover over ADAT when it is not in use. Should the ADAT's error correction system be near the limits of its capability, the rightmost decimal point of the LED display will flash during play. If this should occur, make a digital back up of the tape. If the problem persists, contact Alesis.
9.0C Refer All Servicing to Alesis
Alesis has spent a great deal of effort researching recorder reliability. We believe that ADAT is one of the most reliable recorders that can be made using current technology, and should provide years of trouble-free use. However, if problems occur, do not attempt repairs yourself. The full AC line voltage, as well as high voltage/high current DC voltages, are present at several points within the chassis. Service on this product should be performed only by qualified technicians. THERE ARE NO USER-SERVICEABLE PARTS INSIDE.

ADAT HEAD LIFE

The expected headlife for each ADAT varies according to a number of factors. Given optimum conditions, tape quality, tape care, and operating environment head life for the average ADAT will always be better than if your ADAT is abused, placed in bad environmental conditions and used with badly maintained tapes. Properly cared for, your heads should last for thousands of hours.
You should not subject your ADAT to environmental extremes, humidity or moisture of any kind, dust, dirt, extreme temperatures, extreme temperature fluctuations or any kind of physical abuse (drops, shocks). Under no circumstances should you remove the top or bottom cover of the ADAT. You already know that there are NO user serviceable parts inside. However, you should also be aware that it is extremely easy to damage your heads and other sensitive parts of your ADAT. Do not open up your ADAT to clean the heads. What it comes to is this: ADAT is a very sophisticated piece of digital technology. It is going to be used for your important projects so take the best care of your ADAT and your ADAT heads possible.

ADAT HEAD MAINTENANCE

The heads of each ADAT are pre-aligned at Alesis. No user adjustment is necessary. Over the course of time, depending on the quality of the tapes used and the environmental conditions where the ADAT and its tapes are stored, head cleaning may become necessary. Unlike analog or even video tape recorders, the actual sound quality of an ADAT recording will not be affected until there is quite a bit of dirt on the drum and heads. When the Advanced Information Indicator (dot on the bottom right hand corner of the display) starts appearing frequently, even on brand new tapes, we recommend that you bring your ADAT to an authorized Alesis Service Center for cleaning. If the indicator is not appearing and the unit is performing normally, there is no reason to clean the heads. Periodic or preventative maintenance is not recommended. If head cleaning is necessary and you are unable to bring your ADAT to a service center, you may try using a DRY VHS head cleaning cassette. We recommend: 3M VHSHC Black Watch Head Cleaner Video Cassette

General note: If these errors occur only with a certain tape, or display once in a while, it's probably not cause for concern. Errors 1-3 and 9 can indicate conditions that may damage a tape; the other errors won't damage the tape or the machine.
9.4C Steps To Take Before Calling For Help
If an error message is displayed or if an ADAT starts behaving strangely, then please follow the suggested steps below: Stop the tape playing (or recording). Does the error go away? Rewind the tape a minute or two. Press play. Does the error recur? Eject the tape. Place it back in the ADAT and press play. Does the error recur? Turn down the volume of any mixer or amplifier you have connected to the outputs of the ADAT. Turn the power of the ADAT off, wait a minute and then repower the ADAT. Repeat steps 1 to 3. Does the error come back? If it does, then try a different tape. Repeat steps 1 to 3. Does the problem recur? Try a different ADAT. (If you are using a single ADAT system, see if you can visit your dealer.) It does not make sense to send your ADAT to service when there may be only a problem with, for example, some tapes you are using. If the same problems occur in another ADAT, then either the tape is faulty or it was formatted on an out of alignment ADAT. Call Alesis Product Support. If the problem does not occur, and the tape works fine, then we need to look at your ADAT. You need to call Alesis Product Support.
Whatever happens, the answers to all these questions are useful information for our Product Support representatives. The more we know, the faster we can discover the cause of your problems. You will help us isolate whether the problem lies in the ADAT, the tape or somewhere else.

CHAPTER 10: APPENDICES

10.0 APPENDIX 1: DIGITAL RECORDINGA QUICK TOUR 10.0A Analog Tape Recording Basics
Digital recording works very differently from analog recording. With analog recording, tape containing millions of tiny magnetizable particles move past a record head. The magnetic field around this head fluctuates according to the audio signal present at the tape recorders input. These fluctuations permanently rearrange the particles on the tape to form a pattern that is analogous to the original audio signal. On playback, the patterns on tape are read by a separate playback head (or from the record head, set up to read instead of record signals) that converts the magnetic fluctuations back into an audio signal. The biggest problem with analog recording is that the tape itself alters the sound originally recorded on tape. Tape hiss is one problem; it superimposes a low-level rushing noise onto the audio signal. Although there are ways to minimize noise, such as noise reduction circuitry, this colors the sound in the process of masking the noise. Tapes frequency response is also an issue. Tape has a hard time absorbing higher frequencies, which can dullen the sound. Moving tape faster allows the heads to magnetize more particles and extends the high frequency response, but the tradeoff is increased tape costs, and heftier transports to move bigger reels of tape.

10.0B Digital Tape Recording Basics
With digital tape recording, the technology is very similartape moves past a record head, and plays back through a playback head. However, the signal recorded on tape is very different. Audio signals entering each channel of ADAT first pass through an analog-to-digital converter (ADC), a device that takes 48,000 snapshots of the signal level every second. Each snapshot is assigned a specific numeric value that corresponds to its level. These numbers, which represent coded audio, are then converted into an audio signal that can be recorded on tape. Fortunately, recording a number on tape doesnt degrade the signal. During playback, a digital-to-analog converter (DAC) reads the numbers from tape and outputs a corresponding level. This creates a stairstep reconstruction of the
original signal, which is close to (but not exactly) the same as the original signal. To complete the process, this stairstep signal is smoothed by a low pass filter. The result is natural-sounding audio that sounds virtually unchanged from what was originally recorded.
10.0C Why Does ADAT Use S-VHS Cassettes?
Alesis has built its reputation on providing professional levels of quality and innovation at prices associated with consumer gear. When it was time to produce a digital tape recorder that would be suitable for any application from home/project studios to pro-level audio studios and video dubbing suites, our design team decided to use existing, mass-production technology wherever possible to cut costs without sacrificing performance; and the wide tape width of S-VHS tape allows ADAT to use wider track width for more reliable digital recording. It's especially well suited to ADAT's 8 track format. S-VHS recording technology offers more than enough bandwidth to record eight tracks of audio, low cost, and field-proven engineering. S-VHS tapes are built to higher standards than standard VHS tapes, and can take the tape shuttling required by professional audio applications. Theres also a matter of convenience. S-VHS tape cassettes are inexpensive compared to reel-to-reel tape, readily available, compact, and easy to transport and store.
10.1 APPENDIX 2: GLOSSARY AES/EBU Interface
A two-channel, digital audio hardware/software standard. The AES/EBU interface allows for data communication between professionally-oriented digital devices (such as CD players, digital signal processors, hard disk recording systems, synthesizers with AES/EBU outputs, digital audio workstations, etc.).
Analog-to-Digital Converter
The device responsible for converting analog signals into a digital format. Once encoded, all audio is stored or processed as a series of numbers rather than as the audio itself.

Autolocation

The process of automatically rewinding or fast forwarding, as necessary, to find a specific point on tape. Autolocation is usually initiated by pressing a button that tells the machine the point to which you want it to autolocate.

Balanced Audio Signals

Signals that are carried on three-conductor cables, with two of the conductors carrying the same signal 180 out of phase and the third as ground. Balanced connections usually cost more than unbalanced connections, but are less susceptible to picking up hum and interference with low-level signals.
Digital Audio Tape. This term has come to mean specific digital audio tape recorders that use cartridges smaller than those of a standard cassette, and which record two tracks of digital audio (and sometimes time code).

Digital I/O

Input and output connections where signals passed from one stage to another remain in the digital domain. ADAT has a digital I/O connector that carries digital data for all eight tracks.
Digital-to-Analog Converter
The device responsible for converting digital signals back into an analog format so that humans can hear them.

Fiber Optic Connector

A device that transmits signals through light instead of conventional wires. Advantages include higher speed and the ability to carry multiple channels of information over a single, thin cable.

Hard Disk Recording

A method of recording audio onto a hard disk. The advantages include fast access to any point on the disk, and the option to use a computers graphic capabilities for very detailed editing. Disadvantages include the difficulty of doing multitrack recording, relatively high cost, and the need to back up data to a separate, non-volatile storage medium. Since one minute of CD-quality stereo sound requires approximately 10 megabytes of memory, high-capacity hard disks are necessary for digital recording applications.
Multi-Channel Audio Digital Interface. This digital data transfer specification allows for transfer of up to 56 channels worth of digitized audio between professional digital
devices such as digital audio tape recorders, mixing consoles, etc. Alesiss multichannel interface is proprietary and does not work directly with MADI devices.

Oversampling

The process of taking more samples than is required in order to more accurately reconstruct a digitized signal back into analog.

Punching

The process of entering and/or exiting the record function while the tape is playing. This allows recording over specific pieces of tape, such as recording over a section with bad notes, as opposed to recording over the entire length of a track.

Rotary Head

A type of tape head, as used in ADAT, that spins at a high rate of speed in order to create the same effect as having the tape moving by at rates not physically possible with todays tapes and transports.

Compatibility with Digidesigns SMPTE Slave Driver
ADAT has been optimized to be fully compatible with Digidesigns SMPTE Slave Driver. This is an important element when transferring digital audio between a computer and ADAT, using Digidesigns ADAT Interface. Refer to the Digidesign equipments respective reference manuals for more information on using them with the ADAT.

1994 Alesis Corporation

Specifications Subject To Change Without Notice

Printed In USA

7-51-1121 2/95

A W ORD ON ADAT S S-VHS C ASSETTE TAPE
Alesis recommends you use only premium quality, name brand S-VHS cassettes. We cannot overemphasize the importance of this. We recommend using AMPEX 489 DM Digital Mastering Audio Tape, or Alesis ADAT Mastering Audio Cassettes. Other acceptable brands include Maxell XR-S Black, JVC XZ, 3M Master Broadcast and ASD 40+, and TDK SP Super Pro. The cassette shell, hubs, rollers and tape guides in S-VHS cassettes are precision devices that properly handle and protect the tape within them.
Do not use inexpensive, budget VHS tapes. ONLY USE S-VHS TAPES.
We do not recommend that you use inexpensive, budget VHS cassettes. While they may work technically, their unpredictable quality and less than premium formulation will decrease the reliability of your recording. Inferior tapes not only jeopardize the recordings made on them, they may shed oxide and leave behind a coating of dirt that will interfere with future recordings, even if you switch back to premium quality tape. Defective tape may even clog the head, requiring service. Dont trust your work to anything less than premium quality S-VHS tape. Accidents can happen so, like computer floppy disks and hard disks, your XT tapes should be backed up to prevent loss. Back up your tapes to another XT or ADAT using the fiber optic digital connector (see Making Backups on page 60). Treat your tapes as the precision, fragile components that they are. Do not expose them to extremes of heat, cold, or humidity (in other words, dont leave them in your car). Never place tapes near magnetic fields (such as power amps, TVs, monitors, magnets, etc.) and handle tapes gently.

OPERATING ENVIRONMENT

T HERMAL CONSIDERATIONS IN RACK M OUNTING
The XT 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 XT is designed to perform properly over a range of ambi ent temperatures from 10 C to +40 C (50 F to 104 F), in up to 80% non-condensing humidity. These are not absolute limits, but Alesis cannot guarantee that the XT will meet its published specs or remain reliable if operated outside of these ranges. Always allow adequate ventilation behind the XT. Do not seal any enclosure that holds the XT. It is not necessary to leave an empty rack space above or below the XT unless it runs hot enough to affect equipment above or below it. You will need to remove the screw-on feet from the bottom of the XT if any equipment will be mounted directly below it.
MOUNTING ON A SHELF OR NON -R ACK ENCLOSURE
To mount the XT on a shelf or other flat surface, Alesis recommends using the attached screw-on feet to avoid scratching the shelfs surface with the decks bottom. Please observe the general comments on thermal considerations given under Thermal Considerations in Rack Mounting no matter where or how the deck is mounted.

Hold [RECORD] and press [PLAY].
The XT briefly enters play mode to achieve proper speed and check if the tape is formatted. The XT performs a complete format by recording 15 seconds of leader (the LED display will read LEAd), followed by two minutes of data (the LED display will read data), then time reference starting at -0:00:05.00 and continuing to the end of the tape.

-02:00:00 -02:15:00

00:00:00

40:00:00

If an unformatted tape is not at the very beginning, it will automatically be rewound to the beginning. However, if any formatting is detected while rewinding, the transport will stop rewinding and leave the tape at this position, ready for a format extension (see next page).
If the tape has been previously formatted and is in the data portion (before 0:00:00.00), the tape will be automatically rewound to the beginning of the tape and the XT performs a complete format. If the tape has been previously formatted and is in the audio portion of tape (past 0:00:00.00), the tape will be formatted from that point upon entering record mode (this is called Format Extend; see page 31).
Audio can be recorded while formatting a tape, just in case you need to record something immediately and have no formatted tapes available. To place a track into record-ready, press the RECORD ENABLE button(s) [1] [8] for the track(s) to be recorded before turning on the Format function. When a RECORD ENABLE button is pressed, the INPUT LEDs for the selected track(s) will light and the REC LEDs will flash. Pressing RECORD ENABLE again takes the track(s) out of record-ready. While formatting, record-ready tracks will be recorded with audio from the inputs (analog or digital, depending on the Input Select setting; see page 37). However, audio will not be recorded until the audio portion of tape is reached (0:00:00.00). Tracks not in record-ready (safe) will be recorded with silence while formatting.

F ORMAT E XTEND

It is possible to extend the formatting on a tape that has only been partially formatted. When performing a format extend, you must enter format mode before the end of the previously formatted section by punching-in. The XT begins time-stamping from

INPUT MONITOR

The Input Monitor controls consist of two buttons: [ALL INPUT] and [AUTO INPUT].

AUTO INPUT MONITOR

This feature determines what you will hear from the XTs output jacks when a track is record-enabled (REC LED flashing): tape, or source. The [AUTO INPUT] button toggles the Auto Input Monitor on and off. When a track is monitoring its input signal, its INPUT LED will be lit. When the Auto Input Monitor is off (AUTO icon in the INPUT MON icon group is off), all record-enabled tracks will monitor the input signal and all other tracks will monitor the taped signal. When the Auto Input Monitor is on (AUTO icon is lit), it allows input monitoring of record enabled tracks while in record, stop, rewind or fast fwd; but not in play.
The reason for having these two options is to accommodate different stages of the recording process. Leaving the Auto Input Monitor off is the normal option and is what you would use when first recording tracks. When performing punch-ins and overdubs, you will probably want to turn the Auto Input Monitor on so that you can hear what was recorded on tape for a given track right up to the point you want to punch in. As soon as the XT punches into record mode, the tape signal is replaced by the input signal so you can hear whats being recorded to tape. After you punch-out, the monitor reverts to tape. Typically, Auto Input should be on when the Rehearse feature is used (see page 52).

ALL INPUT MONITOR

When the [ALL INPUT] button is on (ALL icon in the INPUT MON icon group is lit), the Auto Input Monitor setting is overridden so that all tracks monitor their input signals regardless of their record enable status. All eight track INPUT LEDs will be lit. When All Input Monitor is off (ALL icon is off), the Auto Input Monitor setting determines track monitoring. The All Input Monitor will automatically be turned off if Track Copy mode is enabled (by pressing the [TRACK COPY] button (see page 38). The following table indicates the status of tracks that are record-enabled and tracks that are not depending on the status of the [AUTO INPUT] and [ALL INPUT] buttons.
Record-enabled tracks = s ; Tracks not record-enabled = u

Transport Function

Stop,Pause, Rew.,F.Fwd Play Record
Auto = Off Auto = On Auto = Off/On All = Off All = Off All = On
s = Input u = Tape s = Input u = Tape s = Input u = Tape s = Input u = Tape s = Tape u = Tape s = Input u = Tape s = Input u = Input s = Input u = Input s = Input u = Input

METERS

The XT provides two buttons for meter display options: [PEAK MODE] and [PEAK CLEAR].

PEAK MODE BUTTON

The [PEAK MODE] button selects the peak hold mode of the eight level meters. Each time the [PEAK MODE] button is pressed, the peak meters switch between three possible Peak Hold modes: Continuous, Momentary and Off. The currently selected mode may be determined by observing the peak meters themselves. Continuous: Each tracks peak LED indicator will remain lit, until the [PEAK CLEAR] button is pressed, or the Peak Mode is changed. Momentary: Each tracks peak LED indicator will remain lit for about two seconds. Off: No peak indicators will be held on any tracks.

PEAK CLEAR B UTTON

The [PEAK CLEAR] button is used to remove any track peak LED indicators which remain lit while either Continuous or Momentary Peak Mode is selected (see above). This button will have no effect if the Peak Mode is turned Off.

F INE M ETER M ODE

The XT provides a special mode which rescales the peak meters for more specific readings. This is necessary when making very fine level adjustments, such as when recording test tones. When Fine Meter mode is enabled, the meters are rescaled around a center point of -15 dB (middle point of the meters) and goes plus and minus from there in.5 dB increments. This means the -15 dB icon will be the only level marking that is correct in this mode. The meters actual range will be from -18.0 dB to -12.5 dB. However, the MAX icon at the top of each meter will still indicate clipping. To activate Fine Meter mode:
Simultaneously press both [PEAK MODE] and [PEAK CLEAR] buttons.
The TIME counter will momentarily display FinE db and the dB stepped markings will appear on the left side of the meters.
To exit Fine Meter mode, press either [PEAK MODE] or [PEAK CLEAR]. The dB stepped markings will turn off.
Note: The Peak Hold function is disabled (off) when Fine Meter mode is enabled.
RECORDING A B ENCHMARK T APE
We recommend that you format and record a new tape with any signal, such as a test tone, in a single pass with no overdubs during the first week of operation. Store this tape in a safe, dry location and dont use it for any other purpose. Such a benchmark tape is useful to determine if the error correction rate is increasing over time because the heads need to be cleaned, or if a tape is defective (see page 75).

Be sure the output level of your mixer matches the inputs connected to the XT (+4 or -10).

TRANSPORT CONTROLS

The XTs six transport control buttons resemble those of a conventional tape recorder, although there are several extra features.
Press the [EJECT] button to eject the tape from the XT. If the tape is moving, it will stop before ejecting. In a multiple XT system where there is one master and one or more slave XTs and/or ADATs, pressing [EJECT] on the master will eject the tapes on all machines; pressing [EJECT] on a slave machine will only eject the tape on that machine.
The [EJECT] button will not operate while recording or formatting to avoid interrupting these processes.

REWIND /R EVIEW

Press the [REWIND] button to rewind the tape; the [REWIND] LED lights. When fully rewound, the [REWIND] LED turns off and the [STOP] LED lights. Pressing [REWIND] while recording punches out before rewinding. Threaded tapes rewind at about 40 times normal play speed. Unthreaded tapes rewind slightly faster. Pressing [REWIND] while holding the [PLAY] button initiates Review mode. The tape rewinds at about 3 times normal play speed, and you can hear chunks of attenuated audio so you know where you are on the tape. The [PLAY] LED will be lit, and the [REWIND] LED will be flashing. Pressing the [PLAY] button alone returns the transport to normal play mode.

F AST F ORWARD/C UE

Press the [FAST FWD] button to fast forward the tape; the [FAST FWD] LED lights. Upon reaching the tapes end, the [FAST FWD] LED turns off, and the [STOP] LED lights. Pressing [FAST FWD] while recording punches out before fast forwarding. Threaded tapes fast forward at about 40 times normal play speed. Unthreaded tapes fast forward slightly faster. Pressing [FAST FWD] while holding the [PLAY] button initiates Cue mode. The tape fast forwards at about 3 times normal play speed, and you can hear chunks of attenuated audio so you know where you are on the tape. The [PLAY] LED will be lit, and the [FAST FWD] LED will be flashing. Pressing the [PLAY] button alone returns the transport to normal play mode.
Press the [PLAY] button to play the tape ([PLAY] LED will light). The [PLAY] button by itself has no effect while playing, but it will terminate recording. While locating,

Press one of the [LOCATE 0] [LOCATE 9] buttons to select a Locate Point address. The LOCATE icon will light, the selected Locate Points number (0-9) will appear next to it, and the address of the selected Locate Point will be displayed in the TIME counter.
Use [s] and [t] buttons to fine tune the Locate Points address. Alternatively, you may select a specific digit by holding [EDIT VALUE] and using
While still holding [EDIT VALUE], press any of the [LOCATE 0] [LOCATE 9]
buttons to replace the selected digit with. The next digit to the right is automatically selected, so you may continue entering digits.
Once you have stored one or more tape positions into the Locate Point memories, pressing any of the [LOCATE 0] [LOCATE 9] buttons while Edit mode is not selected will initiate a locate to its respective address. The TIME counter will momentarily display the selected Locate Points address and the Locate Points number (09) will appear in the upper-right corner of the display; the transport will either fast forward or rewind to the selected Locate Points address.

AUTO LOOPING

Auto Looping is not a feature in and of itself, but is made up of two important features that, when used together, provide a very useful tool. These two features are: Auto Return and Auto Play. When both are enabled, and set correctly, a section of tape of any length may be continuously repeated.

AUTO RETURN

When Auto Return is enabled, and the transport reaches the Locate 4 point (the end of the loop), it will automatically rewind to the Locate 1 point (the start of the loop). Notice the arrow on the front panel connecting the [LOCATE 1] and [LOCATE 4] buttons. To turn Auto Return on or off, press the [AUTO RETURN] button. The AUTO-RTN icon will light when turned on. If Locate 1s position is after Locate 4, the AUTO-RTN icon will flash, and the transport wont rewind as it passes through Locate 4. For Auto Return to work, Locate 1 must be before Locate 4.

AUTO PLAY

The Auto Play function determines whether or not the transport will automatically go into play when a locate function is completed. This function can also be used in conjunction with the Auto Return function (see above) to create a loop, whereby a section of tape is played over and over. To turn Auto Play on or off, press the [AUTO PLAY] button. The AUTO PLAY icon will light when turned on.

LOOP L IMIT

There is, however, a built-in safeguard that protects the tape and the XTs heads and transport from unnecessary wear and tear by automatically disabling the Auto Loop feature after completing 100 consecutive loops. If this is not to your liking, this safeguard may be disabled. This is done by holding the [SET LOCATE] button and pressing [AUTO RETURN]. However, Alesis recommends doing so only when you absolutely have no other alternative. The 100 loop limit will be enabled again once [STOP] is pressed. While the Auto Loop feature is engaged, you may have a loop count displayed temporarily by holding the [SET LOCATE] button and pressing [AUTO PLAY].

SYNCHRONIZING MACHINES

ADAT XT Reference Manual 55
Chapter 5: Multiple ADAT-XT Operation
Synchronization requires a dual male, 9 pin D connector cable for each slave to be synchronized. Use only Alesis cables. Alesis Sync Cables are available in three different lengths: 8", 30", and 30' from your dealer. Other types of cables may cause incorrect commands to be received, and erratic sync performance. This connection should be made while power is off, but the machines do not need to be turned on in any particular order. For more about connections, refer to the section entitled Sync In/Out in Chapter 3. After youve connected multiple XTs and/or ADATS together and turned them on, the masters display will show ID 1 (identifying itself as the number 1 machine in the system). The second machine will display ID 2, the third ID 3, and so on. The ID order is automatically assigned according to how the cables are hooked up. You can re-check a machines ID at any time by holding [SET LOCATE] and pressing [PLAY].
If a slave does not display an ID number on power-up, then it does not see anything connected to the [SYNC IN] jack. Check the cables and connections.
If needed, the machines will renumber their IDs if more XTs or ADATs are connected later. Example: Suppose you have three XTs hooked up so that machine 1 is the master, and machines 2 and 3 are slaves. If you turn on only machines 2 and 3, machine 1 will not be active so machine 2 decides its the master (ID 1) and machine three the only slave (ID 2). If you then turn on machine 1, the machines will renumber themselves so that machine 1 becomes the master (ID 1), and machines 2 and 3 become the slaves (ID 2 and 3, respectively). Note that in this example, if machines 1 and 3 are turned on but machine 2 is turned off, machine 3 will not slave to machine 1 because machine 2 is turned off, so the sync signal cannot pass through it from 1 to 3. All slave XTs will automatically be placed in External Clock mode (the EXT icon will be lit in the CLOCK icon group). The [CLOCK SELECT] button will not function on the slave XTs since External Clock is their only option. Simultaneously, each slaves CHASE icon will light whenever it is chasing the location of the master.
MASTER/SLAVE I NTERACTION
Pressing any of the transport buttons ([PLAY], [STOP], etc.), or [AUTO REC], [LOCATE 0] [LOCATE 9], [ALL INPUT], [AUTO INPUT], PITCH [s] or [t] will automatically trigger the same functions on the slave machine(s) as well. Alesis recommends that you always initiate operations from the master, including all transport control functions, to minimize confusion. When you press [PLAY] on the master, the slave(s) will locate to the same timecode point and begin playing once sync is achieved (indicated by the LOCKED icon being lit). Pressing [EJECT] on the master ejects all slaves tapes as well. To eject only the masters tape, hold [SET LOCATE] and press [EJECT] on the master. When recording or punching in on the slaves, initiate recording on the master but do not have any master tracks record-enabled (unless, of course, you need to record tracks on the master). Any tracks that are record-enabled on the slaves will go into record, while the master will simply play. This is why record enable is an independent function for each slave. There are two other functions when the slave(s) act independently. Formatting is initiated independently on each slave for a number of reasons, as detailed in the next section; however, simultaneous formatting on all slaves is possible. Digital Input can also be set independently for the slave(s) since you may want to record via the analog inputs on some machines and via the digital inputs on others.

ACHIEVING LOCK

In a multiple ADAT system, the slaves will chase the master (CHASE icon will light on the XT) and can only enter record once they are in perfect sample-lock. Audio will not appear at the outputs of an ADAT until sample-lock sync is achieved. When an XT is in lock, the LOCKED icon will light. To achieve the fastest chase-lock performance from a multi-ADAT system, use the Locate points whenever possible.

INDEPENDENT SLAVE M ODE

If the master XT is stopped, each of the slaves will function independently. For example, press [PLAY] on one of the slaves and it will go into play mode (or press the [AUTO INPUT] button on a slave, etc.); the other slaves and the master will not respond to this command. However, any time you press [PLAY] on the master or initiate any transport function, it will take over and control all the slaves.
FORMATTING MULTIPLE TAPES
Formatting works similarly to formatting on a single ADAT. However, it is necessary to consider what the slave does when formatting is initiated on the master. See the section entitled Tape Formatting in Chapter 4 for more information.
MASTER F ORMAT E NABLED, COMPLETE F ORMAT
If the masters FORMAT icon is on, performing a complete start-to-finish format, and the slave tape is not already formatted: If the slaves FORMAT icon is on, the slave rewinds to the start of the tape and does a complete format along with the master. If the slaves FORMAT icon is off, the slave rewinds to the start of the tape and plays, but the TIME counter reads noFO (no format) while flashing the FORMAT icon.
If the masters FORMAT icon is on, performing a complete start-to-finish format, and the slave tape is already formatted: If the slaves FORMAT icon is on, the slave rewinds to the start of the tape and does a complete format with the master. If the slaves FORMAT icon is off, the slave rewinds to the start of the tape and plays in sync with the master.
If any channels are record-enabled, they will start recording at time 0:00:00.00.
MASTER F ORMAT E NABLED, FORMAT EXTEND
If the masters FORMAT icon is on, and you are extending the format, and the slave tape is not formatted: The slave plays, but the TIME counter reads noFO (no format) while flashing the FORMAT icon.
If the masters FORMAT icon is on, and you are extending the format, and the slave tape is formatted: If the slaves FORMAT icon is on, the slave autolocates to the same time as the master, then format extension begins with the master. If the slaves FORMAT icon is off, the slave autolocates to the same time as the master and plays or records in sync.

Use [s] and [t] buttons to fine tune the Tape Offset value. Alternatively, you may select a specific digit by holding [EDIT VALUE] and using
To change the current value from a positive offset to a negative offset (-), hold [EDIT VALUE] and press [SET LOCATE]. The offset digits will remain exactly the same. However, this step will toggle between positive and negative values by either displaying a - or not. simultaneously.
D To reset the Tape Offset amount to 0:00:00.00, press both [s] and [t]

COMBINING XTS AND ADATS

XT TRANSPORT S PEED
The XTs transport speed has been improved to be four times faster in engaged mode than the original ADAT. Because of this and other unique features, it is recommended that you make the XT the master (ID 1) in your system and your ADAT(s) should be the slave(s). Until you need more than 8 tracks, you may want to avoid inserting tape(s) into the slave unit(s). This is because when locating, the ADATs will move slower than the XT. The result is the XT will locate to a specific tape position, stop and wait for the ADAT(s) to get there before going into play.
SAMPLE RATE VS. PITCH CONTROL
The Clock Select function on the XT is another addition not found on the original ADAT. This function allows you to instantly choose between 48 kHz or 44.1 kHz sampling rates, as well as lets you select a digital clock for applications involving the recording of digital audio from a non-ADAT source). The XT also writes sample rate information when formatting a tape. This way, the XT automatically knows which sample rate a tape was formatted with although either sample rate may be used.
Example: When playing back a tape that was formatted at 48 kHz and the Clock is set to 44.1 kHz, the 44.1K icon will flash, to indicate that you are using 44.1 kHz but it isnt the original sample rate used when the tape was formatted. The same goes when you playback a tape formatted using 44.1 kHz with the Clock set to 48 kHz; the 48K icon will flash.
It is important to remember that on the XT, the Pitch Controls are supplemental to sample rate selection. With the original ADAT, you had to pitch down a tape in order to playback at a 44.1 kHz sample rate. This is no longer necessary on the XT due to the addition of the Clock Select function. If you play back a tape that was formatted on an original ADAT, it will not have any sample rate information written on it (since this is a new feature not found in the original ADAT). The XT will automatically select the 48 kHz setting in this case. Therefore, if you had been pitching-down such a tape to play at 44.1 kHz, you must press the [CLOCK SELECT] button to manually change the XTs Clock to 44.1 kHz.

Practice safe tape at all times because you can never retrieve lost data. If you are archiving your tapes, make sure they are stored in environmentally stable conditions, i.e. a cool dry place. If you do archive your tapes, you need to check them once a year. Run each tape through your ADAT from end to end. This will prevent buildup that can occur when a tape is left simply sitting. Of course, for your super sensitive or important material, nothing beats making multiple digital backups. Every year or so, simply do another digital backup onto a brand new tape.

MAINTENANCE/SERVICE

CLEANING
Disconnect the AC cord, then use a damp cloth to clean the keyboards metal and plastic surfaces. For heavy dirt, use a non-abrasive household cleaner such as
Formula 409 or Fantastik. DO NOT SPRAY THE CLEANER DIRECTLY ONTO THE FRONT OF THE UNIT AS IT MAY DESTROY THE LUBRICANTS USED IN THE SWITCHES AND CONTROLS! Spray onto a cloth, then use the cloth to clean the unit.

MAINTENANCE

Here are some tips for preventive maintenance. Periodically check the AC cord for signs of fraying or damage. Unplug the XT when not in use for extended periods of time. Do not leave tapes inserted halfway into the XT when not in use, as this allows dust to enter the transport chamber. Always leave tapes either fully inserted, or remove them completely.
REFER A LL S ERVICING TO ALESIS
We believe that the XT is one of the most reliable digital recorders that can be made using current technology, and should provide years of trouble-free use. However, should problems occur, DO NOT attempt to service the unit yourself. The full AC line voltage, as well as high voltage/high current DC voltages, are present at several points within the chassis. Service on this product should be performed only by qualified technicians. THERE ARE NO USER-SERVICEABLE PARTS INSIDE.
OBTAINING REPAIR S ERVICE
Before contacting Alesis, check over all your connections, and make sure youve read the manual. Customers in the USA: If the problem persists, call Alesis USA at 1-310-841-2272 and request the Product Support department. Talk the problem over with one of our technicians; if necessary, you will be given a repair order (RO) number and instructions on how to return the unit. All units must be shipped prepaid and COD shipments will not be accepted. For prompt service, indicate the RO number on the shipping label. If you do not have the original packing, ship the XT in a sturdy carton, with shock-absorbing materials such as styrofoam pellets (the kind without CFCs, please) or bubble-pack surrounding the unit. Shipping damage caused by inadequate packing is not covered by the Alesis warranty. Tape a note to the top of the unit describing the problem, include your name and a phone number where Alesis can contact you if necessary, as well as instructions on where you want the product returned. Alesis will pay for standard one-way shipping back to you on any repair covered under the terms of this warranty. Next day service is available for a surcharge. Field repairs are not normally authorized during the warranty period, and repair attempts by unqualified personnel may invalidate the warranty. Service address for customers in the USA: Alesis Product Support 3630 Holdrege Avenue Los Angeles, CA 90016 Customers outside the USA:

Whatever happens, the answers to all these questions are useful information for our Product Support representatives. The more we know, the faster we can discover the cause of your problems. You will help us isolate whether the problem lies in the XT, the tape or somewhere else.

APPENDIX D

SPECIFICATIONS

Transport

Recording Format: Tape Format: ADAT Rotary head digital recording S-VHS cartridge ADAT XT Reference Manual 83
Heads: Approximate Recording Times: ST-60: ST-120/SE-180: ST-160/SE-240: ST-180/SE-260: Fast Wind Rate:
4 (2 Read, 2 Write); Read before Write 22 minutes 40 minutes 54 minutes 62 minutes 40 x play speed (Threaded)
Number of Audio Channels: Audio Conversion: Record (A/D): Playback (D/A): Sample Rate: Vari Speed Range: Frequency Response: Dynamic Range: Distortion: Channel Crosstalk: Wow and Flutter: Reference Level: Eight 18 bit linear audio, 128 times oversampling, single converter per chan. 20 bit linear, 8 times oversampling, single converter per chan. 44.1 /48kHz, Selectable +100/-300 cents (48kHz), 200 cents (44.1kHz) 20Hz 20 kHz, 0.5dB 92 dB, A weighted.009% THD Better than -90 dB @ 1kHz Unmeasurable -15dB

Analog Inputs/Outputs

Connectors: Balanced: Unbalanced: Input Impedance: Balanced: Unbalanced: Output Impedance: Balanced: Unbalanced: Nominal Input levels: Balanced: Unbalanced: Maximum Input levels: Balanced: Unbalanced: One ELCO connector (in/out) Sixteen RCA jacks (8 input, 8 output) 10kW 10kW 150W into 600W Nominal 150W into 10k W Nominal +4 dBu (1.23V) -10 dBV (3.17V) +19 dBu (6.90V) +5 dBV (1.78V)

Digital Inputs/Outputs

Connectors: Communications Protocol: Two EIAJ fiber optical jacks (1 in, 1 out) 8-Channel Serial Communication

General

Power Requirements: Power Consumption: Operating Temperature: Operating Humidity: Dimensions (H x W x D): Weight: 90V250V AC, 50/60 Hz 80W 1040 C for specified performance 80% maximum with no dew condensation for specified performance 5.25" x 19" x 11" (133.3 x 482 x 279.5mm) 20 lbs. (9 kg)
CAUTION: Danger of explosion if battery is incorrectly replaced. Replace only with the same or equivalent type. AVERTISSEMENT: Risque d'explosion si cette pile est mal utilise tel que introduite faussement dans l'appareil ou remplac par une pile non-equivalent.

Glossary

GLOSSARY
A/D or Analog-to-Digital Converter
The device that converts an analog audio signal to digital audio. Once encoded, all audio is stored or processed as a series of numbers rather than as the audio itself.

AES/EBU Interface

A two-channel, digital audio hardware/software standard. The AES/EBU interface allows for data communication between professionally-oriented digital devices (such as digital signal processors, hard disk recording systems, synthesizers with AES/EBU outputs, digital audio workstations, etc.).

MIDI Machine Control (MMC). A subset of MIDI messages which correspond to tape machines transport controls and other functions.
Used as a verb, to mute a channel means to turn off the audio for that channel. Used as a noun, mutes are the buttons which turn off a particular channel. Mutes are usually non-destructive, though not always. Mutes are often automated as part of mixer automation systems.

Output

A path through which audio passes from one device to another. Types of outputs vary in connector type, level, use (sends, monitor, mix), and electrical characteristics (impedance, balanced or unbalanced). They can be analog or digital.

Oversampling

The process of taking more samples than is required in order to more accurately reconstruct a digitized signal back into analog audio.

Post-production

Begins after the film or video location shoot and is the process of combining, editing and processing audio elements into a final product to be married with the picture.

Punching

The process of entering and/or exiting the record function while the tape is playing. This allows recording over specific pieces of tape, such as recording over a section with bad notes, as opposed to recording over the entire length of the track.

Record-Ready

A track mode, often called armed. When you want to record on a track, you ready or arm the track. When you push the record button, all tracks that are ready or armed will go into record mode.

Rotary Head

A type of tape head, as used in the XT, that spins at a high rate of speed in order to create the same effect as having the tape moving by at rates not physically possible with todays tapes and transports.
A track mode. When a track is safe, it is not ready for recording.

Sample Rate

A digital representation of an analog signal created by checking, or sampling, the analog voltage a fixed number of times per second. The greater the number of samples, the more accurate the representation of the analog signal. The CD uses a sampling rate of 44.1 kHz; it checks the analog signal 44,100 times per second.

Sample Rate Conversion

Sample rate conversion is the process by which audio originally recorded at one sample rate is converted to another sample rate. The audio is converted by shifting its pitch up or down, and then played back at the new sample rate.

SMPTE/LTC

Society of Motion Picture and Television Engineers (SMPTE and Longitudinal Time Code (LTC). A standard for LTC was specified by the SMPTE, and has been adopted
by the motion picture and television industries. A complete description of LTC can be found in The Time Code Handbook , by Walter Hickman. SMPTE timecode is the standard sync reference for professional audio and video post-production.

S/PDIF Interface