ERROR CODES S PECIFICATIONS G LOSSARY 112 INDEX 119

105 110

Automatic Brake Calibration Procedure Steps To Take Before Calling For Help 107

Setting Up: Chapter 1

CHAPTER 1

SETTING U P

UNPACKING

AND INSPECTION

Your ADAT-XT20 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 XT20 for servicing. The shipping carton should contain the following items: ADAT-XT20 with the same serial number as shown on shipping carton Power Cable Optical Cable XT20 remote control unit This instruction manual Blank S-VHS ST-120 cassette 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.

AC POWER H OOKUP

With the XT20 off, plug the female end of the power cord into the XT20s [POWER INPUT] socket and the male (plug) end into a source of AC power. Its good practice to not turn on the XT20 until all other cables are hooked up. The XT20 works with any AC voltage from 90 to 250 volts, 50 to 60 Hz. This eliminates the need for transformers or voltage switches. Your XT20 was supplied with the correct power cord for your country or local area, however only the following alternative power cords are approved for use with ADAT: 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 #7-410004. 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 #741-0003. The XT20s IEC-spec AC cord (do not substitute any other AC cord) is designed to feed an outlet that includes three pins, with the third, round pin connected to ground. The ground connection is an important safety feature designed to keep the chassis of electronic devices such as the Alesis ADAT - XT20, BRC and AI-1 at ground potential. Unfortunately, the presence of a third ground pin does not always indicate that an outlet is properly grounded. Use an AC line tester to determine this. If the outlet is not grounded, consult with a licensed electrician.

Chapter 1: Setting Up

When AC currents are suspect of being highly unstable in VAC and Hz, a professional power conditioner should be used.
Alesis cannot be responsible for problems caused by using the XT20 or any associated equipment with improper AC wiring.

AVOIDING GROUND LOOPS

Chapter 2: Your First Session With The ADAT XT20

-- -- -- --

Insert the tape with the hinged door end first, label side up, until you encounter a slight bit of resistance. Push gently on the center of the tape cassette until the XT20 draws the tape inward; never force the tape into the cassette door.
FORMATTING A TAPE A MUST!
Formatting prepares a tape for 8 channels of audio, and adds a master timecode reference, word length, and sample rate information to the data on tape. Similar to formatting a floppy disk to use on a computer or sampler, formatting an XT20 tape time-stamps the tape to single-sample accuracy so that audio is referenced to an accurate time base. This makes the synchronization process between XT20 and ADAT compatible machines possible and provides both accurate tape counter readings and intelligent autolocation functions. For more information, see Tape Formatting in Chapter 4. After completing the following exercise, we recommend you perform a complete format.
Formatting a tape erases audio on all eight tracks. Be sure to check that the tape is either blank or contains unwanted material before formatting. We recommend that you format your tapes completely from beginning to end.
W ORD LENGTH (16/20 BIT ) SELECTION
Before formatting, select the word length you will be using (either 16bit or 20-bit) by pressing the FORMAT button until the length you want is shown in the display. 20-bit offers the greatest audio quality; 16-bit should be used if the master tape must be played in an older, Type-Ionly ADAT or ADAT-XT. (You can always make a 16-bit copy of a 20bit master if needed for this purpose.)

SAMPLE RATE SELECTION

Before formatting, select the sample rate you will be using (either 48 kHz or 44.1 kHz). This is done by pressing the [CLOCK SELECT] button. Each time [CLOCK SELECT] is pressed, the XT20 will cycle between INT 48K, INT 44.1K and DIG (the section on the right side of the display labeled CLOCK will indicate the currently selected sample rate). Note: For more information about the DIG option (Digital Audio Clock), see page 59.

F ORMATTING

To Format a new tape: Insert a fresh, blank tape. The XT20 will acknowledge that this is an unformatted tape; the F O R M A T icon will flash in the display while the counter display reads noFO. Press the [FORMAT] button. The display will briefly read 20 bit or 16 bit The word [FORMAT] in the display will stop flashing and remain lit. The [RECORD] LEDs for tracks 1 through 8 will now be flashing. x Hold [RECORD], and then press [PLAY]. If the tape was not completely rewound, the XT20 will automatically rewind it to the beginning. The XT20 then performs a complete format by recording 15 seconds of leader (the LED display will read LEAd), followed by two minutes of data (the display will read dAtA), then timecode starting at 0:00:00.00 and continuing to the end of the tape.

Transmit at 20 bit, and the receiving unit will ignore the last four bits, essentially cutting them off. Press the [DIGITAL OUT] button (located on the right above the RECORD button) until the display reads:

Ovt 16

This cuts off the data in bits 17-20 and fills the extra 4 bits with zeroes at the transmitting end. In most cases, this has the same sonic results as Method #1.
Press the [DIGITAL OUT] button (located on the right above the RECORD button) until the display reads:

Ovt 16dt

This adds dither, a specially shaped mathmatical noise, to the conversion process which smoothes out the transition at low levels and allows you to get better resolution even though the result is still 16-bit. However, if the signal will be dithered again later, you may want to use one of the first two methods.
To connect the digital optical network: Locate the [DIGITAL IN] and [DIGITAL OUT] connectors. Remove the connectors plugs (if present) and store for later use. Connect one end of the fiber optic cable into the [DIGITAL OUT] jack of the first machine in the system. Remove the clear, plastic tube covering each end of the cable (if present). The cable is non-polarized, so either end can be inserted into the optical output. x Connect the other end of the fiber optic cable to the [DIGITAL IN] of the second machine in the system. Tip: if the machines are on, the cable from the source machine will show a red light at the end. For each additional machine, connect one end of an additional fiber optic cable to the second machines [DIGITAL OUT] jack, and the other end to the third machines [DIGITAL IN] jack. Its [DIGITAL OUT] jack then connects to the fourth machines [DIGITAL IN] jack, and so on. Finally, connect one end of a fiber optic cable to the last machines [DIGITAL OUT] jack, and the other end to the first machines [DIGITAL IN] jack. This last step creates a loop, and thus makes the digital bus accessible to all machines that are connected to it.
When connecting more than two machines, always connect the optical cables in the same order as the sync cables (1 to 2, 2 to 3, etc.), so that the digital routing will work correctly.

INPUT OUTPUT

F OOTSWITCHES
The XT20 provides two footswitch connectors using 1/4" mono (T/S) jacks. One, labeled [LOCATE/PLAY LRC REMOTE], 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 IN/OUT ], is for punch in/out control.
The two footswitch jack functions are designed to be used with any momentary single-pole/single-throw footswitch (either normally open or normally closed). These should be plugged in prior to power-up so that the XT20 can configure itself for the type of footswitch being used.
The Punch In/Out footswitch and XT20 Remote both work in conjunction with the Rehearse and Auto Record features.

Audio can be recorded while formatting a tape, whenever 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 (see page 54) before turning on the Format function. While formatting, record-ready tracks will be recorded with audio from the inputs (analog or digital, depending on the Input Select setting; see page 48). 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. On multiple ADAT systems, you first need to format past the LEAD and DATA sections of the tape before recording while formating in sync (for example, when making a backup tape.) Once this is done, you can Locate 0 and continue formating while you record.

FORMAT EXTEND

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 XT20 begins time-stamping from the last valid time-stamp it reads from tape. This ensures continuous time-stamping when a tape plays from beginning to end. To extend the format on a partially formatted tape: Use [FAST FWD], [REWIND] and/or [PLAY] to locate to the section of tape just before where formatting was discontinued (before noFo shows in the display). Press [FORMAT]. The FORMAT icon lights. x Press [PLAY] to engage playback. When the LOCKED icon appears in the display, hold [PLAY] and press [RECORD]. The EXT icon lights. The XT20 reads the time reference from tape from the formatted portion and begins formatting starting from that time onward.
Exception: If the tape is already formatted but is in the leader or data sections of the tape (i.e., prior to time 0:00:00.00), entering format mode will automatically rewind the tape to the beginning and start reformatting. While rewinding, the TIME counter will read FO (which means format over) and the [REWIND] LED will flash. This indication is telling you that the XT20 must format over from the lead (beginning) portion of the tape. 16/20 Bit: Whichever word-length format (16- or 20-bit) you choose for the beginning of the tape is the type that must be used for the entire tape. A tape cannot be 16-bit for one section and 20-bit on another. If you want to change the word length, you must reformat the entire tape, erasing all existing audio on the tape as you do so.

The XT20 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. The FINE dB icon will turn on. To exit Fine Meter mode, press either [PEAK MODE] or [PEAK CLEAR]. The dB stepped markings and icon will turn off.
Note: The Peak Hold function is disabled (off) when Fine Meter mode is enabled.

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 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 100).

R ECORD ENABLE

To record enable a track, press the tracks RECORD ENABLE button.
When you press a tracks RECORD ENABLE button for the first time, the tracks red REC LED will flash, indicating the track is in record-ready, and its INPUT LED will light (unless Auto Input is on and the transport is in play), indicating you will be able to monitor that tracks input. If the transport is put into record mode (see Transport Controls in this chapter), recording will begin on this track; the tracks REC LED will stop flashing and remain lit. To disable record-ready, press the tracks RECORD ENABLE button once again. The tracks REC LED will turn off. RECORD ENABLE buttons can be turned on or off while you are in record mode.
Unlike analog tape recorders, where signals routinely exceed 0 dB with no apparent ill effects, 0 dB on the XT20 represents the maximum possible signal level. Signals above 0 dB will be clipped and lead to digital distortion. Because of the limitations of analog tape, there was always a tradeoff between noise, level and distortion. More level improved the signal-to-noise ratio, but also increased distortion. This distortion increased linearly, which is why signal-to-noise was often specified for a certain amount of distortion (typically 3%). You could always record with hotter levels or softer levels, but either more distortion or more noise would resultwith analog, you couldnt have low noise, high levels and low distortion. With digital recording, there is a much wider dynamic range, and distortion does not increase with increasing level. Yet once a digital system runs out of headroom and hits 0 dB, thats itthe onset of distortion is immediate and very noticeable if the signal is sustained several dB above the limit. Even though very short peaks above 0 may not last long enough to cause audible distortion, you aren't capturing the signal in its original form. As a result, because of the XT20s signal to noise characteristics, its better to err on the side of setting levels not quite high enough rather than having them distort, especially during live recording when you dont get a second chance. In the studio, where you have more control over levels or are using compressor/ limiters, its OK to light up the MAX LED on the meter on the very loudest peaks, as long as you're sure that signals aren't going beyond that point (by using the meters on your console, if they go beyond +15 dB). However, since 0 dB on the XT20 equals the maximum level, the input reference level is set below 0 VU. With the XT20, a 0 VU signal on a +4 dBu mixer plugged into the XT20s +4 dBu connectors (or a 0 VU signal on a -10 dBV mixer plugged into the XT20s -10 dBV connectors) will register -15 dB (the first green segment) on the XT20s meters. Therefore, you can run the mixer over 0 VU and

Note: European tapes are actually slightly longer than their US equivalents. Therefore, you may get a few more minutes of recording time if using European tape.
If using tapes longer than the standard ST-120, when locating for the first time past the 39 minute position, the transport will slow down (but not stop) and then speed up again. Each time thereafter that you locate beyond this point, the transport will not slow down. This safeguard is suited for the unlikely event that a longer tape length is erroneously selected, to avoid damage to the tape.
If the XT20 is connected to a BRC, and the tape length is set from the BRC, the individual XT20 slaves will retain their tape length setting after power down.

F OOTSWITCH CONTROLS

The XT20 provides two footswitch jacks: [LOCATE/PLAY/LRC REMOTE] and [PUNCH IN/OUT]. Both accept any momentary, single pole/single throw, 1/4inch mono (T/S) footswitch. During power-up, the XT20 checks the footswitch to determine whether it is normally open or normally closed type, and calibrates itself accordingly. If you use a footswitch and its operation seems reversed, make sure it is firmly plugged into the jack, then turn off the XT20, wait a few seconds, and turn the XT20 on again. It will calibrate itself to work with the footswitch. Either the [PUNCH IN/OUT] or [LOCATE/PLAY/LRC REMOTE] jack can also be used for connecting an LRC Remote Control. The PUNCH footswitch and the LRC cannot be used at the same time, since they occupy the same jack, unless you connect them with a Y-cord. However, you can interchange them if you observe certain precautions (see next section).
F OOTSWITCH CONTROLLED PUNCHING
The [PUNCH IN/OUT] footswitch is used to enable and disable recording. If a track (or tracks) is record-enabled, and the tape is playing, pressing the punch footswitch puts the track(s) into record mode at the instant you punch. This is equivalent to pressing [PLAY] and [RECORD] to enter record mode. If the XT20 is already in record mode, pressing the footswitch punches out of record (the track(s) will remain record-enabled should you need to punch in again later on) and the tape will continue to play. This is equivalent to pressing [PLAY].

Multiple ADAT-XT20 Operation: Chapter 5
Each slave XT20 can have its own tape offset, with respect to the master machine. Combine this feature with the ability to bounce tracks in the digital domain, and you have the ability to perform cut-and-paste style assembly editing.

SYNCHRONIZING M ACHINES

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, and the machines should be powered on from first to last with the BRC (if present) powered on after all of the ADATs. For more about connections, refer to the section entitled Sync In/Out in Chapter 3. After youve connected multiple XT20s 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 XT20s or ADATs are connected later. Example: Suppose you have three XT20s 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 XT20s 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 XT20s since External Clock is their only option. Simultaneously, each slaves CHASE icon will light whenever it is chasing the location of the master.

COMBINING XT20S

XT20 TRANSPORT

AND ADAT S SPEED

The XT20s 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 XT20 the master (ID 1) in your system and any 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 XT20. The result is the XT20 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 XT20 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 XT20 also writes sample rate information when formatting a tape. This way, the XT20 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 XT20, 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 XT20 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 XT20 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 XT20s Clock to 44.1 kHz.

Chapter 6: Applications

LIVE/LONG-TERM R ECORDING
The XT20 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 of the PA. Of course, multiple machines may be interconnected and synchronized to allow for more tracks. When using more than one XT20, you can increase the recording time by manually placing the second machine into record just before the first machine is at the end of its tape. Naturally, the audio signals would need to be split and connected to both sets of inputs. If you are using an Alesis BRC with a multiple ADAT system, you can take advantage of a feature called continuous recording. By splitting the system into two (or into two sets of machines), you can offset the second set by a specific amount of time. Example: A 35 minute offset would provide 5 minutes of overlap. The second set of machines would automatically kick into record just before the first sets tape ran out. Refer to chapter 5 for more details on connecting multiple ADATs; refer to the BRC Reference Manual for more information about continuous recording. Besides the typical 120 minute type of S-VHS tapes (which provide 40 minutes of digital audio recording time), 160 minute tapes are also available (which provide over 53 minutes recording time). And the new 3-hour (180 minute) tapes provide over an hour of digital recording time. The XT20 must be setup for the length of tape being used. This is done within the Main Function Menu. To set the tape length: Hold the [SET LOCATE] button and press the [FORMAT] button; This display will briefly read St-60. Repeat step 1 to advance through the available tape length choices. The display will briefly read:St-120, St-60, St-160 and St180. Below is a list of the four S-VHS tapes which can be used with ADAT, with their European equivalents and approximate recording times:
Note: European tapes are actually slightly longer than their US equivalents. Therefore, you may get a few more minutes if using European tape. Refer to page 59 for more information about tape length.

LOCKING

V IDEO: CODE-ONLY M ASTER
A common application in the audio post-production environment is locking to video using the timecode on the video tape as a source. This requires a synchronizer interface, such as the Alesis AI-2 or BRC. The connections consist of running a balanced 1/4" TRS cable between the AI-2s [SMPTE IN] connector and the VTRs SMPTE OUT (if timecode is recorded onto either the left or right audio track of the tape, connect the cable to the proper channels output connector) and a BNC connector from the house sync being provided to the VTR (such as a black-burst generator), or the VTRs video out to the AI-2 [VIDEO IN]. The AI-2s [SYNC OUT] to the XT20s [SYNC IN] connector. When the XT20 detects an on-line AI-2 or BRC, it will ID itself as a slave (ID 1) and the Clock will automatically switch to External (the EXT icon will light in the CLOCK icon group). Refer to your AI-2 or BRC Reference Manual for more information.

CALCULATING TAPE OFFSET

USING THE

LOCATES

The Alesis BRC provides a way of setting tape offsets using any of the 20 Locate memories in a song. This means you can set a Locate at one point, another Locate at another position, then have one of the slave ADATs offset by the amount of time between those two Locate positions. The XT20 allows you to set a Tape Offset by entering a time reference. For example, if you were to set a Tape Offset of 5 minutes (0:05:00.00) and the rest of the ADATs were at 0:03:23.15, the XT20 would be at 0:08:23.15. But lets say you dont know the time difference (i.e. the offset amount) between two sections of music. For example, lets say you wanted to bounce the vocals from the chorus 1 section of a song on an XT20 to a slave ADAT, then bounce them back to the XT20 while it was offset to the second chorus. To do this, the XT20 needs the exact offset time between these two positions in the song. So how many minutes, seconds and hundredths-of-a-second away is chorus 2 from chorus 1? Heres a way to find out by using the Locate Points. Play the tape(s) back from just before chorus #1. Press and hold [SET LOCATE]. x When you get to the downbeat of chorus #1, press [LOCATE 0].
Applications: Chapter 6 This sets the TIME counter to 0:00:00.00, and automatically selects Relative Time mode (the REL icon will light to the left of the TIME counter). While still holding [SET LOCATE], press [LOCATE 5] when you get to the downbeat of chorus #2. Press [STOP]. Press [EDIT VALUE], then press [LOCATE 5]. Edit Mode will now be selected. The TIME counter will display a time for Locate 5 (like 0:00:47.30). Write this number down or memorize it. Press [TAPE OFFSET] (while still in Edit Mode) and enter the value that was displayed for Locate 5 (0:00:47.30). To do this, press and hold the [EDIT VALUE] button and press [LOCATE 4], [LOCATE 7], [LOCATE 3] then [LOCATE 0]; then release [EDIT VALUE]. m Press [EDIT VALUE] to exit Edit Mode. Press [TAPE OFFSET] to turn the Tape Offset function on.
Appendix A: Digital Recording Concepts

APPENDIX A

DIGITAL R ECORDING C ONCEPTS

ANALOG 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.

Appendix C: Error Codes

APPENDIX C

ERROR CODES

The following errors codes may appear from time to time in the TIME counter display. Use this reference to learn the possible cause of the error code before attempting to contact Alesis Product Support. dv Dew Sensor: The unit has been subjected to overly high humidity. Do not operate the unit. Turn on the power without installing a tape. This will allow the unit to warm up and disperse the moisture. If the dv message does not go out after 2 hours contact Alesis for service. noFo No Format: The tape is located at a point that has not been formatted. Rewind the tape to the beginning. Press play. If the tape is formatted the message will change to LEAd for 15 seconds then dAtA for 2 minutes prior to the beginning of the audio section. If these messages do not appear, the tape should be formatted. FULL Serial Buffer Full: Not seen very often. FULL occurs when a slave XT20 is slow to sync to the master XT20. The serial buffer within the micro controller has become full of data. This could be the result of unlike versions of software within each unit. Sometimes the problem is related to the sync cable itself. It is recommended that only shielded and grounded cables be used as sync cables. Finally, this error may occur in slave machines that are playing damaged tapes. The edges of the tape have become damaged. If only one tape is found to cause this problem, don't use it. If the problem is seen with several tapes, the machine should be taken in for service. Contact Alesis for service. Er 0 Tape Load Error: This may be a problem with the TAPE LOAD or (insert) switch. This can be caused by labels that have been applied to the cassette outside of the designated area. If this error message is displayed with only one tape, the cassette may be at fault. If the message is displayed with several tapes, with and without labels, you should contact Alesis for service. Er 1 Er 4 Tape Threading: These error codes are usually related to tape threading. Eject the tape and load it again. If this error message is displayed with only one tape, the cassette may be at fault. If the message is displayed with several tapes, with and without labels, you should contact Alesis for service. Er 5 Drum/Capstan: This error points to the head drum and capstan servos. The problem is caused by anything creating extra resistance in the tape path, an unevenly wound cassette or a misalligned cassette shell. You should fast forward and rewind the cassette from end to end to flex the tape then try the tape again. If this error message is displayed with only one tape the cassette may be at fault. If the message is displayed with several tapes, with and without labels, you should contact Alesis for service.

Appendix C: Error Codes Er 7 Clean Heads: If this error message is seen, it may indicate that the heads are in need of cleaning. See ADAT Head Maintenance for information about cleaning your heads. Er 8 Sync Lost: Error message 8 normally occurs when the tape reaches the end while formatting or recording. It is caused by the fact that the XT20 cannot read timing data from the leader. The error is caused by the unit losing sync. If the unit is being run in the slave mode check the sync cable connection. It is recommended that only shielded and grounded cables be used as sync cables. Er 9 Take-up Reel. This error indicates that the take-up reel didnt move after PLAY or RECORD was engaged. This can spool tape out of the cassette, so the XT20 stops the tape immediately. Its possible that the take up reel of the tape is jammed; try a blank or unimportant tape to see if the error recurs. The idler wheel that turns the take-up reel may need cleaning or replacement. no 9ood tc No Time Code. The XT20 is reading control track pulses, but no helical scan time code. Usually, a video tape has been inserted into the XT20. Format the tape in the ADAT format. NOTE: No good tc will also appear if you insert a Type II (20-bit) tape into an older, Type I-only machine. Make a 16-bit clone of any 20-bit tapes for use in older-generation machines. (Error 10 through 13 and 16 are not used) Crossfade buffer, state or channel error. This indicates a Error 14-15 problem with the RAM buffer used for crossfading. Reinitialize the XT20 using the procedure on page 99. If the problem recurs, the unit must be serviced. Error 17 End sensor error. One of the optical sensors used to detect the clear leader at the head and tail of the tape cartridge is not working or is blocked temporarily. If the error recurs on other tapes, the unit needs to be serviced. AL P This error message may appear when you turn on power to the XT20. If the display also reads "CAL brAC", there may be something wrong with the battery backup of RAM, or the RAM was accidentally scrambled. If no other error messages occur during operation, and the Interpolation Indicator (see page 41) is not flashing, playback and recording are still possible. However, do not format any blank tapes on the XT20 until the PG is reset. AL brAc If this message appears during the turn-on cycle, the brake settings have been set to the default settings due to a problem with RAM memory or the backup battery. Perform the automatic brake calibration (see below). If this message appears in the midst of normal operation more than once in every ten hours of operation, perform the automatic brake calibration (see "Automatic Brake Calibration Procedure", next page).

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.

R OTARY H EAD

A type of tape head, as used in the XT20, 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

Similar to the AES/EBU interface, but created by Sony and Philips with consumer applications in mind. The optional AI-1 from Alesis offers both the consumer S/PDIF interface and professional AES/EBU format for use with the XT20.
Acronym for Super Video Home System, an improved version of VHS with greater resolution and dubbing capabilities, as well as improved sound.
An area of tape on which audio is recorded. A track can be thought of as a picture of an output over time.

UNBALANCED AUDIO SIGNALS

Signals that are carried on two-conductor cables, one hot and one ground. Unbalanced connections save costs, but are more prone to picking up hum and interference with lowlevel signals.
Acronym for Video Home System, a video recording system introduced for consumer use and using standardized cartridges.
Vertical Interval Time Code (VITC) is timecode information encoded in the vertical retrace interval of the video signal (this is the time when the beam is getting back to the top of the screen). The advantage of VITC is that the timecode value can be read when the video deck is paused, and is accurate to the frame.
16-bit, 29, 40, 71 formatting, 35 20-bit, 29, 40 formatting, 35 ABS/REL button, 16, 41 Absolute Time, 41, 56 ADAT, 51, 64, 75 AES/EBU, 72 AI-1, 72 AI-2, 80 ALL INPUT button, 45 analog recording, 84 AUTO INPUT button, 45 Auto Play, 20, 58 Auto record, 21, 59 Auto Return, 20, 58 autolocation, 56 backup, 70 bandwidth, 85 BRC, 60, 65 CHASE, 65, 100 clock, 39, 51, 52, 72, 74 Copying tapes, 70 Crossfade Time, 52 data, 33 DB 9, 28 digital clock, 54, 72 Digital Input, 39, 43, 65 DIGITAL INPUT button, 68 digital recording, 48, 84 display, 37 brightness, 23 Display Icons, 38 dither, 29 Drum Time, 90 EDIT VALUE, 38, 42 eject, 65 EJECT button, 49 ELCO, 26 error codes, 93 error rate, 88 FAST FWD button, 49 FINE dB, 38 footswitches LOCATE/PLAY, 31 LOCATE/PLAY/LRC REMOTE, 61 PUNCH IN/OUT, 31, 61 Formatting, 14, 32 frequency response, 84 head cleaning, 89 ID, 38, 65

Formatting a tape erases the audio on all 8 tracks. Be sure to label your tapes clearly, so you dont accidentally erase something valuable. We recommend that you completely format your tapes from beginning to end.
F ORMATTING CONSIDERATIONS
Blank tapes will automatically be rewound to the beginning before formatting. Before formatting, select the sample rate that you will be using (either 48 kHz or 44.1 kHz). See page 44 for more information. To record on or erase/format 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 PROTECT icon in the display will light and the XT will not record on the tape. This prevents accidental erasure of valuable recordings. To record on a tape that has had the tab broken off, use the Write Protect Override feature (see page 31).
Caution: If you re-format over a previously formatted tape, do not stop in the middle of re-formatting. Reason: When the tape transitions from the newlyformatted section to the previously formatted section, 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 entire tape, from beginning to end, or back up a bit and perform a format extend (see page 31). The only way to stop formatting is to press [STOP]punching out is not sufficient. Tapes can be bulk-erased with a video tape eraser. In a multiple XT setup where one is the master and the other XTs are slaves, there are a few other considerations. See Multiple ADAT Operation in chapter 6.

COMPLETE FORMAT

To format or reformat/erase an entire tape:
Chapter 4: Basic Operations
Be sure the tape is completely rewound.
Press the [FORMAT] button. If the tape was unformatted, the FORMAT icon will have been flashing prior to pressing it. Once pressed, the FORMAT icon will stop flashing and remain lit to indicate that formatting will begin if the XT enters record mode. Also, all eight REC LEDs will flash to indicate all eight tracks will be recorded. Pressing the eight RECORD ENABLE buttons ([1] [8] ) has no effect while the FORMAT icon is lit.
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
the last valid time-stamp it reads from tape. This insures continuous time-stamping when a tape plays from beginning to end. To extend the format on a partially formatted tape:
Use [FAST FWD], [REWIND] and/or [PLAY] to locate to the section of tape just
before where formatting was discontinued.
Press [FORMAT]. The FORMAT icon lights.
Press [PLAY] to engage playback. When the LOCKED icon appears in the display, hold [PLAY] and press
[RECORD]. The EXT icon lights. The XT reads the time reference from tape from the formatted portion and begins formatting starting from that time onward.
Exception: If the tape is already formatted but is in the leader or data sections of the tape (i.e., prior to time 0:00:00.00), entering format mode will automatically rewind the tape to the beginning and start reformatting. While rewinding, the TIME counter will read FO (which means format over) and the [REWIND] LED will flash. This indication is telling you that the XT must format over from the lead (beginning) portion of the tape.

s AND t B UTTONS

Once a function is selected, the s and t buttons are used to increment or decrement its setting by single values. By holding either button, the increment or decrement value increases its speed. By simultaneously pressing both buttons, the selected parameter is reset to 0.

ENTERING NUMERIC V ALUES

If [EDIT VALUE] is held while in Edit mode, you may use the [LOCATE 0] [LOCATE 9] buttons as a 10-digit keypad (from 0 to 9) to enter a specific numerical value for the currently selected parameter in the display. Numbers are entered from left to right.
Examples: If [LOCATE 1] is pressed using this method to edit Track Delay time (displayed as XXX.X ms), the display would show.1 ms. If a [LOCATE 5] is now entered, the display shows 1.5 ms. If the [EDIT VALUE] button is released at this time, the display shows 001.5 ms and that would be the new Track Delay value. Likewise, if this method is used to edit a Locate Point (X:XX:XX.XX) and the sequence of numbers were entered as follows: [LOCATE 1] [LOCATE 2] [LOCATE 3] , the display would successively show. 1,.12, 1.23. If the [EDIT VALUE] button is then released, the display would show 0:00:01.23 and that would be the Locate Points value.
EDITING INDIVIDUAL DIGITS
You can also select a specific digit in the display to edit, by holding the [EDIT VALUE] button and pressing either [s] or [t]; the currently selected digit will flash. While still holding the [EDIT VALUE] button you may press any of the [LOCATE 0] [LOCATE 9] buttons to enter a specific numerical value for the currently selected digit. The selected digit will replace the previous once and will stop flashing, and the next digit to its right will be selected (flashing) so you may continue entering digits using the [LOCATE 0] [LOCATE 9] buttons.

INPUT SELECT

There are three buttons for input select options. These three buttons are labeled [ANALOG INPUT], [DIGITAL INPUT], and [TRACK COPY]. These determine what signals will be recorded on the XT. The currently selected input mode is indicated in the lower right corner of the display: ANALOG, DIGITAL or TRK COPY.
While any of the Input Select buttons are being held, the channel record and input status indicators no longer indicate the current record or input status, and the REC icon turns off. As long as one of these buttons is being held, the tracks INPUT LED is used to indicate channel selection for that particular function, and the RECORD ENABLE buttons [1] [8] are used to select and de-select channels (see page 41).

ANALOG INPUT

Pressing the [ANALOG INPUT] button once selects the analog inputs (both unbalanced and balanced) for recording and monitoring; the ANALOG icon will light in the INPUT icon group in the display. While holding the [ANALOG INPUT] button, the channel input indicators will show the number of analog inputs that are currently selected. There are three selections possible: Two inputs, four inputs, or eight inputs. This allows you to record from a 2 or 4 bus mixing console without repatching. To choose 2-input mode: Press either the channel 1 or 2 RECORD ENABLE buttons while holding [ANALOG INPUT]. This will cause both the channel 1 and 2 input lights to light up, indicating that only input channels 1 and 2 will be used. If any of tracks 1, 3, 5, or 7 are record enabled, they will receive their input signal from the analog input of channel 1. If any of tracks 2, 4, 6, or 8 are record enabled, they will receive their input signal from the analog input of channel 2. To choose 4-input mode: Press RECORD ENABLE button 3 or 4 while holding the [ANALOG INPUT] button. This will cause channels 1 through 4 INPUT LEDs to light up, indicating that only input channels 1 thru 4 will be used. In this case, channels 5 through 8 receive their input from channels 1 through 4, respectively. To choose 8-input (the most common) mode: Press RECORD ENABLE button 5 thru 8 while holding the [ANALOG INPUT] button. This will cause all eight track INPUT LEDs to light. In this mode, each track receives its signal from its own input.

SETTING LEVELS

Unlike analog tape recorders, where signals routinely exceed 0 dB with no apparent ill effects, 0 dB on the XT represents the maximum possible signal level. Signals above 0 dB will be clipped and lead to digital distortion. Because of the limitations of analog tape, there is always a tradeoff between noise, level and distortion. More level improves the signal-to-noise ratio, but also increases distortion. This distortion increases linearly, which is why signal-to-noise is often specified for a certain amount of distortion (typically 3%). You can always record with hotter levels or softer levels, but either more distortion or more noise will resultwith analog, you cant have low noise, high levels and low distortion. With digital recording, there is a much wider dynamic range, and distortion does not increase with increasing level. Yet once a digital system runs out of headroom and hits 0 dB, thats itthe onset of distortion is immediate and very noticeable if the signal is sustained several dB above the limit. Even though very short peaks above 0 may not last long enough to cause audible distortion, you aren't capturing the signal in its original form. As a result, because of the XTs signal to noise characteristics, its better to err on the side of setting levels not quite high enough rather than having them distort, especially during live recording when you dont get a second chance. In the studio, where you have more control over levels or are using compressor/ limiters, its OK to light up the MAX LED on the meter on the very loudest peaks, as long as you're sure that signals aren't going beyond that point (by using the meters on your console, if they go beyond +15 dB). However, since 0 dB on the XT equals the maximum level, the input reference level is set below 0 VU. With the XT, a 0 VU signal on a +4 dBu mixer plugged into the XTs +4 dBu connectors (or a 0 VU signal on a -10 dBV mixer plugged into the XTs -10 dBV connectors) will register -15 dB on the XTs meters. Therefore, you can run the mixer over 0 VU and still have 15 dB of headroom on the XT before distortion occurs. Just remember that no matter what, if the XTs meters indicate over 0 dB, distortion is occurring or is on the verge of occurring.

The Pitch function controls the speed of the tape, and thus the pitch of the audio recorded on tape. It displays speed as percentage and as cents. A cent is 1/100th of a semitone. For example, if a song is originally recorded in the key of C, then played back with the pitch raised 100 cents, it will be in the key of C#. The XTs Pitch control has a range of -300 to +100 cents when using a sample rate of 48 kHz, and a range of -200 to +200 when using 44.1 kHz. The Pitch controls will not function while locking to an external clock (i.e. while the XT is slaved to another ADAT or is locking to an external digital clock). The PITCH [s] and [t] buttons control the amount of pitch change. When either button is pressed once, the PITCH icon lights in the display, and the TIME counter immediately displays the current amount of Pitch change. The Pitch amount is displayed both as a percentage (%) and as cents. After a few seconds, the TIME counter reverts back to its normal mode.
If Edit mode is currently on (EDIT icon lit), press [EDIT VALUE] to exit Edit mode.
The EDIT icon should be off.
Press and hold either PITCH [s] or [t]. After holding for more than.5 seconds, the Pitch amount will start either increasing or decreasing, depending on which button was pressed.
To immediately set the Pitch amount to +100, hold [SET LOCATE] and press [s]. To immediately set the Pitch amount to -300, hold [SET LOCATE] and press [t]. To reset the Pitch amount to 0, simultaneously press both [s] and [t].
Note: This is not possible while recording.

ABOUT PITCH CHANGING

Here are a few things to consider when chaning the XTs pitch: One of the PITCH arrow icons will remain lit in the display to remind you that the pitch has been changed from standard pitch. The counter will not elapse in real time when the pitch is set to a value other than zero. When you change the pitch on ADAT-XT, the sampling rate will also change. The lowest sampling rate is 40.4 kHz, the highest is 50.8 kHz. If the internal clock is set to 48 kHz, but the pitch is lowered -147 cents, the sampling rate is 44.1 kHz. However, for accurate TIME counter display it is better to set the pitch to 0 and change the clock rate (see page 44).
Track Delay lets you delay individual tracks up to 170 ms, in order to achieve a more desirable feel. For example, if the bass track is anticipating the beat, you can push it back so its in the pocket by delaying it a few milliseconds. If you need one track to play back earlier than the others, try offsetting all other tracks by the same amount. This will make the remaining track appear to be playing ahead of the others. Track Delay times are set individually per track (or for a group of tracks) in the Track Delay Edit page. Track Delay for all eight tracks may be turned on and off without altering the Track Delay settings of each track. To turn Track Delay on and off:

If the [LOCATE 0] button is pressed, the transport will immediately begin locating to the 0:00:00.00 time location of the tape. If the TIME counter is in ABS mode when [LOCATE 0] is pressed, the absolute 0:00:00.00 position is located. If the TIME counter is in Relative mode when [LOCATE 0] is pressed, then the relative 0:00:00.00 position is located. [LOCATE 0] is different from the other [LOCATE] buttons in this respect: it may wind the tape to different locations, depending whether the TIME counter is in ABS or REL mode. All the other locate points represent the same actual (physical) position on tape, regardless of whether the display is in ABS or REL mode. The [LOCATE 0] button is also used to set the relative zero time. When this button is pressed while holding [SET LOCATE], the relative tape counter is reset to zero (0:00:00.00). Once this occurs, you have changed the Relative Time zero point, and the display will automatically change to Relative Time mode (REL icon lit).

SETTING LOCATE POINTS

There are two ways of storing Locate Point memories: manually or on the fly. To store a Locate Point memory on the fly:
Press [PLAY] to engage playback.
Alternatively, the transport may be engaged in either Rewind, Review, Fast Forward, Cue, Record or Stop mode (i.e. the transport does not have to be in Play mode to store Locate Points in the following manner; it is simply the most practical way to do it).
Press and/or hold the [SET LOCATE] button. The LOCATE icon will light and a dash () will begin flashing to its right.
Immediately press one of the [LOCATE 0] [LOCATE 9] buttons.
The current tape location will be stored into the Locate Point memory you selected. If [LOCATE] button is not pressed within 2 seconds after releasing [SET LOCATE] , the flashing dash will disappear and none of the Locate Point memories will be changed.
To store multiple Locate Points, you may continue holding the [SET LOCATE]
button and press any of the [LOCATE] buttons when the desired tape positions are reached. To edit a Locate Point memory:
Press [EDIT VALUE] to enter Edit mode.
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.

AUTO R ECORD

The Auto Record function lets you determine exactly where recording should begin and end beforehand, so that the machine automatically takes you in and out of record. Locate Points 2 and 3 determine the in and out points. After setting both Locate Points 2 and 3, press the [AUTO REC] button to enable this function; the AUTO REC icon will light. To execute a take, rewind to a position before Locate Point 2, then hold [RECORD] and press [PLAY], just as you would to record normally. When the Locate 2 position is reached, recording will begin. When the Locate 3 position is reached, recording stops while the transport continues. To execute an Auto Record take:
Record-enable the track(s) you wish to record on (see page 41). Press [AUTO RECORD].
The AUTO REC icon will light.
If [AUTO REC] is pressed when the Locate 2 position is set beyond or at the same position as the Locate 3 position, the TIME counter will momentarily read invALid indicating that this is not possible, and you will not be able to enable the Auto Record function until you change either Locate 2 or 3s position. Rewind the tape to a position prior to the Locate 2 position.
Hold [PLAY] and then press [RECORD].
The [PLAY] LED will light, and the [RECORD] LED will flash. Upon reaching the Locate 2 position, recording will begin on any record enabled tracks and the [RECORD] LED will light solid. If no tracks are record enabled when the Locate 2 position is reached, the [RECORD] LED will continue flashing and no recording will take place. At any time before the Locate 3 position, a track may be record enabled, which will cause the track to immediately enter record and the [RECORD] LED will light solid. Upon reaching the Locate 3 position, recording will cease and the [RECORD] LED will turn off.
Whenever the XT is put into play, it requires a brief moment to locate the timecode reference on tape and lock. If the Locate 2 position is reached while the AUTO REC icon is lit before the XT establishes a lock, the punch in will not take place until a lock has been established (after the LOCKED icon turns on).

LOOPED R ECORDING

The Auto Return and Auto Play functions can be used along with Auto Record to create a recording loop. So, you can record a take over and over until you get it right. Simply set Locate 1 to a position several seconds before Locate 2, and Locate 4 to a position after Locate 3. Refer to page 50 for more information.

REHEARSAL

With Auto Record turned on, you can rehearse before actually recording (or erasing whats already on tape). If you engage Auto Record while Rehearse and Auto Input are enabled, when the Locate Point 2 position is reached, any tracks that are in record-ready will be in input monitor mode and the [RECORD] LED will continue flashing. When the Locate Point 3 position is reached, any tracks that are in recordready may return to tape monitor mode. The [REHEARSE] button turns Rehearse mode on and off; the REHEARSE icon will light when enabled. Note that if Auto Input is not enabled, Rehease will have no effect on what you hear in your monitor mix.

TAPE LENGTH

The XT can take advantage of the extra recording time on tapes longer than the standard ST-120 length. You can use ST-180 tapes, for over one full hour of recording time. ST-60 tapes can also be used for shorter projects; the XT
automatically recognizes the shorter length of the ST-60 because the hubs used in the cassette are larger. However, there is no way for the XT to tell apart a ST-120, ST-160 or ST-180 tape, since these all use the same, smaller size hubs. In this situation, the XT assumes the tape length to be that of a ST-120 tape. Therefore, when using either ST-160 or ST-180 length tape, you should set the tape length on the XT. To set the tape length:
Hold the [SET LOCATE] button and press the [FORMAT] button;
This display will briefly read St-60.
Repeat step to advance through the available tape length choices. The display will cycle through the following choices: St-120 , St-60 , St-160 and St-180. The tape length setting is not reset when a tape is ejected. However, if you power down and up again, the tape length setting will revert to T-120. If connected to a BRC, and you set the tape length from the BRC, the XT remembers the tape length setting, even after power down. If you insert a tape while the Tape Length setting is set to something other than St-120, the display will briefly flash the selected Tape Length setting. This is to remind you that you are using a non-standard setting. If using more than one XT/ADAT, you must make sure all connected XTs/ADATs are loaded with tapes of the same length.

If [DIGITAL INPUT] is selected and there is no optical input, the DIGITAL icon (located in the INPUT icon group) will flash.
When bouncing audio from a master XT to a slave XT, the slave does not need to have its Clock set to DIG since it is already getting accurate clock information from the master, so it is sample-locked to the digital audio it is recording.
REASSIGNING CHANNELS TO DIFFERENT T RACKS
It is possible to reroute the channel/track assignments so that any incoming channel of digital audio can be recorded onto any track, or multiple tracks. This is done by first holding the [DIGITAL INPUT] button and pressing any of the RECORD ENABLE buttons [1] [8] to select which source channels you wish to record (while holding the [DIGITAL INPUT] button, the blue INPUT LEDs will light to indicate the selected source channels; by default, all eight INPUT LEDs will be lit). Then, after releasing the [DIGITAL INPUT] button, use the RECORD ENABLE buttons to select the tracks you wish to record the source channels onto (the INPUT LEDs return to their normal status). The selected source channels are re-routed to the record-enabled destination tracks, in ascending order. Example: If source channels 1 and 5 are selected and tracks 3 and 4 are record enabled, then incoming audio on channel 1 will be routed to track 3 and incoming audio on channel 5 will be routed to track 4. If more destination tracks are selected than source tracks, the source tracks will repeat (cycle). Example: If tracks 7 and 8 were added to the destination tracks of the previous example, then incoming track 1 would be routed to tracks 3 and 7 and incoming track 5 would be routed to tracks 4 and 8. This scheme allows for copying a single incoming channel to multiple tracks. If all 8 channels are selected as source tracks, no digital routing will occur as this gives a one-to-one relationship (and is the power-on default). If no source channels are selected, then digital silence will be input to any record-enabled tracks.

MAKING DIGITAL BACKUPS

XT tapes can be backed up for safety by copying all eight tracks to another XT (or ADAT compatible machine) via the digital bus. The result is a perfect digital duplication of the original. Its a good idea to make backups on a regular basis, whenever you finish work for the day, or complete a project. The backup can either be sample accurate to the time reference or not. This depends on whether or not the two machines are synchronized together via a 9-pin connector cable. It is recommended, however, that you do have the Sync cables connected between the machines, as described in the section entitled Synchronizing Machines on page 56. When making a backup, the tape you are backing up is normally inserted into the master machine. The tape you are backing up to is inserted into one of the slave machines. This is recommended since the slave machine comes after the master machine in the system chain. NOTE: [TRACK COPY] is not used to make digital tape backups from machine to machine. Track Copy is only used to copy between tracks on the same machine. To make a backup tape:

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.

Possible problem: Lets say you had been using a multiple ADAT system and you recorded a stereo signal across two machines (a stereo drum recording on tracks 8 and 9), where there is a common element to each track (i.e. center signal). If you replace one of these machines with an XT, the result would be that the track being played back on the XT will be out of phase from the track played on the ADAT, canceling the center signal. Here are some possible solutions:
Use a phase switch on your mixer (if your mixing board provides this) to invert the phase of the problem track to compensate. Wire your patchbay or ELCO cable to reverse the input and output polarity of the XTs in the system, but use standard cables on the ADATs in the system. This is recommended only for studios where master tapes will be exchanged between units or sent out of house. Digitally bounce one of the stereo tracks to the other ADAT so that both sides play back from the same machine. Most importantly, it is better to plan recording sessions so that stereo tracks reside on the same physical tape in a multiple ADAT system.
If you are replacing one or more of your ADATs with XTs and have been using the short, 8" sync cables, you will need to use 1 meter cables (or longer) to make the connection between ADATs and XTs. This is because the [SYNC IN] and [SYNC OUT] connectors have been moved on the XT rear panel to the opposite side, and the shorter cables will no longer reach.

Applications: Chapter 6

CHAPTER 6

APPLICATIONS

This chapter is designed to give you an idea of the multitude of applications for the XT. These applications are not broken down into great detail. Therefore, where applicable you will need to refer to other sections of this manual for instructions on how to setup the XT for a particular job.
COMBINED M ULTITRACK /M ASTERING D ECK
The XT can serve as a combination 6-track multitrack recorder and 2-track mastering deck. Record your audio onto tracks 16, then run them through a mixer, using the sub or group outs to send them back to tracks 7 and 8. Tracks 7 and 8 will contain the stereo master recording; their outputs should then be connected back to the mixers 2-track playback inputs.

LOCATE/PLAY LRC REMOTE

PUNCH IN/OUT

DIGITAL

In addition, an external synchronizer connected to the XTs [SYNC OUT] can output SMPTE or MTC to simultaneously synchronize a MIDI sequencer to tape. This way, you can mix down not only the first 6 tracks from the XT but your virtual tracks on the sequencer as well, all onto tracks 7 and 8. If you are using a multiple machine system (with one or more XTs and/or ADATs), you can dedicate any two tracks in the system for a stereo mix. Because all machines are perfectly synchronized to one another, you can punch-in and -out of the mix itself. This opens up all sorts of possibilities, like changing the EQ, effects and other mix settings for different sections of the mix.

148,000 samples are taken per second at a sampling rate of 48 kHz; 44,100 samples
are taken per second at a sampling rate of 44.1 kHz.
Appendix A: Digital Recording Concepts
Digital audio requires lots of numbers to represent an analog version of the same sound. Analog signals may require at least 20kHz frequency response to reproduce audio faithfully. Digital signals for the same 20 kHz audio requires a frequency response of several million Hertz. Due to the way individual numbers are transmitted, digital audio requires a wide bandwidth recording medium 2.

WHY S-VHS?

S-VHS recording technology offers more than enough bandwidth to record eight tracks of digital audio. S-VHS tapes are built to higher standards than standard VHS tapes, and can take the tape shuttling required by professional audio applications. S VHS tape cassettes are also inexpensive compared to reel-to-reel tape, readily available, compact, and easy to transport and store.
2.Bandwidth is a measure of the lowest to highest frequency a signal path can handle.
Appendix B: Troubleshooting

APPENDIX B

TROUBLESHOOTING

TROUBLE -S HOOTING INDEX

If you are experience problems while operating the XT, please use the following table to locate possible causes and solutions before contacting Alesis customer service for assistance.

Symptom

The display does not light when the [POWER] switch is turned on. FORMAT icon flashes. The record-enabled tracks meters do not indicate input levels. Cant change the sample rate/clock source. Pressing [AUTO REC] displays invALid. AUTO RETURN icon flashes. When used as a slave in a multiple ADAT system, doesnt follow the master. TIME counter does not show tape position. Interpolation indicator ( ) lights/flashes. 48K or 44.1K icon flashes.

No power.

Solution
Check that the power cable is plugged in properly. Format the tape, or reinsert. Check your audio cables.
Tape is not formatted. Cables are not connected properly or are shorted. DIGITAL INPUT is selected. If slave in a multiple ADAT system, EXT clock is selected automatically. Locate Point 3s position is before Locate Point 2. Locate Point 4s position is before Locate Point 1. No ADAT master is detected.
Press [ANALOG INPUT]. Set the sample rate/clock source on the master XT.

Error Message in display

Set Locate Point 3 past Locate Point 2. Set Locate Point 4 past Locate Point 1. Check sync cables. Power down the Master only, then restart. Edit mode is turned on. Press [EDIT VALUE] to turn Edit mode off. One or more errors have Clean the tape heads. been detected/corrected Make a backup copy of your tape. Tape was formatted at If desired, press [CLOCK different sample rate than SELECT] to use original currently selected. sample rate. Several possible See Appendix C: Error Codes

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

Similar to the AES/EBU interface, but created by Sony and Philips with consumer applications in mind. The optional AI-1 from Alesis offers both the consumer S/PDIF interface and professional AES/EBU format for use with the XT.
Acronym for Super Video Home System, an improved version of VHS with greater resolution and dubbing capabilities, as well as improved sound.
An area of tape on which audio is recorded. A track can be thought of as a picture of an output over time.

Unbalanced Audio Signals

Signals that are carried on two-conductor cables, one hot and one ground. Unbalanced connections save costs, but are more prone to picking up hum and interference with low-level signals.
Acronym for Video Home System, a video recording system introduced for consumer use and using standardized cartridges.
Vertical Interval Time Code (VITC) is timecode information encoded in the vertical retrace interval of the video signal (this is the time when the beam is getting back to the top of the screen). The advantage of VITC is that the timecode value can be read when the video deck is paused, and is accurate to the frame.

W X Y Z

ABS/REL Button 15, 35 Absolute Time 35, 48 ADAT 55, 59, 63-65 AI-AI-All Input 39 Analog Recording 71 Auto Input 39 Auto Play 19, 50 Auto Record 20, 50-51 Auto Return 19, 50 Autolocation 48 Backup 60 Bandwidth 72 BRC 52, 68 Chase 34 Clock 44, 61, 69 Copying Tapes 60 Crossfade Time 45 Cue 42 Data 30 Digital Clock 61 Digital Input 59 Digital Cecording 41, 71 Display 32 Icons 33 Drum Time 75 Edit Value 36 Eject 42 Error Codes 79 Error Rate 74 Fast Forward 42 Footswitches 28, 53 Formatting 14, 29-31 Complete 30 Extend 31 Recording while 30 Head Cleaning 74-76 ID 34, 56 Inputs Balanced 24 Digital 27 Monitor 39 Select 37-38 Unbalanced 23 Lead 30 Locate 48 Locate Reference 69 Locked 34, 57 Loop 19 LRC Remote 28 Meters 40 MIDI 69 Multiple ADAT System Formatting 56 Master 55 Slave 55 Optical 27 Outputs Balanced 24 Digital 27 Unbalanced 23 Peak Clear 40 Peak Mode 40 Phase 64 Pitch 21, 45-46 Play 17, 43 Power 7, 13 Punch In/Out 43, 44 Record 43 Re-initializing 74 Record Crossfade Time 45 RECORD ENABLE Buttons 15, 41 Recording 16 Analog 37, 71 Bouncing 38, 59 Digital 37, 41, 71 Live 68 Track Copy 38 While formatting 30 Rehearse 51 Relative Time 35, 48 Review/Rewind 42 S-VHS 11, 68, 72 Sample Rate 44, 69 Set Locate 35 Signal Level 41 Software Version 75 Stop 44 Sync 26, 55 Tape Length 47, 68 Threaded 11, 42, 44 TIME Counter 13, 15 Track Copy 38 Track Delay 47 Transport 15, 42-44, 63 Unthreaded 11, 42, 44 Video 69 Write protect 29 s and t buttons 36