User manual ALESIS ADAT-XT20

ALESIS ADAT XT20 Reference Manual Introduction/Contents INTRODUCTION Thank you for purchasing the Alesis ADAT-XT20 20-Bit Digital Audio Recorder. To take full advantage of the XT20's functions, and to enjoy long and trouble-free use, please read this user's manual carefully. HOW TO USE THIS MANUAL This manual is divided into the following sections describing the various modes of the XT20. Though we recommend you take time to read through the entire manual once carefully, those having general knowledge about multitrack recorders should use the table of contents and index to reference specific functions while using the XT20. Chapter 1: Introduction. Deals with the necessary preparation before recording and playing, including connections to external devices. This chapter also discusses the difference between "threaded" and "unthreaded" tapes. Chapter 2: Your First Session with the ADAT-XT20. This section provides a brief tour of the XT20, shows you how to format a tape, record and playback, set locate points, auto punch-in and out, bounce tracks, and points out other various features. Chapter 3: Connections. Details rear panel connections (like inputs and outputs, footswitches and the ADAT Optical Digital Interface), and proper hook-up procedures. Chapter 4: Basic Operations. Covers the user interface of the XT20 and the way to use its basic control features, how to read the display, and how to navigate through and edit parameters. Chapter 5: Multiple ADAT Operation. How to lock together multiple ADAT CompatibleTM devices, and how to record and transfer digital audio between them. Chapter 6: Applications. Describes several real-world examples of how the XT20 may be used. Appendices. Features an explanation of digital audio recording concepts, troubleshooting, maintenance and service information, specifications, a Glossary and an Index. CONVENTIONS All front panel buttons, LEDs, display icons and rear panel connectors are referred to in this manual just as their names appear on the XT20, using all capital letters and in brackets (Examples: [PLAY] button, [AUTO INPUT] button, EDIT icon, etc.). When something important appears in the manual, an icon (like the one on the left) will appear in the left margin. This symbol indicates that this information is vital when operating the XT20. ADAT XT20 Reference Manual 1 Introduction/Contents 2 ADAT XT20 Reference Manual Introduction/Contents CONTENTS SETTING UP 7 Unpacking and Inspection 7 AC Power Hookup 7 Avoiding Ground Loops 8 Line Conditioners and Protectors 9 About Audio Cables 9 Basic Audio Hookup 10 Input Normaling 10 "Threaded" vs. "Unthreaded" 11 A Word on ADAT's S-VHS Cassette Tape Operating Environment 12 Thermal Considerations in Rack Mounting Mounting on a Shelf or Non-Rack Enclosure Avoiding Electromagnetic Interference 12 Power-up, and Tape Insertion 13 Formatting A Tape ­ A MUST! 15 Word Length (16/20 Bit) Selection Sample Rate Selection 15 Formatting a New tape 15 Recording While Formatting 16 Making A Recording 17 Track Selection and Setting Levels Time Counter 17 Transport Buttons 19 Recording 19 Playback 20 Reviewing and Cueing 20 Locating 22 Creating A Loop 23 Automated Recording 24 Rehearsing 24 Pitch Control 25 Track Delay 25 Track Copy 26 Display Brightness 26 11 12 12 YOUR FIRST SESSION WITH THE ADAT-XT20 15 13 17 CONNECTIONS 28 Analog Audio ­ Unbalanced Inputs 28 Input jack characteristics 28 Typical input jack hookups 28 Analog Audio ­ Unbalanced Outputs 28 Analog Audio ­ Balanced Inputs and Outputs Analog Input Select Mode 30 Sync In/Out 31 Digital Audio In/Out 32 About 16-bit and 20-bit signal transfers 32 Footswitches 34 The XT20 Remote 34 29 BASIC OPERATIONS 35 ADAT XT20 Reference Manual 3 Introduction/Contents Tape Formatting 35 Formatting Considerations 35 Complete Format 36 Recording While Formatting 37 Format Extend 37 Write Protect Override 39 Reading The Display 40 Display Icons 41 TIME Counter & ABS/REL Button 44 Locate 0 44 Basic Editing 46 EDIT Value Button 46 v and w Buttons 46 Entering Numeric Values 46 Editing Individual Digits 46 Input Select 48 Analog Input 48 Digital Input 48 Track Copy 49 Input Monitor 50 Auto Input Monitor 50 All Input Monitor 50 Meters 52 Peak Mode Button 52 Peak Clear Button 52 Fine Meter Mode 52 Recording a "Benchmark" Tape 53 Record Enable 54 Setting Levels 54 Transport Controls 56 Eject 56 Rewind/Review 56 Fast Forward/Cue 56 Play 58 Record/Punch In or Out 58 Stop 59 Sample Rate (Clock) 59 Record Crossfade Time 60 Displaying Frames vs. 100ths/Seconds 60 Pitch Control 62 About Pitch Changing 62 Track Delay 63 Autolocation Controls 65 Absolute (ABS) Time vs. Relative Time65 Locate 0 65 Setting Locate Points 67 Locating 67 Auto Looping 68 Auto Return 68 Auto Play 68 Loop Limit 68 Looped Recording 68 Auto Record 69 Rehearsal 69 4 ADAT XT20 Reference Manual Introduction/Contents Tape Length 70 Footswitch Controls 71 Footswitch Controlled Punching Footswitch Controlled Autolocating Using the XT20 LRC Remote 72 71 71 MULTIPLE ADAT-XT20 OPERATION 74 Overview 74 Synchronizing Machines 75 Master/Slave Interaction 75 Achieving Lock76 Independent Slave Mode 76 Formatting Multiple Tapes 76 Master Format Enabled, Complete Format Master Format Enabled, Format Extend 76 Master Format Disabled 78 Master Format Disabled, Format Extend Recording Digital Audio 79 Bouncing Tracks Between ADATs 79 Reassigning Channels to Different Tracks Making Digital Backups 81 Making a 16-bit copy from a 20-bit master Recording Digital Audio from Other Sources Digital Clock Considerations 83 Tape Offset 85 Combining XT20s and ADATs 86 XT20 Transport Speed 86 Sample rate vs. Pitch Control 86 Input Monitoring 86 Polarity Differences 88 Connections 89 76 78 80 82 83 APPLICATIONS 91 Overview 91 Combined Multitrack/Mixdown Deck 91 Live/Long-Term Recording 92 Locking to Video: Code-Only Master 93 Computer Control 93 MIDI Systems: Virtual Tracking 93 MIDI Machine Control: Virtual Remote Control93 The ADAT-PCR Computer Interface 94 Libraries and Archives 94 Modular Recording 94 Using Track Copy as a Digital Router 95 Calculating Tape Offset using the Locates 95 DIGITAL RECORDING CONCEPTS 97 Analog Recording Basics 97 Digital Recording Basics 97 The Advantages of 20-Bit Recording Why S-VHS? 98 98 TROUBLESHOOTING Trouble-Shooting Index 99 Re-initializing 99 Checking Software Version Error Rate Display 100 99 100 ADAT XT20 Reference Manual 5 Introduction/Contents About Error Rate Readings ADAT Head Life 100 ADAT Head Maintenance Drum Time Display 102 Tape Maintenance: Safe Tape Maintenance/Service 103 Cleaning 103 Maintenance 103 Obtaining Repair Service 100 101 102 103 107 ERROR CODES SPECIFICATIONS GLOSSARY 112 INDEX 119 105 110 Automatic Brake Calibration Procedure Steps To Take Before Calling For Help 107 6 ADAT XT20 Reference Manual Setting Up: Chapter 1 CHAPTER 1 SETTING UP 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 HOOKUP With the XT20 off, plug the female end of the power cord into the XT20's [POWER INPUT] socket and the male (plug) end into a source of AC power. It's 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 XT20's 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. ADAT XT20 Reference Manual 7 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 In today's studio, where it seems every piece of gear has a computer in it, there are many opportunities for ground loop problems to occur. These show up as hums, buzzes, or sometimes radio reception and can occur if a piece of equipment "sees" two or more different paths to ground, as shown below. shielded cable Device A path 1 Device B path 2 To AC power service One path goes from device A to ground via the ground terminal of the three-conductor AC power cord, but A also sees a path to ground through the shielded cable and AC ground of device B. Because ground wires have a small amount of resistance, small amounts of current can flow through ground and generate a voltage along the cable shield. This signal may end up getting induced into the hot conductor. The loop can also act like an antenna into which hum is induced, or can even pick up radio frequencies. Furthermore, many components in a circuit connect to ground. If that ground is "dirty" and contains noise, it might get picked up by the circuit. Ground loops cause the most problems with high-gain circuits, since massive amplification of even a couple millivolts of noise can give an audible signal. Most ground loop problems can be solved by plugging all equipment into the same grounded AC source. However, it is important to make sure that the AC source is not overloaded and is properly rated to handle the gear plugged into it. For really tough cases, you may need to break the connection that causes the loop condition. If your circuits are balanced, one way to do this is to simply break the shield of the shielded audio cable at some point, usually by disconnecting it from ground at one jack. (The other end 8 ADAT XT20 Reference Manual Setting Up: Chapter 1 should remain connected so that the shielding properties are retained, even if there is no direct path for ground.) Please note that not all hums and buzzes are caused by ground loops; your cables must be of very high quality, particularly with -10 dBV setups. Refer to page 9 for more information. ADAT XT20 Reference Manual 9 Chapter 1: Setting Up LINE CONDITIONERS AND PROTECTORS Although the XT20 is designed to tolerate typical voltage variations, in today's world the voltage coming from the AC line may contain spikes or transients that can possibly stress your gear and, over time, cause a failure. There are three main ways to protect against this, listed in ascending order of cost and complexity: · Line spike/surge protectors. Relatively inexpensive, these are designed to protect against strong surges and spikes, acting somewhat like fuses in that they need to be replaced if they've been hit by an extremely strong spike. · Line filters. These generally combine spike/surge protection with filters that remove some line noise (dimmer hash, transients from other appliances, etc.). · Uninterruptible power supply (UPS). This is the most sophisticated option. A UPS provides power even if the AC power line fails completely. Intended for computer applications, a UPS allows you to complete an orderly shutdown of a computer system in the event of a power outage, and the isolation it provides from the power line minimizes all forms of interference--spikes, noise, etc. ABOUT AUDIO CABLES The connections between the XT20 and your studio are your music's lifeline, so use only high quality cables. These should be low-capacitance shielded cables with a stranded (not solid) internal conductor and a low-resistance shield. Although quality cables cost more, they do make a difference. Route cables to the XT20 correctly by observing the following precautions: · Do not bundle audio cables with AC power cords. · Avoid running audio cables near sources of electromagnetic interference such as transformers, monitors, computers, etc. · Do not place cables where they can be stepped on. Stepping on a cable may not cause immediate damage, but it can compress the insulation between the center conductor and shield (degrading performance) or reduce the cable's reliability. · Avoid twisting the cable or having it make sharp, right angle turns. · Never unplug a cable by pulling on the wire itself. Always unplug by firmly grasping the body of the plug and pulling directly outward. · Although Alesis does not endorse any specific product, chemicals such as Tweek and Cramolin, when applied to electrical connectors, are claimed to improve the electrical contact between connectors. 10 ADAT XT20 Reference Manual Setting Up: Chapter 1 BASIC AUDIO HOOKUP When connecting audio cables and/or turning power on and off, make sure that all devices in your system are turned off and the volume controls are turned down. The XT20 provides eight -10dBV unbalanced analog outputs via phono connectors. These should be connected to your mixer's tape or line inputs. Alternatively, a multi-pin connector can be used with the XT20's +4dBu balanced analog inputs and outputs (see Chapter 3). Mixer Inputs Bus Outputs INPUT NORMALING The XT20 has eight analog inputs, but you can choose between three different Input Modes: 2-Input Mode, 4-Input Mode and 8-Input Mode. These can provide three different analog audio input hookup options, and are available for both -10 dBV and +4dBu analog inputs: · 2 Bus Mixer. Connect the mixer's two bus outputs to the XT20's INPUTS [1] and [2]. Select 2-Input Mode on the XT20 by holding the [ANALOG INPUT] button and pressing either Track Select buttons [1] or [2]; notice that the INPUT LEDs for tracks 1 and 2 remain lit until you release the [ANALOG INPUT] button. · 4 Bus Mixer. Connect the mixer's four bus outputs to the XT20's INPUTS [1] through [4]. Select 4-Input Mode by holding the [ANALOG INPUT] button and pressing either Track Select buttons [3] or [4]; notice that the INPUT LEDs for tracks 1 through 4 remain lit until you release the [ANALOG INPUT] button. · 8 Bus Mixer/Direct Outputs. Connect the mixer's eight bus outputs (or 8 direct outputs) to the XT20's INPUTS [1] through [8]. Select 8-Input Mode by holding the [ANALOG INPUT] button and ADAT XT20 Reference Manual 11 Chapter 1: Setting Up pressing any Track Select button from [5] - [8]; notice that the INPUT LEDs for tracks 1 through 8 remain lit until you release the [ANALOG INPUT] button. In the first two modes, the XT20 internally connects the inputs to the higher tracks (for example, Input 1 goes to tracks 1, 3, 5 and 7 in 2-Input mode). "THREADED" VS. "UNTHREADED" The XT20 uses a rotating head drum which allows it to record and play back digital audio signals from the tape. Even when the tape is stopped, it remains "threaded" or engaged against the spinning heads for a period of time. This allows for going into play or record faster, as well as "cue" and "review" functions that let you monitor the tape audio in fast forward or rewind. When the tape is unthreaded (the [STOP] LED will be flashing), the head is not spinning and it takes slightly longer to go into play or record. This is because the tape moves away from the head automatically after being stopped for 4 minutes, in order to prolong tape and head life. When a tape is threaded, rewinding or fast forwarding will operate 40 times faster than normal play speed. Cue and review functions are not possible while the tape is unthreaded. When the tape is threaded and stopped (the [STOP] LED will remain lit), you can manually unthread it by pressing the [STOP] button. The [STOP] LED will flash, indicating the tape is now unthreaded. Pressing either [PLAY] or [STOP] will re-thread the tape (or by simultaneously pressing [PLAY] and [RECORD] to engage recording). If the tape is threaded, and no transport activity (play, record, rewind, etc.) occurs for 4 minutes, the tape will automatically unthread itself to minimize tape wear. A WORD TAPE ON ADAT'S S-VHS CASSETTE Alesis recommends you use only premium quality, name brand S-VHS cassettes. We cannot overemphasize the importance of this. We recommend using Quantegy 489 DM Digital Mastering Audio Tape, or Alesis ADAT Mastering Audio Cassettes. Other acceptable brands include Maxell XR-S Black, JVC XZ, Sony DASV, BASF Digital Master 938, Apogee AA-40, HHB ADAT45, 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-thanpremium formulation will decrease the reliability of your recording. Inferior tapes not only jeopardize the recordings made on them, they may shed oxide 12 ADAT XT20 Reference Manual Setting Up: Chapter 1 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. Don't trust your work to anything less than premium quality S-VHS tape. Accidents can happen ­ so, like computer floppy disks and hard disks, your XT20 tapes should be backed up to prevent loss. Back up your tapes to another XT20 or ADAT using the fiber optic digital connector (see Making Digital Backups on page 81). 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, don't 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 THERMAL CONSIDERATIONS IN RACK MOUNTING The XT20 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 XT20 is designed to perform properly over a range of ambient temperatures from 10° C to +40° C (50° F to 104° F), in up to 80% noncondensing humidity. These are not absolute limits, but Alesis cannot guarantee that the XT20 will meet its published specs or remain reliable if operated outside of these ranges. · Always allow adequate ventilation behind the XT20 . Do not seal any enclosure that holds the XT20 . It is not necessary to leave an empty rack space above or below the XT20 unless it runs hot enough to affect equipment above or below it. If your environment is unusually warm and not air conditioned, space between units will help the units run cooler and may lessen tape oxide shedding. · You will need to remove the screw-on feet from the bottom of the XT20 if any equipment will be mounted directly below it. MOUNTING ON A SHELF OR NON-RACK ENCLOSURE To mount the XT20 on a shelf or other flat surface, Alesis recommends using the attached screw-on feet to avoid scratching the shelf's surface with the deck's 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. AVOIDING ELECTROMAGNETIC INTERFERENCE Like all tape machines, the XT20 uses magnetic tape that can be sensitive to electromagnetic interference. Generally this is not a problem, but avoid mounting the XT20 next to devices that generate ADAT XT20 Reference Manual 13 Chapter 1: Setting Up strong magnetic fields such as power amplifiers, monitors and video display devices, speakers, etc. 14 ADAT XT20 Reference Manual Your First Session With The ADAT XT20: Chapter 2 CHAPTER 2 YOUR FIRST SESSION WITH THE ADATXT20 POWER-UP, AND TAPE INSERTION Connect the power cord which accompanies the XT20 between the three-prong power socket on the back panel and an AC outlet receptacle. Please note that there are grounding considerations to be aware of. See pages 7­9 for more information. The XT20 can produce a transient audio signal during power up and power down. When turning the XT20 on or off, be sure to keep monitor levels low. Turn the XT20's power on by pressing the [POWER] button. At power-up the display will briefly look like this: 20bit In a few seconds, the display will change depending on the status of the tape chamber. · If a formatted tape is present, the TIME counter will show the elapsed time since the beginning of the tape (unless it is somewhere in the first two minutes of tape, called the "lead" and "data" sections): ABS 0H 15M 48S 21 n0 F0 If there is no tape, the display shows: 15 · If an unformatted tape is present, the FORMAT icon will flash and the TIME counter will read: ABS · ADAT XT20 Reference Manual Chapter 2: Your First Session With The ADAT XT20 ABS -- -- -- -- 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. 16 ADAT XT20 Reference Manual Your First Session With The ADAT XT20: Chapter 2 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. WORD 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. FORMATTING A NEW TAPE 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. ADAT XT20 Reference Manual 17 Chapter 2: Your First Session With The ADAT XT20 RECORDING WHILE FORMATTING You can record onto tape while formatting. Simply press any of the RECORD ENABLE buttons [1]­[8] for any track(s) you wish to record on before pressing the [FORMAT] button. Prepare your source material to start playback at 0:00:00.00 on the XT20 or later (do not begin recording before 0:00:00.00). See the next section for more information on setting levels and recording. 18 ADAT XT20 Reference Manual Your First Session With The ADAT XT20: Chapter 2 MAKING A RECORDING Recording on the XT20 is very similar to most multitrack tape machines. The process involves formatting a tape (see previous tutorial), putting one or more tracks into record-ready, adjusting record levels on your mixer, setting the input monitor mode, locating to the start tape address and engaging record. In this tutorial, we will be recording from the analog audio inputs at the start of the audio portion of the tape (0:00:00.00). TRACK SELECTION AND SETTING LEVELS You'll find the RECORD ENABLE buttons ([1]­[8]) for all eight tracks on the left side of the front panel, beneath the display. A track is considered "safe" when its [REC] LED is off, in "record-ready" when its [REC] LED is flashing, and in record when its [REC] LED is lit solid. To record-enable a track: Choose a track to record on, and press the track's associated RECORD ENABLE button [1]­[8]. The selected track's [REC] LED will flash to indicate it is in record-ready. Send an audio signal to the track(s) you have placed into record-ready. Adjust the levels on your mixer so that the "average" level is at -15 dB on the peak meters of the XT20 and the loudest section never goes beyond 0 dB. Digital audio recording is different from analog recording, and therefore requires a different method when setting levels. For more information, see Setting Levels on page 48. x To take a track out of record-ready (safe), press its associated RECORD ENABLE button again. The selected track's [REC] LED will turn off to indicate it is safe. TIME COUNTER Before recording, you should familiarize yourself with the transport buttons, and the 7-segment TIME counter in the top left corner of the display. Ordinarily, the TIME counter will show Absolute (ABS) time, which is the exact time reference being read directly off of the formatted tape. The tape position is displayed as hours:minutes: seconds.hundredths-of-a-second. (This counter may be changed to show 30 frames per second, see page 60 for more information.) ABS 0H 15M 48S 21 0H 01M 29S 03 Pressing the [ABS/REL] button will toggle the display between ABS Time and Relative Time. The display will either indicate ABS or REL to the left of the TIME counter. REL Relative Time reflects the current tape position relative to where you set the Relative 0:00:00.00 position. This is similar to resetting the tape counter on a cassette deck. However, the XT20 gives you the option of reading the actual tape position (ABS Time) or the tape position relative to the location you marked as 0:00:00.00 (Relative Time). ADAT XT20 Reference Manual 19