A guide to choosing and using digital audio recording media · A guide to choosing and using digital audio recording media • Technical Notes: How the major digital recording formats

A guide to choosing and using digitalaudio recording media

• Technical Notes: How the major digital recording formats work

• Application Notes: The pros and cons of each format explained

• FAQs: Your digital recording questions answered

• Jargon Busters: A glossary of technical terms

• HHB Advanced Media Products: Full specifications

TM

ADVANCED MEDIA

PRODUCTS

ADAT4545 MINUTES

DAT125

ADVANCED MEDIA

PRODUCTS

ADVANCED MEDIA

PRODUCTS

MDD140

ADVANCED MEDIA

PRODUCTS

MO 2.6GBREWRITABLE MAGNETO OPTICAL DISK5.25"(130mm) 1024 BYTES PER SECTOR

MD74

ADVANCED MEDIA

PRODUCTS

Media Guide + Additions A4 30/7/99 3:19 pm Page 1

Contents

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

DAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

CD-R . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

MD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

MO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

ADAT and DTRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

DVD-RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Jargon Busters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16


Foreword

Not one of the eight formats discussed in this book was originally intendedfor professional audio use. Yet all are in daily use on location, in project andcommercial music recording studios, in film dubbing theatres and post-production facilities, in broadcast studios and in mastering and editingsuites the world over. As each new consumer audio, computer data storageor consumer video recording format comes along, professional audio usersand equipment manufacturers consider the suitability of the new mediumfor use in the wide variety of very different professional audio disciplines,adopting it accordingly.

But it’s all data. So what’s the difference? The answer is a great deal.Factors including capacity, access time, durability, long-term archivalstability, compatibility, indexing and even physical size all contribute todetermine a format’s suitability for a particular professional audioapplication.

Even within a given format, there are significant differences. The criticalareas of low block error rates and long term data security are affected byvarying standards of manufacture and the formulation of recording dyes,metal particle recording layers and binders. In tape formats, even thecassette shell plays a key role, ensuring the smooth spooling and safehandling of the tape. And not all cassette shells are the same.

At HHB, we’re committed to providingaudio professionals with the highestpossible levels of performance andlong term archival stability in a rangeof Advanced Recording Media Productsthat spans all the popular digitalformats - DAT, CD-R, MO, MD, MDData, ADAT, DTRS and DVD RAM.Before we launch a new HHB media

product, we test it extensively - not just with a handful of recorders butwith every popular recorder available, to guarantee the highest possiblelevels of performance and compatibility.

Since HHB was established in 1976, we’ve played a pivotal role inestablishing DAT, CD-R, MD and MO as professional audio formats. Thedevelopment of products like the PORTADAT portable DAT recorder, theGenex GX8000 hi-bit, hi-sampling MO recorder and the CDR850 audio CDrecorder has gained us even greater insight into the operation of theseformats in professional audio applications. Other media manufacturers maybe interested primarily in developing and selling products to the muchwider computer and consumer audio markets. At HHB, we specialise inprofessional audio and nothing else.

In response to the growing volume of questions from our customers aboutdigital audio recording formats, we’re pleased to bring you this book – Aguide to choosing and using digital audio recording media. It sets out toexplain in clear and straightforward terms how the formats work, their prosand cons, their primary professional audio applications and the meaningsof the technical terms often used to describe them. Alongside detailedspecifications of all the HHB Advanced Media Products, you’ll also find theanswers to the recording media questions we are most frequently asked.

We hope you will find this book both interesting and informative.

Steve Angel, Sales DirectorHHB Communications, UK.

An electronics graduate, Steve Angel’s audio career began at London’slegendary Trident Studios in 1976. Moving on to Utopia Studios, hemastered hits for many artists, including The Pretenders, Tina Turner andDuran Duran, culminating in the massive selling Band Aid single, ‘Do TheyKnow It’s Christmas’. After 12 years in the studio, Steve emerged to see thelight of day when he joined HHB Communications in 1988. Customersappreciate Steve’s understanding of their industry and today, he’s widelyrespected around the world as Sales Director of HHB.

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Recording times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15, 35, 50, 65, 95 and 125 minutesBlock error rate (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Under 5x10-4

Retentivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2500 GaussCoercivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1520 OeSurface resistance Mag layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2x1010 Ω/sq

Back coating . . . . . . . . . . . . . . . . . . . . . . . . . . . 2x104 Ω/sqTape thickness (total) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13µmArchival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 30 yearsRecommended storage conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15˚C (59˚F) 30% RHRecommended operating conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20˚C (68˚F) 50% RH

• Independently proven to be the most dependablebrand of DAT tape.*

• Exceptional archival stability (> 30 years).• Available in 6 convenient lengths - 15, 35, 50, 65, 95 and 125 minutes.• Specially formulated binder ensures consistently low block error rates,

even after 100 passes.• Flexible base film minimises head wear.• Fast discharge anti-static lid resists dust contamination.• Cassette shell will withstand a temperature of 107°C (224.6°F) without

warping.• New hub lock assembly improves braking action, reduces tape slack

when ejecting, and hence provides better loading.• Shatterproof Polypropylene library case.• Professional labelling.

*Studio Sound ‘DAT On Trial’

DAT15, 35, 50, 65, 95 & 125

Background

After the advent of the Compact Disc, the next logical step was to design arecordable digital audio format. To this end, DAT (Digital Audio Tape) wasdeveloped. Originally designed by Sony as a digital replacement for thehugely popular analogue compact cassette, DAT was launched at the end of1987. DAT did not, however, attract support from the major recordcompanies, who were worried that the potential for digital cloning of CDswould lead to an increase in copyright infringement.

Nevertheless, DAT was soon universally adopted by audio professionals,who jumped at the chance to master digitally at a comparatively low cost.So a format designed originally for the consumer still stands today as themost popular format for professional stereo mastering. Latterly, various 8-track formats have been developed that also use rotary head techniques;these include ADAT (developed by Alesis) and DTRS (as used by theTascam DA88 and compatibles).

How DAT Works

DAT is a 16-bit, rotary-head digital recording system. DAT recording worksin a similar fashion to video recording, in that two or more magnetic headsare mounted inside a rotary drum. In a 2-head DAT recorder, these headsare positioned 180° apart, on opposing sides of the drum. However, unlikevideo, DAT stores data in bursts on the tape - digital audio from the input isstored in memory and then written to tape at a higher rate than used forsampling, leaving gaps in between. The tape does not have to always be in

DAT Digital Audio Tape


contact with the heads and therefore is not wrapped 180° around them,making tape loading and unloading a far simpler process. Indeed, the tapewrap angle on most DAT recorders is 90°, reducing friction and wear on thetape, especially when spooling at high speeds.

To increase the head to tape speed, the heads rotate at 2000 revolutionsper minute in the same direction as the tape motion. This rotary drum isalso at a slight angle to the tape, producing long, narrow slanting tracks ofinformation on the tape itself.

As each head is about 20 microns wide and each tape track space is only13 microns, there will be some overlapping of the tracks. The track fromthe second head will always partially overlap the track that is laid down bythe first. To stop interference between neighbouring tracks, each of theheads is also at a slightly different angle to the tape track (±20° - this angleis known as the azimuth). This change in azimuth reduces crosstalkbetween adjacent tracks during replay, since any unwanted signal from aneighbouring track will be picked up at a level too low to be interpreted aspart of the digital signal. Protective guard bands are therefore unnecessary.There are also two linear tracks which run along the length of the tape butthese are rarely used. As the tape moves so slowly (8.15 mm/sec) it isdifficult for much useful information to be stored on these linear tracks.

When recording information to tape, a digital signal is fed to the recorder’sheads. As the heads are in contact with the tape, the magnetic state of theparticles along the length of the tape track alternates with the signal fromthe heads. As with the CD format, the digital signals are coded beforestorage on the tape.

During replay from tape, the changing magnetic field of the tape particlesinduces signal back into the heads. This signal can then be decoded, fromwhere it may be converted to an analogue signal. The AES/EBU and SPDIFdigital interfaces allow a DAT recorder to make an audio clone of anotherDAT, CD or any other digital source (containing two audio tracks or less).With connection from a CD recorder to a DAT recorder via the SPDIFinterface, CD track starts can be recorded on the tape as IDs (index points).IDs are pieces of subcode information, stored separately from the audio ontape, that tell the DAT recorder where each of the separate ‘tracks’ starts.Amongst other information, DAT subcode shows the sampling rate, thenumber of channels and the copyright status of the recorded material.Timecode information is also contained here. As the subcode is stored inseparate blocks from the audio on the tape, it is possible to record or erasethe IDs without disturbing the audio, giving ultimate flexibility.

Pros and Cons

Pros:• Low media costs• Durable, with long archival life• Many lengths of tape available, minimising tape wastage• Can be used to make one-to-one digital copies• Universally adopted by the professional audio industry as a

2-track mastering format

Cons:• No editing facilities• No random access• Instant track start available only on certain top end recorders

Primary Professional Audio Applications

DAT is still the world’s most popular format for 2-track digital masteringand can be found in almost every recording studio. Its 16-bit resolutionmakes it ideal for CD mastering. The portability of many DAT recorders hasmade the format increasingly popular for film and television locationrecording.

A Word of Warning

All DAT tapes are not the same. HHB DATs use an advanced formulation ofbinder to ensure that the recording layer remains adhered to the tape, evenafter multiple passes. The result is consistently lower block error rates andsuperior archival stability.

Frequently Asked Questions about DAT

• What’s the point in buying a DAT recorder now that CD-R recorders arealmost the same price?

DAT is the primary format used for recording a 2-track audio mix. Theability, especially with timecode recorders, to alter the subcode information(e.g., IDs and timecode) after the recording process has given audioprofessionals great freedom in the way they use their DAT recorders. DATrecorders can be found in all studios and, at the moment, the format seemsto be leading the digital audio market. The main advantage of the DATformat over CD-R is the increased length of recording time. For example,with the HHB DAT125, over two hours of recording time is available - thisdoubles to four hours and ten minutes of continuous playback andrecording time (but with a reduction in the audio quality) when recording inlong play mode.

• Apart from cost, what are the key differences between a consumer and aprofessional DAT recorder?

Professional DAT recorders often havefour heads rather than just two.This enables off-tapemonitoring whilst recording -a very useful security featureduring recording sessions,(used to check whether audiohas actually been sent to thetape correctly). Mostprofessional recorders do notuse the SCMS (SerialCopy ManagementSystem) applied in manyconsumer models,enabling an infinite number of digital clones to be made. These clones canbe made via either the SPDIF or AES/EBU digital interfaces - although theAES/EBU interface is normally only found on professional recorders.

TRACK LAYOUT ON THE TAPE SURFACE

HHB PORTADAT PDR1000TC – A PROFESSIONAL4 HEAD PORTABLE DAT RECORDER

3


• My DAT recorder won’t record at 44.1kHz. Can my recordings be used forCD mastering?

CDs have a sample rate of 44.1kHz. Many computer based masteringprograms are capable of loading information at one sampling rate from DATand converting this to the required 44.1kHz. Normally, each CDmanufacturing plant will specify their preferred format for CD mastering.

• When I clone a DAT, how do I make sure that my IDs are in the sameplace?

The simplest method of achieving this is to connect the two DAT recordersvia the consumer (SPDIF) interface. With the recording DAT’s AUTO IDswitched off (this varies between recorders), the IDs should be successfullycloned along with the audio information.

• Is it possible to link DAT to video?

With the addition of timecode to DAT recorders, it is simple to link them toexternal machines, such as video recorders. This system is often usedwhen scoring music for films, for example, as it allows the composer toplay his recordings in sync with the pictures on screen.

• Can I use DDS tapes in DAT recorders?

The only advantage of using DDS (Digital Data Storage) tapes in a DATrecorder is that a DDS90 (90 metres) tape will allow 180 minutes of audiorecording (360 minutes in long play mode). However, DDS tapes are muchthinner and not so reliable when spooling and playing at high speeds. It isalso not the best idea to have all your audio on one tape in case the tape islost or damaged.

• Is it possible to stop other people cloning my DAT?

A system known as SCMS (Serial Copy Management System), proposed byPhilips, operates via the consumer digital interface. This limits the numberof generations of copyright digital recordings that it is possible to make,depending on the copyright material itself and the equipment used for therecording. SCMS is essentially a method of preventing serial copying ofcopyright material. However, professional DAT recorders will always allow adigital copy to be made via the AES/EBU interface.

• When inserting a new DAT tape into the recorder, do I need to spool tapesto the end and back before I begin recording?

This is a worthwhile procedure if time allows. Spooling to the end of thetape and back will ensure the tape is wound smoothly and firmly on thehub. Also, since the tape has remained wound since its manufacture, it maystick slightly to the layer next to it - spooling the tape will separate theseneighbouring layers, allowing smoother running and preventing unwantederrors on first use.

Recording time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 minutesCapacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 680 MBRecording material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phthalocyanine stable organic dyeProtecting material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UV cured resinBlock error rate (at 1X speed) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 cpsReflection ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 72%Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < +/- 40nm (double pass)Dynamic radiant runout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 70µmArchival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 100 yearsRecommended storage temperature . . . . . . . . . . . . . . . . . . . . . . . . .15 - 20˚C (59 - 68˚F)Recommended storage humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30% RH

• The world’s first CD-R disc optimised for professional audio.• The most dependable CD-R disc on the market - secure archival life well

in excess of 100 years.• Exceeds Orange Book standards in all areas.• Specially formulated Phthalocyanine dye results in exceptional recording

accuracy and is less susceptible to the harmful effects of UV exposure.• Professional labelling.• The HHB range of CD-R media should not be confused with consumer

CD-R audio discs, which can only be used in consumer CD recorders.

CDR74 Gold

CDR74 Silver, Silver P and Bulk

• The silver reflective layer allows increased reflectivity, resulting in greatercompatibility with other CD players and recorders.

• Secure archival life of 100 years.• Exceeds Orange Book standards in all areas.• The CDR74 Silver P, with new improved printing surface, is suitable for

use with inkjet printers, such as Affex, Copytrax, Fargo and IMT.• CDR Bulk is suitable for use with thermal printers, such as Rimage.• Phthalocyanine recording dye.• Professional labelling.

Recording time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 minutesCapacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 680 MBRecording material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phthalocyanine stable organic dyeProtecting material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . UV cured resinBlock error rate (at 1X speed) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1 cpsReflection ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 74%Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < +/- 40nm (double pass)Dynamic radiant runout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 70µmArchival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 100 yearsRecommended storage temperature . . . . . . . . . . . . . . . . . . . . . . . . .15 - 20˚C (59 - 68˚F)Recommended storage humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30% RH

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CDRW74 Rewritable Compact Disc

Recording time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 minutesCapacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650 MBRecording material . . . . . . . . . . . . . . . . . . . . . . . . . Ag-In-Sb-Te phase change recording materialTrack pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 ± 0.1µmSubstrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PolycarbonateReflectance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 - 25%Track eccentricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 70µmTilt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 0.6°Overwrite cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 1000Archival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 100 yearsOperating temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 55˚C (41 - 131˚F)Operating humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 95% RH

• Rewritable compact disc, optimised for professional audio use.• Exceeds Orange Book Part III standards in all areas.• Highly sensitive Ag-In-Sb-Te phase change recording material for

optimum reading and writing performance with a wide range of CDrecorders.

• Secure archival life of over 100 years.• Professional labelling.

Background

During the 1970s, extensive research into laser systems coincided withsignificant developments in the technology of digital audio. The costs ofboth began to fall. Around that time, the music industry was looking for away to introduce digital audio to the consumer, in a form that could replacethe vinyl record. In the early eighties, Sony and Philips invented what isnow the most popular digital audio format ever, the Compact Disc.

The recordable CD format was first marketed at the beginning of thenineties. With the gradual reduction of hardware and media costs, CD-Rusage has increased tremendously, both with audio and data usage. In 1997alone, nearly two million CD-R and CD-RW recorders were sold and astaggering two hundred million discs used. Finally, professional users wereable to produce their work on a high quality medium that almost everyonehas the facility to replay. With the addition of the rewritable formats such asCD-RW and DVD-RAM, many more people are sure to realise the benefits ofsuch flexible systems. A true replacement for the cassette in the racks ofevery home, project and commercial studio has been found.

How CD-R Works

A CD is 120 millimetres (4.75 inches) wide and holds 680MB of digitaldata, or 74 minutes of stereo 16-bit, 44.1kHz digital audio. Unlike mostmedia, a CD does not use electrical or magnetic recording, but uses opticalrecording methods instead. It works on the principle of reflecting a laserlight spot back towards a photosensor inside the CD player. The amount oflight received by the photosensor allows the CD player to determinewhether a particular area of the disc surface contains a pit or a land, andhence whether a digital binary 1 or 0 should be queued in the outgoingdigital datastream.

CD-R & CD-RW Recordable Discs

Pre-recorded CDs are moulded with these physical characteristics (pits andlands) inherent in their design. A CD-R disc, on the other hand, is mouldedwith a continuous pregroove for the laser to follow. It is a WORM disc(Write Once Read Many), since once the data has been written to the disc,it cannot be removed. CD-Rs are covered with photosensitive organic dyes,such as Cyanine, Phthalocyanine or Azo, similar to those used inphotography. Raw Cyanine, green in colour, is quite sensitive to sunlightand therefore the archive life of a Cyanine disc is fairly short - about 10years under normal conditions. Phthalocyanine dye, developed by theMitsui Corporation and gold in colour, is a derivative of Cyanine dye, and isless susceptible to the elements, providing a longer data archive life. Mostmodern CD-R recorders, including the HHB CDR850, use OPC (OptimumPower Control) to determine the best laser writing power for the media.

Lasers generate light with a precisely controlled wavelength with all itsparticles in-phase with each other - this allows accurate focussing of thebeam. A CD recorder uses an in-built laser to alter minute areas of the dyeon the disc surface, creating a structure which, to the laser pick-up,emulates a pre-recorded CD. Once finalized with the addition of the table ofcontents, this CD-R can be played in any CD player.

The wobbled spiral groove in the disc’s polycarbonate substrate containstiming information which keeps the CD-R spinning at the correct rate forwriting data to the disk. It also ensures that the track spacing will becorrect - this is critical for accurate tracking of the laser during recordingand playback.

There are different ways of writing information to CD-R discs - the simplestof which is known as ‘disc-at-once’ mode. Here, the laser is never switchedoff while writing the information. This information will include a lead-inarea, the program and a lead-out section. Alternatively, discs may bewritten as ‘track-at-once’, where data is written as separate packets ofinformation, each containing lead-in and lead-out data. Gaps are leftbetween each track for run-ins and run-outs. Once all data and audio hasbeen recorded onto the disc, a process known as ‘finalization’ should start.This is when the Table of Contents is written, which contains the number oftracks on the disc and where they each start and finish. Finalizationeffectively closes the disc so that it cannot be recorded on again, andmakes the CD-R disc playable on a standard audio CD player. HHB’sCDR850 takes approximately four minutes to finalize a disc.

All CD-Rs should conform to Part II of the Orange Book - a documentwritten by Philips and Sony that describes the specifications for CD-Rtechnology. This specifies not only the physical size of the disc but alsocharacteristics such as which sections of disc will be used for storing non-audio information. Part III of the Orange Book defines the specifications forCD-RW, while audio CD characteristics are described in the Red Book in asimilar way.

The latest addition to the compact disc family is the CD-RW. This is arewritable format, allowing data to be recorded, erased and rerecordedanywhere on the disc. CD-RWs use phase change technology to recordinformation, using a laser at different powers to alter the physical state of

STRUCTURE OF A CD-R DISC

THE HHB CDR850 PROFESSIONAL CD RECORDER

5


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the recording layer in the disc from amorphous to crystalline. Thesedifferent states of material have different levels of reflectivity - these areinterpreted as the audio signal on replay. DVD-RAM optical disks also usephase change technology, allowing the data, once recorded, to be erasedand rewritten.

Pros and Cons

Pros:• Low media cost• Universal format with millions of players in homes and studios worldwide• Ideal for archiving and backing up as it is a removable format• Instant start

Cons:• Write-once medium• Tracks can’t be added once the disc is finalized• No track editing or naming


CD-R technology is fast becoming the industry standard ‘rough mix’ formatin recording studios and project studios alike. The CD-R is widely used in anumber of applications, from archiving data to recording 2-track mixes. Thedifferent ways of writing information gives ultimate flexibility - either thewhole disc may be written at once, or it may be recorded separately insessions.

A Word of Warning

Most CD-R discs are optimised for use in high speed writers designed forcomputer data storage. HHB CD-R media is optimised for professionalaudio CD recorders. As a result, HHB discs offer greater compatibility withboth recorders and players.

Frequently Asked Questions about CD-R

• Will my recorded CD-R disc play on all domestic CD players?

Once the CD-R has been finalized, it should play on all standard CD players.It is also possible to play CD-Rs which have not been finalized on someprofessional CD players.

• What is the archive life of a CD-R?

CD-Rs are coated with different recording dyes - all with varying lifeexpectancies. Phthalocyanine dyes can hold data for an excess of ahundred years - much longer than the expected ten year life of Cyaninedyes. Archive life mainly depends on the care you take of your CDs, bothwith storage and handling.

• What’s the best way to store CD-Rs?

CD-Rs should be stored out of direct sunlight and at low, constanttemperature and humidity. They should be kept in their jewel cases toprotect from scratches or damage, which could result in them beingunreadable by CD players. Although the error correction circuits in CD willcorrect most errors (using data redundancy, by muting or by interpolatingbetween two ‘good’ samples), scratched CD-Rs may not work at all.

• What are the differences between the Red and Orange CD specificationbooks?

These CD specification books, developed by Philips and Sony, define thestandards required for different types of CD formats. However, the RedBook defines CD-DA (CD Audio) and the Orange Book defines CD-WriteOnce formats. This Orange Book is in several parts - part II deals with CD-Rand part III deals with CD-RW.

• What’s the difference between disc-at-once and track-at-once?

Disc-at-once mode writes all the data in one long stream to the disc; thelead-in, the data and then the lead-out. The information for this couldinitially be written to a computer’s hard disk. Track-at-once mode, on theother hand, enables data to be written at different times. The data isrecorded as separate tracks on the disc - when all are written, the disc canthen be finalized.

• Are CD-R discs suitable for mastering?

It is best for the information on the CD-R to be written in one go (disc-at-once) with all correct track start points added. Then, a CD manufacturingplant can use this CD-R to form the glass master which will be used in theproduction of the normal CDs.

• What is PQ subcode?

The CD format allows for the storage of subcode information. In each dataframe (24 audio bytes) one byte of subcode consisting of a bit from each ofeight subcode words (P, Q, R, S, T, U, V and W) is sent. With two additionalframes containing synchronising information, all subcode information issent within 98 data frames, (1/75 second playing time). Only subcodegroups P and Q are normally used, storing information such as track startflags, copy-prohibit status and ISRCs (International Standard RecordingCodes). When PQ encoding a CD, computer systems are often used to insertthese flags, so once the CD-R is written, any CD player will know where onetrack finishes and another starts.

• Why are CD-Rs optimised for use at different recording speeds?

The different speeds used when recording are necessary due to thechemical properties of the disc and the dye when heated by the laser andthen cooled. Many newer CD-R recorders use OPC (Optimum PowerControl) to determine the best laser power to record on any particularmedia type.

• Why can more audio than data be stored on a CD-R?

When formatted as a CD-ROM for non-audio data, less information can bestored than with CD-DA due to the extra layer of error correction required.

• Is it safe to write on CD-Rs with a felt tipped pen?

You should only write on a CD-R with a pen that contains no solvents,since others may corrode the disc’s surface. Soft tipped pens (felt tips) areideal - harder tipped pens (ball point) will damage the disc.

• What printer should I use to print on CD-Rs?

Initially, you need to determine whether the disc is suitable for inkjet orthermal printing. This is important, as damage to printer or discs couldoccur if the wrong printing method for the disc type is used. Inkjet printerscurrently available which are able to print on the surface of HHB’s CD-RSilver P discs are manufactured by Affex, Copytrax, Fargo and IMT. In thecase of thermal printing, HHB’s bulk CD-Rs are suitable for use with aprinter such as Rimage.


MD74 & 80 Professional Audio MiniDiscs

Recording time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 & 80 minutesBlock error rate (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 x 10-4

Disc diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64mm (0.25 ins)Disc thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2mm (0.004 ins)Write / read cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 106

Archival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 10 yearsOperating temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 55˚C (41 - 131˚F)Operating humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 95% RH

• Developed specifically for professional audio use.• Block error rates 10 times lower than consumer MiniDisc media.• Archival stability greater than 10 years.• Can be used reliably for more than 1 million read / write cycles.• Advanced sputter coated recording layer achieves exceptional recording

precision.• High carrier to noise ratio.• Disc protected against extreme environmental conditions by a tough UV

coating.• Advanced foil shutter provides greater protection from dust contamination

than conventional metal shutters.• Special lubricating agent ensures optimum magnetic head contact.• Professional labelling.

7

Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140MBCarrier to noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 46dBBlock error rate (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 3x10-3

Disc diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64mm (0.25 ins)Disc thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2mm (0.004 ins)Write / read cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 107


• MD Data format disc developed specifically for use in MiniDiscmultitrackers (Sony, Tascam, Yamaha, etc.).

• Archival stability greater than 10 years.• High carrier to noise ratio.• Low block error rates, even after repeated passes.• Professional labelling.• If you try and use a HHB MDD140 in a standard audio MiniDisc recorder

it will not work. If, however, you try to use an HHB MD74 MiniDisc in aMiniDisc multitracker designed for use with MD Data format discs, it willwork, but will only allow 2 tracks to be recorded or played.

MDD140 Data MiniDisc

MD MiniDisc and MiniDisc Data

Background

Some years after DAT had failed to take hold of the consumer market,despite its success in professional audio, Sony launched MiniDisc in 1992in another attempt to introduce a recordable digital format to the consumer.Once again, things got off to a rocky start. Despite the allure of namingtracks and some great editing features, there was no denying that, in theearly generations of domestic recorders at least, MiniDisc just didn’t soundquite as good as CD to a generation that had been raised on the ubiquitoussilver discs. But then, with second and third generation recorders, thingsbegan to change.

Although MiniDisc has indeed enjoyedsome success with consumers,particularly in the form of the portable‘MiniDisc personal stereo’, it hasbecome another example of aconsumer format becoming extremelysuccessful in professional circles. Theinstant start properties of somerecorders in particular have beenresponsible for it becoming a standardfeature in many broadcast studios,where MiniDisc acts as a low-costreplacement for carts and analoguecompact cassette recorders.

In the same way as a DAT variant was introduced for storing computerdata, so too a MiniDisc format has emerged for this use. The MD Datasystem was available in 1994. A new generation of MiniDisc multitrackersfrom manufacturers including Yamaha, Tascam and Sony, is based on thisformat. Multitrack recorders use an on-board buffer to store this databefore it is output as separate audio channels.

How MD and MD Data Work

There are two types of MiniDisc - pre-recorded and recordable. A pre-recorded disc is moulded at the time of manufacture, and is read by a laserin the MiniDisc player. MiniDisc has many features in common with CD.The track pitch and speed are identical, and both offer the same playingtime of 74 minutes. MiniDisc, however, employs a data compressionsystem known as ATRAC (Adaptive TRansform Acoustic Coding) tocompress the digital information, making allowances for the MiniDisc beingphysically smaller than a CD. Using the psychoacoustic principles ofmasking, the ATRAC coder analyses the original audio in narrow frequencybands, reducing the resolution of audio signals that are effectively masked.This removes much of the data, yet leaves a signal almost identical insound to the original.

A recordable MiniDisc, however, is physically different. It is essentially amagneto optical disc; Sony call their method of recording ‘Magnetic FieldModulation’. Both heat and magnetism are required for recording onto thistype of disc; a very small portion of the disc’s surface is heated by a laserto a certain temperature, whilst a magnet applies a field from the other sideof the disc. When at this temperature, known as the Curie point, themagnetic particles on the disc’s recording layer assume the polarity of theexternal magnet. As this magnetic field alternates, a changing magneticpattern is set in the disc, representing the coded audio signal.

Both versions of MiniDisc, pre-recorded and recordable, are similar enoughto allow playback on the same recorder. To read from either disc, a laser at alower power than used during recording is applied. When the laser light isreflected from the disc, these reflections are interpreted in one of two ways.In pre-recorded MiniDiscs, the amount of light reflected represents thecoded audio signal. However, in recordable MiniDiscs, the reflected lightpasses over areas which have been magnetised. This causes the reflectedlight’s polarisation angle to change slightly, depending on the polarity of the

YAMAHA MD8 MULTITRACKER USES MINIDISC DATA DISCS


area of disc. The optical reading mechanism recognises these changes andinterprets them accordingly.

MiniDisc employs a RAM buffersystem which can typically holdfrom three to thirty seconds ofaudio on the way to or from disc.This length of time depends greatlyon the recorder. The MiniDiscreads data faster than is requiredfor playback and therefore storesthe excess data here. This makesportable recorders very popularbecause they very rarely skip - ifthey do, audio is played back fromthe buffer while the head finds thecorrect location on the disc again.Professional recorders use this buffer to implement instant start of audio.The MiniDisc format also offers non-linear editing functions such as copy,paste, track divide and assemble, as well as naming of songs and discs.These can be edited at any time, without altering any audio information.

The MD Data disc is similar to the MiniDisc, and uses the same method ofreading information. Capable of storing 140MB of data, the MD Data dischas a higher data transfer rate than MiniDisc. Its file structure is alsoslightly different, enabling storage of many longer file names. Also, aMiniDisc Data drive is capable of playing back a recorded Audio MiniDisc.

Pros and Cons

Pros:• Small encased media• Advanced editing capabilities - copy, paste, track divide and assemble,

naming of tracks and discs• Instant start feature on many recorders• Players are highly resistant to shocks• Fast gaining acceptance as a consumer format• Low cost media• Ease of storage and transportation

Cons:• Early MD recorders used less sophisticated versions of ATRAC

compression which, while highly faithful, resulted in some loss of soundquality. The latest version of ATRAC has been greatly improved, bearing aclose resemblance to the original signal.


MiniDisc’s instant start properties mean that the format is used extensivelyin broadcasting, replacing carts. It is becoming increasingly popular withradio journalists and musicians working on the move, as it is easilyportable.

A Word of Warning

Never use consumer MiniDisc media in professional applications. The HHBMD74 MiniDisc exhibits block error rates ten times lower than someconsumer MiniDiscs.

DENON DN 990RPROFESSIONAL MINIDISC RECORDER

8

Frequently Asked Questions about MD and MDD

• What’s the difference between MiniDisc and MiniDisc Data?

MD Data has a higher data transfer rate than MiniDisc. This is necessary forrapid storage and retrieval of computer based data. MD Data is also used inmultitrack MD recorders, allowing up to eight channels of audio.

• When cloning a CD to MiniDisc, by how much is the data compressed?

MiniDisc contains a fifth of the amount of data that CD holds, for the sameamount of audio. This is due to the ATRAC compression.

• Will IDs from CD be transferred to MD when cloning?

When cloning to MiniDisc from CD via the SPDIF digital I/O, each new trackon the CD produces a start of a new MiniDisc track.

• Why should I buy a MiniDisc player when CD-R recorders are readilyavailable?

There are no editing facilities on CD-R recorders once the data has beenwritten. However, MiniDiscs allow tracks to be renamed, moved or deletedafter they have been recorded.

• When editing, does the disc get fragmented?

The amount your disc gets fragmented depends on the way you record andedit. The MiniDisc’s buffer plays a great part in ensuring that there is nointerruption of music due to the disc searching for the next section ofaudio. As MiniDisc reads the data faster than is required, the head cansearch for a long time before any interruption occurs. Disc fragmentationalso causes a loss of free recording space, as any unused sections of disclasting less than 12 seconds cannot be re-used.

• How does the recordable MiniDisc keep on track?

This system of tracking is similar to that employed in CD-R technology. Thediscs are stamped with a pregroove which, when followed by the laser,gives out a signal at 22.05kHz. This is half the 44.1kHz sampling rate andtells the MiniDisc recorder the correct speed to rotate the disc. However,this 22.05kHz signal is also modulated with data known as ADIP (ADdressIn Pregroove) which gives the same control and address information forevery single recordable MiniDisc.


Background

The magneto optical disk is a high capacity, removable storage medium.Developed about ten years ago, it was originally designed to be used forbacking up computer data. MO is ideal for use in the new generation of hi-sampling, hi-bit recorders, of which Genex leads the field. With high speedaccess to data on the disk, MO provides a convenient and portable methodof storing vast quantities of audio and data information.

The capacity of magneto optical disks has increased dramatically since theirfirst introduction. This is mainly due to the many developments in lasertechnology. As the wavelength of laser light reduces, this enables greaterdensity of information storage - the laser does not cover such a largeamount of the disk’s surface area. In fact, the laser wavelength has reducedby almost a quarter since 1993 - from 830 nanometres down to about 630nanometres today. Access time has also fallen rapidly, making the magnetooptical storage system ideal for a variety of different applications wherespeed is important. And with projected disk capacities rising to 10Gigabytes or thereabouts over the next couple of years, the future for MOtechnology looks promising.

How MO Works

Magneto optical disks are rewritable, employing a combination of magneticand optical technology to store information. MO disks can be formatted in anumber of ways, depending greatly on the requirements of the recorder andapplication. They are produced from several thin layers, containingprotective films and reflective layers along with the actual magneto opticalrecording material. This recording layer is made from an alloy that resistsexternal magnetic influence at normal temperatures, but which allows theparticles, once heated, to become magnetised and align themselves.

Data is represented by changes in the magnetic polarity of sections on theMO disk’s recordable surface. Writing information to a magneto optical diskinitially involves erasing old data that may be present. The relevant sectionsof the disk’s recordable surface are heated with a laser at high power, untilthe temperature of the material reaches a certain point (the Curie point). Atthis temperature, the material is susceptible to a magnetic field supplied byan external magnet and will assume its polarity. This effectively sets all thedata on the disk to ‘zero’. Then, to write new data, only the sections of thesurface which should become a binary ‘one’ will be heated with the laser, anda reverse polarity magnetic field applied. Lasers are used in MO recordingsince they contain enough energy to instantaneously heat material to theCurie point. They are also simple to focus accurately onto the tiniest area.

Direct over write MO disks are recorded to in a slightly different way since, astheir name suggests, new information may be recorded over old informationwithout the need for erasing. By controlling the intensity of the laser, data canbe rewritten in a single pass, speeding up the writing process.The direct overwrite MO disks contain magnetic reference layers as well as a recording layerand therefore, depending on the laser power, the memory layer will orientateitself to either the external magnetic force or the magnetic force of thereference layer, to either store or erase the disk's information.

When reading data from an MO disk, a laser at a lower power detectsdifferences in polarisation due to the alternating magnetic field. Unlike CD,where the laser used for reading information is only concerned with theamount of light getting diffracted, MO pickups need to be able to

GENEX GX8000 HI-BIT, HI-SAMPLING MO DISK RECORDER

9

MO 640MB & 640MB DOW

Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6GB & 5.2GBBytes / sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1024 (2.6GB) & 2048 (5.2GB)Format . . . . . . . . . . . . . . . . . . . . . . ISO/IEC 14517 (2.6GB) & ISO/IEC-FCD15286 (5.2GB)Cartridge size . . . . . . . . . . . . . . . . 135mm (width) x 153mm (length) x 11mm (thickness)Write / read cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 107

Carrier to noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 45dBError rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 10-12 (after correction)Archival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 100 yearsOperating temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 55˚C (41 - 131˚F)Operating humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 85% RH

• 5.25" disk, available in two capacities - 2.6GB (1024 bytes per sector) and5.2GB (2048 bytes per sector).

• Each disk individually tested and certified.• Carries a lifetime (100 years) guarantee.• Developed specifically for hi-bit, hi-sampling digital audio recording.• Exceptionally stable recording layer.• Carrier to noise ratio in excess of 45dB.• Consistently low block error rates.• Specially compounded polycarbonate substrate functions dependably

under extreme variations in temperature and humidity.• Anti-static hard coating repels dust and minimises scratching.• Professional labelling.

MO 2.6GB & 5.2GB

Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 640MBBytes / sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2048Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ISO/IEC 15041Cartridge size . . . . . . . . . . . . . . . . . . 90mm (width) x 94mm (length) x 6mm (thickness)Write / read cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 106

Carrier to noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 45dBError rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 5 x 10-5


• 3.5" 640MB removable MO disks, available in two versions.• New data is recorded in a single pass with the MO 640MB DOW disks,

increasing rewriting speed.• Both disks conform to ISO/IEC CD 15041 format for compatibility with

MO drives.• Exceptionally stable recording layer.• High carrier to noise ratio and low block error rates.• Anti-static hard coating repels dust and minimises scratching• Professional labelling.

MO Magneto Optical Disk


Recording time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 and 60 minutesCoercivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 OeRetentivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1800 GaussBlock error rate (average) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . < 1x10-5

Tape thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 µmYield strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 NArchival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 30 yearsOperating temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 - 25˚C (59 - 77˚F)Operating humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 - 60% RH

• Developed specifically for use with the Alesis ADAT8-track recorder and its derivatives. Recommended by Alesis.

• Exhaustively tested in a wide variety of typical ADAT applications.• Archival stability > 30 years.• Ultra-fine cobalt ferric oxide (metal particle) magnetic surface delivers

enhanced high frequency response.• High output.• Consistently low block error rates.• Special high density binder stops oxide shedding, even after 100 passes.• Rigid, high performance cassette shell ensures precision tape handling.• Also available in library cases (ADAT45L / 60L).

Recording time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30, 60 and 113 minutesThickness: base . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7.0µmThickness: backcoating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0µmThickness: magnetic layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5µmThickness: total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.5µmWidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.0mmYield strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.0 NBreaking tensile strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.0 NResidual elongation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.02%Intrinsic coercivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123KA/m (1550 Oe)Retentivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250mT (2500 Gauss)Archival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 10 years

• Metal particle DTRS tape developed specifically for use with the TascamDA88 and its derivatives. Recommended by Tascam.

• Designed to withstand the notoriously harsh conditions of DTRS 8-trackrecording.

• Exhaustively tested in a wide variety of applications from music recordingto film dubbing.

• Archival stability > 10 years.• Hi-packing recording surface delivers 54dB carrier to noise ratio.• Flexible base film eradicates stretching and snapping.• Specially formulated binder ensures negligible drop out, even after 100

passes (-0.5dB).• Exceptionally rigid, heat resistant cassette shell.• Professional labelling.

DA30, 60 & 113 DTRS Audio Tape

ADAT45, 45L, 60Ldistinguish different planes of polarisation of the light. These differences,known as the Kerr effect, are caused when plane polarised light is reflectedfrom a magnetised surface. Plane polarised light will alter its direction 0.5°one way if reflected from a positively magnetised disk area, and 0.5° theother way if reflected from an area with the opposite magnetisation. Theintensity of light reflected back does not change. These small differences inthe polarity of the reflected laser beam are easily detectable by the MO’soptical pickup mechanism and interpreted accordingly.

Pros and Cons

Pros:• Exceptional archiving stability• High capacity• Removable format• Established future upgrade path

Cons:• Disk formats vary between MO recorders• Relatively expensive media


A removable medium with excellent archival stability, MO is widely used inmultichannel mastering and recording. Due to its high storage capacity, it isoften used for hi-bit, hi-sample recording.

A Word of Warning

The secure archival life of the MO format is intrinsically long, but only HHBoffers a lifetime (100 years) warranty on its disk.

Frequently Asked Questions about MO

• What’s the difference between MO and MD?

Both MO and the recordable MD use magneto optical processes. However,MiniDiscs are much smaller, both in size and capacity, than MO disks. Theyalso use CLV recording (Constant Linear Velocity) and the same rotationalspeed as CD, so the access time is longer than for MO.

• What’s a typical recording time for MO disks?

Recording time depends on the length of each audio word, the samplingrate and the number of tracks which are required. The higher these valuesare, the shorter the record time. To a certain extent also, different versionsof software used by individual MO recorders affect the way in which audiois stored on the disk, altering the possible recording time. In the GenexGX8000, for example, a 2.6GB MO disk will typically allow four hours of 16-bit, mono audio at a sampling rate of 44.1kHz and just over 16 minutesof 24-bit, 4-track audio at 96kHz. These values are approximate for eachside of the MO disk.

• Can I play a 2.6GB disk in a 5.2GB drive?

It is possible to play a 2.6GB disk in a 5.2GB drive, but not the other wayaround. Most drives are backwards compatible.

• How many different audio tracks can be recorded onto a MO disk?

This depends on the recorder. Typically, up to eight tracks of audio may bestored on any one side of a MO disk.

• Why should you use MO if you can use a hard disk?

For large amounts of data and instant access, only a hard disk or amagneto optical disk will suffice. The main advantage of the MO format isthat the disks are easily removable and transportable, making them ideal foruse with audio workstations. Projects can be stopped and started quicklysince no downloading is required - a new disc may simply be added orremoved. And with the HHB MO disks, you are also assured that each andevery disk is tested in a drive from beginning to end.

10


ADAT & DTRS 8-Track Digital Audio Tape

Background

The project recording market has increased considerably over the last fewyears, resulting in the need for a low cost digital multitrack recorder.Reflecting the popularity of DAT in the professional audio industry, several8-track digital cassette formats were designed. The most successful ofthese have been ADAT (by Alesis) and DTRS (used by Tascam’s DA88).Both of these use formats originally designed for video, which alreadypossess the additional bandwidth required for recording eight channels ofdigital audio.

The S-VHS formatwas developed in1987 by the VictorCompany of Japan(JVC). Alesis startedexperimenting withusing different videoformats for their ADAT recorder,before finally deciding onS-VHS in 1989. ADAT was eventually introduced in 1991, spawninga whole new generation of project studios capable of digital multitrackrecording. ADAT has gone on to become one of the most popularprofessional multitrack formats. Over a million ADAT tapes were sold in1997, and the population of ADAT recorders had grown to more than100,000 units in use worldwide. Since the introduction of the Type II 20-bitmachine, recorder numbers have continued to rise even further.

Meanwhile, Tascam were developing the DA88 using the 8mm Hi-8 videoformat. Launched in 1992, the DA88 became a popular recorder for postproduction and film-dubbing work. It is a fairly low cost digital multitrackrecorder, capable of recording up to eight tracks of audio.

How ADAT and DTRS Work

Based on the S-VHS video format, ADAT is a rotary head recording system.It operates in a similar way to DAT, with the tracks being recordeddiagonally along the length of the tape. An analogue timecode track is alsoadded to the format. Instead of left and right channels and odd and evensamples being interleaved, the eight individual channels on ADAT are placedas blocks on separate tape tracks. There have been some developmentslately with ADAT, increasing the audio word length from 16-bits to 20-bits.

DTRS is another rotary head system, similar to ADAT, with up to eighttracks of high quality digital audio. It uses Hi-8 video cassettes. Operatingas a scaled up version of DAT, DTRS recorders have four heads, eachrecording a track in turn on the tape.

The success of ADAT and DTRS is further enhanced in professionalmarkets since it is possible to lock recorders together, achieving more thanjust eight tracks of audio. It is also simple to transfer digital audio betweenrecorders.

Pros and Cons

Pros:• 8 tracks of full bandwidth digital audio on one cassette• Relatively low cost hardware and media

Cons:• No random access• Some video cassettes do not perform well in the audio environment

ALESIS ADAT-XT208-TRACK DIGITAL RECORDER

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The low cost of ADAT and DTRS formats mean they are ideal for projectstudio music recording. Also widely used for film and television post-production.

A Word of Warning

The DA88 and its derivatives are notoriously tough on tape. Originallydesigned as a consumer format, the video tape has to withstand constanthigh speed shuttling and re-recording in professional audio applications.Never use conventional Hi-8 video tapes. The HHB DA30, 60 and 113 arespecifically designed to withstand the punishing professional audioenvironment.

Conventional S-VHS video tapes and some ADAT-specific media shed theiroxide recording layers after continued contact with the head. HHB ADATmedia features a high density binder, minimising oxide loss and ensuringcontinuously low error rates.

Frequently Asked Questions about ADAT and DTRS

• What’s the best way to store ADAT and DTRS tapes?

Wind tape fully forwards then back to the start after use to ensure it’ssmoothly wound. Always eject tapes when not in use - this closes the tapeflap and keeps dust out. Store the tape in its library case somewhere dry,out of direct sunlight and at a constant temperature. Keep your tapes awayfrom powerful magnets and clone them regularly - especially if error lightson the recorders are flashing. Occasionally clean the head on the recorderto stop any deterioration in audio quality.

• What different applications are ADAT and DTRS used for?

Multitrack recorders such as ADAT and DTRS have a wide variety of uses;from project studio music recording to film and television post-production.With two or three recorders locked together, many more audio tracks canbe recorded.

• How is timecode stored on DTRS systems?

The timecode information is multiplexed with the eight channels of audioand stored on the tape in a data stream. Timecode is often added to thedata on the tape during the initial formatting process.

• How do the ADAT and DTRS recording times differ?

An HHB DA113 DTRS tape will provide just under two hours of continuousrecording and playback time. The HHB ADAT60 tape will last for 67 minutesat 16-bit, 44.1kHz and 62 minutes if sampled at 48kHz. A tape can beformatted at either 16-bit or at20-bit with the newer ADAT Type II recorders and will be automaticallyrecognised as such when it’s inserted into the tape transport.

• How compatible is ADAT with other pieces of hardware?

ADAT’s compatibility with other audio products is achieved through theOptical and Sync interfaces. Other professional audio manufacturers haveincluded these interfaces in their products, resulting in a direct digitalconnection to ADAT recorders.

TASCAM DA88 8-TRACK DTRS RECORDER


DVD-RAM 5.2GB

Disc Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase-change rewritableCapacity (unformatted) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2GBBytes / Sector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2048Sector Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17-40 tracks (ZCLV)Block Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32KBTracks / Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45701 tracksTrack Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.74µmTrack format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wobbled land-grooveSubstrate material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PolycarbonateDisc diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120mmDisc thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2mm (0.6mm x 2)Cartridge dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124.6 x 138.0 x 8.0mmWeight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90gErase / write / read cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 1x105

Archival stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . > 30 yearsOperating temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-60°C (41-140°F)Operating humidity (without condensation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-85%

• Phase change rewritable disc.• High density, double sided disc, storing up to 5.2GB data• Uses mark-edge recording.• Achieves more than 100,000 erase/write/read cycles.• Housed in a protective cartridge.• Removable format.

DVD-RAM Rewritable Digital Versatile Disc

Background

With the advent of multi-channel surround sound and greater amounts ofdata for storage, there has been a need to increase the capacity of thestandard CD. Seventy-four minutes of stereo 16-bit, 44.1kHz audio is justnot a sufficient amount of storage space any more.

In 1993, a double-density CD format was developed by Nimbus Technologyand Engineering. Containing 120 minutes of MPEG-1 video, this was seenby companies as further developments to the CD format. And by 1995, twoother digital video disc formats had been developed - Super Density DigitalVideo Disc (SD-DVD) by Toshiba / Matsushita / Time-Warner, and the MultiMedia Compact Disc (MMCD) by Philips and Sony. This was to be the startof the format which would later become known as Digital Versatile Disc.

One of the main reasons why CD was so successful was due to itsuniversally compatible format. Everyone had a CD recorder which wascapable of playing any CD. To ensure the same happened with DVD, acommittee was formed to decide the final format for a new disc. So, at theend of 1995, the physical format for DVD was eventually defined. Split intoseveral Books similarly to CD, the DVD format caters for all types of audioand video storage. These Books are DVD-ROM, DVD Video, DVD Audio,DVD Recordable and DVD-RAM.

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How DVD-RAM Works

DVD-RAM is the DVD equivalent of CD-RW. It is a rewritable format - itshigh capacity for data storage makes it suitable for a wide range of mediaapplications. DVD-RAM discs use phase change recording. This is where alaser changes the physical state of the material on the disc, using heat, fromcrystalline to amorphous (or vice versa), representing the two states of adigital signal.

Unlike magneto optical disks, DVD-RAM does not use a magnetic field toalter the plane polarisation of reflected light from the disc’s recordingsurface. Instead, the laser changes the properties of the recording materialso that its reflectivity changes. An amorphous surface is not as smooth ascrystalline areas and therefore the incident light gets scattered and not asmuch is picked up by the optical sensor. This difference in reflectivity tells aDVD-RAM recorder whether the laser is over a pit or land. Furthercompatibility with CD and read-only DVD discs is achieved here, since thereading methods used are similar - it is possible to read a CD in a DVDplayer.

DVD-RAM discs use high density track pitch and land-groove recordingtechnology. The tracks along the disc are narrower than in CD, allowingmore data to be stored. In fact, DVD-RAM discs are capable of storingabout four times the capacity of a CD on each side. The recording methodused is mark-edge - this detects both edges of a mark on the recordablesurface.

Data deletion and writing happen simultaneously with DVD-RAM so, unlikeMO, the discs rotate only once during the rewriting process. This enablesdata rewriting to take place at much faster rates. Also, the speed of datatransfer is around three times faster than for MO discs. The discsthemselves are contained in special cartridges to protect from dust andfingerprints, which could alter the accuracy of the recording process.

Having two sides to every DVD disc has many more advantages than justincreasing the storage capacity. Every time a normal CD is made, the plasticon one side cools a little faster than on the other, causing the CD to warp.As the pit density is greater on DVD discs than on CDs and a singlesubstrate is only 0.6mm thick, this slight warping of the disc causesgreater problems with the lasers correctly reading back the information.With two discs mounted back to back, any bending of one disc will becancelled out by the bending of the other, creating a flat, rigid structure.

Pros and Cons

Pros:• High capacity removable storage medium• Rewritable• Suitable for storage of high sample rate and high audio word length

digital data

Cons:• Format in its infancy• Yet to become established as an industry standard• Slow access time

PHASE-CHANGE TECHNOLOGY EMPLOYED IN DVD-RAM



Achieving more than 100,000 erase/write/read cycles, DVD-RAM is an idealmethod for audio and data storage, increasingly used for Digital AudioWorkstation back up. In the future, it will inevitably be used in hardwarerecorders, and for multichannel mastering, archiving and video.

A Word of Warning

The access time of a DVD-RAM drive is slower than an MO drive, due partlyto the CLV (Constant Linear Velocity) recording and reading methods.

Frequently Asked Questions about DVD-RAM

• Will DVD-RAM take over from CD-R?

At this early stage in DVD’s development, it is impossible to say. However,it is looking increasingly certain that the DVD format will be liked byeveryone for its high storage capacity and subsequent quality of the audioand video. Prices of DVD media and recorders must fall to comparefavourably with CD-R at the present moment.

• What’s the typical access time to the disc?

This depends on the recorder in which the disc is inserted. Access time forDVD discs must be as short as possible to read and output the high bitand sample rate data without any drop-outs. A typical value for accesstime is 120 milliseconds.

• Can I play my DVD-RAM disc in an ordinary CD player?

No, it isn’t possible to play a DVD-RAM disc in an ordinary CD player. Youcan, however, put a CD in a DVD player and hear the correct output. TheDVD system was designed to be backwards compatible - themanufacturers realised that they weren’t going to sell many DVD playersunless people had some means of playing back the many CDs that theyalready owned.

• Why is a DVD-RAM disc housed in a cartridge?

The cartridge is there to protect the disc from dust, dirt and fingerprints,all of which could reduce the disc’s performance during the writingprocess.

• Why can more information be stored on a DVD-RAM disc than on a CD?

The high storage capacity of a DVD-RAM disc is due mainly toimprovements in laser technology. As the wavelength of laser light isreduced, this allows smaller spots on the surface of the disc to be alteredin state, therefore increasing the amount of data that is possible to fit onthe surface. The spiral information tracks can also be closer together, andthe disc is two-sided. These features, and a number of other technicalimprovements, afford DVD-RAM discs an extra 4.5GB of storage spaceover the 680MB of a normal CD.

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CD-RW Compact Disc Rewritable. A rewritable type of CDwhich uses phase change technology.

CIRC Cross Interleave Reed-Solomon Coding. A type oferror correction used in CD, CD-ROM and MiniDisc.MiniDisc uses ACIRC (Advanced CIRC) with greaterdelay and more interleave added.

CLV Constant Linear Velocity. This is where a disc’srotational speed is reduced as the laser reaches theedge of the disc, thereby keeping the laser’s velocityalong the track the same.

Clone An exact digital copy of digital material. It willessentially contain the same digital bit stream.

Coercivity The strength of an external magnetic field requiredto swap over the polarity of a magnetic particle. Allparticles on magnetic tape have certain coercivityvalues, showing the force required by the externalmagnet to change the particle’s polarity from Northto South, or vice versa.

Copyright Protection given to the original owner (possibly thecomposer or the performer) of musical material.The advent of DAT and CD-R has made it simple todigitally clone copyright material. A system calledSCMS (Serial Copy Management System) putscopyright information in the subcode of digital data,which can then be read by another digital recorder.Depending upon the individual settings of thesedata bits, the recorder may not be allowed to cloneany digital information.

CPS Cycles per second.

CRC Cyclic Redundancy Check. A type of data codingused for error checking in tape-based digitalrecording systems. This extra error correction datais added to the bit stream before recording and thenchecked during playback. Any differences betweenthe two will cause the recorder to indicate an error,which might be correctable.

Crosstalk Interference to a signal from a neighbouring tapetrack or electrical circuit.

Curie Point The critical temperature at which a magneto opticalmedium undergoes a change and will orientate itselfto a magnetic field.

Cyanine Organic dye, used to form the recording layer inCD-R discs.

DAC Digital to Analogue Convertor. Changes theincoming digital word stream into an outgoinganalogue signal.

DASH Digital Audio Stationary Head recorders. Sony openreel digital recorders, using 1/2 or 1/4 inch tape.

DAT Digital Audio Tape. A 4mm wide rotary-headcassette format.

Data Layer The layer on a recordable CD which is manufacturedperfectly flat, and is then subjected to burning whenthe CD is recorded.

Decibel (dB) One tenth of a Bel. Measures the ratio of twopowers or voltages.

Digital Information in a binary form.

Access Time The time taken for a drive to locate information.

ADAT Alesis Digital Audio Tape. An eight track rotary-headdigital recording format.

ADC Analogue to digital convertor. Periodically samplesan incoming analogue waveform for output as adigital signal.

AES/EBU Audio Engineering Society / European BroadcastingUnion. A professional format digital interface.

Archival Stability The length of time during which data can be readreliably from any recording media.

A-Time Absolute-time from the start of a tape or disc,measured in hours, mins and secs.

ATRAC Adaptive TRansform Acoustic Coding. Datareduction technique used in MiniDisc, based on thepsychoacoustic phenomenon of masking.

Azimuth The angle of the record head’s gap in relation to thehead’s longitudinal direction. Alternates between±20° from the normal angle with each DAT track.

Bandwidth The difference between the low and high frequencycut-off points on a response curve. Often quoted inspecifications.

Binder Adhesive layer which binds metal oxide particles toa tape’s backing.

Bit Contraction of ‘binary digit’. The smallest piece ofdigital information - either a 1 or 0.

Bit Resolution The number of bits in each sample of digital audio.The greater the bit resolution, the greater thedynamic range and the better the signal to noiseratio. CD uses 16-bit resolution.

BLER BLock Error Rate. The digital error rate before errorcorrection.

Blue Book The specification for CD-EXTRA technology. This isa multisession enhanced CD, often combining onesession of audio with another of computer data.Care must be taken not to play the data track(normally Track 1 on the CD) over loudspeakers asthey could be damaged.

Buffer Memory set aside for temporary data storage. Helpsto avoid drop-outs due to the different transfer ratesof devices. Buffers are necessary for interleavedsignals.

Byte A group of eight bits.

CAV Constant Angular Velocity. This is where a discrotates at a constant speed.

CD Compact Disc. A 16-bit, 44.1kHz digital audiomedium, capable of storing 74 minutes of stereoaudio.

CD-R Compact Disc Recordable. A write-once recordableversion of CD.

Jargon Busters

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Land Sections of a CD’s surface between and to each sideof the pits.

LASER Light Amplification by the Stimulated Emission ofRadiation. Light consisting of particles of the samewavelength and in-phase with each other.

Lead-In An area at the start of each session on a CD-Rcontaining information about track numbers and thestarting points for each track.

Lead-Out An area at the end of each session on aCD-R to show that it has finished. The first lead outon a multisession disc is always slightly longer thanlater ones.

Micron A millionth of a metre.

Magnetic Field A force field produced by a permanent magnet or anelectric current.

Magnetic Tape Plastic tape coated with magnetic particles. Theseparticles change direction depending on the fieldapplied by a magnetic tape head.

MD MiniDisc digital recording format. In two versions -pre-recorded (similar to CD) and recordable (similarto MO).

MDD MiniDisc Data digital recording format. Originallydeveloped for computer data backup. Used inmultitrack MiniDisc recorders.

MO Magneto Optical disk-based format for data storage.Uses a combination of magnetic and opticaltechnology to record information to disk.

MPEG Moving Picture Experts Group. MPEG is a group ofdata compression standards used in audio-visualdigital systems. Widely used in DVD manufacturefor reducing the amount of data required.

Nanometre A millionth of a millimetre (10-9 metre)

Oersted A measurement of magnetic strength, abbreviatedto Oe.

Orange Book The specification for write-once CD-Recordabletechnology. Part II contains the specifications forCD-R, with both physical and recordingcharacteristics, and Part III defines CD-RW.

Organic Dye The data layer of a CD-R disc is made from eitherCyanine, Phthalocyanine or Azo organic dye whichis melted during the recording process. Whenmelted, it becomes opaque or refractive, scatteringthe reading laser beam so it is not reflected backinto the reader’s sensors. The difference betweenreflected and non-reflected light is interpreted bythe CD player as a binary signal.

Oxide Substance which has undergone the chemicaladdition of oxygen.

PCA Power Calibration Area. An area at the start of a CD-R used during optimum power calibration (OPC)for calibrating the power of laser needed to write onthe disc.

PCM Pulse Code Modulation. A digital representation ofan analogue signal. The voltage level of theanalogue signal is measured a number of timeseach second. These levels are represented with a

Drop-out A temporary loss of signal, usually from a tape-based format.

Disk-at-once A process of writing an entire CD-R, including lead-in, data, and lead-out, from beginning to end.

DTRS Digital Tape Recording System. An 8-track digitalrotary head recording system, using Hi-8 videotape, as used in Tascam’s DA88.

DVD Digital Versatile Disc. Available in several differentformats - DVD-ROM, DVD Video, DVD Audio, DVDRecordable and DVD-RAM.

Dynamic Range The difference between the lowest and highest levelsounds in a signal.

EFM Code Eight-to-Fourteen bit modulation code, used in thechannel code of the CD format.

Errors Errors in digital data have differing levels ofsignificance - with CD-Rs, for example, E12 errorsmay be correctable. However, an E32 error maymake the disc unacceptable for mastering use.

Filter An electronic device which removes or selectscertain frequencies in an audio signal. A low-passfilter allows low frequency signals to passunaffected, yet removes the high frequency contentabove a certain frequency (that of the filter).

Finalization The process which renders a CD-R disc playable ona standard audio CD player, sometimes known asfix-up. The table of contents (TOC) is written andthe disc is closed, meaning that it cannot berecorded on again.

Flag Data recorded along with audio data which givesinformation such as the sampling frequency andcopyright status.

Flux Density The concentration of a magnetic or electric field.

Frame The smallest recordable part of a CD, with 75subcode frames in every second.

Frequency The repetition rate of a periodic signal. Measured inHertz (Hz) or cycles per sec.

Green Book The specification for CD-I technology. Separateaudio and data tracks are synchronised on the sameCD.

Guard Bands Spacing between the tracks on multitrack taperecorders.

Head An electro-magnetic device, used to transfer anelectronic signal into a magnetic pattern on either atape or a disk.

Hub The wheel around which tape is wound in a DATcassette, sometimes known as a clumper.

Interleaving Process of rearranging streams of digital audio inorder to spread any burst errors out. This makeserrors easier to correct.

ISO 9660 The standard logical file format used for CD-ROM,containing a hierarchy of directories and files.

Kerr Effect The effect of reflected light changing polarity insidea magnetic field. This principal is used in thereading of data from magneto optical discs.

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Timecode Contains information about the hour, minute,second and frames. Normally recorded on media asa reference and for use when synchronising to otheraudio and video equipment.

TOC Table of Contents. An area on a CD which storesinformation about the disc’s contents.

Track-at-once A recording process for CD-R, where up to 99tracks of any format, audio or data, can be writtenseparately to the disc. Lead-in and lead-outinformation is written for each individual track.

VHS A 1/2" rotary head video format. S-VHS tapes areused by Alesis ADAT recorders.

White Book The specification for Video CD, defining how MPEG-1 compressed video and audio is stored on the disc.

WORM Write Once Read Many. The writing method used inCD-R recording.

Yellow Book The specification for CD-ROM technology, defininghow much the disc can hold and how it is dividedup into physical sectors. The error correction usedis greater than for audio CDs as it will be used forchecking computer data.

Yield Strength The stress point at which an elastic materialbecomes permanently deformed. Applies to tapebased media such as DAT.

binary number - when strung together, the numbersform the digital PCM data stream.

PMA Program Memory Area - an area on a CD-R discused to contain a table of contents when a disc iswritten in different sessions.

Phthalocyanine The most stable organic dye, used to form the datalayer in some CD-Recordable discs.

Pits and Lands Raised or unraised areas on the data layer of a CDwhich determine the way in which light is reflected.

PQ Data Subcode information in the CD format, includingtrack start and end points and index points. Thedata is recorded on the P and Q tracks of thesubcode.

Quantisation An analogue signal can be split into a number ofdifferent quantisation levels according to theamplitude of the signal at each point. These levelsare represented by a binary number. For example, ina 16-bit system, there will be 216 different levels(65536 different values representing the amplitudeof the analogue signal at any point in time).

RAM Random Access Memory. Originally used to describememory for storing digital data, the term may nowbe applied to other rewritable media.

Rainbow Book The specification for MiniDisc technology - so calledsince it is based on a number of the CDspecification books.

Red Book The specification for CD audio (CD-DA) technology,defining how 74 minutes of stereo 16-bit, 44.1kHzaudio is stored. Audio files are placed in one ormore tracks on a CD; up to 99 tracks are allowed.

Reflectivity A quotient which quantifies the amount of lightreflected by a material.

Residual Elongation Added length of a material resulting from astretching force having been applied.

Retentivity A value showing a material’s ability to hold itsmagnetism once removed from an externalmagnetic field.

RH Relative humidity.

ROM Read Only Memory. Originally used to describememory circuits which were set at the time ofmanufacture and could not be altered, the term hascome to be used to describe any non-rewritable, orread only, medium.

SCMS Serial Copy Management System. A system forlimiting the number of digital clones made (via theconsumer digital interface) of copyright material.

S:N Ratio Ratio in dB of the amplitude of a signal comparedwith that of the noise.

SPDIF Sony / Philips Digital InterFace. Consumer formatdigital interface.

Sputtering A method of applying the recording layers in opticaldisc manufacture.

Subcode Supplementary data that is not audio, often used forcontrol purposes.

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Borwick, J. (ed.) Sound Recording Practice

Maes, J. The MiniDisc

OSTA CD-Recordable Questions and Answers

Parsons, A., Foster, B. The Master Tape Book & Hollebone, C.

Pohlmann, K. The Compact Disc Handbook

Rumsey, F. The Audio Workstation Handbook

Rumsey, F. & Watkinson, J. The Digital Interface Handbook

Sony Europe Digital Audio and Compact Disc Technology

Watkinson, J. RDAT

Watkinson, J. The Art of Digital Audio

To ensure consistently high standards of manufacture and minimumenvironmental damage, HHB Advanced Media Products conform to ISO9002 manufacturing standards and ISO 14001 environmental standards.

All trademarks acknowledged.

© Copyright HHB Communications Ltd. 1999

Further Reading

HHB Standards Policy


Documents

A guide to choosing and using digital audio recording media · A guide to choosing and using digital audio recording media • Technical Notes: How the major digital recording formats