Digital Pipelines

The introduction of the Alesis ADAT in 1992 was a huge step toward the annihilation of analog technology and the development of the all-digital studio.
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Theintroduction of the Alesis ADAT in 1992 was a huge step toward theannihilation of analog technology and the development of theall-digital studio. True, digital audio technology had been around fora while at that point, but it really wasn’t until the ADAT and,later, the Tascam DA-88 hit the streets that the majority of musiciansbegan to understand the potential of this technology.

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The success of these two machines initiated a quest to improvefidelity in other areas. Soon digital mixers popped up, digital audioworkstations gained widespread popularity, digital dynamics processorshit the market, and various digital support gear joined the party.

Today studios on virtually every level can produce an almostentirely digital recording, starting at the soundmodule/sampler/preamp, going to the console, to the multitrack, througheffects processors, and finally to 2-track. Several companies have evenstarted to manufacture microphones and speakers with built-in digitalconverters, so the digital chain can begin and end right at thetransducers. For better or for worse, the all-digital world hasarrived.

The mere presence of digital devices, however, does not make astudio completely digital. Sure, the more digital equipment you own,the greater fidelity your recordings will have. But to reallycapitalize on this technology, you need to have digital connectivitybetween gear. After all, the signal path is only as strong as itsweakest link, and if you’re constantly sending audio throughconverters, from analog to digital and back again, degradation isinescapable.

Although 2-channel digital transfer formats such as S/PDIF andAES/EBU are a big part of successfully connecting equipment, whatreally makes the all-digital studio possible is multichannel (that is,more than 2-channel) digital audio transfer formats, specifically ADATOptical and Tascam’s TDIF. These two protocols have revolutionizedthe industry almost as much as their respective MDMs have. Today peoplewho don’t even own ADATs or DA-series recorders are using ADATOptical and TDIF connections to get from one piece of gear to the next.This month, we take an in-depth look at these two formats, the productsthat use them, and ways of getting from one format to another.

History Lesson

Neither ADAT Optical nor TDIF was originally designed to be what ithas evolved into. The initial idea behind each was to provide a way totransfer multiple audio tracks simultaneously between identical MDMs(ADAT to ADAT, or DA-88 to DA-88), not between MDMs and other gear.

Our story begins with Alesis circa 1991 and the development of therevolutionary ADAT. While the company was designing the original unit,the good folks at Alesis realized that they needed to provide a meansof transferring audio digitally between two machines. After all, theADAT was to be a modular recorder, intended to connect with others ofits kind; it would be silly if users lost a generation every time theymade a backup tape or copied tracks to another machine. Alesis knew alltoo well that critics would have a field day if it didn’t come upwith a solution.

At the time, AES/EBU and S/PDIF were the only widely used digitalaudio formats, and they could handle only two channels of audio.Obviously, using either one to transfer eight tracks between ADATswould be cumbersome. So Alesis created its own format that was capableof carrying eight separate signals, and ADAT Optical (also known asLightpipe) was born. I distinctly remember doing a session in 1993 andbeing amazed to discover that the ADAT could digitally transfer all itstracks from one machine to another at the same time. Wow!

In 1994, Alesis realized that Lightpipe had much potential that wasnot yet being exploited. The company started offering ADAT Opticalconnectivity on some of its higher-end synthesizers and signalprocessors as a way of directly interfacing with an ADAT. Othermanufacturers realized that this format could potentially become the defacto standard and wanted to get in on the action. Shortly thereafter,the ADAT Group was formed, consisting of third-party manufacturersworking together to build (and capitalize on) the ADAT empire. Todaymore than 300 companies belong to the ADAT Group, and a good portion ofthem manufacture products with Lightpipe connectivity.

Over in the competing camp, Tascam wheeled out the DA-88 in 1993,and along with it came the company’s answer to Lightpipe, theproprietary Tascam Digital Interface Format (TDIF). That was around thesame time that Alesis began contracting with third-party developers. Sodid Tascam, and a struggle over digital data formats soonensued–another battle in the war already occurring between the twocompanies.(For an interesting retrospective look at the state of MDMsin the early ’90s, check out "Brave New World" in the October 1993issue of EM.)

Fast-forward five years to 1998. The ADAT and DA-88 have establishedtheir places in the annals of audio history, Alesis and Tascam haveboth expanded their lines of MDMs, and the Lightpipe and TDIF protocolsare more popular than ever. Alesis has even created an entire divisiondevoted to developing and promoting ADAT Optical technologies. At thispoint, Lightpipe connections are certainly more abundant in third-partyproducts than are TDIF connections; that’s probably because ADATsare more popular than DA-series recorders in personal studios. In anyevent, it’s almost unheard of for a major digital product to bereleased today without options for ADAT Optical, and very often TDIF,connectivity.

In a moment, we’ll take a look at some of the products thatsupport each format, as well as the many products on the market thatchange signals from one format to another. But first, let’s take alook at the nuts and bolts of the unique format that spawned arevolution.

Lighting the Pipe

Although Lightpipe and TDIF accomplish the same thing, they do so invery different ways. The ADAT Optical protocol works on a 24-bit NRZ(Non-Return-to-Zero) encoding scheme that sends information along ahigh-bandwidth fiber-optic cable.

What does that mean in English? Basically, each audio channel can becarried at 24-bit resolution (regardless of whether you’reactually working with a bit resolution that high). The samples from alleight audio channels are organized into a single block of informationcalled a "data frame," each of which contains 256 bits. If you do themath, you’ll discover that this leaves 64 bits that can be usedfor synchronization and specialized "user" applications (discussedshortly).

This data frame is then sent through a fiber-optic cable by means ofa light transmitter (hence the name "Lightpipe") and is received in theother unit by a light-detecting element. A single-sided, 5-volt powersupply runs the system. When all is said and done, the receiver’soutput produces an exact replica of the signal that was introduced atthe transmitter, save for a nominal propagation delay.

Lightpipe cables typically can run up to about 33 feet, althoughsome people have had success with runs as long as 50 feet. By usingmore expensive glass cable, you can run ADAT Optical cables quite a bitfarther, even without special drivers. Alesis claims that it hassuccessfully tested runs up to 100 feet using these speciallyterminated glass cables.

One of the greatest benefits of an optical format is the low cost ofthe cables; in fact, they’re so cheap that Alesis gives away a1-meter cable with every new ADAT. Also, the connections are smallenough to fit on a PCI card or digital-mixer card without the need fora breakout box, and the fiber-optic design virtually eliminates thepossibility of electromagnetic interference and ground hum.

But the coolest thing about the ADAT Optical format is that afteryou account for sync bits and various other information bits, four bitsare left over in every data frame. Of those, two are reserved forpotential future uses to be determined by Alesis (for example,upgrading the system resolution without the need to change formats),and the other two are denoted as "user-definable." This doesn’tmean that just any ADAT owners can simply decide what they want to sendthrough the Lightpipe; rather, these bits are available to designerslooking to implement Lightpipe in new products. For example, themanufacturer of a remote-controlled digital mic preamp could use theextra bits to send control messages between the stage unit and the mixposition.

The ADAT Optical format is free to anyone who wants to incorporateit into a design; all you have to pay for is licensing the ADAT logo,should you decide to use it to market your product. As I mentionedearlier, Alesis recently created a separate division, AlesisSemiconductor, devoted to the development of Lightpipe. Its mandate isto promote ADAT Optical as the industry standard in digital audiotransfer. Whether this will actually happen remains to be seen, but itseems like a good bet. Although the company’s plans for futureLightpipe implementation are still hush-hush, the live-sound industryappears to be the next frontier. The use of Lightpipe in home-theatersystems opens up a great many possibilities, so that direction willprobably be explored, too. The future looks exciting for the pro-audioindustry and consumers alike.

Keep in mind that although the ADAT Optical specification currentlysupports 24-bit data, not all gear is capable of handling 24-bitdigital audio transfers. Some equipment can send and receive only20-bit information, a limitation of the Alesis controller chips used toimplement Lightpipe in certain products. In fact, Alesis’s currentcrop of ADAT recorders supports 20-bit Lightpipe transfers only.

T-otally DIF-ferent

Tascam was reluctant to provide me with information on the specificsof the TDIF format (something about the folks in Tokyo not wanting usto publish their secrets). I searched the Internet, talked to myengineering friends, and begged and pleaded, but I still came up withsquat. Tascam keeps this stuff pretty well guarded!

Here’s what I do know: whereas the Lightpipe format collapsesthe multichannel digital information into a single frame of data, TDIFuses a multiwire 25-pin D-sub cable that transmits channel informationindependently, without creating a composite stream. Obviously, thesecustom cables are a bit more expensive than optical cable–a 3-footcable retails for $110, and a 16-foot cable will cost you $135–butthey can be run farther than their optical counterparts, albeit withmore susceptibility to interference.

The Supporting Cast

Of course, this article cannot possibly serve as an exhaustive guideto every product that supports ADAT Optical and TDIF–there aremore than 300 companies manufacturing Lightpipe products alone. But Ihave compiled a list based on data provided by Alesis and Tascam andfrom new-product information that I gathered at the 1999 Winter NAMMshow in Los Angeles. It’s not comprehensive, but I think it’sa good representation of the gear that affects most personal-studioowners. The focus here is on digital connectivity–specificallyTDIF, Lightpipe, AES/EBU, and S/PDIF options. (Unless noted otherwise,AES/EBU and S/PDIF I/O refer to 2-channel connections.)

MDMs. Ironically, simply interfacing between two identicalMDMs doesn’t seem very exciting anymore. But being able to connectthose machines to the wealth of mixers, DAWs, hard-disk recorders,sound cards, synths, outboard gear, and even competing MDMs thatsupport TDIF and Lightpipe certainly is exciting. (Actually, with theadvent of onboard digital patch bays, the ability to digitally transferfrom one MDM to another is quite cool in itself.)

Lightpipe I/O currently comes standard on the full line of AlesisADAT recorders, including the ADAT XT20, LX20, andpost-production-oriented M-20. ADAT recording is now at 20-bitresolution, but you can set the Type II recorders to produce a 16-bitoutput signal complete with dither so that they’re compatible withthe older ADAT-XT and "blackface" models.

Other MDM manufacturers–not surprisingly, companies that havedeveloped S-VHS recorders based on the ADAT–also offer Lightpipeconnectivity. For example, the 20-bit Studer V-Eight offers eightchannels of ADAT Optical I/O. If you feel like dusting off a 16-bitFostex CX8 or RD8, each of those units provides standard Lightpipeports, as does the Panasonic MDA-1. (The Fostex and Panasonic MDMs areno longer manufactured, so they’re not included in the table"Putting It All Together.")

On the Tascam front, 8-channel TDIF I/O is standard fare on all ofthe DA-series multitracks, including the DA-38, the DA-88, and theultrahip DA-98. All three Tascam decks can interface with the AES/EBUformat via the optional IF-88AE.

Interestingly, you’ll find no TDIF connections on thediscontinued Sony version of the DA-88, the 16-bit PCM-800; there areonly eight channels of AES/EBU. Not surprisingly, Alesis doesn’toffer a TDIF option for ADATs, and Tascam doesn’t provideLightpipe connectivity. Tascam, however, recently released a niftyTDIF/Lightpipe converter, the IF-TAD.

MHDRs. The ability to digitally connect a modular hard-diskrecorder (MHDR) with an MDM can be a valuable asset to thepersonal-studio owner. For example, you might want to use the MDM asyour main recording medium, fly tracks out to the MHDR for editing, andthen fly them back to the MDM, all the while maintaining sync betweenthe decks. Or you could do all your work within the MHDR and use theMDM just for backup purposes. Many people use a combination of MDM andMHDR simply to double their track count.

Akai, Fostex, and E-mu are leading manufacturers of MHDRs, and allthree companies offer Lightpipe I/O options for their units. The FostexD-90 offers eight channels of Lightpipe I/O as a standard feature, andthe D-160 has two Lightpipe ports for interfacing with a 16-track ADATsystem. Both 16-bit units offer optical S/PDIF I/O for backing up datato DAT. E-mu’s 16-bit Darwin recorder has an 8-channel Lightpipeoption in addition to the S/PDIF I/O that ships with the standardunit.

Akai’s machines offer both ADAT Optical and TDIF connections.The Akai DR8 and DR16 Plus recorders have options for 8-channelLightpipe I/O, 8- channel TDIF I/O, and 8-channel AES/EBU I/O.Connections for AES/EBU and S/PDIF come standard with both decks.

Roland’s DM-800, predecessor to the company’s popular VSline of production systems, had an option that allowed 8-channel TDIFand Lightpipe connections. So, if you can find a DM-800, it may or maynot be outfitted for multitrack digital audio transfer. For those folkswho have $24,950 to spend, Otari’s 24-track RADAR II system offers24 channels of TDIF I/O.

Digital mixers. In any studio, audio is constantly beingrouted between the multitrack and the mixing console, so maintainingdigital integrity is probably more important here than anywhere else inthe signal path. That’s why most digital mixers offer an abundanceof connectivity options.

The Panasonic WR-DA7’s digital I/O must be configured fromscratch by adding expansion cards. It has three card slots, each ofwhich can accommodate an 8-channel ADAT Optical, TDIF, or AES/EBU(hardware switchable to S/PDIF) card. There is also an 8-channel A/D/Acard, and the mixer provides switchable AES/EBU and S/PDIF 2-trackinputs and record outputs (on XLR jacks). Furthermore, aux sends 1 and2 employ S/PDIF on RCA jacks.

Sporting just as many I/O options, the Yamaha 02R offers fourexpansion slots that accept 8-channel Lightpipe, TDIF, and AES/EBUcards. The stock mixer also comes with AES/EBU and S/PDIF I/O. The02R’s smaller cousin, the Yamaha 03D, offers the same card optionsbut has only one available slot, as does the even smaller 01V. The 03Dprovides both AES/EBU and S/PDIF I/O, while the 01V offers S/PDIF only.The long-anticipated Mackie Digital 8•Bus (D8B) also has threecard slots for adding Lightpipe or TDIF inputs, and it comes standardwith AES/EBU and S/PDIF connections.

The Tascam TM-D1000 comes standard, of course, with 8-channel TDIFI/O. The TM-D1000 also gives you two XLR AES/EBU outputs; an optionalexpansion card adds eight more channels of TDIF plus four channels ofAES/EBU or S/PDIF. The Tascam TM-D4000 ships with S/PDIF and AES/EBUI/O and allows you to install up to three 8-channel cards foradditional TDIF, ADAT Optical, AES/EBU, or analog I/O. Tascam’stop-of-the-line console, the TM-D8000, provides 24 dedicated TDIF tapereturns and inputs that can be configured to accept analog, TDIF,S/PDIF, or AES/ EBU signals.

The Spirit Digital 328 offers 16 channels of ADAT Optical input, 24channels of Lightpipe output, and 16 channels of TDIF I/O on the baseunit, along with AES/EBU and S/PDIF I/O. Similarly, thenow-discontinued Korg 168 RC provides 16 channels of Lightpipe I/O andstereo S/PDIF, but it has no TDIF or AES/EBU ports. The 24-bit RolandVM-3100 will have an optional interface box that adds both Lightpipeand TDIF connections.

Finally, for those with fat wallets, RSP Technologies’ ProjectX ($3,500 for a basic system) can be outfitted with both Lightpipe andTDIF cards, as well with an 8-channel AES/EBU card or several A/D/Acards.

Audio cards/DAWs. Although you’d think that a digitalaudio workstation is a self-contained environment, in reality it rarelyis. Many people prefer to use DAWs like MHDRs, employing them asediting and processing tools rather than as comprehensive recordingsystems. Others like to back up data to a particular MDM format simplybecause random-access storage can get to be a bit expensive. And thenthere’s the fact that any facility set up to work on outsideprojects should be equipped to handle whatever tape format the clientmight provide. So even if you use a DAW, chances are you’ll needto connect to other gear.

For the past five years, Digidesign’s Pro Tools system hasremained the most popular Macintosh-based DAW for audio production. ProTools is a customizable working environment, and to get any I/O withit, you have to buy interface modules. Pro Tools can interface directlywith an ADAT system by using the Digidesign ADAT I/O Bridge, arack-mount unit that provides 16 channels of Lightpipe I/O. Digidesigndoes not currently make a dedicated TDIF module, but that doesn’tmean you can’t use Pro Tools with, say, a DA-88. You’d justneed to have a format converter to translate the TDIF signals tooptical or AES/EBU and then fly the audio into the appropriateDigidesign interface (the ADAT I/O Bridge for Lightpipe, or the 888 forAES/EBU). The same, of course, is true for any piece of gear discussedhere that doesn’t support a particular format.

A strong entry into the cross-platform DAW market last year wasEnsoniq’s PARIS. Like Pro Tools, PARIS offers a customizable I/Osystem in the form of a modular expansion chassis. The Interface MECcan be loaded with up to nine 8-channel A/D, D/A, or ADAT Opticalcards. S/PDIF I/O is standard on the MEC, as well as on most otherPARIS interfaces. The A/D and D/A cards both offer 24-bitconversion.

The cross-platform Lexicon Studio accommodates a number of digitalformats. As of this writing, two I/O modules are available: the LDI-12Toffers two channels of analog I/O and two channels of switchableS/PDIF/Lightpipe I/O, while the LDI-16S provides eight channels of bothTDIF and analog I/O. Options are available for the LDI-16S that addeight channels of AES/EBU I/O or eight channels of ADAT OpticalI/O.

The PC-based V8 workstation from Digital Audio Labs can use optionalPCI I/O cards for interfacing with both Lightpipe and TDIF devices.Multiple I/O cards may be cascaded, and the V8 provides full transportcontrol of ADAT and DA-series recorders directly from software. AES/EBUand S/PDIF I/O options are available as well.

Soundscape’s integrated PC-based SSHDR-1 hard-disk recordingsystem comes standard with eight channels of TDIF I/O and two channelsof S/PDIF I/O. But to send and receive Lightpipe signals, you must havean additional I/O module. The company’s Mixtreme PCI audio cardprovides 16 channels of TDIF; however, you’ll still need anexternal breakout box to gain access to Lightpipe and other types ofI/O. There are three I/O modules that can be connected to eithersystem: the SS8IO-1 (balanced analog/Lightpipe/TDIF), the SS8IO-2(TDIF/Lightpipe), and the SS8IO-3 (unbalanced analog/TDIF), all ofwhich will be discussed later. TDIF ports are used to connect allSoundscape hardware.

The Otari PD-80 digital audio workstation has options for TDIF andLightpipe and comes standard with AES/EBU I/O. Otari’s RADAR IIsystem provides TDIF connections on the base unit, and you can gainADAT Optical and AES/EBU I/O with the assistance of the company’sstand-alone UFC-24 format converter. The Pyramix Virtual Studio fromMerging Technologies also offers TDIF and Lightpipe I/O options.

As part of its Soundlink line of products (which includes the 168 RCmixing console), Korg has introduced the 1212 I/O, a cross-platform PCIaudio card that offers 8-channel ADAT Optical I/O, as well as 2-channelanalog and S/PDIF I/O. More analog I/O channels can be added using thecompany’s 880 A/D and 880 D/A, both of which can also function asstand-alone Lightpipe-to-analog converters.

Along the same lines, Sonorus offers the StudI/O PCI audio card,which provides two sets of optical I/O parts that can be independentlyswitched between stereo S/PDIF and 8-channel ADAT Lightpipe formats.When used in combination with one of the company’s hardware AudI/Ounits, the StudI/O can accept AES/EBU, TDIF, and analog signals.SEK’D recently rolled out its Prodif Gold ADAT card, which bringsLightpipe and S/PDIF signals into and out of a PC.

Also taking advantage of the Lightpipe format is Mytek, best knownfor its high-end mastering converters. Through a joint venture withSonorus, it has developed the expandable DAW 9624, which consists of aStudI/O card and the Mytek 8X96-series 24-bit/96 kHz 8-channel A/D andD/A converters. In addition, the Mytek units provide conversion to andfrom AES/EBU and TDIF (optional). The DAW 9624 is yet another great wayto bring analog signals into an ADAT system.

One of my favorite devices is the MOTU 2408. This ingenious box canserve either as the front end to a DAW or as a stand-alone audio-formatconverter. The 2408 supports 24 channels of I/O that can use anycombination of its three sets of TDIF ports, three sets of Lightpipeports, two sets of S/PDIF ports, and eight analog inputs and outputs. APCI card allows direct connection to either a Mac or a PC for use witha variety of software applications, and you can connect additional2408s to your system for a total of 72 channels of simultaneousI/O.

Lastly, the cross-platform ADAT Edit package from Alesis simplyprovides eight channels of Lightpipe I/O on an ADAT/PCR PCI card. Itdoes not come with other types of digital or analog I/O.

Synthesizers. It seems only logical that synths with multipleoutputs should take advantage of TDIF and Lightpipe. Well, it’staken a while, but manufacturers are now coming around. Obviously,Alesis would be foolish not to implement Lightpipe on its synths: inthe company’s current product line, the QS7 and QS8 have ADATOptical outputs.

Korg’s Trinity line of workstations, including the Trinity,Trinity Pro, and Trinity ProX, offer Lightpipe output options. Andusing the Kurzweil DMTi format converter, you can interface a K2500with both Lightpipe and TDIF devices. I think we’ll see a lot moreof such products in the next few years.

Other gear. Although TDIF and Lightpipe are designed to carrymultiple audio channels, they can also serve lesser functions. Severalcompanies have recently started incorporating these formats into theirmulti-effects processors and preamps.

Currently, you can find ADAT Optical and TDIF outputs on several micpreamps, including the Drawmer 1962 tube preamp, which delivers a24-bit signal in either format at the output. The Aphex 1788 8-channelmic preamp can also be outfitted to connect with TDIF- andLightpipe-friendly units (a great solution for live recording).

The Studer D19 MicValve 2-channel mic/line preamp card for themodular D19 series offers ADAT Optical output and 20-bit D/Aconversion. The company’s D19 MicA/D for the same series alsosupports Lightpipe. Alesis’s Q2–a descendant of theQuadraverb, the first non-ADAT machine to employLightpipe–provides ADAT Optical I/O, as well.

Digital Labs has pioneered quite a neat device: the first FiberOptic Patch Panel for ADAT Optical and S/PDIF optical formats. This boxallows you to patch digital signals just as you would on an analogpatch bay. The single- rackspace panel has eight fiber inputs andoutputs on both the front and rear panels. Also included is aToslink-to-glass connector that allows you to run cable lengths up to amile.

Confounding Conversion

It’s great to be able to stay in the digital domain throughoutthe recording and mixing process, but what happens when you need tosend eight or more channels from one multitrack format to another, orto analog, or to a completely different digital format such as AES/EBUor S/PDIF? Several companies make format converters, and they come inall shapes and sizes. What follows here is the lowdown on the currentcrop of useful little boxes that will get you from one format toanother.

But remember, it’s not always necessary to have a stand-aloneconverter to go from format to format. Other devices (especially mixersand DAWs) can often be used to convert signals, provided they offercompatibility with the formats you’re working with.

For example, if you have a Panasonic WR-DA7 with a sufficient numberof expansion cards, you can generally get wherever you need to go, beit from Lightpipe to TDIF, Lightpipe to S/PDIF, TDIF to AES/EBU, orTDIF to analog. The same is true of the Yamaha series of digitalrecording consoles: an 02R or 03D makes a great centerpiece for astudio, simply because of all the I/O options it provides. (For acomparative look at the gear discussed in this article, including thedigital formats supported, refer to the tables "Putting It AllTogether" and "Converters Compared.")

Alesis AI-3. The Alesis AI-3 ($499) is a stand-alone8-channel A/D/A converter that translates signals to and from theLightpipe format. The AI-3 provides eight analog inputs and outputs onbalanced 1Ú4-inch TRS connectors. The converters are 20-bit with128-times oversampling and deliver a dynamic range of 96 dB. The frontpanel comes with signal-present and peak LEDs for each channel, and theunit can be switched between +4 dBu and -10 dBV operation.

Apogee AD-8000. The AD-8000 ($5,995) is a comprehensive8-channel conversion solution, capable of interfacing with ADATOptical, TDIF, AES/EBU, S/PDIF, and the analog world. It features eight24-bit A/D line-level converters that boast a dynamic range of 114dB.

The AD-8000 outputs the converted signals through Lightpipe(optional), TDIF (optional), or eight channels of either AES/EBU orS/PDIF (selectable). The unit has stereo S/PDIF and AES/EBU inputs aswell, and options provide an additional two or eight analog outputs.The AD-8000 can also be used as a multiple-format conversion system totransfer signals between all available interfaces simultaneously. Andbecause all outputs are active at once, the AD-8000 makes a greatdistribution system.

The AD-8000 features the patented UV22 process for translatinghigh-resolution digital audio to 16 or 20 bits without losing quality.In addition to the standard 44.1 and 48 kHz sampling rates, the AD-8000locks intelligently to word clock or any digital input, including video(with the optional video synchronization card).

Apogee FC-8. The FC-8 ($549) is a reasonably priced transfersystem for moving between TDIF and ADAT Optical. The unit isbidirectional, so the TDIF and ADAT machines can each act as eithermaster or slave, and the FC-8 will simultaneously transfer signals inboth directions. Housed in a freestanding enclosure about the size of aDI box, the FC-8 has three LEDs that indicate Lock, TDIF Active, andADAT Active. In addition to the 25-pin TDIF port and the optical port,there’s a BNC connector that provides word-clock output.

Apogee Rosetta AD. The Rosetta AD ($1,295) is a 2-channel,24-bit A/D converter that outputs either ADAT Optical, TDIF, AES/EBU,or S/PDIF–all are standard on the base unit. (Apogee is planning acompanion unit, the Rosetta DA.) There are also two AES/EBU outputs, sotwo signals can always be fed simultaneously from the unit. The RosettaAD features balanced XLR connections and has an impressive dynamicrange of 120 dB. Sampling rate on the standard unit is switchablebetween 44.1 and 48 kHz, but as an option you can also get the RosettaAD with selectable 88.2 and 96 kHz rates ($1,995). An A/D/A version,the PSX-100 ($2,995), is also available.

Graham-Patten ADAT Interfaces. This line of converters isdesigned for use with computer sound cards that offer only ADAT Opticalconnections. Four models are available.

The ADAT-1 ($1,499) converts eight channels of analog audio into aLightpipe signal. Input connectors are 1Ú4-inch TRS jacks, andlevel trims are provided for each of the inputs. A/D conversion is20-bit. Audio sampling and the ADAT output can be internally referencedor synchronized to word clock or to an AES3-ID signal from thereference input. Two versions are available: one that operates at 44.1kHz and another that works at 48 kHz.

The ADAT-2 ($1,499) is the D/A companion to the ADAT-1. It adds astereo headphone output with associated volume control to allowmonitoring of any channel pair. There is also a sync output providingeither a silent AES3-ID signal or word-clock reference.

The ADAT-3 ($899 to $1,299) takes four AES/EBU pairs and convertsthem into a single 8-channel Lightpipe stream. It has a referenceinput/output connector and a 9-pin D-sub miniature remote-controlconnector. The ADAT output can be synched to any one of the main AESinputs or to word clock or a secondary AES3-ID sync signal fed to thereference input. With the ADAT-3 synched to one of the AES inputs, youcan also use the reference connector to output word clock. The controlconnector allows you to individually mute each input pair andidentifies which of the main AES inputs is being used as the syncsource. Six models of the ADAT-3 are available. The ADAT-3/A0,ADAT-3/A2, and ADAT-3/A4 have AES/EBU inputs on XLR connectors, withzero, two, or four sample-rate converters, respectively. The ADAT-3/B0,ADAT-3/B2, and ADAT-3/B4 have AES3-ID sync inputs on BNC connectors,with zero, two, or four sample-rate converters, respectively.

The ADAT-4 ($899) performs the reverse function of the ADAT-3. Here,Lightpipe signals are converted back into four AES/EBU pairs. The AESoutputs are synchronous with the ADAT input, and there is also a syncconnector providing a silent AES3-ID sync or word-clock output. Twoversions are available: the ADAT-4/A uses XLR connectors, while theADAT-4/B employs BNC connectors.

Korg 880 A/D and D/A. The Korg 880 A/D ($950) and 880 D/A($800) are designed for use with either the 168 RC or 1212 I/O toexpand the analog I/O of those units via ADAT Optical. However, you canalso use these gizmos with any device that supports Lightpipe. Bothunits offer eight balanced analog connections on 1Ú4-inch TRSjacks, with 18-bit A/D and 20-bit D/A converters.

Kurzweil DMTi. The DMTi ($1,310) is another converterdesigned for use with a specific product–in this case with theKurzweil K2500. But it works well as a stand-alone converter fortranslating between ADAT Optical, TDIF, AES/EBU, and S/PDIF.

On the input side are eight channels of K2500 protocol, eightchannels of TDIF or Lightpipe (optional), and two stereo channels ofAES/EBU (one of which is switchable to a stereo channel of S/PDIFoptical). Outputs include four stereo AES/EBU channels (or three stereoAES/EBU and one stereo S/PDIF optical), eight ADAT or TDIF channels(optional), and eight Kurzweil Digital Stream channels. In order totransfer directly between TDIF and Lightpipe, two DMTi’s arerequired. Any of the outputs can be synched to an external clock or to44.1 or 48 kHz internal rates.

Lucid Technology ADA8824. The latest offering from thishigh-flying converter company is the ADA8824 ($3,295), a 24-bit A/D andD/A interface designed for Lightpipe systems. The ADA8824 changes eightanalog signals into ADAT Optical (and vice versa) using delta-sigmaconverters that yield a dynamic range of 113 dB; special digitallycontrolled attenuators on the inputs and outputs help the user achievethe greatest dynamic range possible. Connections are made via balancedXLR jacks. There are also eight channels of AES/EBU I/O and an S/PDIFI/O. The 2-rackspace unit features discrete LED meters for eachchannel.

Midiman Pipeline 858. The Pipeline 858 ($899.95) is an8-channel, 24-bit conversion system that takes analog signals andoutputs them in Lightpipe format (or vice versa). The Pipeline providesbalanced and unbalanced analog I/O, selectable word widths, MIDI I/O,word-clock I/O, and selectable internal sample rates of 44.1 and 48kHz. The Pipeline also features patented BitRazor technology, whichautomatically encodes and decodes 24-bit audio on two ADAT tracks,turning any ADAT into a 24-bit recorder.

Midiman SAM. The other offering from Midiman is the SAM($399.95), the "S/PDIF ADAT mixer." It accepts Lightpipe and S/PDIFI/O, providing conversion between the two formats. But with the SAM,you can also mix all eight ADAT Optical signals down to a stereo pairof S/PDIF, using the individual channel gain and pan controls includedon the unit.

MusicNet AD24 and DA24. Available from Wave Distribution, thehalf-rackspace MusicNet AD24 ($749) and DA24 ($549) provide 24-bitanalog-to-Lightpipe and Lightpipe-to-analog conversion, respectively.All analog connections for the two units are via XLR jacks, and bothsupport 44.1 and 48 kHz sampling rates. The DA24 also is switchablebetween 16- and 24-bit conversion.

The AD24 can generate or sync to word clock, while the DA24 onlygenerates word clock. The AD24 features a Calibration mode that keepsthe converter’s internal modulators and integrators properlymatched. The DA24 includes a deemphasis filter that eliminates thehigh-frequency boost that is often used with commercial CDs.

Otari UFC-24/8. The UFC-24/8 ($2,595) universal formatconverter from Otari can transfer up to 24 channels at a time to andfrom PD, SDIF-II, Lightpipe, TDIF, and AES/EBU formats. (There are 8AES/EBU channels on the base unit, and it can be retrofitted for 24channels). You can link multiple units to provide sample-accuratetransfer of more than 48 channels.

All outputs (except what’s being used as the source) are activesimultaneously, so the UFC-24/8 also makes a terrific distributionsystem. MIDI I/O is provided for control of routing presets andinput-format selection. You can save all parameters of the UFC-24/8, asSystem Exclusive data, to a MIDI storage device and later recallit.

Prism Sound MR-2024T. The Prism MR-2024T ($2,570) is designedto bring AES/EBU connectivity to Tascam DA-38, DA-88, and DA-98recorders. The MR-2024T converts between TDIF and AES/EBU or S/PDIF(selectable) and offers some other features aimed at high-qualityapplications.

The recording mode can be set to eight 16-bit tracks, six 20-bittracks, four 24-bit tracks, or two tracks at 24-bit and 96 kHz. TheMR-2024T tags the tape so that the correct mode is always selected onplayback. You can connect a second Tascam machine to the same MR-2024Tas a security backup; a monitor selector is provided to determine theplayback machine.

The MR-2024T’s synchronization options are versatile. UsingDA-88 sync, the transport can run free or locked to video or word clockwhile the unit provides sync outputs. Alternatively, the MR-2024T cansynchronize the DA-88 to an AES3 or S/PDIF input. You can slave up to16 machines, for a total of 96 tracks at 20-bit or 64 tracks at24-bit.

Sonorus AudI/O. Sonorus recently introduced a line ofconverters intended to work as both stand-alone units and interfacesfor the company’s StudI/O digital audio card.

First up is the AudI/O AES/8 ($999), which has eight channels ofTDIF, Lightpipe (used to network with the StudI/O card), and AES/EBU(switchable to S/PDIF) I/O. The outputs are not simultaneouslyavailable, so the AES/8 can’t operate as a distributiondevice.

Also available are the AD/9624 and DA/9624 ($2,995 each), bothhigh-quality 24-bit/96 kHz converters. The AD/9624 accepts analogsignals via balanced XLR connections and converts them to Lightpipe,four pairs of AES/EBU outputs, or TDIF (optional). The DA/9624 takesany of these digital data formats and delivers it as analogsignals.

Sonorus’s AD/24 ($799) and DA/24 ($599) are also 24-bitconverters, but both are designed to work with digital data only in theLightpipe format. Analog connections are handled by balanced XLR jacks,and the internal clock runs at 44.1 or 48 kHz. All three units provideword-clock connections.

Soundscape SS8IO-1. The SS8IO-1 ($1,695) provides a means ofconverting signals between TDIF and Lightpipe, and between eitherformat and analog. The 2-rackspace unit offers eight channels ofbalanced analog I/O on XLR connectors, which are fed to 20-bit Crystalconverters. Simultaneous transfer in both directions is possible. Ifyou’re connecting the system to a Soundscape DAW or audio card,the TDIF port is used to make the connection, so the SS8IO-1 can serveas either an analog or ADAT front end. Word-clock and Superclock RCAjacks are included. The internal sampling rate is switchable between44.1 and 48 kHz.

Soundscape SS8IO-2. The SS8IO-2 ($349.95) offers many of thesame functions as the SS8IO-1, except it lacks analog I/O. Thehalf-rackspace SS8IO-2 can serve as a TDIF-to-Lightpipe converter or asan ADAT interface for a Soundscape mixing system. (If you’re usingthe Mixtreme audio card, which has two TDIF ports, you could employ theSS8IO-2 as a Lightpipe I/O and use the spare TDIF port for TDIF, givingyour system eight channels of each format.) As with the SS8IO-1, datacan be transferred in both directions simultaneously, word-clock andSuperclock connections are present, and the clock is switchable.

Soundscape SS8IO-3. The third offering from the folks atSoundscape is the SS8IO-3 ($599), which converts between eight channelsof unbalanced analog audio and TDIF. This unit is designed to providean inexpensive analog I/O solution for owners of the Mixtreme digitalaudio card, but it also serves as a stand-alone unit for convertingTDIF to unbalanced analog.

Spectral Translator. The Translator ($995) gives you aneffortless way of transferring eight audio channels from one digitalformat to another. The unit provides compatibility with Lightpipe,TDIF, SMDAI, and Yamaha Y2 devices. An upgraded model, the TranslatorPlus ($1,495), adds AES/EBU transfer.

The Translator can slave to external clock signals from any of thesupported devices. If the selected source is not present, theTranslator provides master clock to keep sync-dependent equipmentrunning. A handy bypass mode ensures that you never have to disconnectcables.

Studer D19 MultiDAC. The MultiDAC ($3,175 for a basicsystem), part of Studer’s D19 line of modular processors, delivers24-bit D/A conversion from a number of formats. AES/EBU inputs arestandard, and there are options for either ADAT Optical or TDIF inputs.Outputs appear on balanced XLR jacks. A monitor output is alsoincluded, and you can selectively monitor certain channels or sum alleight channels into a rough submix. This one is a stretch for thepersonal studio, though: I don’t know of too many that areequipped with a Studer D19 rack.

Tascam IF-88AE. The IF-88AE ($1,245) is a single-rackspaceunit designed to bring AES/EBU capabilities to a DA-series multitracksystem. It has four XLR jacks that accept AES/EBU signals, in additionto a D-sub jack for TDIF signals. Conversion can take place in eitherdirection, so the IF-88AE makes a decent stand-alone converter for anyTDIF or AES device.

Tascam IF-TAD. Lo and behold, Tascam blinked first! TheIF-TAD ($199) is a converter designed to connect ADAT Optical and TDIFdevices. It has LEDs to indicate data present for each format, as wellas a BNC word-clock output. I was floored when I saw the IF-TAD in anAlesis third-party developer catalog. When Alesis and Tascam startadvertising each other’s products, you know that times havechanged for the better.

Piping Hot

Perhaps we’re getting a little carried away with all this fussover digital connectivity. With the wide array of options andaccompanying confusion, the eternal cynic in me says, "Give me ananalog cable...I want a TT patch bay!" But I know those days arenumbered, and that’s probably for the better.

The death knell of analog has sounded, and the all-digital world isupon us. We must be prepared for the new millennium, and ADAT Opticaland TDIF will play a big role in ensuring that we are. Without a doubt,these two formats will be around long after the ADAT and DA-seriesdecks disappear.

FormerEMAssociate EditorJeff Caseyis still looking to get a record deal but recently realized that heprobably needs to finish producing the record before that willhappen.