The thing about standards is there's just so many of them (as the old saying goes), but if your digital equipment isn't as talkative as you'd like it to be, then Alesis may have the answer. Bob Dormon checks out the AI-1 digital interface, and discovers it might just get those binary-coded tongues wagging.

I was a little dewy-eyed when I opened up the box containing the Alesis AI-1. It's a simple 1u rack unit of customary Alesis ADAT styling; in other words, it's very black and could easily be mistaken for something rather boring.

But 'boring' is the last word I'd use to describe what turns out be one of the most useful digital devices known to man. High praise indeed... enough to have you asking, 'How's it gonna help me, man?'

Well, have you an ADAT? Don't worry if you haven't. The AI-1 talks to ADATs and more besides. Have you got a CD, DAT, DCC or MiniDisk? 'Cos it talks to them too. Interested? Not yet, huh?

How about if I told you you could record CDs digitally, directly to your DAT machine even 'though CDs are sampled at 44.1kHz and consumer DATs sample at 48kHz? Or be able to make digital back-ups at a sampling rate of your choice?

How about being able to play sounds from the digital output of a sampler or digital audio workstation direct to an ADAT without going anywhere near a desk? And there's more - but put simply, the AI-1 is an interface in the broadest sense of the word.

It translates the digital data of one format and then sends it out again in another. The AI-1 performs the task of preserving the quality of your digital audio recordings by enabling totally digital transfers between a whole range of formats, and their associated interfaces.

There is a catch though. The AI-1 doesn't come cheap. But when you discover all the things that it can do (sample rate conversion in particular), then it starts to look like very good value.

Overview

The AI-1's front panel is simple, but not deceptively so. The tasks you may want it to perform may be great in technical terms but for the user, the methods of achieving them couldn't be easier.

Twelve buttons on the front panel in two groups of six control the AI-1's functions. Lime-green LEDs within each button relay the current status. The first four buttons select the ADAT tracks that will either receive incoming digital audio from non-ADAT sources, or will be sent from the ADAT to other devices.

The next two determine the sample rate: 48kHz or 44.1kHz. The ADAT itself uses 48kHz, but using the BRC (Big Remote Controller), it can be effectively vari-speeded down to work at 44.1kHz. If you start mixing up your sample rates on the same ADAT tape you're in for a headache, as it will need to operate at one or other rate.

It won't be able to tell the difference from the tape itself. The result will be stuff playing about nine percent too fast (44.1kHz played back at 48kHz) or 8 percent too slow (48kHz played at 44.1 kHz). It's the BRC in conjunction with the AI-1 that provides the timing information when sampling rates are altered.

"'Boring' is the last word I'd use to describe one of the most useful digital devices known to man."

The six buttons on the right of the front panel deal with the routing of the digital audio. The top three determine the source: ADAT, AES/EBU or S/PDIF while those below are labelled identically: they are the possible destinations. From this, you've probably gathered that you don't need an ADAT at all to make use of the AI-1.

Suppose you're in the studio and you want to make a DAT back-up on your old Sony TCD D3, but the studio has a pro-DAT machine that doesn't have the same connectors? Well, so long as you've got the cables, it'll be no problem. The AI-1 will take the pro DAT's AES/EBU output, convert it to S/PDIF and send it out at 48kHz, so your 'consumer' DAT will accept it. It's all achieved simply with just two cables and three button pushes on the AI-1: source (AES/EBU), destination (S/PDIF) and sampling rate (48kHz).

It's that easy, as the AI-1 is just a rather fancy routing device that allows you to communicate with anything that's connected to it, so long as it's an ADAT or a digital audio device that complies with the AES/EBU or S/PDIF protocols. So if you want to play birdsong from a sound effects CD at the beginning of a track and record it to ADAT, you can do this digitally.

First, hook up the digital out from the CD player to the AI-1. Second, take the AI-1's (ADAT) optical out and connect it to the ADAT recorder's digital input. Put the ADAT in digital in/out mode, and select a pair of tracks to record. Then, on the front panel of the AI-1 select S/PDIF as the source, ADAT as the destination, the pair of tracks you wish to record onto, and go!

While the front panel is simplicity itself, the back panel is serious, to say the least. The IEC mains socket accepts a voltage range of 90 to 250 volts at 50 or 60Hz. Next is a 48kHz clock output on a BNC connector, that provides vital timing information for the BRC. Basically, if you've got a BRC hooked up in your ADAT system then you must connect this word clock output to it, otherwise the AI-1 won't work.

A cluster of four (EIAJ) optical connectors accommodate the ADAT and S/PDIF optical inputs and outputs. S/PDIF is well catered for, as there are also RCA (phono/coax) connectors here too. AES/EBU has the usual male/female arrangement for its digital interfacing. Finally, there's the ADAT nine pin D-type plugs for sync in and out.

The manual only gives uses for the AI-1's sync input; it's utilised as the last of an ADAT sync chain when a BRC is in operation. The AI-1's sync out will no doubt be employed in other devices, as the ADAT system's innovation continues to mushroom.

In Use

The AI-1 certainly got used, and last month's CD (compression) tutorial bears testimony to that. I'd used an ADAT system to record the voice-over on the tutorial, but the music examples were on DAT. Using the AI-1, compiling a complete ADAT tape was possible without having to re-record the music to ADAT via the desk. And once I'd mixed it all to DAT, I was able to back-up the DAT on two spare tracks on the ADAT tape via the AI-1.

Using the AI-1 without a BRC is just a matter of pressing the right buttons on the front panel, yet the BRC will actually remotely control the unit for you. Sample rate changes in the ADAT format can be performed, and all tracks are available for sending via the AI-1 to another ADAT. As for the other formats, you can still only select two tracks for transmission to them, but they don't have to be adjacent pairs. It's done using the track select buttons on the BRC when it is in digital I/O edit mode.

This BRC page has a few additions when an AI-1 is plumbed in. There's the 'bounce ADAT tracks' facility as usual. This allows digital track copying within the ADAT format. A new feature is 'select tracks to output to AI-1', which allows you to choose which ADAT tracks (if any) you want to transmit out of any of the outputs. Curiously enough, you can perform an ADAT bounce, and a transfer of a couple of ADAT tracks to another format simultaneously. The tracks for both operations can be completely different too. So you can back-up an ADAT tape, and pinch a load of brass riffs or whatever to a DAT tape or some other digital format at the same time.

"The AI-1 could certainly become something that producers using the ADAT system insist on having."

More new pages on the BRC select the destination format, destination sample rate and the digital input. I did notice when swapping digital inputs that it is easy to make the ADAT recorder(s) sound very sick indeed. When an external source such as S/PDIF is selected, the BRC automatically goes in to external sync. If, while you're still in digital I/O edit mode you then choose to do some ADAT to ADAT bouncing, the BRC won't have switched out of external sync mode, and the ADATs will whirr up and down trying to ascertain what speed they should be at, changing pitch continuously while the lime green LEDs on the AI-1 blink furiously. It's awful. You eventually realise what's happening and have to exit the digital I/O edit and knock the BRC out of external sync.

Conclusion

The AI-1 is not entirely unique - Digidesign produce their own ADAT interface which is ideally suited to the Session 8 hard disk recording system. The associated ProTools hardware also provides S/PDIF and AES/EBU interfaces but alas, has no optical S/PDIF connectors. Tascam, pioneers of their own 8-track digital multi-track (DA88), also have format convertors in the form of the IF-88AE (4 in/out, AES/EBU stereo pairs plus one S/PDIF I/O) and the IF-88SD which offers the old S/DIF-2 used on the Sony 1610/1630 U-matic digital audio mastering machines. Tascam also produce an interface for Sony DASH multi-tracks.

But the AI-1 does provide sample rate conversion, a feature that has previously cost silly money. At this price plus all the other features, the AI-1 has certainly been groomed for success. It could well become something that producers using an ADAT system insist on having. Being able to take solos or vocal takes home on a DAT, and reconstruct them with a computer based, hard disk recording setup, could certainly find favour - it might even help keep the use of commercial studio time concentrated around more important things... like music! Technology or no technology, that's what it's all about.

The essentials...

Price inc VAT: £999

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