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Alesis AI-4 AES/EBU to ADAT Optical Interface

Alesis AI-4 8-Channel AES/EBU to ADAT Optical Digital Audio Interface

The Alesis AI-4 is an 8 channel of AES/EBU formatted audio into the ADAT Optical format as well as 8 channels of ADAT into 8 channels of AES/EBU format. This is very useful in studio where there is more than one type of digital interface. Many video and audio studios use AES though other audio formats are also being used. You'll find this type of connection on CD burners, DAT machines and other digital audio equipment.

It can accept full duplex single wire AES lines and transmit and receive at up to 96 kHz samplerate. The four AES/EBU XLR inputs are on the back panel. Each input connects two audio channels directly to the ADAT optical output. There are also four AES/EBU XLR outputs again where each AES/EBU XLR output contains two channels of audio.

In order for the AI-4 to operate at the 96 kHz samplerate it has to be run in S/MUX mode or sample split mode which means that you get 4 channels of conversion and not 8. This is standard and perfectly acceptable. The first two channels will be routed out to the ADAT lightpipe outputs 1 through 4 and the 2nd two channels with be routed out ADAT lightpipe outputs 5 through 8.

But in order for the AI4 to accommodate higher resolutions up to 96 kHz, Alesis supports a "sample split" format that accepts four channels of 24-bit/96kHz audio per cable. You have two options in setting up the AI4 for ADAT Optical. For signals with sample rates up to 48 kHz, use the jacks labeled CH 1–8 (Ch 1–4). Signal coming from your source goes into the AI4's inputs; signal returning to the source goes to the AI4's outputs. If you're working with higher resolutions, you'll divide the signal between two jacks. Route channels 1–4 to the CH 1–8 (Ch 1–4) jack; route channels 5–8 to the second jack, labeled (CH 5–8).

The ADAT optical input and output connectors can be found on the back panel as well. They connect to ADAT optical equipment and can communicate and transmit audio data freely. Each of the AES/EBU inputs is the standard 110 ohms impedance.

To synchronize different machines together the AI-4 comes with a WORD CLOCK input and output. This signal is meant to be feed to all the different machines in a studio allowing them to use a single clock source. This is only really required when trying to sync more than two different machines together. The unit comes with the standard 75-ohm BNC connector which is what you'll find for almost all WORD CLOCK connections.


  • Conversion of AES/EBU digital audio to ADAT Optical Format
  • Lets different audio formatted equipement talk to one another (AES/EBU and ADAT)
  • Four 110-ohm XLR AES ins
  • Four 110-ohm XLR AES outs
  • 2 Toslink ADAT Lightpipe ins
  • 2 Toslink ADAT Lightpipe outs
  • 75-ohm BNC word clock in
  • Internal switching power supply (100-230VAC) 


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