What ADAT is and why you would chain them

ADAT stands for Alesis Digital Audio Tape, a format that lets you record and play back eight channels of audio at once on a single device. When you need more than eight channels — say you're recording a full band with separate microphones for drums, bass, guitars, and vocals — you can connect multiple ADAT machines together so they work as one larger system. The machines stay in perfect sync with each other, and your recording software sees all the channels as if they came from a single device.

ADAT devices are less common in new studios than they were in the 1990s and early 2000s, but they're still used in many professional and semi-professional setups, especially in music production and live recording. If you already own ADAT machines or inherited them as part of a studio, chaining them is straightforward once you understand the three things you need to do: connect the audio cables, connect the sync cables, and configure the machines to recognize each other.

Key Takeaways

  • ADAT machines connect through optical cables (TOSLINK connectors) for audio and either word clock or MIDI cables for timing synchronization.
  • One machine acts as the master and controls the timing; the others are slaves that follow its tempo and start/stop commands.
  • You need to set the slave machines to receive sync from the master, usually through a menu setting on the front panel or LCD screen.
  • The optical audio cables carry eight channels per connection, so two ADAT machines chained together give you sixteen total channels.

The three types of connections you need

ADAT machines use optical cables to send and receive audio. These cables have square connectors called TOSLINK (Toshiba Link) on each end. One ADAT machine has an optical output and an optical input. To chain two machines, you run a cable from the output of the first machine into the input of the second. If you're chaining three machines, the second machine's output goes into the third machine's input, and so on.

The second connection type is for synchronization — keeping all the machines playing at exactly the same speed and starting at exactly the same moment. You have two options here: word clock or MIDI. Word clock is a dedicated timing signal that runs through a separate cable (usually a coaxial cable with RCA connectors, the same kind used for audio in older equipment). MIDI is a data protocol that can carry timing information alongside other commands. Not all ADAT machines support both; check your manual to see which your machines have.

The third connection is optional but useful: a control cable. Some ADAT machines can send transport commands (play, stop, record) to each other through MIDI or through a proprietary control protocol. This lets you press play on the master machine and have all the slaves start automatically. Without this, you have to press play on each machine separately, which is error-prone in a live or time-sensitive recording situation.

Setting up the master and slave machines

Before you plug anything in, decide which machine will be the master. The master is the one that controls timing and, if you're using MIDI or control cables, the one that sends start and stop commands. In most setups, the master is the machine connected to your recording software or mixing console, because that's the one you'll be controlling directly. The other machines are slaves.

On the master machine, set the sync output to send either word clock or MIDI clock, depending on what your slave machines support. This setting is usually in a menu accessed through buttons on the front panel. Consult your manual for the exact steps, because the menu structure varies between ADAT models.

On each slave machine, set the sync input to receive from the master. Again, this is a menu setting. The slave needs to know whether it's receiving word clock or MIDI clock, and it needs to be told to use that external sync instead of its own internal clock. Once you set this, the slave will lock to the master's timing as soon as the sync signal arrives.

Connecting the optical audio cables

Run an optical TOSLINK cable from the optical output of your first ADAT machine to the optical input of your second. If you have a third machine, run a cable from the second machine's output to the third machine's input. Each optical connection carries eight channels, so the second machine adds eight more channels to your total.

The order matters only if you care about which channels appear in which order in your recording software. Most people arrange them so the first machine's channels are 1–8, the second machine's channels are 9–16, and so on. Your recording software will see them in the order they're chained.

Optical cables are fragile. Don't bend them sharply, don't step on them, and don't leave them coiled tightly for long periods. A damaged optical cable will either not work at all or will drop data, causing clicks and pops in your audio. If you have a cable that's not working, try a different one before assuming the ADAT machine is broken.

Connecting the sync cables

If you're using word clock, run a coaxial cable from the word clock output of the master machine to the word clock input of the first slave. Then run another cable from the first slave's word clock output to the second slave's input, and so on. Word clock can be daisy-chained this way, but the signal degrades slightly with each connection. If you have more than three machines, consider using a word clock distribution amplifier, which is a small box that takes one word clock input and sends clean copies to multiple outputs.

If you're using MIDI clock, connect a MIDI cable from the MIDI output of the master to the MIDI input of the first slave, then from that slave's MIDI output to the next slave's input. MIDI cables are five-pin DIN connectors, different from the RCA connectors used for word clock. Don't confuse them.

Some ADAT machines have both word clock and MIDI connectors. If yours do, pick one sync method and stick with it. Mixing word clock and MIDI sync on the same system can cause timing problems.

Testing the sync before you record

Once everything is plugged in, power on the master machine first, then the slaves. This order matters because the slaves need to see the sync signal from the master when they boot up. Wait a few seconds for each machine to fully initialize.

Press play on the master machine and watch the slave machines. Their transport controls (the play, stop, and record buttons) should respond, and their display screens should show that they're locked to external sync. If a slave machine shows "no sync" or "unlocked," check that the sync cable is plugged in firmly on both ends and that the slave is set to receive external sync in its menu.

Record a test tone or a few seconds of audio on the master machine. Stop and rewind, then play back. The audio should be clean with no clicks, pops, or dropouts. If you hear artifacts, the sync signal may be unstable. Check that all cables are fully seated and that you're not running sync cables near power cables or other sources of electrical noise.

Common problems and how to fix them

If the slave machines won't lock to sync, the most common cause is that the sync output on the master is turned off or set to the wrong type. Check the master's menu to confirm that sync output is enabled and set to the same type (word clock or MIDI) that the slaves are set to receive.

If you hear clicks or pops during playback, the sync signal may be weak or intermittent. Try replacing the sync cable. If the problem persists, check that the master machine's sync output level is set correctly — some machines have a level control for word clock output, and if it's too low, the slaves won't lock reliably.

If the optical audio cable isn't working, make sure both the output and input are enabled on the respective machines. Some ADAT machines let you disable individual outputs or inputs through the menu. Also check that you're not trying to send audio in both directions on the same cable — optical TOSLINK is one-way only.

Frequently Asked Questions

Can I chain more than three ADAT machines together?

Yes, you can chain as many as you need. Each machine adds eight channels, so four machines give you thirty-two channels total. The main limitation is that your recording software and audio interface need to support that many channels, and you need enough sync cables and optical cables to connect them all.

Do I need word clock or MIDI sync, or can I use both?

Use one or the other, not both. Word clock is more stable for timing but requires a dedicated cable. MIDI clock works through MIDI cables and can carry other commands alongside timing, but it's slightly less stable over long cable runs. Pick whichever your machines support and stick with it.

What if my ADAT machine doesn't have an optical output?

Older ADAT machines used different connectors. Check your manual to see what audio outputs your machine has. Some used RCA connectors or XLR connectors instead of optical. You'll need to use the connectors your machine has, and you won't be able to chain it with machines that use optical unless you use an external converter.

Can I use ADAT machines with modern recording software?

Yes, if your computer has an audio interface with ADAT inputs. Many professional audio interfaces have one or more TOSLINK connectors that accept ADAT signals. Plug the optical output of your chained ADAT machines into the interface, and your recording software will see all the channels. You'll still need to sync the ADAT machines to your computer's clock, usually through word clock or MIDI.

What happens if the sync signal drops while I'm recording?

The slave machines will usually continue playing at their last known tempo, but they'll drift out of sync with the master. This causes timing problems and can ruin a take. To prevent this, use high-quality sync cables, keep them away from power cables, and test the sync before every recording session.