If you’ve been in the music business for a while now, you’ve probably heard the term “ADAT” thrown around when discussing audio equipment.
It is every music producer’s dream to have more output and more input channels.
However, if you’re still curious about the most commonly used functions of audio interfaces, here’s a complete guide on what is ADAT and how to use it!
All About ADAT
One of the BEST ways to further understand something is to understand its point of origin. In this case, we’ll be delving into ADAT’s history first before focusing on its modern uses.
- ADAT, short for Alesis Digital Audio Tape, was first introduced in 1992.
- It is a recording machine that used video cassette tapes (specifically S-VHS) to record data.
- It also had an 8 channel digital audio optical format.
The main difference between analog recorders and the ADAT interface was that the latter made it possible for individuals to have extra ADAT recorders, which could copy up to 8 channels!
Up to 16 ADAT recorders could be connected with ADAT Lightpipe or ADAT cables and produce approximately 128 tracks.
Various models were then produced throughout the years. The earlier ones used the ADAT Type I format, which recorded at 16-bits:
- Original ADAT (also known as Blackface)
- ADAT XT
The later ones used the Type II ADAT format and recorded at 20-bits:
- XT-20
- LX-20
- M-20
Interesting trivia: The tapes recorded with Type I could still be used in Type II machines, but NOT vice versa.
ADAT Remote Controls
Similar to toy cars or television sets remote controls are also used for ADAT machines.
- The Alesis LRC (little remote control) controlled single or multiple ADAT machines by offering transport controls and other functions.
- The BRC (big remote control) included song naming and MIDI timecode synchronization features.
How Does ADAT Work?
Now that we’ve covered the history of ADAT, we can tackle its main function: expanding your interface’s channel count.
Number of Output and Input Channels
Most audio interfaces include 2 ADAT inputs/2 ADAT outputs, which ensures up to eight channels of audio!
They can also handle additional preamps if they’re connected with optical ADAT outputs.
Toslink Cable
But how does ADAT transfer digital audio between an interface and a peripheral device?
The answer is a Toslink cable, an older digital standard invented by Toshiba in 1983. This format was adopted by Alesis and became known as the ADAT optical interface or the ADAT Lightpipe.
Lightpipe
The Lightpipe carries 8 channels of uncompressed digital audio at 48kHz. This is roughly 48,000 samples per second!
All Lightpipe signals can transmit at 24-bit resolution and use MSB to contain information.
- If you use a Lightpipe to send a 16-bit signal, it’ll contain audio information, and the other 8 will have zeroes.
- This means that the receiving device ignores information that it can’t understand or process.
- The Lightpipe is also known for its trait of being ‘hot-pluggable,’ which means devices don’t need to be turned off when plugged or unplugged.
Just make sure to MUTE your monitors when repatching to avoid sudden loud noises!
What Is ADAT: Higher Sample Rates
It’s important to note that Toslink can transfer audio at higher sample rates (i.e., 88.2/96 kHz).
This was done by using bit-splitting techniques to modify the Lightpipe format.
- The technique of sample multiplexing (S/MUX) allowed people to record at higher rates like 96 kHz (four channels) or 192 kHz (two channels), using one optical cable.
- The only downside to using S/MUX is that the available inputs would only be 4, which aligns with the ADAT’s bandwidth limit.
If you’ve noticed that some digital audio equipment often have multiple Toslink ADAT connections (and, therefore, multiple optical cables), this is because the channel count needs to be maintained.
What Is ADAT: ADAT Units
Tired of replacing equipment 24/7?
Another convenient fact about ADAT is that it allows you to add units, which helps you expand your studio setup.
Various audio interfaces have ADAT ports that make it possible to have additional inputs. Imagine that you’re planning to buy a small interface with a few mic inputs.
If you buy a unit with additional microphone preamps, a higher channel count, and an ADAT output, you could increase the number of mic inputs from 2 to 10!
Can You Connect Two ADAT Devices?
Have you ever wondered if you could connect two audio devices (i.e., an audio interface to another ADAT)?
The good news is that you CAN, and the process itself is quite simple!
1- Connecting ADAT Inputs
- Use a Toslink cable to connect the ADAT output of the external device to the ADAT input of the audio interface.
- Set the sample rate to 44.1 kHz or 48 kHz to get eight channels; set the rate higher to get fewer channels.
- Ensure that all devices in the setup are receiving clock signal from a single master device.
- Route the signal in the DAW.
- Assign the DAW input to the corresponding ADAT input.
2- Connecting ADAT Outputs
- Use a Toslink cable to connect the ADAT output of the audio interface to the ADAT input of the external device.
- Set the sample rate to 44.1 kHz or 48 kHz to get eight channels; set the sample rate higher to get fewer channels.
- Ensure that all devices in the setup are receiving clock signal from a single master device.
- Route the signal in the DAW.
- Assign the track’s output in the DAW to the corresponding ADAT output.
The Art of Clocking
Try and imagine the frames that you see in videos and movies. These frames are also present in digital audio signals.
When connecting two or more units, you need to ensure that the frames are synched so that you don’t get any ‘clicks’ or ‘pops’. This also ensures that all of the frames will start simultaneously!
- As you’re connecting two devices, you need to check the devices’ clock settings.
- Make sure to format the Clock Source of the receiving device.
- The clock source should be the ADAT input.
Audio Interfaces with ADAT Inputs
If your old interface doesn’t need a computer connected to be able to run, you can use this as an expansion. This means that the more modern interface would be the host.
However, you might be interested in purchasing a new ADAT recorder.
If this is the case, you’d need to be familiar with those that have the appropriate ADAT input and appropriate ADAT output.
Among the thousands of popular audio interfaces, a few have ADAT inputs. While these interfaces have pros and cons, note that they need to work at the same sample rate.
1- Focusrite Scarlett 18i20
The Focusrite Scarlett 18i20 includes 18 inputs and 20 outputs of clear sound quality and ensures high-end details in your recordings. It also includes the following functions:
- 2 high headroom instrument inputs
- Anti-thump tech
- Speaker switching
- Built-in talkback mic
2- PreSonus Studio 192
The PreSonus Studio 192 has 18 digital inputs and outputs, making professional monitoring possible and ensuring versatility. It also includes the following functions:
- Onboard talkback mic
- Dim and Mono options
- Monitor mixing
- Speaker switching
3- Steinberg UR816C
The Steinberg UR816C has multiple inputs and outputs that ensure the feasibility of multitrack recordings. It also includes the following functions:
- Word Clock
- Dim and Mute options
- Latency-free monitoring with built-in DSP
- Loopback function
4- Apogee Ensemble
The Apogee Ensemble has 10 analog inputs and 16 analog outputs and impressive functionality. It also includes the following functions:
- AD/DA conversion
- Thunderbolt connectivity and ultra-low latency
- Talkback functionality
- Word Clock
5- Universal Apollo Twin MKII
The Universal Apollo Twin MKII has 2 Unison-enabled mic preamps and an efficient A/D and D/A conversion. It also includes the following functions:
- UAD-2 DUO Core Processing
- Ultra-low THD
- Accelerated Real-time Monitoring
- Built-in talkback mic
Final Thoughts
To summarize, the Alesis Digital Audio Tape is MORE than just the little square connector that you can find at the back of your audio interface.
It’s an 8-channel audio interface that includes an optical audio protocol designed to ensure efficient audio expansion.
Make sure to delve further into the multiple functions of this interface so that you can use it to its FULLEST capability!
