Applies to:
- Scarlett 18i20 3rd Gen
- Scarlett 16i16, 18i16, and 18i20 4th Gen
- Clarett 4Pre and 8Pre (+, USB, and Thunderbolt)
Digital I/O modes determine the configuration of the optical and S/PDIF coaxial (RCA) sockets of your interface.
After changing any of the configurations, you will need to restart your interface for the settings to take effect.
Scarlett 18i20 3rd Gen
Mode 1: Coaxial (RCA) S/PDIF
This is the factory default mode, and your Scarlett 18i20 will adopt these assignments out of the box.
Use this mode if you need a coaxial S/PDIF audio input, or if you wish to use a coaxial S/PDIF
signal as a clock source. See also: How do I use RCA S/PDIF inputs and outputs?
When the Digital I/O Mode is set to 'Coaxial (RCA) S/PDIF', the optical ports will still send and receive ADAT signals (audio and clock) - you can use this mode if you are looking to send or receive ADAT signals (audio and clock) at 44.1/48 or 88.2/96 kHz sample rate using a Tolinsk optical cable via the optical ports. See also: Connecting an external preamp to your interface via ADAT
Digital Port | Sample Rate (kHz) | |||
44.1/48 | 88.2/96 | 176.4/192 | ||
Input | S/PDIF In | S/PDIF | S/PDIF | S/PDIF |
Optical In 1 | ADAT 1-8 | ADAT 1-4 | X | |
Optical In 2 | X | X | X | |
Output | S/PDIF Out | S/PDIF | S/PDIF | S/PDIF |
Optical Out 1 | ADAT 1-8 | ADAT 1-4 | X | |
Optical Out 2 | ADAT 1-8 | ADAT 1-4 | X |
Mode 2: Optical S/PDIF
Select this mode when you are working at 44.1/48 or 88.2/96 kHz sample rates and you need to send or receive a S/PDIF audio signal via an optical port, using a Toslink cable.
You should also use this mode if you want to use an optical S/PDIF signal as a clock source, or send a clock signal to another device via optical S/PDIF.
Digital Port | Sample Rate (kHz) | |||
44.1/48 | 88.2/96 | 176.4/192 | ||
Input | S/PDIF In | X | X | X |
Optical In 1 | ADAT 1-8 | ADAT 1-4 | X | |
Optical In 2 | S/PDIF | S/PDIF | X | |
Output | S/PDIF Out | S/PDIF | S/PDIF | S/PDIF |
Optical Out 1 | ADAT 1-8 | ADAT 1-4 | X | |
Optical Out 2 | S/PDIF | S/PDIF | X |
Mode 3: Dual ADAT
Select this mode when working at a sample rate of 88.2 or 96 kHz (also known as dual band) and you need more than four ADAT input and/or output channels.
At dual band sample rates the maximum number of channels that can be transmitted over a single optical ADAT connection is 4 - Dual ADAT mode lets you transmit up to 8 channels in total (i.e. 4 channels for each optical port). See also: Connecting two ADAT Devices to the Scarlett 18i20 3rd Gen
Digital Port | Sample Rate (kHz) | |||
44.1/48 | 88.2/96 | 176.4/192 | ||
Input | S/PDIF In | X | X | X |
Optical In 1 | ADAT 1-8 | ADAT 1-4 | X | |
Optical In 2 | X | ADAT 5-8 | X | |
Output | S/PDIF Out | S/PDIF | S/PDIF | S/PDIF |
Optical Out 1 | ADAT 1-8 | ADAT 1-4 | X | |
Optical Out 2 | ADAT 1-8 | ADAT 5-8 | X |
Scarlett 16i16, 18i16, and 18i20 4th Gen
The functionality of the digital ports on Scarlett 16i16, 18i16, and 18i20 4th Gen can be changed in Focusrite Control 2 (the control app for the Scarlett) under 'Sample rate & clocking'. To do so, go to: Focusrite Control 2 > ... (top-right corner icon) > Preferences > Sample rate & clocking
Depending on the interface you have, see the settings in the section below.
Scarlett 16i16 and 18i16 4th Gen
You can change the type of digital signal the Optical ports will send and receive. The default setting out of the factory is 'ADAT'.
The tables below outline the type of signal and the number of channels each port will pass depending on the setting.
ADAT (Default)
S/PDIF
Scarlett 18i20 4th Gen
On Scarlett 18i20 4th Gen, you can change which digital port will send and receive S/PDIF By changing the S/PDIF mode.
You can also change the number of ADAT channels you can use at once when using 88.2 or 96 kHz sample rates by changing the ADAT mode. The S/PDIF and ADAT configurations are interlinked at these sample rates, meaning that adjusting one will affect the other.
Below are some tables which outline the type of signal and the number of channels each port will pass depending on the setting.
S/PDIF mode
RCA (Coaxial)
Optical
S/PDIF via the Optical ports is unavailable when the ADAT mode is set to Dual.
ADAT mode
ADAT mode is only applicable when using a sample rate of 88.2 or 96 kHz.
Single
Dual
Select the Dual ADAT mode when working at a sample rate of 88.2 or 96 kHz (also known as dual band) and you need more than four ADAT input and/or output channels.
At dual band sample rates the maximum number of channels that can be transmitted over a single optical ADAT connection is 4 - Dual ADAT mode lets you transmit up to 8 channels in total (i.e. 4 channels for each optical port).
Clarett 4Pre and 8Pre (+, USB, and Thunderbolt)
On Clarett 4Pre and 8Pre, you can change which digital input you are using to receive S/PDIF.
S/PDIF Source
RCA
RCA is the default setting. Use this when you need to send an S/PDIF signal to the Clarett using a coaxial (RCA) connection. See also: How do I use RCA S/PDIF inputs and outputs?
The optical ports will still send and receive ADAT signals (audio and clock).
Optical
You can set the S/PDIF Source to Optical to connect to consumer devices with optical S/PDIF outputs, such as a connection to a games console or TV.
In this mode, the optical ports will no longer send and receive ADAT signals (audio and clock).
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