Focusrite Scarlett 18i20 USB-C Audio/MIDI Interface (3rd Generation) - Manual (Page 26)

26
Channel Listing tables
The 18i20’s inputs and outputs will appear in Focusrite Control with slightly different channel
numbers depending on the sample rate being used. The channel numbers will also vary when the
optical ADAT ports are in use, depending on which Digital I/O Mode is selected (see Digital I/O Modes
below).
Digital I/O Modes
The Scarlett 18i20 supports three Digital I/O modes: these are selected from the Device Settings
pane of Focusrite Control. The modes determine how the audio inputs and outputs are mapped to
the optical (ADAT) ports and the S/PDIF input and output coaxial (RCA) sockets.
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.
Digital port
Sample rate (kHz)
44 .1/48 88 .2/96 176 .4/192
Inputs
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
Outputs
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 rate and you need to send
or receive an S/PDIF signal via an optical port. Also use this mode if you want to use a clock source
sent as an optical S/PDIF signal.
Digital port
Sample rate (kHz)
44 .1/48 88 .2/96 176 .4/192
Inputs
S/PDIF IN x x x
OPTICAL IN 1 ADAT 1-8 ADAT 1-4 x
OPTICAL IN 2 S/PDIF S/PDIF x
Outputs
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