Applies to:
Scarlett 18i20 (all generations)
Scarlett 18i20 lets you record up to 18 channels on 1st, 2nd, and 3rd Gen units, and up to 26 channels on 4th Gen units. Aside from the 8 analogue inputs, Scarlett 18i20 features two types of digital connections that let you expand your channel count: S/PDIF and ADAT.
The S/PDIF connection can send 2 channels of digital audio into the 18i20 via the RCA (coaxial) connector on the back of the unit. Optical S/PDIF is available on 3rd and 4th Gen units.
See this artcile for reference: How do I use RCA S/PDIF inputs and outputs?
Many types of devices have S/PDIF outputs that you can connect to the 18i20 S/PDIF inputs, for example, 2-channel mic pres and analogue converters like the Focusrite ISA One with its digital card.
The optical ADAT connections on the back of the 18i20 can be used to transmit an additional 8 channels of digital audio per port.
ADAT is a one-way connection that can carry a maximum of 8 channels at 44.1/48 kHz per connection. The number of channels transferred between two devices over a single ADAT cable depends on the sample rate used; each time the sample rate doubles, the channel count per connection halves.
See this artcile for reference: How many channels can I send/receive using ADAT?
Examples of devices you could connect to the 18i20 over ADAT are:
- Scarlett OctoPre
- Clarett+ OctoPre
- Any other ADAT preamp/expansion unit
When connecting multiple digital devices, you must make sure they are synchronised and locked together. To do this with a Scarlett 18i20, you need to set the Sync Source in the control app for your interface (i.e. Focusrite Control 2 for 18i20 4th Gen, Focusrite Control for 18i20 3rd and 2nd Gen, Scarlett MixControl for 18i20 1st Gen) to be the digital input you are using, and make sure both devices are at the same sample rate.
See this artcile for reference: Connecting an external preamp to your interface via ADAT
Depending on the Scarlett 18i20 you have, see the channel listing tables below for reference:
Scarlett 18i20 1st and 2nd Gen
| DAW Input | Sample Rate (kHz) | |
| 44.1/48 | 88.2/96 | |
| 1 | Analogue 1 | Analogue 1 |
| 2 | Analogue 2 | Analogue 2 |
| 3 | Analogue 3 | Analogue 3 |
| 4 | Analogue 4 | Analogue 4 |
| 5 | Analogue 5 | Analogue 5 |
| 6 | Analogue 6 | Analogue 6 |
| 7 | Analogue 7 | Analogue 7 |
| 8 | Analogue 8 | Analogue 8 |
| 9 | S/PDIF L | S/PDIF L |
| 10 | S/PDIF R | S/PDIF R |
| 11 | ADAT 1 | ADAT 1 |
| 12 | ADAT 2 | ADAT 2 |
| 13 | ADAT 3 | ADAT 3 |
| 14 | ADAT 4 | ADAT 4 |
| 15 | ADAT 5 | |
| 16 | ADAT 6 | |
| 17 | ADAT 7 | |
| 18 | ADAT 8 | |
Scarlett 18i20 3rd Gen
| DAW Input | Sample Rate (kHz) | ||
| 44.1/48 | 88.2/96 | 176.4/192 | |
| 1 | Analogue 1 | Analogue 1 | Analogue 1 |
| 2 | Analogue 2 | Analogue 2 | Analogue 2 |
| 3 | Analogue 3 | Analogue 3 | Analogue 3 |
| 4 | Analogue 4 | Analogue 4 | Analogue 4 |
| 5 | Analogue 5 | Analogue 5 | Analogue 5 |
| 6 | Analogue 6 | Analogue 6 | Analogue 6 |
| 7 | Analogue 7 | Analogue 7 | Analogue 7 |
| 8 | Analogue 8 | Analogue 8 | Analogue 8 |
| 9 | Loopback L | Loopback L | S/PDIF L |
| 10 | Loopback R | Loopback R | S/PDIF R |
| 11 | S/PDIF L | S/PDIF L | |
| 12 | S/PDIF R | S/PDIF R | |
| 13 | ADAT 1 | ADAT 1 | |
| 14 | ADAT 2 | ADAT 2 | |
| 15 | ADAT 3 | ADAT 3 | |
| 16 | ADAT 4 | ADAT 4 | |
| 17 | ADAT 5 | ||
| 18 | ADAT 6 | ||
| 19 | ADAT 7 | ||
| 20 | ADAT 8 | ||
Scarlett 18i20 4th Gen (RCA or Optical S/PDIF Mode)
| DAW Input | Sample Rate (kHz) | ||
| 44.1/48 | 88.2/96 | 176.4/192 | |
| 1 | Analogue 1 | Analogue 1 | Analogue 1 |
| 2 | Analogue 2 | Analogue 2 | Analogue 2 |
| 3 | Analogue 3 | Analogue 3 | Analogue 3 |
| 4 | Analogue 4 | Analogue 4 | Analogue 4 |
| 5 | Analogue 5 | Analogue 5 | Analogue 5 |
| 6 | Analogue 6 | Analogue 6 | Analogue 6 |
| 7 | Analogue 7 | Analogue 7 | Analogue 7 |
| 8 | Analogue 8 | Analogue 8 | Analogue 8 |
| 9 | Loopback L | Loopback L | Loopback L |
| 10 | Loopback R | Loopback R | Loopback R |
| 11 | S/PDIF L | S/PDIF L | |
| 12 | S/PDIF R | S/PDIF R | |
| 13 | ADAT 1 | ADAT 1 | |
| 14 | ADAT 2 | ADAT 2 | |
| 15 | ADAT 3 | ADAT 3 | |
| 16 | ADAT 4 | ADAT 4 | |
| 17 | ADAT 5 | ||
| 18 | ADAT 6 | ||
| 19 | ADAT 7 | ||
| 20 | ADAT 8 | ||
Scarlett 18i20 4th Gen (Dual ADAT mode)
| DAW Input | Sample Rate (kHz) | ||
| 44.1/48 | 88.2/96 | 176.4/192 | |
| 1 | Analogue 1 | Analogue 1 | Analogue 1 |
| 2 | Analogue 2 | Analogue 2 | Analogue 2 |
| 3 | Analogue 3 | Analogue 3 | Analogue 3 |
| 4 | Analogue 4 | Analogue 4 | Analogue 4 |
| 5 | Analogue 5 | Analogue 5 | Analogue 5 |
| 6 | Analogue 6 | Analogue 6 | Analogue 6 |
| 7 | Analogue 7 | Analogue 7 | Analogue 7 |
| 8 | Analogue 8 | Analogue 8 | Analogue 8 |
| 9 | Loopback L | Loopback L | Loopback L |
| 10 | Loopback R | Loopback R | Loopback R |
| 11 | ADAT 1 | ADAT 1 | |
| 12 | ADAT 2 | ADAT 2 | |
| 13 | ADAT 3 | ADAT 3 | |
| 14 | ADAT 4 | ADAT 4 | |
| 15 | ADAT 5 | ADAT 5 | |
| 16 | ADAT 6 | ADAT 6 | |
| 17 | ADAT 7 | ADAT 7 | |
| 18 | ADAT 8 | ADAT 8 | |
| 19 | ADAT 9 | ||
| 20 | ADAT 10 | ||
| 21 | ADAT 11 | ||
| 22 | ADAT 12 | ||
| 23 | ADAT 13 | ||
| 24 | ADAT 14 | ||
| 25 | ADAT 15 | ||
| 26 | ADAT 16 | ||