Applies to Scarlett 18i20 4th Gen.

This article is for Scarlett 18i20 4th Generation only. For Scarlett 18i16 4th Gen, see this article: Scarlett 18i16 4th Gen Standalone Mode setup. For Scarlett 16i16 4th Gen, see this article: Scarlett 16i16 4th Gen Standalone Mode setup. For all other Focusrite audio interfaces, refer to this article: Using Standalone Mode to increase your channel count.

What is Standalone Mode?

Some Focusrite interfaces can operate in Standalone Mode, which allows them to pass audio signals even when they’re not connected to a computer.

Why is Standalone Mode useful?

The most common use for Standalone Mode is to expand your recording setup by adding more input — and sometimes output — channels.

• One interface (the Host) is connected to your computer.
• The other interface (the Expansion) is set to Standalone Mode and connected to the Host via a digital format like ADAT (Optical) or S/PDIF (RCA).

This allows the expansion unit to function like a Focusrite OctoPre or other external mic preamp, seamlessly integrating into your system.

Other uses for Standalone Mode

You can also use Standalone Mode for tasks beyond recording expansion:

• Pre Amplifier — Convert a microphone or instrument input to a line-level signal for use with other analogue gear.
• Direct Monitoring — Hear a mic, guitar, keyboard, or synth through your speakers or headphones without a computer.
• Digital Playback — Listen to audio from a device connected via ADAT or S/PDIF, such as a TV or games console (Connecting TVs, Consoles, or other device to your interface).

How to set up Standalone Mode

To configure your interface for Standalone Mode, you need to walk through these top level steps. We'll break each one of these down in this article:

• Connect it to a Mac or Windows computer with the relevant control software installed.
• Adjust routing and clocking settings as needed.
• Once configured, these settings are saved directly to the interface’s internal memory.

Note: The setup will vary depending on how you intend to use Standalone Mode.

The rest of this article will guide you through the most common setup — using your Focusrite interface as an expansion preamp.

Step 1: Install Focusrite Control 2

If you haven't already done so, download and install Focusrite Control 2. This setup requires the computer software, not the phone and tablet remote control application.

Make sure Focusrite Control 2 is up-to-date so you can access the features you'll need for this setup:

More options → Check for updates

Once Focusrite Control is installed and up to date, accept any firmware updates for your 18i20 4th Gen.

We also recommend that you restore the default settings of your 18i20, unless there are specific settings you want to preserve:

More options → Preferences → Device settings → Reset to default settings

Step 2: Connect your Focusrite device and open Focusrite Control 2

Physically connect your interface to your computer:

• Use the USB cable that came with your Focusrite interface.
• Plug one end into the interface’s USB port.
• Plug the other end into an available USB port on your computer.
• Make sure your interface is powered on.

Launch Focusrite Control 2:

• Open the Focusrite Control 2 application from your Start Menu (Windows) or Applications folder (macOS).
• The software should detect your connected interface. If it doesn’t after 30 seconds or so, see this guide: Why isn't Focusrite Control 2 detecting my unit?

Step 3: Routing

In the Focusrite Control window, navigate to the Routing tab.

Scroll down until you see the Digital outputs section.

Adjust the source for the digital outputs to suit your setup. In most cases, you’ll want to route the analogue Inputs to the ADAT outputs.

In Focusrite Control 2, the outputs are on the left, and you can select the Source for each on the right. For this standard standalone expansion preamp setup, you should route inputs Analogue 1–8 to outputs ADAT 1–8.

As for the analogue outputs, by default, Output 1 - 2 and 3 - 4 are assigned to the Main and Alt monitor groups respectively. For more information, see How to use Monitor Groups in Focusrite Control 2.

If you don’t want the front panel Output encoder to control any output levels, click the Edit button next to the Main monitor group.

Now, deselect the outputs assigned both monitor groups. By default, this will be Output 1 - 2. Repeat the same process for the Alt monitor group.

Once you've done this, the Routing tab should display No outputs assigned under both monitor groups.

Next, you can route the ADAT inputs to the Analogue outputs. If you're following our standard standalone expansion preamp setup, set the Sources for Analogue outputs 1–8 to ADAT 1–8, as shown below. If you're using the interface as a standalone mic pre instead, you may want to route inputs Analogue 1–8 to their respective Analogue outputs.

If you've configured the Routing as described above, inputs ADAT 1–8 will be assigned to eight of the ten Analogue outputs.

You can choose what to assign to the two remaining Analogue outputs — and the two Headphone outputs — either by creating mixes in the Mixer tab or by assigning sources directly in the Routing tab.

To learn more about using the Mixer and Routing tabs, take a look at these links: Using the Focusrite Control 2 Mixer tab and Using the Focusrite Control 2 Routing tab.

Step 4: Sample rate & clocking

When using the device in Standalone Mode, especially when using ADAT or S/PDIF, it's essential to set the sample rate and clock source correctly. To do this, go to:

More options → Preferences → Sample rate & clocking.

The correct setting depends on your intended use. The sample rate will need to match between any connected digital devices and software, but bear in mind that some features are limited at higher sample rates: Scarlett 4th Gen missing features at high sample rates.

We're aware of an issue where Scarlett 18i20 4th Gen doesn't clock correctly over ADAT when set to 44.1 kHz or 88.2 kHz. Whilst we're looking for a fix, the current workaround is to use different sample rates (e.g. 48 kHz or 96 kHz) when clocking over ADAT, or to clock over S/PDIF if you need to work at 44.1 kHz or 88.2 kHz.

As for clock sources, here’s an overview of when you might use each clock source in Standalone Mode.

• Internal — Use this when the 18i20 doesn't have any digital connections, or if you want the 18i20 to be the clock leader, providing its internal clock for other connected digital gear to sync to.
• S/PDIF — Choose this if you're receiving clock via the S/PDIF inputs, RCA or optical, depending on the Digital clock mode. The S/PDIF signal must match the 18i20's sample rate.
• ADAT — Select this to follow clock signals received by the ADAT inputs. On 18i20 4th Gen, you can choose either ADAT Port 1 or Port 2, depending on the Digital clock mode. The ADAT signal must match the 18i20's sample rate.

Note: Word Clock is not available as a clock source because the 18i20 4th Gen only has a word clock output.

For more information about sample rates, see this article: Sample Rate, Bit Depth & Buffer Size Explained and if you'd like to know more about selecting clock sources, check out this article: Understanding Clocking.

Clocking may also depend on your selected Digital port mode:

• RCA S/PDIF — Uses Optical Port 1 for ADAT and the RCA (coaxial) port for S/PDIF.
• Optical S/PDIF — Uses Optical Port 1 for ADAT and Optical Port 2 for S/PDIF.
• Dual ADAT — Uses both Optical Ports for ADAT.

To learn more about selecting Digital port modes, see this article: Digital I/O Modes.

Once configuration is complete, you can close Focusrite Control 2 and disconnect the device. Your interface will now operate based on the saved routing, even without a computer connection.

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