Requirements:

• Ensure you have one or two ¼ inch jack to ¼ inch jack cable(s) available.
• Install the latest version of Focusrite Control 2:

Download Focusrite Control 2

In the example below, we are setting up a Scarlett 18i16 (4th Gen) with a VoIP app that only streams in mono and only accepts the first input of your audio device (Input 1). However, the same theory applies regardless of whether you are using a VoIP app that accepts two input channels (Inputs 1–2) or you are using a different model interface — in these cases, you might need to alter the routing described accordingly.

1. Backup your current routing and settings

To save your current routing and settings, open Focusrite Control 2 and click on:

Preset (bottom-left corner) → New Preset

2. Reset Scarlett to its default settings

Reset the Scarlett to its default settings. To do so, go to:

More options → Preferences → Device → Reset to default settings

Confirm the Reset when prompted:

Wait for the Scarlett to reset, then click Continue.

3. Select a Mix

Under the Mixer view, select a mix with no outputs assigned. In this example, we'll use Mix B:

4. Avoid feedback loops

Mute both Analogue 1 and Playback 1-2; this is to avoid a feedback loop and the VoIP audience hearing themselves.

5. Add your inputs

Add any other inputs you need into this Mix by turning up the corresponding faders. Use Input 2 and onward (since Input 1 is muted) for the Mic Inputs (XLR) or Line/Instrument Inputs (¼ inch jack). 

You can rename these for clarity by clicking in the text box above each fader:

6. Route your mix to a line output 

Under the Routing view, choose an output to use. In this example, split Line Outputs 3-4 into two mono outputs by toggling the Stereo option to use Line Output 3 as a mono output. You can then route your mix (Mix B) to Line Output 3 as mono by selecting:

Source → Mixes → Mix B → Mix B (Left)

The routing for Output 3 (or your chosen output if you are using a different one) should look like this:

7. Set up the hardware loop

Connect one end of a ¼ inch jack to ¼ inch jack cable to Line Output 3, and the other end to Line Input 1.

This lets you send all your audio sources in your custom mix (i.e. Mix B) over to Input 1, which can then be received by your VoIP application as the audio input source.

If you choose a different Line Output, ensure that you connect the cable to that output. In addition, if your VoIP application accepts two channels, rather than one, be sure to leave the outputs as a stereo pair at step 6, and use two ¼ inch jack to ¼ inch jack cables, with Inputs 1 and 2 as your returns.

8. Set up your Scarlett in the video call/streaming software

In your VoIP application, select your interface in the audio settings. The VoIP application might display the output device as 'Speaker' and the input device as 'Microphone'.

9. Adjust your mix levels

You can now use the software faders in the Focusrite Control 2 Mix B (under the Mix view) to mix the levels of all your input signals while you are live on the call or streaming session. For example, if your microphone or an instrument is much louder than another, you can turn down the corresponding software fader.

In addition, by selecting the Mix your headphones and/or speakers are routed to (e.g. Mix A), you can adjust the volume separately for what you are hearing, independently of what the VoIP audience is hearing (Mix B).

10. Adjust the input volume

You can now use the Input 1 gain dial to set the overall amount of your mix signal going into your VoIP application, ensuring the gain halo LED does not turn red to indicate the input clipping.

You can also activate Clip Safe (Safe button) to prevent clipping, and Auto Gain (Auto button) to adjust your input level automatically; see the Scarlett user guide for reference: Scarlett 4th Gen User Guides.

Requirements:

• Ensure you have one or two ¼ inch jack to ¼ inch jack cable(s) available.
• Install the latest version of Focusrite Control. You can find this on the Downloads page for your product: Focusrite Downloads.

In the example below, we are setting up a Scarlett 18i20 (3rd Gen) with a VoIP app that only streams in mono and only accepts the first input of your audio device (Input 1). However, the same theory applies regardless of whether you are using a VoIP app that accepts two input channels (Inputs 1-2) or you are using a different model interface – in these cases, you might need to alter the routing described accordingly.

1. Backup your current routing and settings

To save your current routing and settings, open Focusrite Control and click on:

File > Save Snapshot

2. Restore the default routing and settings

Reset the Scarlett to its default settings. To do so, go to:

File > Restore Factory Defaults

This will reset all mixer, routing, and monitor settings.

3. Select a line output

Under the Output Routing view, choose an output to use. In this example, we are splitting Line Outputs 3-4 into two mono outputs by toggling the 'Stereo' option, and using Line Output 3 as a mono output.

4. Set the output to Custom Mix

In the grey box for Line Output 3, select ‘Custom Mix’. This lets you choose which audio you wish to send to this output. In this case, the Custom Mix will be a mix of all your multiple inputs that will be sent over to the VoIP app. 

Note that Custom Mixes are disabled at 176.4 and 192 kHz: Focusrite Control: Mixer is disabled at this sample rate

5. Avoid feedback loops

With Line Output 3 selected, Mute both Analogue Input 1 and Playback 1-2; this is to avoid a feedback loop and the VoIP audience hearing themselves.
 

6. Add your inputs to the Custom Mix

Add any other inputs you need into this Custom Mix by clicking on the '+' button.

In the pop up menu that appears on the right hand side, add your inputs to the Custom Mix – use Input 2 and onward, since Input 1 is muted, for the Mic Inputs (XLR) or Line/Instrument Inputs (¼ inch jack). 

You can label these for clarity by clicking in the text box above each fader.

7. Set up the hardware loop

Connect one end of a ¼ inch jack to ¼ inch jack cable to Line Output 3, and the other end to Line Input 1:

This lets you send all your audio sources in your Custom Mix from Output 3 over to Input 1 – this can then be received by your VoIP application as the audio input source.

If you choose to use a different Line Output, be sure to connect the cable to that output. In addition, if your VoIP application accepts two channels, be sure to leave the outputs as a stereo pair at step 3, and use two ¼ inch jack to ¼ inch jack cables, using Inputs 1 and 2 as your returns.

8. Set up your audio interface in the video call/streaming software

In your VoIP application, select your interface in the audio settings. Note that VoIP application may display the output device as 'Speaker' and the input device as 'Microphone'.

9. Adjust your levels in the Custom Mix

You can now use the software faders in the Custom Mix for Line Output 3 to mix the levels of the inputs while you are live on the call.

For example, if your microphone or an instrument is much louder than another, you can turn down the corresponding software fader.

Additionally, by selecting the Output your headphones or speakers are connected to and assigning a Custom Mix to them in Focusrite Control, you can adjust the volume separately for what you are hearing (Custom Mix on Line Outputs 1-2/Headphone Output) – this is independent of what the VoIP audience is hearing (Custom Mix on Line Output 3).

10. Adjust the input volume

You can now use the Input 1 gain dial to set the overall amount of your Custom Mix signal going into your VoIP application, ensuring the gain halo or meter LED does not turn red to indicate the input clipping.