Hardware Features

The preamp input gain controls how much signal you are sending into your computer and recording software.

It's essential to set a good level for the preamp input gain so you get the best quality recording. If the preamp input gain is too low, your signal will be too quiet and when you try to boost its level later you may hear noise in the recording; if the preamp input gain is too high you might 'clip' the input and hear harsh distortion in your recording.

To adjust the preamp input gain on your Scarlett 18i20 you first need to select the preamp you would like to adjust. Press the corresponding select button (1-8). The Input gain control now controls the preamp you selected.

To increase the input gain, turn the gain control clockwise. As you move the gain control, the Gain Halo gradually lights clockwise to show you the gain level. This diagram shows the gain at various levels:

Software Gain Control

You can also control the preamp gain remotely using Focusrite Control 2.

To adjust the preamp gain in Focusrite Control 2:

1. Click the virtual knob for the channel you'd like to adjust or use the tab key to select the preamp gain control.

2. Move your mouse up and down or use the arrow keys to increase or decrease the gain (in ±1dB increments).

The following images show the preamp gain at minimum, medium and maximum gain.

No input gain

50% Gain

100% Gain

Input Metering

The meters 1 -8 show the input level of each of your Scarlett 18i20's input channels.

As you increase the preamp input gain for a channel, or as the source gets louder the meters will show more level coming into your computer.

On the far right of the meters, there's a scale from -42dBFS to 0dBFS. When you're recording it's a good idea to have a signal level around -18dBFS with the loudest parts of the signal reaching -12dBFS.

Tip

If your signal clips the clip indicator at the top of the meter lights red. If this happens, select that channel and reduce the gain.

Many front panel controls on your Scarlett 18i20 are shared across the preamp inputs. The select buttons, labelled 1 to 8 move the preamp controls to different inputs.

At least one preamp is always selected, to change which preamp(s) the controls are affecting, press one of the buttons labelled 1 to 8. When you do this, the newly selected preamp's number lights green and the preamp setting lights change to match the new preamp.

When you turn on your Scarlett 18i20 the last selected preamp before you turned it off remains the selected preamp.

Linking Preamps

Linking preamps allows you to control two preamps simultaneously using one set of preamp controls. You can match gain controls for two preamps and enable other preamp controls. This is useful for stereo recording, for example, a microphone pair, stereo synthesiser, or keyboard.

Note

You can only link adjacent preamps with the left channel set as odd-numbered input channels, e.g. you can link input channels 1 and 2, or 3 and 4, but not 2 and 3.

To link preamps:

1. Press the select button (1-8) to choose one side of the pair.

2. Press the Link button to link the preamps.

When you've made the preamp Link:

• Both preamp numbers light green when you select that pair.

• The preamp gain level is set to the lowest value of the newly linked pair.

• The preamp settings are inherited from the currently selected preamp, e.g. preamp 1 is selected, therefore preamp 2 inherits, Air, Safe and Inst settings from Preamp 1.

• Changing any preamp setting changes the state of both preamps.

• Adjusting either gain control changes the gain level for both preamps and is shown on both Gain Halos.

• 48V is disabled for both preamps.

Unlinking Preamps

To unlink preamps

1. Press the select button (1-8) to choose one side of the pair.

2. Press the Link button to unlink the preamps.

Linking Preamps in Focusrite Control 2 - coming soon

Linking Preamps

To link preamps from Focusrite Control 2, click the link icon at the top of the channel strip .

When you link two preamps, the link icon turns green , one set of preamp controls disappears, and the meters for each channel merge to form a stereo meter.

Two unlinked channels.

Linked channels with merged preamp controls.

Unlinking Preamps

To unlink preamps from Focusrite Control 2 and control them independently again, click the green link icon at the top of the channel strip.

When you unlink two preamps, the link icon returns to black/white , two sets of preamp controls appear, and the meters split again for each separate channel.

When you unlink preamps:

• The first preamp of the previously linked pair becomes selected and lights green.

• Gain levels and preamp settings stay the same, but you can now change them independently.

48V, also commonly referred to as 'Phantom Power', sends 48 Volts from your interface's XLR connector to devices needing power to work. The most common use is sending power to condenser microphones, but you may also need 48V for inline mic preamps, active dynamic microphones and active DI boxes.

To turn on 48V:

The 48V icon lights green to show it is enabled.

48V phantom power is now being sent to the selected XLR input and to any devices connected to the XLR input.

48V (Phantom Power) Software Control

To enable 48V (Phantom Power) from Focusrite Control 2 click the +48V button for the input you want to enable it on. This is the same as pressing the 48V button on the Scarlett 18i20 hardware.

+48V Phantom Power off

+48V Phantom Power on

Inst, or instrument, changes the impedance and input level of the 6.35mm (1/4") jack inputs on your Scarlett so the inputs sound their best for either an instrument or line-level source. We list the input impedance values in the Specifications section. If you don't turn on Inst and connect an electric guitar, the resulting sound can be muddy and quiet compared to with Inst on.

The Inst (Instrument) button only affects the 6.35mm (1/4") line input for the selected channel, either input 1 or input 2. It changes it from an input suitable for line-level devices to an input better suited for instrument-level devices.

To enable, or disable, instrument mode for the 6.35mm (1/4") jack input, select the channel and press the Inst button once. Green shows Inst is enabled, and white shows Inst is disabled. When you enable Inst and connect a jack to your Scarlett, the minimum gain for the input is changed to +7dB.

When Inst is enabled (green) you can connect instrument-level devices to the 1/4" inputs such as, but not limited to:

When Inst is disabled (white) you can connect line-level devices to the 6.35mm (1/4") inputs such as, but not limited to:

Instrument/Line Software Control

To change inputs 1 or 2 between instrument and line from Focusrite Control 2 click the Inst button once.

Line	Instrument

Auto Gain allows you to send a signal into your Scarlett 18i20 (for example singing or playing your instrument) for 10 seconds and let the Scarlett set a good level for your preamps. If you find the levels aren't right, you can adjust the gain controls manually to fine-tune the levels before recording.

To use Auto Gain:

If the Auto Gain was successful, the Gain Halo lights green before the gain value is shown on the Gain Halo for a second. The gain is now set at a good level for your recording.

If Auto Gain fails, the Gain Halo lights red. Please see the section, The Gain Halo turned Red, for more information.

Auto Gain Software Control

To use Auto Gain in Focusrite Control 2:

1. Click the Auto Gain button in Focusrite Control 2.

2. Speak or sing into the microphone, or play your instrument during the Auto Gain countdown. Perform as you would while you're recording to make sure Auto Gain sets a good level.

   The Auto Gain process starts and the software Gain halo turns into a countdown timer.

If the Auto Gain was successful, the Gain Halo lights green before the gain value is shown on the Gain Halo for a second. The gain is now set at a good level for your recording.

Auto Gain failed and the gain halo turned red

If the input signal is unsuitable for Auto Gain (for example there's no signal detected), after ten seconds, Auto Gain stops and the Gain Halo lights red for a second. The gain returns to the value you set before starting Auto Gain.

Hardware Gain Halo

Focusrite Control 2 Auto Gain unsuccessful

Before running Auto Gain again, make sure your input has something connected to it correctly, if you're using a condenser microphone, 48V is on, and you are making sound while Auto Gain runs.

Auto Gain allows you to send a signal into your Scarlett 18i20 (for example singing or playing your instrument) for 10 seconds and let the Scarlett set a good level for your preamps. If you find the levels aren't right, you can adjust the gain controls manually to fine-tune the levels before recording.

You can use Auto Gain on as many channels as you like on your Scarlett 18i20.

Multichannel Auto Gain in Focusrite Control 2

You can also run multichannel Auto Gain from within Focusrite Control 2. To do this:

1. Open Focusrite Control 2 and go to the Inputs tab.

2. Click the dropdown arrow to the right of the usual Auto Gain button.

3. Choose Auto Gain all or Auto Gain multiple….

   • Auto Gain all starts running Auto Gain for all the channels on your Scarlett 18i20.

   • Auto Gain multiple allows you to choose the channels you want to run Auto Gain for.

4. If you clicked Auto Gain multiple, tick the channels you want to run Auto Gain for.

5. Click Start Auto Gain.

Once Auto Gain has finished, Focusrite Control 2 shows the channels that have been set and their new gain levels:

All Channels

Multiple Channels

Multichannel Auto Gain failed

Multichannel Auto Gain might fail during the process for one, multiple, or all channels. If this happens, you'll see one of two messages:

If Auto Gain fails for all channels, you'll see the Auto Gain failed message.

If Auto Gain fails for one or some channels, you'll see the Auto Gain complete message, but with the option to Retry Auto Gain on all channels.

You can either:

• Click Retry and all Auto Gain runs again for all the channels you ran Auto Gain for, even the successful channels.

• Click close and run Auto Gain for any failed channels.

• Click close and manually adjust the gain for any failed channels.

The Safe button applies Clip Safe, which automatically adjusts your preamp gain if you're at risk of clipping.

Clipping happens when your gain is set too high for the sound being recorded and your input overloads the preamp. A clipping symptom is preamp distortion, which is often unpleasant and can ruin a recording. Clip Safe helps you avoid this so if your input gets near to clipping, Clip Safe reduces the preamp gain, so you won't have to re-record your take.

To enable Clip Safe:

When you enable Safe, the Safe icon lights green.

When you have two inputs selected using Preamp Link, Safe is applied to both preamps.

Clip Safe Focusrite Control 2

To enable Clip Safe from Focusrite Control 2, click the Safe button:

Safe off

Safe on

Air lets you change your Scarlett's preamp sound with two different modes; Air Presence or Air Presence and Harmonic Drive.

Air affects the mic, line, and instrument inputs.

To enable Air, select your input, press the Air button once for Air Presence, again for Air Presence and Harmonic Drive and again to turn off. The Air LED changes colour to show which mode you have selected:

Air Software Control

To enable AIR from Focusrite Control 2 click the Air button. This is the same as pressing the Air button on the Scarlett 18i20 hardware.

Air Off

Air Presence selected

Air Presence and Drive selected

When you click Focusrite Control 2's Air button, the last selected Air mode becomes activated. To change the selected Air mode (Presence or Presence and Drive) click the arrow to show the dropdown menu.

Air Presence selected

Air Presence and Drive selected

The Scarlett 18i20's Alt (alternate) button gives you the ability to alternate between two sets of monitor speakers. This is useful for referencing your mixes on a different set of speakers.

To set up the speakers for speaker switching:

After setting up your monitors, you can switch between your main monitors (Outputs 1-2) and the Alt monitors (Outputs 3-4) either by pressing the front panel Alt button or by clicking on the Alt button in Focusrite Control 2.

When Alt is active, the Source set for Main and Alt is sent to the Alt outputs instead of the Main outputs, and Alt lights green.

The Dim button reduces the output level being sent to your outputs by 18dB. When active, Dim lights green.

Dim off (white)

Dim on (green)

The Dim button is useful to help allow conversation or to try ideas in the room without stopping playback.

By default, Dim affects the Main monitor outputs 1 and 2, but in Focusrite Control 2 you can change this to control your Alt outputs.

Dim Software Control

To enable/disable Dim in Focusrite Control 2 click the Dim button in the Outputs section on the right.

The Dim button works in the same way as the Dim button on the front panel of your Scarlett 18i20 and reduces the output level being sent to your outputs by 18dB. When active, Dim lights green.

Dim off.

Dim on.

The Output button changes the meters 1-8 from the inputs they are metering to pre-fade meters for the corresponding outputs. Pre-fade means the meters aren't affected by the monitor dial in the same way the L and R meters are affected by the Output dial.

When active, Output lights green.

For example, rather than the meters showing the levels of analogue inputs 1-8, when Output is active the meters show the levels for analogue outputs 1-8.

Output off (white), metering the inputs.

Output on (green) metering the outputs.

The Mute button silences the signal being sent to your outputs. When active, Mute lights green.

Mute off (white).

Mute on (green).

By default, Mute affects the Main monitor outputs 1 and 2, but in Focusrite Control 2 you can change this to control your Alt outputs.

Mute Software Control

To enable/disable Mute in Focusrite Control 2 click the Mute button in the Outputs section on the right.

The Mute button works in the same way as the Mute button on the front panel of your Scarlett 18i20. When active, Mute lights green.

Mute off.

Mute on.

The Output control and Output level meters are related to the signals going to the Outputs on the back of your Scarlett 18i20. The meters show the level going to your selected Monitor Outputs, either 1-2 or 3-4 when Alt is on.

The halo around the Monitor control on your Scarlett 18i20 lights white to show where the monitor control is set.

The output level meters L and R are pre-fade meters (they aren't affected by the Output control's position) showing you the signal level coming from your computer going to Outputs 1 and 2.

Focusrite Control 2 Output section

On the right-hand side of Focusrite Control 2 the Output section is a visual representation of the Output control and level meters.

Output control selection

At the top of the Outputs section, you can use the drop-down to change the outputs you're controlling.

Output control dial

The dial in Focusrite Control 2 is a software representation of the Output control on your Scarlett 18i20's front panel. When you change the control on the hardware, the software updates, when you move the control on the front panel, the dial in Focusrite Control 2 updates.

Speaker Switching (Alt) software control

The Output section allows you to control the Alt, or speaker switching, function. Click Main or Alt to switch between your Main or Alt monitors.

For more information, see Speaker Switching (Alt).

Output level meters

The output level meters mirror the front panel meters are pre-fade meters (they aren't affected by the Output control's position) showing you the signal level coming from your computer going to Outputs 1 and 2 (or 3 and 4 if you enable Alt).

Mute, Dim and Talk

See the Mute, Dim and Talk sections.

The Sync Status icon on the front panel lights green when your Scarlett 18i20 is 'locked' to or 'synchronised' with a clock source.

The Sync Status indicator is most useful when you're trying to expand the channel count using your Scarlett 18i20 with other equipment connected to your Scarlett 18i20's digital inputs or outputs; the ADAT or S/PDIF IO.

When you're using the digital inputs your Scarlett 18i20 and the other audio devices need to have their internal clocks synchronised, using clock signals, so their audio is recorded in time.

Depending on what type of digital device you're connecting to your Scarlett 18i20 (ADAT, coaxial S/PDIF, or optical S/PDIF) you need to make sure the digital IO mode is set correctly; for more information see Setting the digital IO modes - coming soon.

There are a few principles when you're trying to synchronise multiple digital audio devices:

Setup 1 - Scarlett 18i20 as a Clock Follower

This is the most basic setup and involves one expansion device, increasing the channel count of your Scarlett 18i20.

We've outlined the steps for an ADAT expansion device, but the same theory applies for S/PDIF expansion devices. Depending on which S/PDIF type you are using (coaxial or optical) you may need to change your Digital IO Mode settings in Focusrite Control 2, for more information see Setting the digital IO modes - coming soon.

Equipment:

• An external ADAT preamp - such as a Clarett+ OctoPre.

• One TOSLINK cable (also referred to as an ADAT cable).

Setup:

1. Connected the TOSLINK cable from the ADAT preamp's ADAT Out port to the ADAT In port on the Scarlett 18i20.

2. Set the ADAT preamp clock to Internal and your chosen sample rate.

3. In Focusrite Control 2, set the Scarlett 18i20 clock to ADAT and match the sample rate to the ADAT preamp.

4. In your DAW, set your channels to inputs 13 - 20, these are the eight ADAT inputs.

Note

The Scarlett 18i20 has two ADAT In ports. With ADAT, when you go up a sample rate band, e.g. from 44.1kHz to 88.2kHz, the number of channels the cable can send halves. This means with the Scarlett 18i20 you can use two cables to get eight channels at 88.2 and 96kHz.

To use two ADAT cables for eight channels at dual-band sample rates, set your ADAT mode to Dual in Focusrite Control 2's preferences; for more information, see Setting the digital IO modes - coming soon

Setup 2 - Scarlett 18i20 as a Clock Leader

This is similar to Setup 1; however, it involves more cables. It's useful if you only use your expansion device occasionally, so you'd prefer to keep your Scarlett 18i20 as your clock leader.

We've outlined the steps for an ADAT expansion device, but the same theory applies for S/PDIF expansion devices. Depending on which S/PDIF type you are using (coaxial or optical) you may need to change your Digital IO Mode settings in Focusrite Control 2, for more information see Setting the digital IO modes - coming soon.

Equipment:

• An external ADAT preamp - such as a Clarett+ OctoPre.

• Two TOSLINK cables (also referred to as an ADAT cable).

Setup:

1. Connected the TOSLINK cable from the ADAT preamp's ADAT Out port to the ADAT In port on the Scarlett 18i20.

2. Connect a second TOSLINK cable from the Scarlett 18i20's ADAT Out to the ADAT preamp's ADAT In.

   This cable is just to send clock data, but if your ADAT preamp has outputs, you can also send signals back out of your computer to gain extra analogue outputs.

3. Set the ADAT preamp clock to ADAT and your chosen sample rate.

4. In Focusrite Control 2, set the Scarlett 18i20 clock to Internal and march the sample rate to the ADAT preamp.

5. In your DAW, set your channels to inputs 13 - 20, these are the eight ADAT inputs.

Note

The Scarlett 18i20 has two ADAT In ports. With ADAT, when you go up a sample rate band, e.g. from 44.1kHz to 88.2kHz, the number of channels the cable can send halves. This means with the Scarlett 18i20 you can use two cables to get eight channels at 88.2 and 96kHz.

To use two ADAT cables for eight channels at dual-band sample rates, set your ADAT mode to Dual in Focusrite Control 2's preferences; for more information, see Setting the digital IO modes - coming soon

Setup 3 - Using more than one expansion device

In this setup, we’re using two expansion devices: an ADAT device and an S/PDIF device. For ADAT, you might use a preamp like an OctoPre or a mic preamp. For S/PDIF, you could connect another interface in standalone mode or a guitar amp modeller.

Using the Scarlett 18i20 as your clock leader is useful if you only use your expansion devices occasionally, so don't need to turn them on every time you use your Scarlett 18i20.

Equipment:

• An external ADAT preamp - such as a Clarett+ OctoPre.

• A S/PDIF device - such as a guitar amp.

• Two ADAT cables.

• Two S/PDIF cables.

Setup:

1. Connected the TOSLINK cable from the ADAT preamp's ADAT Out port to the ADAT In port on the Scarlett 18i20.

   Connect the S/PDIF cable from the S/PDIF device's S/PDIF Out to the S/PDIF In on the Scarlett 18i20.

2. Connect a second TOSLINK cable from the Scarlett 18i20's ADAT Out to the ADAT preamp's ADAT In.

   Connect a second S/PDIF cable from the Scarlett 18i20's S/PDIF Out to the S/PDIF device's S/PDIF In.

3. Set the S/PDIF preamp clock to S/PDIF and your chosen sample rate. Some S/PDIF devices don't allow you to change these settings, if this is the case, see ….

4. Set the Scarlett 18i20's clock to internal and match the sample rate.

5. Set the ADAT preamp to clock to ADAT and match the sample rate (it's getting its clock from the Scarlett 18i20 via the second ADAT cable).

Note

At dual-band sample rates (88.2kHz and 96kHz) it's only possible to get the following configurations using two devices:

• Two coaxial S/PDIF channels and four ADAT channels

• Two optical S/PDIF channels and four ADAT channels

• Eight ADAT channels

At all sample rates, it is not possible to use coaxial S/PDIF and both ADAT ports simultaneously. See the Scarlett 18i20 input channel order for more information on the possible input combinations.

Press and hold Talk button to activate talkback. When active, Talk lights green, and the talkback microphone is routed to the outputs of your choice. By default, talkback routes to the two headphone outputs.

When you enable Talk, the rest of the outputs in the mix dim, by 25dB, to make it easier to hear the talkback microphone.

You can change the Talkback routing in Focusrite Control 2 to feed any combination of mixes.

By default, the Talk button is ‘momentary’ – talkback is only active while you hold the button. You can change the Talkback button between momentary or latching from Focusrite Control 2.

Your Scarlett 18i20 has two headphones outputs. Both headphones outputs are completely independent of the other analogue outputs, so they can have their own dedicated mix.

The headphone outputs are 6.35mm (¼”) TRS jacks. Many headphones have a 3.5mm TRS jack, to connect them to your Scarlett 18i20 you must use a TRS 6.35mm to 3.5mm adaptor.

The controls above the headphone outputs control the level going to your headphones.

Around the headphone controls are halo meters. These fill up clockwise, from green to amber, to show the level going to your headphone outputs. The meters are pre-fade, meaning they are not affected by the headphone control setting.

The headphones output controls are encoders so you can control the level either from the dial, or in Focusrite Control 2.

The USB Type-C port labelled USB is to connect your Scarlett to your computer.

Use the included USB-C cable to connect to a USB-C port on your computer, or use the USB-C to A adaptor to connect to a USB-A port on your computer.

The S/PDIF ports give you two channels of digital I/O to connect to other audio equipment with S/PDIF I/O such as guitar amps, mic preamps or any device with an S/PDIF output.

There are many ways to connect and clock your Scarlett 18i20 when you're using an external device connected via S/PDIF. For information on clocking and digital IO setups, please see the Sync Status Indicator section.

The Sync Status Indicator on your Scarlett 18i20 should light green. When you send audio from the external device to your Scarlett 18i20 you should see the S/PDIF channels coming in on channels 11-12.

The Scarlett 18i20's Word Clock output is there so you can send clock signals to external devices connected via ADAT or S/PDIF. The main reason for using this output is if your external ADAT or S/PDIF devices don't have the relevant clocking options, but may have a Word Clock input.

The word clock output doesn't carry any audio, it sends only clock signals.

The Scarlett 18i20 only has a Word Clock output, so it cannot receive Word Clock. You must connect to the Word Clock input on any external device.

The Optical connections on the back of your Scarlett 18i20 allow you to connect external devices digitally to expand the channel count of your Scarlett 18i20.

The Scarlett 18i20 MIDI In and Out ports allow you to use your Scarlett as a USB MIDI interface. MIDI IN receives MIDI signals from keyboards or controllers; MIDI OUT sends MIDI information to Synths, Drum machines or MIDI-controllable equipment.

The MIDI IO doesn't require any setup for you to use your Scarlett 18i20 as a USB MIDI interface. The Scarlett 18i20's MIDI ports appear in your MIDI-enabled software, and you can either send or receive MIDI data between your computer and MIDI hardware via the Scarlett's 5-pin DIN MIDI ports.

Outputs 1 and 2 are line-level outputs to connect your Scarlett 18i20 to an amplifier or active monitors. The outputs are balanced 1/4" TRS jack outputs, you can use them with either unbalanced TS or balanced TRS jack cables and connect to speakers with 1/4" jack, RCA or XLR inputs.

Your Scarlett 18i20's front panel Output dial controls the level sent to Outputs 1 and 2.

Line Outputs 5-10 have identical electrical characteristics to the Monitor line Outputs 1 to 2 but aren't controlled by the Output control.

You can set the signals available at these outputs using Focusrite Control 2, and use the outputs to drive additional speakers in a multichannel monitoring system, such as a subwoofer or to send signals to outboard effects processors.

The 3-pin XLR Input connectors are designed to accept at microphone level signals.

You can control your microphone level using the corresponding input gain control on the front panel. 48V phantom power is also available if you are using a condenser mic, you can enable phantom power using the front panel 48V button.

You can enable 48V phantom power on a per-channel basis.