This document describes how to use the ALSA Scarlett2 Control Panel with the Scarlett 4th Gen interfaces:
- Scarlett 4th Gen Solo, 2i2, and 4i4
If you are familiar with the Scarlett 2nd and 3rd Gen interfaces or the Clarett interfaces, the major differences to the 4th Gen interfaces from the point of view of this software are:
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The 4th Gen Solo and 2i2 interfaces have the full routing and mixing capabilities of the larger 2nd and 3rd Gen and Clarett interfaces (although the line outputs and the headphone outputs are still linked).
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The 4th Gen 2i2 and 4i4 interfaces have software-controllable (“remote”) input gain controls.
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The 4th Gen interfaces don’t have the output volume and mute controls that the 2nd and 3rd Gen and Clarett interfaces have.
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The Air mode with Presence+Drive is implemented with a DSP which is separately routable.
The main window is divided into three sections:
- Global Controls
- Analogue Input Controls
- Analogue Output Controls
The main window for the Solo and 2i2 interfaces is shown below; the 4i4 interface is similar to the 2i2, but doesn’t have the Direct Monitor control, and can show the position of the front panel volume knobs.
Sync Status indicates if the interface is locked to a valid digital clock. This should only ever briefly show “Unlocked” when the sample rate is changed as these interfaces can only use their internal clock.
The 4i4 has a “Power” control that displays the power status. It can be “Fail”, “Bus”, or “External”. “Fail” means that the interface is not receiving sufficient power; please see the Scarlett 4i4 4th Gen User Guide for more information. “Bus” vs. “External” indicates whether the interface is receiving power from the second USB-C port (“External”) or not (“Bus”).
Sample Rate is informative only, and displays the current sample rate if the interface is currently in use. In ALSA, the sample rate is set by the application using the interface, which is usually a sound server such as PulseAudio, JACK, or PipeWire.
The analogue input controls available depend on the interface model:
- Instrument, Air, and Phantom Power: All models
- Mix: Solo only (described later in the Solo Mix Control section)
- Input Select, Link, Gain, Autogain, and Safe: 2i2 and 4i4
The Inst button(s) are used to select between Mic/Line and Instrument level/impedance. When plugging in microphones or line-level equipment (such as a synthesizer, external preamp, or effects processor) to the input, set it to “Line”. The “Inst” setting is for instruments with pickups such as guitars.
The Scarlett 3rd Gen introduced Air mode which transformed your recordings and inspired you while making music by boosting the signal’s high-end. The 4th Gen interfaces now call that “Air Presence” and add a new mode “Air Presence+Drive” which boosts mid-range harmonics in your sound.
Turning the “48V” switch on sends “Phantom Power” to the XLR microphone input. This is required for some microphones (such as condensor microphones), and damaging to some microphones (particularly vintage ribbon microphones).
The 2i2 has a single 48V switch that controls both channels, and the 4i4 has an independent 48V switch for each channel.
The 2i2 and 4i4 interfaces have hardware buttons for 48V, Inst, Air, Auto, and Safe. The “Input Select” control allows you to choose which channel those buttons control.
The “Link” control links the 48V, Inst, Air, Auto, and Safe controls together so that they control both channels simultaneously.
The “Gain” controls adjust the input gain for the selected channel. Click and drag up/down on the control to adjust the gain, use your mouse scroll wheel, or click the control to select it and use the arrow keys, Page Up, Page Down, Home, and End keys.
When the “Autogain” control is enabled, the interface will listen to the input signal for ten seconds and automatically adjust the gain to get the best signal level. When autogain is not running, the most-recent autogain exit status is shown below the “Autogain” control.
“Safe” mode is a feature that automatically reduces the gain if the signal is too loud. This can be useful to prevent clipping.
The analogue output controls available depend on the interface model:
- Direct Monitor: Solo and 2i2
- Volume Knobs: 4i4
Enabling Direct Monitor sends the analogue input signals to the analogue outputs (speakers/headphones) for zero-latency monitoring.
On the 2i2, you have the choice of Mono or Stereo monitoring when you click the button:
- Mono sends both inputs to the left and right outputs
- Stereo sends input 1 to the left, and input 2 to the right output.
As the 4th Gen Solo and 2i2 interfaces have the full routing and mixing capabilities of the larger 2nd and 3rd Gen interfaces, the Direct Monitor levels can be adjusted in the mixer.
The 4i4 has no Direct Monitor button, but that functionality can be achieved with appropriate configuration in the routing and mixing windows.
The 4i4 interface has volume knobs on the front panel, the position of which is shown in the main window.
The routing and mixing capabilities of the 4th Gen interfaces are the same in concept as the 2nd and 3rd Gen interfaces, but there is a DSP which is separately routable, and the default routing uses the mixer extensively.
From the main window, open the Routing window with the View → Routing menu option or pressing Ctrl-R:
To understand the signal flow, note the following:
- The Analogue 1 & 2 Inputs (i.e. the Mic/Line/Inst inputs) are routed to the DSP Inputs.
- The DSP Outputs are routed to the PCM 1 & 2 Inputs (that’s what ALSA sees as the first two inputs from the interface for recording).
- The PCM Outputs (that’s what ALSA sees as the interface outputs for playback) and the DSP Outputs are all connected to the Mixer Inputs.
- The Mixer A & B Outputs are connected to the Hardware Analogue outputs (i.e. your speakers/headphones) so you can hear any mix of the PCM and DSP Outputs (this is how the Direct Monitor function works).
- The Mixer C & D Outputs are connected to the PCM 3 & 4 Inputs (this is referred to as Loopback, for recording audio from your computer, but can be used for another purpose if you want).
Important Notes:
- The “Presets” are generally not useful with the 4th Gen interfaces as they are designed for the 2nd and 3rd Gen interfaces. If you try these out, you’ll probably want to reset back to the factory defaults afterwards.
- Besides Air Mode, the DSP is also used for the gain halo level meters and autogain, so if you route something else to the DSP Inputs, those features will work “rather differently”.
- The Focusrite Control 2 software can’t control most of this routing,
so if you make changes here and then want to use Focusrite Control
2, you’ll probably need to reset the routing back to the factory
default settings. There’s currently no way to reset to factory
default settings from the Focusrite Control 2 software; you’ll need
to use the Reset Configuration option
in this software, or the
scarlett2utility.
To adjust the routing:
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Click and drag from a source to a sink or a sink to a source to connect them. Audio from the source will then be sent to that sink.
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Click on a source or a sink to clear the links connected to that source/sink.
Note that a sink can only be connected to one source, but one source can be connected to many sinks.
To adjust the mixer output levels:
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Open the mixer window with the main window View → Mixer menu option, or press Ctrl-M.
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Mixer levels can be adjusted with your keyboard or mouse in the same way as the Gain Controls.
When you enable or disable Direct Monitor on the Solo interface, the interface will update the Mix A and B Outputs so that the DSP 1 & 2 Outputs are mixed in (or not) with the PCM 1 & 2 Outputs. Note how the volume of the PCM outputs is also reduced when Direct Monitor is enabled so that you can hear the DSP outputs (i.e. your Analogue inputs) more clearly.
If you customise the Mix A/B mixer levels while Direct Monitor is enabled, the new settings will be saved and used when Direct Monitor is enabled again.
Similarly to the Solo interface, the 2i2 interface will update the Mix A and B Outputs when you enable or disable Direct Monitor, but the 2i2 has Mono and Stereo options:
Note how in Mono mode:
- the DSP 1 & 2 Outputs are mixed to both the left and right outputs
and in Stereo mode:
- DSP 1 (i.e. Analogue Input 1) is sent to the left output (Mix A), and
- DSP 2 (i.e. Analogue Input 2) is sent to the right output (Mix B).
The Mix control is only available on the Solo interface. It switches the source for the PCM 1 & 2 Inputs between the DSP Outputs and the Mixer E & F Outputs.
By default, enabling this control will mix the Analogue 1 & 2 Inputs together before they are sent to the PCM 1 & 2 Inputs:
This can be useful if you want to treat the PCM 1 & 2 Inputs as a stereo pair, and not have the line/instrument input panned hard left and the microphone input panned hard right.
The mixer levels for the Mix E & F Outputs can adjusted to suit.
Although the 4th Gen 4i4 has no explicit Direct Monitor control, it is far more flexible because it has 6 PCM inputs, 6 PCM outputs, a 10×6 mixer, and 6 Analogue Hardware outputs.
Analogue Outputs 1–4 correspond to the Line Outputs 1–4 on the back of the interface, and Analogue Outputs 5–6 correspond to the Headphone Output on the front of the interface.
The default routing and mix for the 4i4 is shown below:
Note that with the default routing/mix settings:
- The Analogue Inputs 1–4 are routed to the PCM Inputs 1–4 (the first two going via the DSP).
- PCM Inputs 5–6 are used for Loopback (recording audio from your computer).
- All the Hardware Inputs and PCM Outputs are connected to the Mixer Inputs.
- PCM Outputs 1–4 are connected to the Analogue Outputs 1–4 (via the mixer).
- The Line 1–2 Outputs (Analogue Outputs 1–2) and the Headphones (Analogue Outputs 5–6) share the Mixer Outputs A & B.
A common configuration for the 4i4 is to send the PCM 1 & 2 Outputs mixed with the Analogue Inputs 1 & 2 to the Headphones, while leaving the Analogue Outputs 1–2 as they are. This is an advanced version of the direct monitoring feature that is available on the Solo and 2i2. It can be implemented by:
- Route Mixer Outputs E & F to Analogue Outputs 5 & 6.
- Turn up Mix E & F DSP 1 & 2 levels in the mixer (see the mixer example above for 2i2 Direct Monitor).
As there are only 6 Mixer Outputs, the PCM 5 & 6 Inputs (Loopback) are now shared with the headphones. If you want to retain the Loopback functionality without having the Analogue Inputs mixed in, you could:
- Route the PCM 1 & 2 Outputs directly to the PCM 5 & 6 Inputs, rather than going via the mixer, or
- Free up Mixer Outputs A & B for Loopback by routing PCM Outputs 1 & 2 directly to Analogue Outputs 1 & 2.
Besides Direct Monitor, there are many other possibilities for routing/mixing with the 4i4. For example, by using the additional PCM Outputs and Inputs you could set up a mix-minus configuration for a podcast/video call.
The meters show the levels seen by the interface at every routing sink: Hardware Outputs, Mixer Inputs, DSP Inputs, and PCM Inputs. Open this window by selecting the View → Levels menu option or pressing Ctrl-L.
Look at this in conjunction with the routing window to understand which meter corresponds to which source or sink.
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