211 lines
6.8 KiB
Markdown
211 lines
6.8 KiB
Markdown
# ALSA Scarlett Control Panel
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## Scarlett Big 4th Gen Interfaces
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This document describes how to use the ALSA Scarlett Control Panel
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with the big Scarlett 4th Gen interfaces:
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- Scarlett 4th Gen 16i16, 18i16, 18i20
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### FCP Driver
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The big 4th Gen interfaces are supported by a new “FCP” (Focusrite
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Control Protocol) driver introduced in Linux 6.14. If you haven’t
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installed
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[fcp-support](https://github.com/geoffreybennett/fcp-support) yet, you
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need to do that (and update the firmware) before you can use
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alsa-scarlett-gui.
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## Main Window
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The main window is divided into three sections:
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- Global Controls
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- Analogue Input Controls
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- Analogue Output Controls
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The main window for the 16i16 interface is shown below. The 18i16 and
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18i20 interfaces are similar, but with more controls.
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### Global Controls
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#### Clock Source (interfaces with S/PDIF or ADAT inputs only)
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Clock Source selects where the interface receives its digital clock
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from. If you aren’t using S/PDIF or ADAT inputs, set this to Internal.
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#### Sync Status
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Sync Status indicates if the interface is locked to a valid digital
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clock. If you aren’t using S/PDIF or ADAT inputs and the Sync Status
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is Unlocked, change the Clock Source to Internal.
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#### Sample Rate
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Sample Rate is informative only, and displays the current sample rate
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if the interface is currently in use. In ALSA, the sample rate is set
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by the application using the interface, which is usually a sound
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server such as PulseAudio, JACK, or PipeWire.
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#### Speaker Switching
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Speaker Switching lets you swap between two pairs of monitoring
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speakers very easily.
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### Analogue Input Controls
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#### Input Select
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The “Input Select” control allows you to choose which channel the
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hardware 48V, Inst, Air, Auto, and Safe buttons control.
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#### Link
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The “Link” control links the 48V, Inst, Air, Auto, and Safe controls
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together so that they control a stereo pair of channels
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simultaneously.
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#### Gain
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The “Gain” controls adjust the input gain for the selected channel.
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Click and drag up/down on the control to adjust the gain, use your
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mouse scroll wheel, or click the control to select it and use the
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arrow keys, Page Up, Page Down, Home, and End keys.
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#### Autogain
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When the “Autogain” control is enabled, the interface will listen to
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the input signal for ten seconds and automatically adjust the gain to
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get the best signal level. When autogain is not running, the
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most-recent autogain exit status is shown below the “Autogain”
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control.
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#### Safe
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“Safe” mode is a feature that automatically reduces the gain if the
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signal is too loud. This can be useful to prevent clipping.
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#### Instrument
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The Inst button(s) are used to select between Mic/Line and Instrument
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level/impedance. When plugging in microphones or line-level equipment
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(such as a synthesizer, external preamp, or effects processor) to the
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input, set it to “Line”. The “Inst” setting is for instruments with
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pickups such as guitars.
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#### Air
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The Scarlett 3rd Gen introduced Air mode which transformed your
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recordings and inspired you while making music by boosting the
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signal’s high-end. The 4th Gen interfaces now call that “Air Presence”
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and add a new mode “Air Presence+Drive” which boosts mid-range
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harmonics in your sound.
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#### Phantom Power (48V)
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Turning the “48V” switch on sends “Phantom Power” to the XLR
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microphone input. This is required for some microphones (such as
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condensor microphones), and damaging to some microphones (particularly
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vintage ribbon microphones).
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### Analogue Output Controls
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The analogue output controls are a bit sparse. More controls are
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coming soon.
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#### Volume Knobs
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The volume knobs control the volume of the analogue outputs. The two
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channels of the stereo pairs are shown separately, but are internally
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linked together.
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#### Mute and Dim
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The speaker icon buttons are “mute” and “dim” (reduce volume) buttons,
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corresponding to the front-panel buttons on the interface (although
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only the 18i20 has a physical dim button).
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## Routing and Mixing
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The routing window allows (almost) complete control of signal routing
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between the hardware inputs/outputs, internal mixer, and PCM (USB)
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inputs/outputs.
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The routing and mixing capabilities of the big 4th Gen interfaces are
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the same in concept as the older interfaces, but the mixer inputs are
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fixed and not shown in the routing window as there are too many to
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sensibly display.
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From the main window, open the Routing window with the View → Routing
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menu option or pressing Ctrl-R:
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To manage the routing connections:
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- Click and drag from a source to a sink or a sink to a source to
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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
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source/sink.
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Note that a sink can only be connected to one source, but one source
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can be connected to many sinks. If you want a sink to receive input
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from more than one source, connect the sinks to mixer outputs:
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- Connect mixer outputs to the sinks that you want to receive the
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mixed audio
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- Use the Mixer window to set the amount of each mixer input that is
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sent to each mixer output
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The Presets menu can be used to clear all connections, or to set up
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common configurations:
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- The “Direct” preset sets up the usual configuration using the
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interface as a regular audio interface by connecting:
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- all Hardware Inputs to PCM Inputs
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- all PCM Outputs to Hardware Outputs
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- The “Preamp” preset connects all Hardware Inputs to Hardware
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Outputs.
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- The “Stereo Out” preset connects PCM 1 and 2 Outputs to pairs of
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Hardware Outputs.
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To adjust the routing:
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- Click and drag from a source to a sink or a sink to a source to
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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
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source/sink.
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Note that a sink can only be connected to one source, but one source
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can be connected to many sinks.
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To adjust the mixer output levels:
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1) Open the mixer window with the main window View → Mixer menu
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option, or press Ctrl-M.
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2) Mixer levels can be adjusted with your keyboard or mouse in the
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same way as the [Gain Controls](#gain).
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## Levels
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The meters show the levels seen by the interface at every routing
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source as well as the analogue outputs. Open this window by selecting
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the View → Levels menu option or pressing Ctrl-L.
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Look at this in conjunction with the routing window to understand
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which meter corresponds to which source or sink.
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Thanks for reading this far! If you appreciate the hundreds of hours
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of work that went into the kernel driver, the control panel, and this
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documentation, please consider supporting the author with a
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[donation](../README.md#donations).
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