View source for Electric guitar interface setup

= Electric guitar interface setup =

This guide covers setting up an electric guitar with NixOS to achieve professional, low-latency audio processing. It targets live playing with round-trip latency under 6 ms using the modern PipeWire/JACK stack.

== Introduction ==

The digital signal chain for a guitar consists of:
# '''Instrument-level signal''' from Hi-Z pickups.
# '''Analog-to-Digital conversion''' via an external audio interface.
# '''Real-time processing''' on NixOS using a low-latency kernel and specialized software.

== Installation ==

=== System Configuration ===

Add the following to your `/etc/nixos/configuration.nix`. This configuration is optimized for high-performance CPUs like the '''AMD Ryzen 7 9700X'''.

<syntaxhighlight lang="nix">
{ pkgs, ... }:

{
  # 1. Sound Server: PipeWire with JACK/PulseAudio support
  services.pipewire = {
    enable = true;
    alsa.enable = true;
    alsa.support32Bit = true;
    pulse.enable = true;
    jack.enable = true;
    wireplumber.enable = true;
    
    # Global low-latency defaults
    extraConfig.pipewire."92-low-latency" = {
      "context.properties" = {
        "default.clock.rate" = 48000;
        "default.clock.quantum" = 128;      # ~5ms latency
        "default.clock.min-quantum" = 64;   # ~2.5ms latency
        "default.clock.max-quantum" = 512;
      };
    };
  };

  # 2. Real-time Scheduling and Privileges
  security.rtkit.enable = true;
  users.users.yourname.extraGroups = [ "audio" "realtime" ];

  # 3. Kernel and Performance Tweaks
  boot.kernelPackages = pkgs.linuxPackages_zen; 
  boot.kernelParams = [ 
    "preempt=full" 
    "threadirqs" 
    "usbcore.autosuspend=-1" 
    "processor.max_cstate=1" 
  ];

  powerManagement.cpuFreqGovernor = "performance";

  # 4. Essential Packages
  nixpkgs.config.allowUnfree = true; 
  environment.systemPackages = with pkgs; [
    qpwgraph
    pavucontrol
    ardour
    reaper
    carla
    guitarix
    gxplugins-lv2
    lsp-plugins
    calf
    dragonfly-reverb
    neural-amp-modeler-lv2
    proteus
    kapitonov-plugins-pack
    tuxguitar
    hydrogen
    cpupower
  ];
}
</syntaxhighlight>

=== Applying Changes ===

<syntaxhighlight lang="bash">
sudo nixos-rebuild switch
</syntaxhighlight>

== Hardware & Connection ==

=== Audio Interface ===

Standard PC line-ins are unsuitable for guitar. Use a dedicated interface with a '''Hi-Z (Instrument)''' input.

'''Verified compatible devices (2026):'''
* '''Focusrite Scarlett Solo (4th Gen):''' Plug-and-play, excellent Linux support.
* '''Arturia MiniFuse 1:''' Stable performance under PipeWire.

=== Verification ===

<syntaxhighlight lang="bash">
lsusb      # Confirm hardware connection
aplay -l   # Confirm ALSA sees the interface
</syntaxhighlight>

== Audio Server Setup ==

=== Pro Audio Profile ===

To achieve minimal latency, you must bypass standard software mixing:
# Open <nowiki>pavucontrol</nowiki>.
# Go to '''Configuration'''.
# Set your interface profile to '''Pro Audio'''.

=== Dynamic Buffer Control ===

You can change latency without rebuilding the system:

<syntaxhighlight lang="bash">
# Force a specific buffer size (quantum)
pw-metadata -n settings 0 clock.force-quantum 64

# Verify current status
pw-metadata -n settings 0
</syntaxhighlight>

== Software Hosts ==

{| class="wikitable"
! Type !! Examples !! Best Use Case
|-
| '''Standalone''' || Guitarix || Quick practice, simple pedalboard
|-
| '''Modular''' || Carla || Flexible routing, loading Windows VSTs
|-
| '''DAW''' || Ardour, Reaper || Professional recording, lowest latency via ALSA
|}

== Plugin Ecosystem (March 2026 Status) ==

=== Available in Nixpkgs ===

* '''Neural Amp Modeler (NAM):''' <nowiki>neural-amp-modeler-lv2</nowiki>. Current standard for high-fidelity amp captures.
* '''LSP Plugins:''' Includes <nowiki>LSP Latency Meter</nowiki>.
* '''Proteus:''' Excellent for RNN-based captures.

=== Unavailable / Alternatives ===

* '''Ratatouille / AIDA-X:''' Currently not in nixpkgs. Use '''NAM''' or '''Proteus'''.
* '''MOD Desktop:''' Use '''Carla''' for similar modular functionality.

== Measuring Latency ==

Never trust software reports. Always perform a physical loopback test:
# Connect a cable from your interface '''Output''' back into the '''Input'''.
# Open '''LSP Latency Meter'''.
# Measure the '''Round-trip Latency (RTL)'''.

{| class="wikitable"
! Latency !! Perception
|-
| < 5 ms || Professional / Imperceptible
|-
| 5-10 ms || Acceptable for practice
|-
| > 12 ms || Noticable "lag", difficult to play
|}

== Troubleshooting ==

* '''Xruns (Audio Glitches):''' Ensure <nowiki>powerManagement.cpuFreqGovernor = "performance"</nowiki> is active.
* '''No Sound:''' Check <nowiki>qpwgraph</nowiki>. PipeWire does not always auto-connect.
* '''NVIDIA Latency:''' Add <nowiki>nvidia.NVreg_EnablePowerManagement=0</nowiki> to <nowiki>boot.kernelParams</nowiki>.

== See Also ==
* [[PipeWire]]
* [https://github.com/musnix/musnix musnix] - Deep NixOS audio optimizations.

[[Category:Guides]]
[[Category:Hardware]]
[[Category:Sound]]