Playing Guitar on Linux (approved by the CEO of PipeWire)

My bootlegged guitar amplifier sounds very bad and it makes my counterfeit Squier guitar sounds even worse. I don’t want to build a crazy effect board if I’m limited to this one amplifier. Instead of getting a good amplifier, I decided to get a USB audio interface and let my computer processes the effects!

There is a good piece of software for this purpose, Guitarix, which is a virtual guitar amplifier.

In short

Guitarix runs on JACK but I’m a PipeWire fan. Thank God PipeWire is pretty good now, so I can copy random commands I found on the Internet while logged in as root:

pacman -S pipewire pipewire-pulse pipewire-jack guitarix helvum

Now, Helvum is a patchbay for PipeWire. You can do more with it such as managing connections between audio sources and outputs. However, I use this simply to connect the audio interface to Guitarix and finally to the speaker. You can also use other patchbays but I will stick to Helvum for a while since it has a cool name.

Those are the bare minimum since I use PipeWire. However, I need to address my personal problems and the thing about delay.

Artix Linux

Sadly, I fell for the Artix Linux meme. There is no guitarix and helvum packages in the official repo. There are the git version of both in the AUR. I can compile Helvum without any problem. However, in order to compile Guitarix, I need zita-convolver which doesn’t exist in both Artix repo and the AUR!

I probably can get that library from somewhere else, but I want to minimize frustration. The simplest way to solve this is just to add Arch repo to the system.¹

pacman -S artix-archlinux-support

Append the following to /etc/pacman.conf:

[extra]
Include = /etc/pacman.d/mirrorlist-arch

And then:

pacman-key --populate archlinux
pacman -Sy

Now I can get Guitarix, either from the Arch repo or from the AUR (which will pull the previously mentioned dependency from the Arch repo anyway).

Latency

It’s possible to set a custom buffer size:

PIPEWIRE_LATENCY="128/48000" guitarix

However, thanks to this blog², I learned that it’s possible to make this persistent either system-wide or local. For local changes only:

cp /usr/share/pipewire/jack.conf ~/.config/pipewire/jack.conf

Uncomment node.latency under jack.properties and set its value to 128/48000. This will apply to all jack clients. You can create specific rules for certain clients under jack.rules, but I don’t need it.

Ulimit

You’ll get a warning system init *** mlockall failed in Guitarix. To solve this, we need to set our resource limits.

Create the file /etc/security/limits.d/audio.conf with the content:

@audio  -   rtprio      95
@audio  -   memlock     unlimited

This is probably a boring Linux stuff, but you can read the manual for limits.conf if you’re interested. Basically, @audio indicates a group name while the last column is the limit value.

So, we need to actually add our user to the audio group:

sudo usermod -a -G audio $USER

DAW

It’s possible to use Guitarix as a DAW plugin. I encountered this cool blog³ that mentions this. However, since my use case is still simple, I’ll be using Gutarix as a standalone program.

Physical Audio Output

a.k.a. speakers

I don’t actually have a real computer speaker, so I use my bootlegged guitar amplifier as an audio output for my computer.

The USB audio interface and the bootleg amplifier

It feels like I get a new amplifier without actually buying one!