# Using Linux as a Guitar Amp
by Seth Kenlon
Back in the old days, if you wanted to record music at home (or,
classically, in your garage), you bought some instrument capable of
making noise, such as a synthesizer or electric guitar, an amp to
actually produce the sound, some effect pedals to customize the sound,
and a multitrack recorder such as a 4-track or 8-track recorder. You
would plug the guitar into the effects pedals, the pedals into the
amp, and the amp into the recorder (or you might mic the amp and
record that). That was the classic setup, and it endures today because
it's powerful, raw, flexible, and all round beautiful. Modern
technology, however, has provided musicians with more options, like
using Linux as the entire tool chain after the initial purchase of a
guitar.
## Choosing a guitar
If you're an experienced guitar player, you'll know exactly what
guitar you want and you'll have some level of standards. If you're a
beginner, you may have more flexibility, because to you, any guitar is
better than no guitar. Purchasing an electric guitar is easier than it
might seem. Nearly every thrift store or pawn shop I've ever been in
has had at least one electric guitar sitting in a corner. For under
$100, you should be able to get a guitar that's good enough to start
practicing on.
Contrary to what you might think, an electric guitar isn't actually
electric, itself. It's an analogue sound generator, just like a
traditional guitar. The difference between an electric and a classical
guitar is that the latter amplifies the sound with its hollow wooden
body, while the former requires electricity for amplification. That means you need cables to wire your guitar to something electrical, like an amp.
Electric guitars accept ¼-inch audio jacks. Your computer, however,
probably accepts ⅛-inch audio jacks. This is pretty common, so cables
with a ¼-inch jack on one end and ⅛-inch jack on the other are easy to
find. You might have to go to a guitar or music store for them, since
the larger ¼-inch jack is not widely used outside of pro audio. If
you're adventurous, you can even fashion your own for just a few
dollars and just a little soldering.
Since your guitar is a single source of sound, you only need a mono
audio cable.
The good news is that since you're using Linux as your amp and effects
rack, that's all the money you need to spend!
## Applications
Part of the beauty of music engineering is the flexibility in its
setup, but this is a simple schema that will get you up and running.
1. Start JACK with QJackCtl or from a terminal, depending on your preferred interface.
2. Start a virtual effects rack, such as Rakarrack, Guitarix, or whatever you prefer. Since Rakarrack has a fun collection of presets, that's the one I recommend to start with.
Everything's live now, so now hook it all together.
## Cabling
1. Turn the volume down on your physical guitar and plug your guitar into the **Line In** of your computer.
2. Turn the volume up. You won't hear anything yet, but this prevents you from banging on your guitar, wondering why you're not getting a signal, later.
3. In the **Connections** window of QJackCtl, send the output of **System capture** to **Rakarrack**. This sends sound from **Line In** to your effects.
4. Send the output of **Rakarrack** to your **System playback** so that you can hear what you're playing.
5. You should now hear something, even if it's just the buzz of cable interference. If you hear nothing, and you're using Pulse audio on your system, open it to verify that your speakers or headphones are active, and that **Line In** is detected. If you're using ALSA only, verify your levels in ``alsamixer``.
6. Play your guitar. The sonorous sounds of your guitar pipe through the Rakarrack effects and out of your amp or headphones.
## Effects
There are several packages available for Linux that provide effects. [Rakarrack](
http://rakarrack.sourceforge.net) is easy to an easy gateway to soft effects because it's self-contained and comes with plenty of great presets to get you started.
[Guitarix](
http://guitarix.org/) is slightly more modular, at least in its UI. It models itself after a physical rack, with each effect unit being a separate rackable item.
[Calf](
http://calf-studio-gear.org/) is similar in look and feel to Guitarix. It's got the visuals of a physical rack of effects, with **Edit** buttons that pop up the detailed interface for each item.
The list doesn't stop there. There is a host of LADSPA and LV2 plugins out there, and they're waiting to be discovered, jacked, tweaked, and used.
## Recording
There are several ways to record what you do, but the easiest way is jack-record.
Jack Capture, by default, records anything connected to JACK. It's just a recorder, so it's a lot like turning on a minidisc or tape recorder. Once you have your recording, you can take it into your favorite audio editor, whether that's [Qtractor](
https://opensource.com/article/17/6/qtractor-audio) or [Ardour](
http://ardour.org) or something simple like [Audacity](
http://audacityteam.org).
## Jam
It's never been easier to make noise. If you have the inclination, find a guitar, plug it in, and jam. And if you make anything cool, be sure to share!
