EEEPC and Shure SM57

This tutorial will show you how to install and setup a linux recording environment on your EEE PC or other netbook, for the purpose of mobile audio recording and audio sampling.

I am using an Asus EEE PC 901 with 4GB and 16GB SSD’s (that comes with Xandros Linux pre-installed) but this method will work for other models of EEE PC’s and netbooks, even those with Windows pre-installed.

This is not meant to be an advanced guide for those already involved in Linux audio recording but should hopefully be a handy introduction for beginners who want to turn their EEE PC into a mobile recording machine at no cost.

Installing

There are some excellent Linux distributions for full desktop (and laptop) audio production, (64 Studio, Ubuntu Studio e.t.c.) however we are going to use and slightly modify the Ubuntu Netbook Remix distribution for our needs.

As the netbook has no built-in CD drive, unless you have an external CD drive, you will need to image a USB key or SD card with Ubuntu Netbook Remix in order to install the Operating System.

So first of all head over and download the image file for the latest version of Ubuntu Netbook Remix.

There is also a simple guide that will show you how to easily make a bootable USB key with the .img file you downloaded.

Once you have downloaded the file and imaged you USB key, it is a simple matter of booting your eee pc with the key attached and pressing the Esc key just after you turn the machine on, at the BIOS screen. This will enable you to choose to boot from the USB drive.

Hydrogen on the EEE PC

Alternatively, you could press F2 instead of Esc and change your boot device order in the BIOS settings.

In a short time you will be presented with an options screen where you are able to choose between booting into Ubuntu in Live CD mode or installing straight away. It does not matter greatly which option you choose, as you are also able to install the Operating System from Live CD mode.

Installation is a simple matter of following the on-screen instructions and setting your options.

Probably the most important part of the installation and the point at which you should make sure you are paying attention is when you come to the disk partitioning screen, as this is where you can choose where Ubuntu will be installed on your disk.

If you are running Windows and would like to keep your Windows install as a dual boot, you will have to resize one of your partitions to make space for Ubuntu.

I personally would rather chew through my arm than run Windows so here is how I setup my disks using the manual partitioner :

• 4GB SSD (/dev/sda) : 3.5GB ext3 root + 220MB swap (optional)
• 16GB SSD (/dev/sdb) : 16GB ext as /home

This puts Ubuntu and swap on the faster 4GB SSD and my /home folder on the slower but larger 16GB SSD.

Once you have chosen your partitions continue with the installation and when it is finished you can remove your USB key and reboot when prompted.

The installer will have installed the GRUB bootloader – If you are dual-booting with Wiindows or another OS you may need to choose to boot Ubuntu at the boot screen.

ASUS 901 WPA2 Wifi fix

At the time of writing there is a regression bug with the latest version of the driver for the rt2860 wireless card on my 901 EEE PC; depending on what model of netbook you are using and your wireless Access Point setup, you may or may not encounter this bug relating to certain WPA2 encryption settings.

If you do encounter the problem, you will need to either temporarily change your Access Point encryption settings or use the wired connection to connect to the internet and do a simple downgrade of the driver is required as follows :

Install dkms – At a terminal type :

sudo apt-get install dkms

Next, rename the existing driver so that it is not loaded :

cd /lib/modules/2.6.28-11-generic/kernel/drivers/staging/rt2860/
sudo mv rt2860sta.ko rt2860sta.bak

Then you need to download and install this .deb version of the dkms driver for the wifi card.

After installing the driver, reboot your EEE PC and WPA2 connectivity should be fixed.

Realtime Kernel

One thing you’re certainly going to need if you want to make music with your netbook is a realtime kernel.

A realtime kernel allows for lower latency communications between software and hardware. It is useful in audio production cases as otherwise you can run into ‘xruns’, which are buffer over/underruns, where the application is too slow to process the data from the audio buffers. In your recording you would hear something like clicks and pops and other weird noises when you get xruns.

Realtime kernel packages are available in the Ubuntu repository, to install one run this in a terminal :

sudo apt-get install linux-rt

Or find the linux-rt package in the synaptic package manager.

Once you have downloaded the realtime kernel, you can choose to boot into the realtime kernel at the grub boot menu at startup.

Or, if you want to boot into the realtime kernel (or Windows if you are dual-booting) by default you can set this in /boot/grub/menu.lst

Linux recording programs installation

At this point you should have a working Ubuntu install on your netbook with a realtime kernel. We are almost there and it is time to grab the applications we will use for recording and editing our music.

There are a wide variety of music creation applications available in the repositories that allow you to create music in many different ways.  I would advise you to try out some of the other applications as well, but I’m going to recommend a few of the most popular applications that will allow to you to record, edit and manipulate audio, create drum loops and add some effects to your recordings.

These applications are :

• jackd – Jack Audio Connection Kit (depends on libjack0)
• qjackctl – Graphical User Interface for managing jackd
• ardour-i686 – Definitely one of the best and most versatile DAW’s available for Linux
• Audacity – Audio/.wav editor
• Hydrogen – Drum machine/step sequencer
• hydrogen-drumkits – extra drum kits for Hydrogen
• Creox – real-time effects suite
• Ecamegapedal – another real-time effects suite
• cmt – Computer Music Toolkit ladspa effects plugins
• caps – ladspa effects plugins by C* Audio
• swh-plugins – ladspa effects plugins by Steve Harris
• tap-plugins – ladspa effects plugins by Tom Szilagyi

You can locate and install these programs in the synaptic package manager manually or run the following in a terminal to install :

sudo apt-get install jackd qjackctl ardour-i686 audacity hydrogen hydrogen-drumkits creox
ecamegapedal cmt caps swh-plugins tap-plugins

Audio interfaces

With an EEE PC, there are at least two ways you can record audio into the system :

a) Using the built-in soundcard

b) Using a USB audio interface.

A USB audio interface offers the best sound quality as it will typically feature balanced XLR inputs, quality pre-amps and 48v DC Phantom Power, allowing you to use condenser microphones.

With the built-in soundcard you will have to use the built-in stereo microphones, or plug a dynamic microphone into the microphone input of the netbook. With this method you are sacrificing some sound quality but gain portability and increased battery life – as when mobile recording, the usb audio interface will be drawing power from the EEEPC’s battery.

In this tutorial I am going to use the built-in sound-card with a dynamic microphone plugged into the microphone port with an XLR to mini jack cable, but the steps are more or less the same whichever method you use.

Setting up JACK

JACK is the system on top of which we will be running nearly all of our audio programs, so it is important to get its setup correct for the best performance of the audio system.

We need to setup realtime priorities for the audio group, so enter this at a terminal :

echo '    @audio     - rtprio 99' | sudo tee -a /etc/security/limits.conf
echo '    @audio     - memlock 512000' | sudo tee -a /etc/security/limits.conf
echo '    @audio     - nice -10' | sudo tee -a /etc/security/limits.conf

This sets a realtime priority and nice value for the audio group and gives the audio processes a locked amount of memory, in this case 512000 being half of the EEE PC’s stock 1GB of RAM. If you have added more RAM to your netbook you can increase this figure, or even set it as unlimited.

Then we need to add our user to the audio group. Enter this at a terminal, replacing ‘YOUR_USERNAME’ with your actual username :

sudo adduser YOUR_USERNAME audio

Next you can open JACK Control and configure it using the ‘Setup’ button, here is how I have setup JACK Control (click for full-size) :

JACK Control settings on the eee pc

Once you have configured your settings here you can press OK and start JACK by pressing Start.

Your system is now configured and ready to start recording. Remember to start JACK with JACK Control when you want to use Ardour, Hydrogen e.t.c. in the future.

In the next part of this series of posts I will show you some good music production uses you can get out of this setup.