An Open Source Digital Audio Workstation Setup


Recording Guitar


Once the proper hardware connections have been established and correctly installed, you are ready to begin recording. Alsa is a sound architecture and software framework that provides a higher level of abstraction for software needing to interface with low-level hardware features. It comes pre-installed with many different Linux-based distributions, and supports many soundcards without any additional configuration after installation. The Lexicon Omega is one such sound card as it works simply by plugging it into a Linux-based system that has Alsa pre-installed.

JACK Setup

iJACK (Jack Audio Connection Kit) provides an easy means of making connections between the various inputs and outputs of your hardware and software audio tools.

Start JACK and click the "Configure" button to modify the Parameters section to match the illustration below.

Not everybody's JACK configuration will be the same but you can find the most important parameters to tweak (for a relatively modern computer) to suit your own configuration needs highlighted below.

Realtime Effects Processor

Once JACK is up and running you can plug your guitar into your SoundCard with a TS cable and start Rakarrack. Rakarrack will attempt to connect your guitar's signal to it's inputs, but may not succeed locating the channel that your guitar is plugged into. For example, on the Lexicon Omega the "Instrument" input sends a signal to Channel Number 3 (identified as "capture_3" by JACK). As a result in JACK you will need to modify the connections Rakarrack has setup by default.

  • To do this open the "Connections" dialog box in JACK and expand the "system" Output Ports list in the left panel under the Audio tab.
  • In the Input Ports Panel, on the right, expand the Rakarrack Input Ports list.
  • Select both erroneous connections "capture_1" (from system Output Ports list) and "in_1" (from Rakarrack Input Ports list) and click the disconnect button.
  • Repeat this procedure for "in_2", as Rakarrack will duplicate the system capture signal in order to create a stereo effect.

  • To send the guitar's signal to Rakarrack select "capture_3" from the system Output Ports list and connect it to both of Rakarrack's Input Ports "in_1" and "in_2".
    iThis duplicates the guitar's signal and sends it to both the left and right channels.
  • Rakarrack's Output Ports "out_1" and "out_2" should remain connected to the system Input Ports "playback_1" and "playback_2" so that you can hear the signal that Rakarrack has created.

  • Although other soundcards may send the guitar/instrument signal to another capture Output Port, the procedure for establishing a connection between this Output signal to Rakarrack via JACK may be similar.

Ardour Setup

Start Ardour and add a new stereo track for recording the guitars processed signal from Rakarrack.

    In Ardour click Window -> Show Mixer
  • In the Mixer Window, locate the track that you created, click the Input button below the track's name and choose Edit.
  • By default this button is labeled 1/2 (which indicates that it is setup to record channel 1 and 2). We need to configure this track to record Rakarrack's output signal.

  • Click "System: Capture_1" and "System: Capture_2" in the Inputs panel to remove these connections, then select the Rakarrack tab and click the two outputs for Rakarrack in the right panel. You could also achieve the same configuration by using JACK's connection editor.
  • In Ardour's transport controls click the Record button and also select the record button associated with the track you wish to record to. Recording will not commence until you click the Play button in Ardour's main transport controls or hit spacebar on your keyboard.