Here’s how to get Ardour set up so that the DAW can control a MIDI synthesizer. I’m using Ubuntu Studio, Ubuntu 20.04.1 LTS, Ardour 5.12.0.

  • Start Jack (I use QjackCtl).

  • In a terminal, type

      a2jmidid -j default
    

a2jmidid is a bridge between the ALSA MIDI system and JACK.

  • Start Qsynth (a front-end to the fluidsynth MIDI synthesizer) and make sure a soundfont is loaded.

  • In the QjackCtl MIDI connections tab, connect the Output Port ‘midi_out’ of the MIDI track in Ardour to the Input Port a2j ‘FLUID Synth’.

  • In QjackCtl Audio tab, make sure that the qsynth left and right channels are connected either to a system audio output (for listening) or to an Ardour audio track (for recording).