Step 1
Install qsynth, which should simultaneously install fluidsynth, the actual synth engine.
Install Jack and qjackctl the gui.
Install your preferred sequencer, in this case I am using rosegarden.
Download a Soundfont for your synth. Google will provide plenty of these.
Step 2
Launch QSynth and ignore the error about Jack for the moment. Click Setup on the bottom left and make sure Jack is the Audio driver under the Audio tab. Next click the Soundfonts tab and find and select the soundfont you downloaded earlier. Now exit QSynth.
Step 3
Launch Jack. Click setup and select alsa as the driver. Then click the > symbol beside interface and select your audio card. Close the setup screen and click Start. If you encounter errors about buffer size then change the Frames/Period and Periods/Buffer settings in Setup. Otherwise you should see that Jack is now running.
If you get an error about realtime scheduling then you need to edit the /etc/security/limits.conf
and add :
@audio - rtprio 99
@audio - memlock 512000
@audio - nice -10
You can set the memlock to a different value if you prefer.
Then open System > Administration > Users and Groups and create a new group called audio. Then make the users who are going to use Jack a member of this group.
*N.B.* You should restart your computer now as it may save alot of headaches with errors. *N.B.*
Step 4
Launch Jack and start it.
Launch QSynth next and it should start automatically.
Step 5
Launch Rosegarden and ignore the error about realtime configuration, however, you may want to follow the instructions regarding any error about sequencer modules.
Step 6
Open the Jack Connections screen and disconnect all on the Audio and Alsa Tabs. Then reconnect the following :
Audio Tab – Connect qsynth output to system input
Alsa Tab – Connect rosegarden output to fluidsynth input(i.e. qsynth).
In Rosegarden select Midi output system device in the playback parameters on the right of the screen.
Next open Studio > Manage Midi-Devices and select Synth input port under General midi device and Midi output system device.
Step 7
Play some notes in Rosegarden and it should work. Otherwise you should be able to troubleshoot by knowing that the little green button on QSynth will flash everytime a note in Rosegarden is played if the two are connected properly.
Abstract notion: Jack, therefore, is a connections manager. So the most important thing to bear in mind is that the output from the final device in your chain, in this case the synth but it could be a DAW etc., should connect to your system input. Because the system input OUTPUTS as sound from your speakers.
Hopefully, this will help people setting up and using Jack for the first time.
