Making music on Linux is a considerable headache. There are loads of interesting programs and sound systems but often they barely work, – if at all and only after considerable setup.
One of the nice programs is ZynAddSubFx made by Romanian Nasca O. Paul. It is a ridiculously configurable synthesizer with several methods for constructing sounds. It got effect and it even allows you to play via the qwerty keyboard.
On startup ZynAddSubFx will attempt to hook up to Jack. It does not start Jack by itself. Although ZynAddSubFx will play through Jack annoying clicks appear in the audio, and these clicks I have never been able to get rid off.
If ZynAddSubFx cannot use jack it will attempt to use the Open Sound System by looking after the /dev/dsp device. If this is not available one usually runs into an error message like “Using OSS instead. ERROR – I can’t open the /dev/dsp.” On an Ubuntu you can then try to install the alsa-oss package for alsa wrapping oss-programs. Once this package is installed you may try to start with “aoss ZynAddSubFx” from the command line.
There may still occur problems though.