New MIDI Synth Sounds?

Hi, I'm currently playing around with MIDI sounds in Java, and I'd like to know if there is any tutorial for how to install and utilize a new MIDI synthesizer in Ubuntu. The default MIDI synth that comes with Ubuntu based distros seems to have a fairly limited range of MIDI instruments avaible. Essentially, when I run a Java program to loop through and play each individual MIDI instrument in Ubuntu based distros, the program only plays about 31 instruments before throwing a MIDI Unavailable Exception. If I run the same program on a Windows machine it will play at least 127 instruments. I would like to install a MIDI synth on my Ubuntu system with a high number of available instruments, similar to what can be found on Windows, if that is possible.