Java Midi Synthesizer

Hello,

I've been having a little trouble working with the Java midi
synthesizer included with the API.

I found a peice of code on a forum something like what follows:

import java.util.*;
import javax.sound.midi.*;

class SoundTest
{
   public static void main(String[] args) {
       try {
           Synthesizer synth = MidiSystem.getSynthesizer();
           synth.open();

           final MidiChannel[] mc = synth.getChannels();
           Instrument[] instr =
synth.getAvailableInstruments();
           synth.loadInstrument(instr[55]);
           for (int i = 20; i < 80; ++i) {
               try {
                   Thread.sleep(200);
               } catch (InterruptedException e) {}
               mc[4].noteOn(i,100);
           }
       } catch (MidiUnavailableException e) {}
   }
}

Though I'm not very familier with the sound API (I've just come
accross it today), I'm not confused with the code. The problem is, I
would expect, when modifying the line
"synth.loadInstrument(instr[55]);" to get a different instrument, but
I haven't.

Can anyone help me out?

-Bryan