Some basic explanations are in order for what these terms mean in MIDI:
- Volume - the overall loudness of the instrument in 0-127 - effectively relative to others in the track (one is set at 50, another 100 etc).
- Velocity - the specific note intensity separate from the volume, also in 0-127. There iIf you imagine a keyboard, s note on and off, but that's beyond the scope here. If you imagine a physical piano or keyboard, 0-30 is (roughly speaking) barely pressing the key, 30-60 is a light press, 60-90 is a normal press and 90-127 is a strong press. So this further modulates the volume.
In this specific case, the MIDI is set originally with velocities that are unsuitably low - pretty much all under 30. So you can imagine a person at a piano and playing a song but each time they're barely touching the key. That should help to understand why the result is unsatisfactory.
For reference, Roland typically uses velocities 90 and up for Sound Canvases (the MT-32 was lower on average).
I edited the file some more. However, I didn't use the full velocity values I normally would because of the velocity controller that's extensively used throughout. So, I changed note on velocity to increase by 60, and note off by 30.
Percentages (scale) is not an appropriate way to alter velocity in this case because of the low initial values - it will emphasise differences too greatly. I.e., notes of 6 and then 12 will become 24 and 48 at 400%. Even though both sets of notes have the second note at twice the velocity of the first, it's exponentially (logarithmically?) different in volume and so is the gap between the values.
If you increase both by 30 (random value to be similar to 24-48), you get 36 and 42. These notes (and the resulting difference) will be more analogous to the original values.
