This follows the basic STAX format:
Upright Bass is at mid 0 through 31, C1 through G3
Drums are at midi 35 through 59, and follow general midi placements with the the following exceptions:
40 is a snare rimshot
52 is ride cymbal outer edge
58 is shaker
Harp, from C3 through C6, is, coincidentally, at 60 through 96.
Strings, from C#2 through G4 are at 97 through 127
The effect is to give a nice chamber jazz ensemble. Bass, and drums, with harp taking the place of piano, you playing the guitar, and a string section to give some ambience.