Notice
This is a tune off of Giant Steps that utilizes the "Coltrane Changes" found in Giant Steps, but continue to shift down whole steps. The song strongly resembles "Tune-Up". Trane rehearsed these substitutions for about two years before bringing out Giant Steps. The Coltrane changes are chord substitutions that can be played over any II-V-I.
Over a typical II-V-I, we'll use Em7, A7, DMaj7 (II-V-I in Dmajor). Em7 and A7 get one measure each, while DMaj7 gets two whole measures.
Now giving each substutute chord two beats play: Em7 F7 BbMaj7 Db7 GbMaj7 A7 DMaj7. So in the 4th measure you land on Dmaj7. Dominant 7th chords resolve well going up a fourth (down a fifth). Here the Key Center is Dmaj7, but Coltrane is using other key centers in a cycle of Major 3rds (D, Gb, Bb). Upon returning to the original key center of D the cycle is shifted down a whole step (C, E, Ab) for the A section. "Tune-Up" behaves the same way but follows the cycle of fourths-fifths only. "Countdown" incorporates both cycles and the result is well worth the woodshedding. For music lovers, check out Trane's A Love Supreme
Make sure to check out the other Chord melodies I've submitted. The Giant Steps CM has a lot of information as well.
