2.40Level 15 — Reharmonization

Now we start changing things.

Do not alter everything.

One useful move:

before B♭maj7, substitute F7 with its tritone substitute:

B7

because F7 ↔ B7 are a tritone apart.

Then:

Cm7 → B7 → B♭maj7

Bass:

C → B → B♭

Beautiful chromatic descent.