Here's Herbie Hancock's solo off the classic Miles Davis record "Miles Smiles." I transcribed this in one week and learned it over the course of a couple weeks. This was probably the most challenging solo I have attempted. The chromaticism and the up-tempo was a recipe for many weeks of painstakingly slow practice with the recording.
Oribts is a great example of the "time, no changes" approach to improvising. The improvised sections were free, meaning there were no written chords. Although the harmony was free, the tempo and feel stayed constant. It was up to the individual improvisor to listen and direct the harmony.
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