Hi there, I hope you can help me with this one: it's a scene where a black musician is sitting playing what sounds like a ballad or maybe blues on a red or black Les Paul. He's behind a cristal door in a recording studio, then an actor (I don't even remember his face to describe him) comes in with another person and says "hi" to this musician, he says "hi" too and speak very briefly. The man who came in says something good to the musician, like "keep up the good job!" or something like that, and the musician starts playing again.
I'd like to see that movie again and most of all: find out the musician's name to get some records of him.
It was a film made on the mid 60's or early 70's I guess, judging by the furniture and clothes used.