hi guys

I have a question to those ones who know a bit about picking in gypsy jazz. How is this type of picking different from picking performed by petrucci, mclaughlin, di meola? What they play in gypsy guitar is this typical alternate picking? Let's say somebody who can play regular alternate picking wants to play gypsy jazz. Does he have to make serious alterations in his picking? Well, I heard that they don't do a lot of alternate picking in gypsy jazz. I was told that there is only a lot of downstrokes involved. Is that true? Do you think that if petrucci wanted to learn typical gypsy picking techniques he would lose over time his skills to play regular alternate picking?