I am currently playing lots of old blues music such as BB King, Peter Green and Clapton . I recently developed a liking for gypsy jazz; specifically, Django's work. I tried to improvise using Mixolydian , Dorian as well as major/minor pentatonic, but it didn't give an authentic gypsy jazz sound. What theory must I learn so that I understand feel gypsy jazz better?
This is almost exactly the path I started down a year or so ago! There is a lot to learn in this style to get the authentic sound and I feel like I've only scratched the surface.
This melodic lines played by Django and others generally come from arpeggios and enclosures with scale tones in between. This isn't a hard and fast rule, but if you start to analyze the music and look at the lines in context of the chord, then pick out the chord tones only, you will start to see the common patterns that were used to create a skeleton of sorts.
In many cases the arpeggios are played from the 3rd to the 9th leaving out the root.
Over dominant chords many times you will hear a diminished arpeggio starting a semi-tone up from the root. For more on this, you could look into Dominant 7b9 chords and how these are actually diminished 7th chords, etc.
Even looking at the style of Charlie Christian will help here!
I will try come back later and cite some more informational material that may help, but in this style arpeggios are definitely the bread and butter!
The harmonic minor scale, which is used at the beginning of Django’s Minor Swing, will work perfectly.
To be clear, the harmonic minor is the same as the natural minor (Aeolian mode) except the seventh degree is raised 1/2 step. That creates a gap of 1 and 1/2 steps between the 6th and 7th degrees. That gap, along with the help steps between the 7th degree and the octave, the second and third degrees, and the fifth and sixth degrees, give the harmonic minor its particular sound.
If you raise the fourth degree a half step also, then you get the gypsy minor scale. also called the Hungarian minor or double harmonic minor. I think the first name says it all. Once again this creates an gap of 1 and 1/2 steps between the third and the fourth degrees Depending on the changes you may need to play around with when you do and don't raise the seventh and fourth degrees, but playing around with the harmonic minor and double harmonic minor scales should open up some of the sounds you're looking for.
Have you tried using arpeggios instead of the scales? This wiki page has a nice description...
I would give the "major mode" of the blues scale a try.
Basically, it is a major pentatonic, with the "blue note" being the minor third. I think I've heard Stephane Grappelli getting some mileage out of this one.
I'm not a pro on the style though. And I'm sure the music has too much going on harmonically for a one-scale-fits-all approach.
From Jazzology, combined with info from a guitarist friend who has been playing gypsy jazz as a pro for well over a decade: Become familiar with these scales and how they are applicable to the chords used in gypsy jazz:
( In general Piano scales-Exotic scales and the site at large appears to be a good resource. )