Misikdoc is right, most of the blues is vocal based unless it's blues based jazz. As far as blues being an aab vocal form i would say that it's better defined as some permutation of a I, IV, V chord progression based on a major scale and the dorian and mixolydian modes thereof, though the vocal field call roots of the blues can never be denied.. The use of 3 to 5 note chords is not confined to modal music nor is it a defining feature. Modal music tends to have a static tonic over long time intervals and the harmony is implied during improvisation throught the use of modes of the scale defined by the tonic. I don't think corinthian is a mode (scale) in any western music i have ever heard of. That said, look into Ronnie Earl's Guitar Virtuoso in Europe for all instramental blues..real good stuff. Ronnie also did a great album with Pinetop Perkins and 2 other guys..i don't remember the title but search out the album it's worth it. The cover has the 4 guys on it with ronnie holding a resonator guitar For that matter anything with pinetop playing on it has proven to be good, roomful of blues did an early album with pintop that is also real cool. Duke Robillard is another great guy to check into and a good bit of his work (especially on after hours swing session) is instrumental. If you like the more swinging version of the blues you might as well check out Gatemouth Brown...a true living legend . Good luck on your search and remember da blues is a good thing
