6 OB is the easiest, and easily made use of in 1st & 2nd positions. I've discovered it 'growls' beautifully if I let blow 7 in on the act, just a bit. I think it works the same as finding the spot between the full blow bend on 8,9, or 10 and the unbent note, and making the two fight it out, as exemplified in Blues Birdhead's 'Mean and Low Blues', discussed here a some hours ago. RD