I wrote this for another member of this forum, so it appears on another page somewhere this version is slightly different in content but not much.
If you are serious about playing the blues you must get this under your belt until it is second nature, it may sound complicated but unless you know it you will not advance in your blues playing, this is the method taught by all the pros, I would urge you to study it, but don’t take my word for it, get out on utube and learn,it’s all there for you.
What follows describes the 1st and 2nd position on a Diatonic ten hole Harmonica, there are 12 positions in total, most of which you will never use but that are nevertheless available on the humble Blues Harp.
So, you have your brand new harp which for arguments sake is in the key of C.
Start at the 4th hole. 4 Blow, 4 Draw, 5 Blow, 5 Draw, 6 Blow, 6 Draw, 7 Draw, 8 Blow. (Draw means suck)
You have just played the scale of C Major in 1st position
(Doesn’t really matter what key your harp is in, if it is a ten hole diatonic that sequence of blows and draws will play a Major scale in whatever key is marked on the harp)
You can play hundreds of melodies using that scale, I play ‘Oh Susanna’, ‘Shenandoah’, ‘The Streets of Laredo’, ‘Scarborough Fair’, ‘Jesu Joy Of Man’s Desiring’, ‘Amazing Grace’, and whatever comes into my head but I never play ‘The Blues’ in that position.
2nd Position or ‘Crossharp’
Draw the first four holes, This gives you a chord of G Major.
Add the 5th hole and the chord becomes G7.
7th chords are restless and always want to pull you to another chord which, since this is a G7th chord will always be C major which you will get by blowing the first four holes (the key of the harp)
Most blues only ever use three chords and you already have two of them by drawing and blowing the first four holes, the third chord is not so easy since it is not just a draw or blow alternative, but has to be suggested by using single notes, can you see already how 2nd position lends itself to playing the Blues, both melodically and chordially?
All this info is available on Utube, check out Howard Levy, Adam Gusso, Jason Richie, and many other top harp men who generously give their knowledge away for free and from whom I have learned so much.
You will probably now see the significance of the Hohner Marine Band ‘Crossover’ harps (of which I currently have nine.
I will close this missive by saying that the best key for your harp is the one that is most useful to you,
There is no strong reason to pick your first harp in the key of C, it can be in any key you want it to be , the main criteria for picking the popular keys, C. A. and F, stems from the very likely possibility that sooner or later you are going to want somebody to accompany you as you lash you way confidently through your first Blues solo! probably a mate who plays guitar, and so things will not be to difficult for him, you choose your harp key so that the key he plays in will not break his fingers since he will not be playing in your key (2nd position) so if you harp Key is C, in 2nd position it is G, and G is an easy key for a Guitarist as is E (2nd position of an A harp) and C (2nd position of an F harp)
The other main criteria for choosing the key of your harp is, Do you have backing tracks?, (there are lots of free ones on utube) if so get a harp that is in the same key as your backing tracks, but remember that you now play the blues in the key of G on a C harp.
So, Harp key C, you want backing in G, Harp key D you want backing in A, Harp Key A you want backing in E, always five notes away from the harp key, Hope this isn’t too heavy, it’s vital stuff to know.