The 10 hole Diatonic Harmonica, used by most Blues players is usually tuned to a major scale. Each Harmonica is marked with the key of the Major Scale to which it is tuned.
A Harmonica player, playing the notes of the Major scale, over a piece of music in the marked key of that Harmonica is said to be playing in “straight harp”, or “first position”. That is to say, to play “straight harp” over G, you need a Harmonica tuned to the scale of G major.
The 10 hole Diatonic Harmonica, used by most Blues players is usually tuned to a major scale.
However, the characteristics of, for example, Blues Music demand that the player is able to achieve notes not available in a normal Major scale, such as the flattened seventh tone and sharpened 2nd. Therefore, to play Blues, you need a Harmonica in a differant key to the key of the song.
A Harmonica marked in a key a perfect 5th below the key of the song will provide the sharpened and flattened tones needed to produce this Bluesy sound. Therefore, to play Blues in G, you need a Harmonica marked in C major.
Playing this way is known as “Cross Harp” or second position” and it is a vital technique in blues style playing…
| SONG KEY | CROSS HARP HARMONICA |
| A | D |
| A# / Bb | Eb |
| B | E |
| C | F |
| C# / Db | F# |
| D | G |
| D# / Eb | Ab |
| E | A |
| F | Bb |
| F# / Gb | B |
| G | C |
| G# / Ab | Db |
