The diatonic harmonica is designed to play in just one key. Even though you can play it in several keys or positions, you’ll likely want several keys of harps so you can just pick up a harp in the right key for whatever song comes up.
If you can play a tune on a harmonica in one key, you can play that tune in any key just by picking up a harmonica in the appropriate key and executing the same sequence of holes and breaths you already know. For instance, if you play “Mary Had a Little Lamb” on a C-harp, it comes out in the key of C.
Want to play it in A instead? Just pick up an A-harp and play the exact same sequence of holes and breaths you played on the C-harp, and that familiar melody comes out in the key of A. To play that tune in different keys on a piano or saxophone, you need to learn a different set of note names, fingerings, and action patterns for each of the different keys.
Playing in different keys on different harmonicas means that you need a collection of different-keyed harmonicas and you need to change harps as the keys of songs change. That’s why you may see harp players onstage constantly picking up and putting down different harmonicas between songs, switching harps in the middle of tunes, or wearing vests or bandoliers festooned with pouches containing a dozen or so harmonicas.
The most popular keys are available just about everywhere harmonicas are sold. As you start to seek out harps in the more obscure sharp and flat keys, you may have to special order them or get them from online retailers that specialize in harmonicas.
Purchasing popular keys
As a general rule, the most popular keys of harmonica are C, A, D, and G, in roughly that order. Add to that the keys of F and B♭ó, and you have a basic set of six that’s versatile and travels light. This set also gives you the most popular keys for playing with guitar players.
If you want to work your way up to a full set with all 12 keys, here are three possible strategies:
Acquire the remaining six keys in diminishing order of popularity: E♭ó, E, A♭ó, D♭ó, B, and F♯.
Acquire harps for the keys of specific tunes you play or to play in the favorite keys of the musicians and singers you regularly play or jam with.
If you play a lot with horns, then you’ll want harps that play in flat keys — keys that have a flat in the name or in the scale. The best order to get these keys is F, B♭ó, E♭ó, A♭ó, and D♭ó. To those keys, add a harmonica in G, and you’ll have the flat keys covered pretty well.
Expanding your range with harps in high and low keys
A C-harp has middle C as its lowest note, and its range is more or less in the middle of harmonica ranges.
Harmonicas in the keys of G, A♭ó, A, B♭ó, and B are all lower in pitch than a C-harp and have a deeper, mellower sound, while harps in the keys of D♭ó, D, E♭ó, E, F, and F♯ are higher than a C-harp and have a crisper sound.
Harp players like to extend the range of harmonica sounds with high G and high A harps for an even brighter, crisper response than an F♯ harp. But players also like the deep, mellow, muscular sounds as the range of harmonica keys extends down toward the bass, from low F all the way down to double-low F, two full octaves below a regular F harp.
High and low harps can be a lot of fun to play and can add variety to your sound.
