The Hugh Tracey Alto and Pentatonic kalimbas are closely related to each other in that they have the same tine width and the same two octave range from G below middle C to G above high C.
A fundamental concept in both western music and all other musical systems around the world is the octave. Sing "Do Re Mi Fa So La Ti Do." The high note Do is one octave above the low note Do. In physical terms, the frequency of the high note is twice that of the low note, and our ears hear them as the same note, or at least a very closely related note. This physical basis of octaves makes them fundamental to all musical systems.
Exactly how we arrange the notes in a scale between the octave notes is another matter. On the piano, there are twelve notes per octave, equally spaced in some sense, i.e., differing by a half step. This 12-note scale is called the chromatic scale. Other non-western systems will have different numbers of notes, and will put them in different places.
While the 12-note system is the most general western system, it may not be the most useful. Music that uses all 12 tones tends to sound very complex and not very melodic. Most of the songs that you know and sing use a subset of the 12 equally spaced notes. The 7 tone diatonic scale, Do Re Mi Fa So La Ti Do, can accomodate most of the songs you might want to play.
We can indicate notes of different octaves by adding a number: Do1 Re1 Mi1 Fa1 So1 La1 Ti1 Do2 Re2 Mi2 Fa2 So2 La2 Ti2 Do3... and so on. Just as Do2 is an octave higher than Do1, Re2 will be an octave higher than Re1 and Ti3 will be two octaves higher than Ti1.
Let's look at a case in which the 7 tone diatonic scale can not accommodate a well known melody, that of the American national anthem. "Oh-o say can you see" is "So1 Mi1 Do1 Mi1 So1 Do2", and "By the dawn's ear-ly light" is "Mi2 Re2 Do2 Mi1 Fa1+ So1." That Fa1+ is actually a note that is between Fa1 and So1, one of the 5 notes of the 12 that are NOT in the 7 note diatonic scale.
But MOST songs you know, and large chunks of the rest, can be played using just those 7 notes of the diatonic scale. And these are the notes you find on the 15 note High Tracey Alto Kalimba. How do we get from 7 to 15? 7 for the lower octave, 7 for the upper octave, and 1 more note to repeat the high G two octaves above the low note - for a total of 15 notes.
One way to look at the pentatonic scale is that it is the 5 out of the 12 chromatic notes that aren't in the 7 note diatonic scale. If you want to play chromatic music, the Hugh Tracey chromatic kalimba takes the 7 diatonic notes and puts them on the front, while the 5 pentatonic notes are placed on the back to cover all 12 tones per octave.
Those 5 notes of the pentatonic scale can be shifted down so the root note coincides with the root of the diatonic 7 note scale, and then all of the 5 notes also coincide with notes in the diatonic scale but, of course, there are two notes in the diatonic that are missing in the pentatonic scale. In this list showing the 7-note scale, the pentatonic scale (or let's call it the major pentatonic scale) is in bold: Do, Re, Mi, Fa, So, La, Ti, Do. That is, the notes Fa (the 4th) and Ti (the 7th) are missing in the pentatonmic scale. This means that most of those songs that you might play on the diatonic Alto kalimba won't work on the pentatonic kalimba.
If you are interested in learning what sorts of songs you can play on the Alto (diatonic) kalimba, one place to look is our new Kalimba Americana for the Alto Kalimba collection. If you are interested in learning what songs can be played on the pentatonic kalimba, check out our new Pentatonic Kalimba Song Book. You can actually play all of these songs on the Alto kalimba; however, the music tablature provided in the Pentatonic Kalimba Song Book won't help much since the notes are arranged differently on the two kalimbas.
Alternatively, you can play the Alto and Pentatonic Hugh Tracey kalimbas together a number of ways. You can play both improvisationally, you can play songs on the Pentatonic and support them harmonically on the Alto or you can play songs on the Alto and let the Pentatonic notes dance around improvisationally.