The Christensen System

Now, on the Christensen system. (Full disclosure: I designed it, so this will be slanted.) It is not isomorphic like the Chromotone, Thummer, or Axis. And it is not a reproduction of an existing acoustic system like the Ztar. Well, that is not completely true, it is a variation on the violin’s system which has it’s strings tuned a fifth apart. This system expands upon it with the instrument having the equivalent of twelve strings. The strings are short however, spanning the distance of seven half steps, or a tritone. This eliminates the “shift” but does add a wrap-around “break”. (More on this in later posts.) Finally, instead of the lowest note bring at the top (away from the player) left side, the lowest note is on the bottom left.

What the system is, however, is symmertic and absolute, and in my experience, it works.

There are a number of reasons it works. The first is intuitiveness. The shortest distance between any two notes in western harmony is a half step. This is the relationship of adjacent keys in this system on the Y axis. This is where all the isometric systems become difficult to understand. There is no natural musical instruments that require an equivalent or further physical movement for a semitone, than for some larger interval, excerpt some wind instruments with elaborate keying or valve systems, and those instruments are considered the more difficult ones to play. On the x axis of the Christensen system, are fifths, which are very commonly played together and are very closely related harmonically. As I stated above, the lowest note is on the bottom left. Different, yes, but doesn’t moving up and away physically, suggest going up pitch-wise?

This is how it is symmetric; unlike the piano keyboard with it’s C Major foundation, or the guitar with that major third between the forth and fifth strings, the Christensen system has consistent relationships between key locations. Knowing that, a move of any interval, while not being always the same as would be in a isomorphic system, is greatly reduced to two possible options, due to the “break”, or wrap-around.

Ergonomically, this system works too. Any interval within six octaves can be reached with one hand. And, most three note combinations within three plus octaves, can be achieved with one hand, as well as many four note chords and, even a few five note chords. Orientation of the players hands and the surface is not dictated by the instrument so there is a little more freedom in hand position. Palms face the body which is a more comfortable position than having palms face down, which all “tabletop” systems require.

This system allows for a large range in a small area, a requirement for portability. This is due to what I call it being “absolute”. This means that there is one key per note. Again, isometric and string emulating systems have to sacrifice range or small size because they have redundant note buttons. Which brings us to the question of the value of having the same note represented in different locations. Beyond the fact that it means more buttons or keys, there is also the added complexity of having to figure out which key of a given note is best in a given situation, as opposed to knowing that if you need a certain pitch you always know where you are going to go. Many would argue that redundant notes provides options which is good, especially when it comes to ergonomics, and, the relationships between notes are better if kept consistent. I don’t disagree, but it is important to realize that there are consequences for these designs.

Finally, why seven by twelve? There are twelve notes in an octave and twelve keys, and seven notes in a diatonic scale, and seven notes to a perfect fifth. More on this in a later post.


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