I have converted two c-thru music Axis 49 MIDI keyboards to a Tri-Color Janko key arrangement.
As you can see from the figure, the Axis is a 7 x 14 hexagonal grid of buttons. (The original Axis layout is the “harmonic table.”) For Janko, I need two rows of keys, with alternate rows offset by 1/2 key width. The adjacent-key rows on the Axis run vertically, not horizontally, so the maximum number of notes per row either horizontally or vertically is seven. However, there are also adjacent-key rows along the diagonals. The maximum diagonal is 14 keys, with others of decreasing length.
Because of the mechanical construction of the Axis, it is not possible to change the physical geometry of the keys. (The entire keyboard is a single piece of molded plastic forming the channels for the key pistons which engage the etched electrical contacts on the single PC board below.)
In order to get the maximum range, I have used the diagonal rows upper-left to lower-right (diagonals 01-98 and 02-91 in selfless mode). I mapped these to the notes F3-G5 for RH and F2-G4 for LH.
(MIDI notes 53-79 RH and 41-67 LH). I also mapped the pairs of diagonals “above” and “below” those. The choice of range was purely personal preference; this includes the “baritone” range I can comfortably sing. Since I have two keyboards, this gives me 2+ octaves in each hand, the two hands overlapping for over 3 octaves overall. This covers all the lines on the Grand Staff, and the space above and below.
I also applied the Axis 49 firmware update ver 1.11 (available from c-thru) to change the MIDI channel of one of my keyboards from channel 1 to channel 2, so I can get different voices from each keyboard.
I wanted to use the tri-color key scheme discussed in earlier posts, in which adjacent notes rotate through three colors. This correlates to my Chroma-Tonnetz shape-note notation, and other three-color notations such as John Keller’s Tri-Color ExpressStave.
So, I rearranged the key tops into a tri-color pattern: black, blue, white.
Since there were not enough “blue” keytops, I created additional “blue” keys with blue star stickers on white keytops. I may eventually get around to painting these keys.
Finally, I needed to map the MIDI notes. The Axis has a “selfless” mode in which the keys are numbered column-wise, top to bottom, from 1 to 98, and output the corresponding MIDI note messages.
At first I attempted to create an Arduino program to do the MIDI note mapping, but I encountered difficulties creating a MIDI host with my Arduino. [I hope to have a blog entry on the Arduino project at a later date.] So currently I am using a commercial software product: Bome MidiTranslator Pro, running on my Mac computer, to translate individual MIDI note-on and note-off messages.
I’ve had my first “lesson” on the new arrangement with my piano teacher yesterday.
(Actually, it’s not clear who was teaching whom, but we both agree this arrangement has potential.)
Our next step is to develop a beginner curriculum for Janko, probably based on a more “professional” instrument like the Chromatone.
FOR MORE INFORMATION:
Axis 40 MIDI Keyboard: http://www.c-thru-music.com/cgi/?page=prod_axis-49
Janko keyboard layout: https://en.wikipedia.org/wiki/Jankó_keyboard
Tri-color keyboard coloring scheme (Patented by Roy Pertchik): https://www.youtube.com/watch?v=wkX4YMcGw7g
Bome MidiTranslator Pro: http://www.bome.com/products/miditranslator
Chromatone: http://chromatone.jp/ (The website is in Japanese, but Google Chrome will translate.)