How to use
- The main 8x8 grid contains pads that send MPE pitch-fluid notes and aftertouch (EDO notes)
- The top button row allows transposing, accessing menus, and exiting the EDO mode.
- The right button row is used to navigate in submenus.
The EXIT button (last of top row) switches the Launchpad X to its original functioning, but keeps it connected to all MIDI devices connected. There is currently no other way to come back to EDO mode than rebooting the Raspberry Pi.
The first menu MPE SETTINGS is about the connected synth. The second menu LAYOUT SETTINGS is about the Launchpad X. The 8x8 grid's pad colors and notes depend on the configuration set in the second menu.
Transposition mostly functions like the Launchpad X's normal operation. The blue buttons (top row 1 and 2) shift the octave up and down, and the pink buttons (top row 3 and 4) shift the notes by one increment. Of course, the increment is not the semitone but depends on the divisions of octave (except in 12 EDO). Minor difference the normal mode: changing these settings will interrupt notes currently played.
The MPE SETTINGS page does not have submenu. Its single page has three areas:
- The first two rows represent the MIDI channels from 1 to 16. Each can be independently enabled or disabled, except channels 1 and 16 that cannot be enabled. Enabled channels are used to round-robin the notes.
- The fourth row represents four settings for the pitch range: 12, 24, 48 and 96 semitones. It must match the setting in the connected synth. 48 is the default value.
- The bottom-right pad disables the help. By default, menu values are followed by a short text flashing on the pads, to help you understand what you are doing. Once you know the menus and/or you find it annoying, disable it here.
Hit this menu's button (top row button 5) to exit it.
Different synths may for require different settings. For instance, the Modal Skulpt uses a pitch range of 48 semitones, while the Haken ContinuuMini uses a pitch range of 96 semitones. Some synths allow you to set the value you want. 48 is recommended by the MPE norm.
How to hear that the pitch range is wrong: with an EDO that is not 1, 12 or a multiple of 12 (for ex. 17), hit a whole row of pads from left to right, successively. The pitches should sound equally separated, regular, homogeneous (although it might sound dissonant). If it sounds that certain pads are too low or too high, then the pitch range setting needs to be changed.
Note: I am pretty sure my implementation is not exactly the MPE norm. I had to learn all of that and I have certainly made mistakes.
The LAYOUT MENU has three submenus that can be accessed from the right button column:
-
EDOsets the divisions of the octave -
ROWsets the pads offset between one row and the following -
COLORsets which notes to display
Hit this menu's button (top row button 6) to exit it.
Each of the 64 pads represents an equal division of the octave, from 1 to 64. Tap one to set the EDO. The pink pad highlights the classic EDO-12.
The top pad row (below the buttons) represent offsets from 1 to 8 between one row and the next. It is similar to the Launchpad X's normal way of operating, except more values are allowed. Offsets below 8 are not offered because they would "omit" certain rows (file an issue if you think you need it).
The paradigm of how pads are displayed is different from the Launchpad X except on one point: the root note is always displayed, and it is pink. You get to choose which other notes are highlighted.
Highlighted pads are picked by frequency ratios. For instance, the ratio 3/2, aka the perfect fifth, is very stable and consonant when played along with the root note. You can choose to display this ratio in white or in color, or not at all. It will appear in any EDO, with a twist: it will be dimmed if the pitch of the note is too inexact. Indeed, in a given EDO, certain frequency ratio will be better represented than others. You can find the properties of different EDO on the Xenharmonic Wiki.
Each row is separated in 2 groups of 4 pads. Each group of 4 pads correspond to one ratio, and three settings:
- Off (not lightened)
- White
- Color (you do not chose the color)
- The fourth pad flashes information: the ratio and its name in music theory
Depending on your settings, this page may then look like this:
The ratios have been picked from the harmonic series. They cover the most important intervals: the fifth, the fourth, the major and minor thirds... But these names are misleading. The 5 of the fifth, the 4 of the fourth, and the 3 of the thirds correspond to the piano keyboard and the music theory associated with the 12-tone temperament, inherited from the aesthetic criteria of the 18th century European musicians. Of course we are acculturated to EDO-12 but in other EDOs, these names bring more problems than solutions. For instance, I find the harmonic stability of the perfect fifth better represented by the number 3 of its ratio, as the harmonic series grounds how we perceive pitch relations. Similarly, the fourth is the complement of the fifth, and related to the number 3 as well, while the major and minor thirds are related to the number 5. This is confusing.
The ratios offered for display are the following:
And here are their classic names:
I placed each ratio in front of its octave complement (with one exception): the 3/2 ratio is to the tonic (2/1) what the tonic is to its complement (4/3). Basically, the complement is the inverse ratio, but we always tweak the ratios by doubles or halves so that they fall between 1 and 2. If this gets confusing, let's just say that the complement defines the exact same note interval (and pad interval) but seen from the point of view of either the lower or the higher note. In addition to that, the fifth complement is also sometimes important and has been taken into account.
The important ratios are the simplest. In this context, it means with the smallest numbers, but disregarding any power of 2 (4, 8, 16...). I suggest this order:
- 3/2 (Perfect fifth)
- 4/3 (Perfect fourth)
- 5/3 (Major sixth)
- 5/4 (Classic major third)
- 6/5 (Classic minor third)
- 7/4 (Harmonic seventh)
- 7/5 (Narrow tritone)
- 7/6 (Septimal minor third)
- 8/5 (Classic minor sixth)
- 8/7 (Septimal major second)
- 9/5 (Just minor seventh)
- 9/7 (Septimal major third)
- 9/8 (Whole tone)
- 10/7 (High tritone)
- 10/9 (Small whole tone)
- 12/7 (Septimal major sixth)
The paradigm of this system is, in fact, different from the Launchpad's. The highlighted pads do not define a scale, but interesting intervals to explore. The approach I suggest is to pick a few intervals and visualize by yourself how these intervals form patterns by themselves. These patterns would form scales in the traditional sense, but they would also be specific to a given EDO. In that sense, the colors are more of a teaching tool than scales that you can use to compose and improvise.
Each ratio corresponds to a frequency and a pitch (insofar as a root note has been fixed, in this case the middle C aka MIDI note 60). I assume that we perceive pitches as octave-independent (which can be discussed). Then the notes can be represented in a circle, where we can place precisely each ratio as well as each EDO-note. I used this circle to pick the colors, using the similarly circular topology of hues. This way, ratios that are close also have similar colors.
Remark that octave complements are always on the same horizontal line, because they are by definition to the same distance to the tonic, on top (but in the other direction). Fifth complements are also on parallel lines, but with a different angles: the distance to the tonic must be the same as to the complement's to the fifth.
Also remark that there are not many pitches close to the tonic. This is because I prioritized simple frequency ratios, but it does not mean that these intervals are meaningless.
I pictured below how a few EDO match these ratios. Look at how the points of the stars align with the ratios: sometimes they do, and sometimes they don't. This means that certain ratios are better represented than others in different EDOs. This does not mean that it is worse or better, but it is good to know.
