The Instrument

The quickest way to learn about the prepared digital piano and bitKlavier is to watch this short informative film by Troy Herion:

and to check out the FAQ.

For those interested in possibly playing the instrument, read on below to see what it’s all about.

The Prepared Digital Piano consists of a standard MIDI piano-style keyboard controller attached to a computer running custom software (bitKlavierfor OSX and iPad; iPhone-player and Windows versions are planned) with the digital “preparations” and dynamic tuning. The audio output of the computer runs to speakers or headphones.

The main software window looks like this:
For musicians interested in playing the Nostalgic Synchronic etudes or exploring the instrument and not necessarily creating their own preparations, this is all you will ever need to look at, and it’s really quite simple: choose the preset for the particular etude, begin playing!

For those interested in learning more about the innards, read on.

 Synchronic Preparations:

This preparation began in the piece 120bpm, from neither Anvil nor Pulley, that I composed for So Percussion. In that piece, the starting point of a digital metronomic click is reset by striking a wood-block. Put another way: the metronome runs nonstop at a set tempo – let’s say two beats per second, a standard march – but every time the wood-block is struck, the next metronome click comes a half-second later, no matter when it’s hit. I have found this almost inanely simple (though perhaps no more inane than putting a screw between a pair of piano strings) “machine” to be remarkably inspiring.

The synchronic piano is similar except that instead of a click, the metronome sounds the most recent piano notes played. Playing the piano resets the metronome, and any notes struck within a given “cluster threshold” are gathered and struck on every tick of the “metronome.” The whole keyboard can function this way, or particular keys can be selected to be “synchronic.”


The keyboard above is where the synchronic “keymap” can be setup, turning on/off the synchronic behavior for those keys. Other things there:

  • how many: how many metronome cycles to play before stopping
  • cluster threshold (ms): how close notes need to be played together to be included in the metronome “cluster”
  • cluster minimum: minimum number of notes to be played within that threshold to create a metronome (so, in this example, playing a single note will effectively silence the metronome — very handy)
  • cluster maximum: just like the cluster minimum, except sets the maximum number of notes that can create a metronome; play more, and you silence the metronome.
  • synchronic tuning: more on tunings later, but this sets the tuning system for the metronome notes
  • sync mode: determines how the syncing is triggered:
    • last note sync: the last note in the cluster within the threshold sync the metronome
    • first note sync: the first note in the cluster within the threshold sync the metronome
    • note off sync: each note off syncs the metronome
    • note off start: like note off sync, except the metronome starts just as the note is released, as opposed to one cycle later
    • first note start: like first note sync, except the metronome starts when the note is struck, rather than one cycle later
  • tempo: sets the tempo, in bpm, for the metronome
  • accents: defines a sequence of accents for the metronome to cycle through
  • pulse interval multipliers: multiplies the basic time difference between metronome clicks (the inter-onset-interval, or IOI). In this example, the single value essentially slows down the tempo of the metronome, while other examples (like preset “Etude7-2”) go through a sequence of values, essentially warping the meter.
  • note length multipliers: multiplies the base length of each metronome note, so some can be longer than others.

 Nostalgic Preparations:

This preparation also began in 120bpm from neither Anvil nor Pulley. In 120bpm, metal pipes are struck and sampled live by the computer. When the computer hears that a pipe has been struck, it notes how much time needs to pass until the next metronome click, then it waits (while sampling the pipe) until half that time has passed, and then begins playing the newly sampled pipe backwards so that it reaches its attack in sync with the next click. The effect of this is a reverse delay that is shaped and constrained by the prevailing metronome pulse.


In the figure above, the top channel shows the metronome pulses, while the bottom channel shows two different pipe strikes, placed at different time locations between pulses, and then the reverse of that strike, peaking at the subsequent metro pulse.

As with the synchronic settings, the nostalgia can be limited to particular pitches, as set with the keyboard in the top of Feeling Nostalgic section:nostalgicOther nostalgic parameters include:

  • length multiplier: stretches (or compresses) the nostalgia relative to the expected time (set by played note length, so this only works when the sync mode is set to “note length;” see below)
  • beats to skip: rather then reversing to the next click, skip some before peaking (only works when sync mode is set to “synchronic”)
  • nostalgic tuning: tuning for the nostalgic notes; again, more on this later
  • sync mode: determines how to time the nostalgic notes
    • synchronic: as described above, time the nostalgic notes so they peak with the metronome pulses
    • note length: the length of the nostalgic notes are set by how long the original notes are actually played; so this is completely decoupled from the synchronic metronome pulse
  • wave distance (ms): when this is non-zero, the nostalgic note peaks a given time short of its attack, and then reverses direction, now moving forward for a certain amount of time (set by undertow). This has the effect of smoothing out the peaks, giving a swell rather than an attack
  • undertow (ms): as just described, this determines how long to continue forward in the live sample after peaking


Both the synchronic and nostalgic preparations are at least partially notated in the score. Only partially to avoid clutter; otherwise, I have attempted to include enough to be performatively useful.

Synchronic metronome pulses are indicated with downward facing triangles and small note-heads, stemmed opposite to normal notes (see bar 115, right hand, below, from the end of Etude 1). Nostalgic swells are indicated with dashed hairpins, cresting/peaking at small angled triangle note-heads:

notation_ex2check out the complete score for Etude #1.


In addition to equal temperament, this piano uses two tunings that I began working with in Justice Partial, a piece I composed for the Kalamazoo Laptop Orchestra and two disklaviers. The just tuning is a conventional just-intonation temperament, while the partial tuning is based in part on intervals drawn from the overtone series (both tunings, with A fundamental):tuning These tunings are variously inspired. The most direct inspiration is from a recording of the Norwegian bridal march Bruremarsj frå Engerdal by Sven Nyus, the first Norwegian fiddle tune I ever learned, In particular, the 6th (F/A) is usually somewhere between and major and minor-6th, sounding similarly to the 13th partial; an awesome sound. He sometimes at the ends of phrases lets this rise up slightly to a just-tuned major-6th—glorious difference tones!—and occasionally lets it sink to a just-tuned minor-6th. This was the starting point for building these two scales, and why they are so named. In Hardanger fiddle music, I often hear the major-7th tuned quite flat (11/6 sounds like the closest ratio to what I often hear, and I’ve chosen to use ratios of some sort for all these intervals), and similarly, the raised 4th—giving the Hardanger music its characteristic “Lydian” sound—is not so raised (it also sounds a bit flat, to equal-tempered ears). While I am not typically drawn to number games in music, there is a certain symmetry to the way this D# is mirrored by the “partial” F around the perfect 5th E (11/8 : 12/8 : 13/8), and for that reason, I chose to tune the minor-3rd C similarly symmetrical to the previously described “flat” major-7th (7/6 : 9/6 : 11/6). I love the way these two scales sound relative to one another; the qualities of the 6ths and minor-3rds in particular are vivid, and it’s not hard to start hearing voice leading patterns between them.

Partial tuning is probably not the best name for this tuning, as it is not consistently based on overtones (“bruremarsj tuning” or “fiddle tuning” might be better, I suppose), but it is the name I’ve used for some time now and I feel stuck with it.


These tunings can be set independently for the played piano notes, the synchronic notes, and the nostalgic notes. They can also change on the fly, depending on the notes played, with the “tuning keymap” (see image above). When notes in the keymap keyboard are selected, a dialog box opens to set what tuning and fundamental to switch to when that note is actually played.


All of these settings can be saved as presets and then recalled using the main pulldown menu (see below). For each of the Etudes, an initial preset is specified in the score that the player should select before beginning.


However, as with tuning, there is also a preset keymap, so specific keys can call up new presets. This is leveraged in many of the Etudes (#4 and #7, for instance). The player doesn’t have to worry about these changes as they are composed into the piece; however, when practicing in the middle of one of the Etudes, it will be important to choose the correct preset for that moment (preset changes are indicated in the score, so it should be possible to find the needed preset)

If you are interested in inventing your own presets, you can save new ones (with the “new preset” button on the main page). Just make sure you then “write” the collection of presets to disc (from the main window, in the menu under “presets.” It will create a .json file that includes all the current presets). You can make your own new .json file as well with your own collection of presets, if you prefer, that you then “read” when you next open the program. Finally, you can also edit that .json file directly (it’s just text), if you want to do some copy-pasting from preset to preset or algorithmically generate presets; this can be quite handy and I do it a fair amount.

** NOTE regarding MIDI keyboards: not all MIDI keyboards handle NoteOffs messages correctly, and while the Prepared Digital Piano is certainly playable with these keyboards, it is much better sounding and feeling with one that sends NoteOff velocity messages (reflecting how quickly the keys are released). Keyboards like the Roland A-88 and Kurzweil SP88 do this correctly, and I’m sure there are others, but it is remarkable how many don’t.

Ok, that’s it for the Prepared Digital Piano. Most of this you don’t need to know in order to play the pieces; simply choose the preset indicated at the start of each Etude and play away! We will keep updating these pages as the software changes, so this should serve as a manual of sorts. Contact us (manyarrowsmusic [at] gmail [dot] com) if you have questions.