Sonoclast New Instruments for New Music

Plastic Pitch Pro | Buy (

Liberate your music from equal temperament and static tuning! Awarded Second Prize at the MIDI Innovation Awards 2021, the Plastic Pitch Pro (Patent Pending) is a high-resolution MIDI microtuner made for experimenting with tuning while using the familiar 12-tone keyboard layout.

Ever wonder how a tuning change might change the feel of a song? Tune while you play. Dial a scale to better fit an uncommon timbre. Modulate a scale to a new key, even a microtonal one, while you are playing. Play your favorite MIDI synthesizers, and tune individual notes as you please using the intuitive one-knob-per-note interface

Notice that the Plastic Pitch Pro simultaneously tunes a Sub 37 using MIDI Tuning Standard, an OB-6 using MIDI Polyphonic Expression, and a Yamaha MODX using MIDI pitch bend.
The video demo for the MIDI Innovation Awards 2021 showcases the Plastic Pitch Pro used in a more “conventional” piano setting and in particular modulating keys while playing with a microtonal preset.

Possible Applications:

  • Who needs equal temperament? Tune a digital piano to a just intonation scale. While playing with two hands, modulate keys with another MIDI controller, perhaps an organ pedal one. Yes, modulate keys on every chord change (or more) if you like.
  • Find a compelling inharmonic timbre, perhaps with an FM synthesizer. Then find a scale or tuning that works for it.
  • Stretch the octave a few cents to make a digital piano sound less digital.
  • Experiment with the Bohlen-Pierce tritave or another pseudo-octave.
  • Play a familiar tune, and retune while you play to discover new musical variations.
  • Dissonance is your only friend. Fixed scales are overrated. Break all the rules. Untune your music.

Summary of Features

  • Real-time twelve-tone tuning with fourteen high-resolution potentiometers.
  • Wide tuning spots for easy tuning to neutral.
  • Presets in the Scala scale file format (.scl) stored on a micro SD card for importing and exporting tunings.
  • Multiple MIDI inputs for multiple controller options.
  • Multiple MIDI outputs for tuning multiple synths simultaneously.
  • MIDI I/O via DIN, USB B (as a device), and USB A (as a host).
  • Large display that shows all tuning information in real-time.
  • Modulate keys with a MIDI controller while playing.
  • Tune with MIDI Pitch Bend messages, MIDI Tuning Standard messages, and MIDI Polyphonic Expression (MPE) messages.
  • Configurable to tune any sounding notes immediately or tune on the next played note.
  • Each output port has its own configuration to be customized for a particular synth.
  • Designed to be maximally configurable to tune any MIDI synthesizer.

The Manual and More Details Below

The Tuning Knobs

The Plastic Pitch Pro has fourteen real-time tuning knobs. The twelve black and white knobs correspond to the twelve keys of an octave. Each knob independently tunes its respective key sharp or flat across all octaves. The other two knobs are for “Range” and “Width.”

The Range knob sets the maximum range of all twelve black and white knobs so that that distance from neutral tuning can be changed all at once. Turning the Range knob all the way down results in neutral tuning, and turning it all the way up results in the largest range. Setting it to 50% sets the tuning halfway between the maximum and neutral. The maximum range in +/- whole semitones is user-selectable.

The Width knob specifies the cents width of an octave of keys from 600 to 2400 cents in 1 cent increments. 600 cents width is equivalent to half an octave of a quarter tone scale mapped to an octave of keys, and 2400 cents width is equivalent to two octaves of whole tone scales mapped to an octave of keys. 1902* cents wide is the Bohlen-Pierce tritave. And, of course, 1200 cents width is the standard octave width.

(*1901.955 is the tritave cents width to 3 decimal places and is used in calculations when the tritave width of “1902” is selected.)

There is no audible stepping when tuning because all fourteen knobs tune at a one-cent resolution. They are all single-turn potentiometers, so the current tuning is visible by the knobs’ pointer positions. Additionally, the cents values are updated in real-time and shown on the display. The twelve black and white knobs have wide spots at neutral for easy tuning to neutral. Also, the Width knob has wide spots at 600, 1200, 1902, and 2400.

A Typical Setup

The Plastic Pitch Pro is made to sit in the middle of a MIDI chain between a MIDI controller and a MIDI synthesizer. MIDI messages received from a MIDI controller are processed and combined with tuning messages and then sent to a MIDI synthesizer.

The Plastic Pitch Pro has multiple MIDI inputs and outputs via USB and DIN connectors. So, multiple controllers can be used to send MIDI messages in, and multiple synthesizers can be simultaneously tuned to a single scale. Output ports are selected by incoming user-configurable MIDI channels.

MIDI tuning messages can take one of three forms for a given output port: MIDI Pitch Bend, MIDI Tuning Standard, or MIDI Polyphonic Expression. MIDI Pitch Bend tuning works with monosynths and multitimbral polysynths. Tuning polyphonically in this mode requires using multiple MIDI channels, so a multitimbral synth is required so that a duplicate voice can be assigned to each channel.

MIDI Tuning Standard (MTS) messages can tune any synth that supports MTS such as the ones listed on Wikipedia. Note that some synths claim MTS support but may only support a subset of the MTS message formats. The Plastic Pitch Pro tunes with “single-note tuning change 2-byte” formats, because they are the most flexible and highest resolution. MTS tuning dumps are also supported.

MIDI Polyphonic Expression (MPE) messages, the newest of the tuning methods, can tune any synth that supports it. The Sequential OB-6 and Prophet-6 were the first hardware synths to support MPE. Hopefully musical instrument manufacturers will continue to add support for it.

Presets and Other Features

In addition to the fourteen tuning knobs, there is a rotary encoder knob and a pair of buttons for changing settings shown on the display. There are 40+ user-configurable settings that customize the behavior to a particular setup.

Presets are supported in the form of Scala scale (.scl) files saved on a micro SD card. Any tuning specified by the fourteen tuning knobs can be saved as a preset/Scala file and then transferred to other devices that support Scala. Scala files from other sources can also be loaded as presets and played with the Plastic Pitch Pro.

When playing a preset/Scala file, the root note can be modulated to a new root note using the rotary encoder knob and buttons or a MIDI controller set to a distinct user-configurable MIDI channel. This makes it possible to modulate keys while playing.

The root note can be modulated in two possible ways. One way modulates to an absolute MIDI note, and the other way modulates to a note in the current preset scale. For example, starting with a Pythagorean scale with root note middle C (261.63 Hz), then modulating to A above as an absolute MIDI note would set the root note to A-440. Whereas, modulating to A in the Pythagorean scale would set the root note to 441.49 Hz (27/16 x 261.626).