Microtonal Synthesizers Chart Terms and Definitions

Information on scales

Instruments with only preset or preprogrammed scales are not listed. Quantities of user programmable octave and keyboard scales are given in the tables.

Octave scales allow only repeating 12 note scales to be created, usually with the retunings limited to +-50 to 100 cents of the normal equal tempered value.

Keyboard scales allow any note to be assigned to any key. These type of scales allow more than 12 notes per octave. Be forewarned that many wavetable based synthesizers do not remap the samples properly when the retuned note is out of the sample range of the original sample pitch. For instance, on the early Proteus modules if you retune C4 to a value near C5 in the key tuning table, the instrument plays the correct pitch but the wrong sample. It still plays the sample created for the C4 pitch, rather than the correct sample for the C5 pitch. This creates chipmunk type effects even worse than the normal sampling transposition.

Octave and Keyboard scales can be applied to the instruments in different ways. The most common is global, which applies the scale to every patch or program playing on every MIDI channel. Other instruments allow different scales for each program or MIDI channel (a "part" in Roland's GS instruments).

Most synthesizers are limited in resolution to 1 to 2 cents for pitch. This resolution is not necessarily constant over the entire range of the synthesizer. Most synthesizers and samplers also have an absolute pitch resolution in Hertz that limits the bass frequency resolution.

A cent is a unit of measurement for pitch that is linear over intervals, as opposed to frequency which is logarithmic. An octave spans 1200 cents, and a semitone is 100 cents. Many synthesizers use cents as the retuning measurement, while others use proprietary increments that match the tuning capability of the instrument. Most synthesizers that "appear" to have 1 cent resolution actually have an internal resolution, often 768 steps per octave, that the user programmable tuning table is mapped to. Unfortunately, this can cause tuning errors worse than you might program otherwise.

SysEx (System Exclusive) is a MIDI data stream specific to each manufacturer's instrument. Since the MIDI Tuning Dump standard is not well supported, tables of intonation tables are generally stored in this format. With the proper software this allows storage and editing on your computer.

Tune with sustain means that held notes can be retuned to a new scale. This may or may not be desirable depending upon your application.

Explanation of column headings in the Synthesizer tables:

Manufacturer The name of the instrument maker is given here. A link is provided, normally indicating they are still in business but sometimes this is a link to historical information.

Model(s) The instrument numbers or names. Models that are currently in production are highlighted in color and followed by an asterisk.

Instrument Type

Additive Synthesizer - A synthesizer which creates sound through the summation of sine waves into more complex composite tones. All practical implementations are digital by design.

Analog Controller - A non-traditional, non-piano style controller for analog synthesizers, such as a touch pad or theremin controlled by relative distance from a body. Outuputs control voltages to control an analog synthesizer or analog modular synthesizer. May have its own built in analog synthesizer voice.

Analog Modular Synthesizer - A synthesizer designed from analog circuits with patch points on the front, usually 1/4 jack, 1/8 jack or banana jack, for interconnecting modules to create a "patch" or sound. May be controlled from analog controllers, analog keyboards, or external control voltages such as from and MIDI to Control Voltage converter.

Analog Synthesizer - A synthesizer design from analog circuits. May be controlled for its own keyboard, from external control voltages, or sometimes from MIDI.

Arranger - Desktop unit that has functions similar to digital pianos or portable keyboards: built in accompaniments, limited synthesis, sequencing and recording.

Digital Modular Synthesizer - A digital synthesizer with multiple means of synthesis and processing that can be freely programmed to interact between these algorithms.

Digital Piano - An instrument in a piano style cabinet. Usually the synthesis is some form of wavetable synthesis, but physical modeling and other variations are possible. Auto-accompaniment is a common feature for these instruments.

Digital Synthesizer - An instrument that uses multiple digital synthesis techniques for generating tones. May include FM synthesis, sampling, wavetable synthesis, additive synthesis or other forms of synthesis.

Electronic Organ - An instrument based upon tube or transistor design to generate notes, packaged in a traditional organ format.

FM Synthesis - Frequency modulation synthesis based upon modulating one more oscillators from other oscillators, creating complex overtones.

Hybrid digital/FM analog synthesizer - A mixture of analog and digital synthesis techniques in one synthesizer design.

MIDI Controller - A non-traditional controller, such as a hexagonal keyboard array, continuous controller or theremin with MIDI output.

MIDI file renderer - A program which generates or "renders" an audio file from MIDI input and instrument files. The audio is not generated in real time but may be played back after the rendering process.

MIDI processor - Hardware which converts MIDI messages for support of additional functions such as microtuning.

PCMCIA wavetable sound card - see wavetable sound card

Physical Modeling Synthesizer or sound card- A digital synthesizer with algorithms which model the characteristics of physical instruments, and sometimes of analog synthesizers.

Portable Keyboard - Keyboard with builtin speakers and "consumer friendly" features, typically marketed by Yamaha, Casio, GEM and others. Synthesis is normally accomplished through wavetables and more limited in user adjustment than synthesizers. Usually, but not always, a low cost instrument. Often has features such as auto accompaniment and sequencing/recording.

Portable music unit - Like a Personal Digital Assistant.

Realtime Software Synthesizer - See software synthesizer

Sampler - A device which uses samples or recordings of instruments for playback and provides the facility for custom samples loaded from disk. These instruments have MIDI interfaces and are in keyboard, rack mount or desktop formats.

Semi-modular analog synthesizer - A hybrid between an analog modular synthesizer and an analog synthesizer, where pre-patched connections are "normalled" through jacks but may be overridden by patch cords.

Software Synthesizer - A synthesizer which runs on a computer platform such as a PC running Windows or Macintosh running OS X. All synthesis functions are accomplished in real time on the computer platform's CPU. Software synthesizers can usually be played back on any supported computer sound card, though for best results a professional level card is preferred, such as ASIO compatibility, for lowest latency, resilience to dropouts, and best audio fidelity.

Software Synthesizer Programming Language - A program used to enter statements or functions through text files and then compiled into a file which can generate audio files. May include utilities for graphical editing, MIDI input or real time synthesis.

VAST synthesizer - A Kurzweil term referring to variable processing algorithms that can be applied to wavetable or sample based synthesis.

Virtual analog modeled synthesizer - Provides similar features and functions of an analog synthesizer, but the realization is through software algorithms and digital means.

Wavesequencing Synthesizer - Similar to a wavetable synthesizer, with samples of instruments or sounds which are crossfaded for additional timbral and compositional movement.

Waveshaping Synthesizer - Similar to wavetable synthesizer but adds waveshaping to the waveforms for additional timbral complexity.

Wavetable Synthesizer - A synthesizer which uses samples of instruments for playback but typically does not provide for loading of custom samples. These instruments have MIDI interfaces and are in keyboard, rack mount or desktop formats.

Wavetable sound card (expander) - A sound card with a built in wavetable synthesizer. The sound card has wavetable hardware which plays back the instrument samples, sometimes provide filtering andother functions, as opposed to a software synthesizer which plays back through digital to analog converters. Some wavetable sound cards allow loading of Soundfonts which can provide additional instrument samples.

Wavetable sound card emulation software - Emulates the features of a wavetable sound card, but completely software in implementation except for the final digital to analog conversion stage. Very similar to a software synthesizer.

12 Note Octave Scales A 12 note octave scale means that every twelve notes must repeat the same values. This type of scale can only support 12 notes per octave. The column entry lists the number of scales that can be contained in the instrument's memory and the type of scale assignment. Global assignment means that all instruments being played at the same time will have the same tuning. Per program, instrument, part or patch means that each program, instrument, part or patch can have its own tuning that is different from other programs or patches in the instrument. A part is normally a considered a MIDI channel assignment in Roland GS type synthesizers.

Full Keyboard Scales A Full Keyboard Scale means that all notes of the keyboard can be retuned independently of each other, so that scales of other than 12 notes per octave can be supported. For instance, this type of tuning could have 31 notes per octave. This column lists the number of scales that can be contained in the instrument's memory and the type of scale assignment. Global assignment means that all instruments being played at the same time will have the same tuning. Per program, instrument, part or patch means that each program, instrument, part or patch can have its own tuning that is different from other programs or patches in the instrument. A part is normally a considered a MIDI channel assignment in Roland GS type synthesizers. Equal tempered only means that scales which require unequal spacings between notes such as just intonation cannot be tuned. This restriction normally applies to analog synthesizers due to the method of retuning. Note that many MIDI instruments with "keyboard scaling" have insufficient resolution in the scaling to achieve the desired scales. For instance, you might be able to get 19.25 notes per octave rather than 19 notes per octave because the keyboard scaling is normally limited to only 128 values.

Scale Resolution This column specifies the resolution of each note retuning. For instance, 1 cent means that a note can be tuned +1 cent, +2 cents, + 3 cents, etc. from the normal 12 equal setting of 0 cents, 100 cents, 200 cents, etc.

Tuning Range per Note This column specifies the range that each note can be retuned. For instance, full MIDI means that each note can be retuned freely within the entire MIDI range to the scale resolution of the instrument. This normally applies to full keyboard scales. +/- 100 cents means that the note C could be tuned 100 cents up or down, up to C# or down to B. If an instrument with full keyboard scales is limited to +/- 100 cent tuning then it is realistically limited to 12 note per octave scales.

Scales User Interface This column describes how the tuning may be adjusted by the user to the desired values. Numeric front panel refers to a panel with simple numeric and possibly limited alphanumeric characters, such as a 3 to 4 digit 7 segment LED display, and using buttons for numeric entry . Digital front panel usually refers to a 2x16 or greater character display and buttons as the user interface. Sysex is MIDI System Exclusive which is manufacturer and instrument specific MIDI messages that are often supported by computer based synthesizer patch editors. Mac OS, Windows, Linux, etc. refer to a graphical interface based upon the specified computer operating systems. MTS refers to the MIDI Tuning Standard. SCALA .scl refers to the file format supported by the program SCALA which is a text based file. TUN or .tun refers to the file format originated for the Korg Oasys which is a text based file.

Other Features This column includes any additional notes that could not be covered in the preceeding columns.