MIDI Sequences

A music sequencer (or audio sequencer or simply sequencer) is a device or application software that can record, edit, or play back music, by handling note and performance information in several forms, typically CV/Gate, MIDI, or Open Sound Control (OSC), and possibly audio and automation data for DAWs and plug-ins.
On WhatIs.com of TechTarget (whatis.techtarget.com), an author seems to define a term "Sequencer" as an abbreviation of "MIDI sequencer".
* Note: an example of section title containing "''Audio Sequencer''"

Overview

Modern sequencers

The advent of Musical Instrument Digital Interface (MIDI) and the Atari ST home computer in the 1980s gave programmers the opportunity to design software that could more easily record and play back sequences of notes played or programmed by a musician. This software also improved on the quality of the earlier sequencers which tended to be mechanical sounding and were only able to play back notes of exactly equal duration. Software-based sequencers allowed musicians to program performances that were more expressive and more human. These new sequencers could also be used to control external synthesizers, especially rackmounted sound modules, and it was no longer necessary for each synthesizer to have its own devoted keyboard.

As the technology matured, sequencers gained more features, such as the ability to record multitrack audio. Sequencers used for audio recording are called digital audio workstations (or DAWs).

Many modern sequencers can be used to control virtual instruments implemented as software plug-ins. This allows musicians to replace expensive and cumbersome standalone synthesizers with their software equivalents.

Today the term "sequencer" is often used to describe software. However, hardware sequencers still exist. Workstation keyboards have their own proprietary built-in MIDI sequencers. Drum machines and some older synthesizers have their own step sequencer built in. There are still also standalone hardware MIDI sequencers, although the market demand for those has diminished greatly due to the greater feature set of their software counterparts.

Types of music sequencer

Music sequencers can be categorized by handling data types, such as:
* MIDI data on the MIDI sequencers (implemented as hardware or software)

* CV/Gate data on the analog sequencers

"Subotnick suggested that using a light source to control sound might be promising. ... Later he uchlaturned this into an electro mechanical sequencer by introducing step relays and a dial. ... Buchla, like Moog, realized that voltage control ... But Buchla was after something different; ... Buchla was led to the electronic sequencer—a device that later was used to make much influential pop, rock, and dance music. A sequencer produces predetermined control voltages in a cycle or sequence and can endlessly recycle ..."

Note: for a sequencer using a light source, see "Circle Machine" on #Analog sequencers and Raymond Scott#Electronics and research. and possibly others (via CV/Gate interfaces)
* Automation data for mixing-automation on the DAWs,
Automation parameters on the DAW are often interoperable with MIDI messages (Control Changes (CC) or System Exclusive (SysEx); in that case, it can be controlled in real-time via pre-assigned MIDI messages generated by MIDI controllers or MIDI sequencers, ''etc''.   And even more, on the several DAWs, automation parameters are explicitly recorded as MIDI messages on their embedded MIDI sequencers. (See )
and the software effect /  instrument plug-ins on the DAWs with sequencing features
* Audio data on the audio sequencers
(sub-section title contains the expression "''Audio Sequencer''")

The term "audio sequencer" seems to be relatively new expression and seems to be not clearly defined, yet. For example, "DAW integrated with MIDI sequencer" is often referred as "Audio and MIDI sequencer". However, in this usage, the term "audio sequencer" is just a synonym for the "DAW", and beyond the scope of this article. In that case, please check Digital audio workstation.
including DAW, loop-based music software, etc.; or, the phrase samplers including Groove machines, etc.

Alternative subsets of audio sequencers include:

Also, music sequencer can be categorized by its construction and supporting modes.

Realtime sequencer (realtime recording mode)

Realtime sequencers record the musical notes in real-time as on audio recorders, and play back musical notes with designated tempo, quantizations, and pitch. For editing, usually " punch in/punch out" features originated in the tape recording are provided, although it requires sufficient skills to obtain the desired result. For detailed editing, possibly another visual editing mode under graphical user interface may be more suitable. Anyway, this mode provides usability similar to audio recorders already familiar to musicians, and it is widely supported on software sequencers, DAWs, and built-in hardware sequencers.

Analog sequencer

Analog sequencers are typically implemented with analog electronics, and play the musical notes designated by a series of knobs or sliders corresponding to each musical note (step). It is designed for both composition and live performance; users can change the musical notes at any time without regarding recording mode. And also possibly, the time-interval between each musical note (length of each step) can be independently adjustable. Typically, analog sequencers are used to generate the repeated minimalistic phrases which may be reminiscent of Tangerine Dream, Giorgio Moroder or trance music.

Step sequencer (step recording mode)

On step sequencers, musical notes are rounded into steps of equal time-intervals, and users can enter each musical note without exact timing; instead, the timing and duration of each step can be designated in several different ways:
* On the drum machines: select a trigger timing from a row of step-buttons.
* On the bass machines: select a step note (or rest) from a chromatic keypads, then select a step duration (or tie) from a group of length-buttons, sequentially.
* On the several home keyboards:in addition to the realtime sequencer, a pair of step trigger button is provided; using it, notes on the pre-recorded sequence can be triggered in arbitrary timings for the timing dedicated recordings or performances. (''See List of music sequencers#Step sequencers (supported on).'')

In general, step mode, along with roughly quantized semi-realtime mode, is often supported on the drum machines, bass machines and several groove machines.

Software sequencer

Software sequencer is a class of application software providing a functionality of music sequencer, and often provided as one feature of the DAW or the integrated music authoring environments. The features provided as sequencers vary widely depending on the software; even an analog sequencer can be simulated. The user may control the software sequencer either by using the graphical user interfaces or a specialized input devices, such as a MIDI controller.

Typical features on software sequencers

History

Early sequencers

The early music sequencers were sound producing devices such as automatic musical instruments, music boxes, mechanical organs, player pianos, and Orchestrions. Player pianos, for example, had much in common with contemporary sequencers. Composers or arrangers transmitted music to piano rolls which were subsequently edited by technicians who prepared the rolls for mass duplication. Eventually consumers were able to purchase these rolls and play them back on their own player pianos.

The origin of automatic musical instruments seems remarkably old. As early as the 9th century, the Persian (Iranian) Banū Mūsā brothers invented a hydropowered organ using exchangeable cylinders with pins, and also an automatic flute playing machine using steam power,

as described in their ''Book of Ingenious Devices''. The Banu Musa brothers' automatic flute player was the first programmable music sequencer device, and the first example of repetitive music technology, powered by hydraulics.

In 1206, Al-Jazari, an Arab engineer, invented programmable musical automata, a "robot band" which performed "more than fifty facial and body actions during each musical selection." It was notably the first programmable drum machine. Among the four automaton musicians were two drummers. It was a drum machine where pegs (cams) bump into little levers that operated the percussion. The drummers could be made to play different rhythms and different drum patterns if the pegs were moved around.Noel Sharkey
A 13th Century Programmable Robot (Archive)
University of Sheffield.

In the 14th century, rotating cylinders with pins were used to play a carillon (steam organ) in Flanders, and at least in the 15th century, barrel organs were seen in the Netherlands.

In the late-18th or early-19th century, with technological advances of the Industrial Revolution various automatic musical instruments were invented. Some examples: music boxes, barrel organs and barrel pianos consisting of a barrel or cylinder with pins or a flat metal disc with punched holes; or mechanical organs, player pianos and orchestrions using book music / music rolls ( piano rolls) with punched holes, etc. These instruments were disseminated widely as popular entertainment devices prior to the inventions of phonographs, radios, and sound films which eventually eclipsed all such home music production devices.
Of them all, punched-paper-tape media had been used until the mid-20th century. The earliest programmable music synthesizers including the RCA Mark II Sound Synthesizer in 1957, and the Siemens Synthesizer in 1959, were also controlled via punch tapes similar to piano rolls.
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See also excerpt from pp. 157-160 i
Chapter 6
of ''Early Synthesizers and Experimenters''.

Additional inventions grew out of sound film audio technology. The drawn sound technique which appeared in the late 1920s, is notable as a precursor of today's intuitive graphical user interfaces. In this technique, notes and various sound parameters are triggered by hand-drawn black ink waveforms directly upon the film substrate, hence they resemble piano rolls (or the 'strip charts' of the modern sequencers/DAWs). Drawn soundtrack was often used in early experimental electronic music, including the Variophone developed by Yevgeny Sholpo in 1930, and the Oramics designed by Daphne Oram in 1957, and so forth.

Analog sequencers

During the 1940s–1960s, Raymond Scott, an American composer of electronic music, invented various kind of music sequencers for his electric compositions. The "Wall of Sound", once covered on the wall of his studio in New York during the 1940s–1950s, was an electro-mechanical sequencer to produce rhythmic patterns, consisting of stepping relays (used on dial pulse telephone exchange), solenoids, control switches, and tone circuits with 16 individual oscillators.

Later, Robert Moog would explain it in such terms as "the whole room would go 'clack - clack - clack', and the sounds would come out all over the place".
The Circle Machine, developed in 1959, had incandescent bulbs each with its own rheostat, arranged in a ring, and a rotating arm with photocell scanning over the ring, to generate an arbitrary waveform. Also, the rotating speed of the arm was controlled via the brightness of lights, and as a result, arbitrary rhythms were generated.
—includes 2 sound files: Raymond Scott's demonstration, and commercial soundtrack for new batteries of Ford Motors.

The first electronic sequencer was invented by Raymond Scott, using thyratrons and relays.

Clavivox, developed since 1952, was a kind of keyboard synthesizer with sequencer. On its prototype, a theremin manufactured by young Robert Moog was utilized to enable portamento over 3-octave range, and on later version, it was replaced by a pair of photographic film and photocell for controlling the pitch by voltage.

In 1968 Ralph Lundsten and Leo Nilsson had a polyphonic synthesizer with sequencer called Andromatic built for them by Erkki Kurenniemi.

Step sequencers

The step sequencers played rigid patterns of notes using a grid of (usually) 16 buttons, or steps, each step being 1/16 of a measure. These patterns of notes were then chained together to form longer compositions. Sequencers of this kind are still in use, mostly built into drum machines and grooveboxes. They are monophonic by nature, although some are multi-timbral, meaning that they can control several different sounds but only play one note on each of those sounds.

Early computers

On the other hand, software sequencers were continuously utilized since the 1950s in the context of computer music, including computer-''played'' music (software sequencer), computer-''composed'' music (music synthesis), and computer ''sound generation'' (sound synthesis). In June 1951, the first computer music ''Colonel Bogey'' was played on CSIRAC, Australia's first digital computer.—another oldest known recording of computer realized music played by the Ferranti Mark 1, captured by BBC
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