Music sequencer

A music 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. (See § Types of music sequencers)^{[note 1]}

Overview

Modern sequencers

1980s typical software sequencer platform, using Atari Mega ST computer.

Today's typical software sequencer, supporting multitrack audio (DAW) and plug-ins (Steinberg Cubase 6^[1])

User interface on Steinberg Cubase v6.0, a digital audio workstation with an integrated software sequencer.

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 sequencers

Music sequencers are often categorized by handling data types, as following:.

• MIDI data on the MIDI sequencers (implemented as hardware or software)^[2]
• CV/Gate data on the analog sequencers^[3] and possibly others (via CV/Gate interfaces)
• Automation data for mixing-automation on the DAWs,^{[note 2][4]} and the software effect / instrument plug-ins on the DAWs with sequencing features
• Audio data on the audio sequencers^{[5][note 3]} including DAW, loop-based music software, etc.; or, the phrase samplers including Groove machines, etc.

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

Realtime sequencer (realtime recording mode)

A realtime sequencer on the synthesizer

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" feature originated in the tape recording is provided, although it requires enough skills to obtain desired result. For detailed editing, possibly another visual editing modes under graphical user interface may be more suitable. Anyway, this mode provides usability similar to the audio recorder already familiarized by musicians, and it is widely supported on software sequencer, DAW, and built-in hardware sequencers.

Analog sequencer

An 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 sequencer is used to generate the repeated minimalistic phrases which is reminiscent of Tangerine Dream, Giorgio Moroder or trance music.

Step sequencer (step recording mode)

A step rhythm sequencer on the drum machine

A step note sequencer on the bass machine

On the step sequencers, musical notes are rounded into the steps of equal time-interval, and users can enter each musical note without exact timing; Instead, each timing and duration of step are designated in several 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 #Step sequencers (supported on).)

In general, step mode, along with roughly quantized semi-realtime mode, is often supported on the analog 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

Numerical editor on Tracker

Score editor

Piano roll editor with strip chart

Audio and MIDI tracks on DAW

Loop sequencer

Sample editor with beat slicer

Vocal editor for pitch and timing

History

Early sequencers

Barrel with pins on a large stationary barrel organ

Music roll
on barrel organ

Player piano (1920) controlled by piano roll.

RCA Mark II (1957),
controlled via wide punched paper roll

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 considerably old. As early as the 9th century, Persian inventors Banū Mūsā brothers invented hydropowered organ using exchangeable cylinders with pins,^[6] and also automatic flute player using steam power,^[7][8] as described on their Book of Ingenious Devices. In the 14th century, rotating cylinder with pins were used to play carillon in Flanders, and at least in the 15th century, barrel organs were seen in the Netherlands.^[9]

In the late-18th or early-19th century, as the results of Industrial Revolution, various automatic musical instruments were invented, for examples: music box, barrel organ and barrel piano using barrel / cylinder with pins or metal disc with punched holes; or mechanical organ, player piano and orchestrion using book music / music rolls (piano rolls) with punched holes, etc. These instruments were widely spread as the popular entertainment devices before the inventions of phonograph, radio, and sound film. Amongst of all, especially the punched tape media had been long lived until the mid-20th century: earliest programmable music synthesizers including RCA Mark II Sound Synthesizer in 1957, and Siemens Synthesizer in 1959, were also controlled via punch tapes similar to piano rolls.^[10][11][12]

Another inventions were came from sound film technology. The drawn sound technique which appeared in the late 1920s, is notable as a precursor of today's intuitive graphical user interfaces. On this technique, notes and various sound parameters were controlled by hand-drawn waves on the films, resembling piano rolls or strip charts on the modern sequencers/DAWs. It was often utilized on early experiments of electronic music, including Variophone developed by Yevgeny Sholpo in 1930, and Oramics designed by Daphne Oram in 1957, etc.

Analog sequencers

Earliest commercially available analog sequencers (front) on Buchla 100 (1964/1966)^[13]

Moog sequencer module (left, probably added after 1968) on Moog Modular (1964)

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.^[14] Later, Robert Moog explained it as "the whole room would go 'clack - clack - clack', and the sounds would come out all over the place".^[15] The Circle Machine, developed in 1959, had dimmer bulbs arranged in a ring, and a rotating arm with photocell scanning over the ring, to generate arbitrary waveform. Also, the rotating speed of arm was controlled via brightness of lights, and as the results, arbitrary rhythms were generated.^[16] And relatively well known 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.^[15]

In 1965 Ralph Lundsten had a polyphonic synthesizer with sequencer called Andromatic. built for him by Erkki Kurenniemi.^[17]

Step sequencers

Electro-mechanical disc sequencer on early drum machine (1959)

Eko ComputeRhythm (1972),^[18][19] one of the earliest programmable drum machines

Firstman SQ-01 (1980),^[20] one of the earliest step bass machines

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.

Computer music

CSIRAC played the earliest computer music in 1951

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.^[21][22] In 1956, Lejaren Hiller at the University of Illinois at Urbana-Champaign wrote one of the earliest programs for computer music composition on ILLIAC, and collaborated on the first piece, Illiac Suite for String Quartet, with Leonard Issaction.^[23] In 1957 Max Mathews at Bell Labs wrote MUSIC, the first widely used program for sound generation, and a 17-second composition was performed by the IBM 704 computer. Subsequently, computer music was mainly researched on the expensive mainframe computers in computer centers, until the 1970s when minicomputers and then microcomputers became available in this field.

Digital sequencers

EMS Sequencer 256 (1971), a branched product of the Synthi 100

Roland MC-8 Microcomposer (1977)

In 1971, Electronic Music Studios (EMS) released one of the first digital sequencer products as a module of Synthi 100, and its derivation, Synthi Sequencer series.^[24][25] After then, Oberheim released the DS-2 Digital Sequencer in 1974,^[26] and Sequential Circuits released Model 800 in 1977 ^[27]

Also in 1977, Roland Corporation released their first microprocessor-based digital sequencer, MC-8 Microcomposer, also called computer music composer by Roland.^[28] It equipped a keypad to enter notes as numeric codes, 16KB RAM for a maximum of 5200 notes (large at the time), and a polyphony function which allocated multiple pitch CVs to a single Gate.^[29] The earliest known user was Yellow Magic Orchestra in 1978.

Software sequencers

Synclavier I (1977)

Fairlight CMI (1979)

In 1975, New England Digital (NED) released ABLE computer (microcomputer)^[30] as a dedicated data processing unit for Dartmouth Digital Synthesizer (1973), and based on it, later Synclavier series were developed. The Synclavier I, released in September 1977,^[31] was one of the earliest digital music workstation product with multitrack sequencer. Synclavier series evolved throughout the late-1970s to the mid-1980s, and they also established integration of digital-audio and music-sequencer, on their Direct-to-Disk option in 1984, and later Tapeless Studio system.

Page R on Fairlight

Tracker software

In 1980, renewed Fairlight CMI Series II with its sequencer, "Page R", combined step sequencing with sample playback. In 1987, this led to the development of similar software sequencers of this kind, called Trackers, which became popular in the 1980s and 1990s as simple sequencers for creating computer game music, and are yet popular in the demoscene and chiptunes.

Visual timeline of rhythm sequencers

Mechanical (pre 20c)

Rhythmicon (1930)

Drum machine (late 1950s–)

Transistorized drum machine (mid-1960s)

Step drum machine (1972–)

Digital drum machine (1980–)

“Page R” on Fairlight (c.1980)

Groove machine (mid-1980s–)

Tracker (1987–)

Beat slicer (1990s–)

Spectrogram editing (1994)

Loop sequencer (1998–)

Note manipulation on audio tracks (2009–)

Hardware sequencers

Many synthesizers, and by definition all music workstations, groove machines and drum machines, contain their own sequencers.

The following are specifically designed to function primarily as the music sequencers:

Rotating object with pins or holes

• Barrel or cylinder with pins (since 9th or 14th century) — utilized on barrel organs, carillons, music boxes
• Metal disc with punched holes (late 18th century) — utilized on several music boxes such as Polyphon, Regina, Symphonion, Ariston, Graphonola (early version), etc.

Punched paper

• Book music (since 1890) for pneumatics system — utilized on several mechanical organs
• Music roll for pneumatics system — utilized on player pianos (using piano rolls), Orchestrions, several mechanical organs, etc.
• Punch tape system for earliest studio synthesizers
  • RCA Mark II Sound Synthesizer by Herbert Belar and Harry Olson at RCA, a room-filling device built in 1957 for half a million dollars. Included a 4-polyphony synth with 12 oscillators, a sequencer fed with wide paper tape, and output were recorded on a shellac record lathe
  • Siemens Synthesizer (1959) at Siemens-Studio für elektronische Musik^[11][12]

Sound-on-film

Oramics (1957) controls sounds by graphics on films

• Variophone (1930) by Evgeny Sholpo—on earliest version, hand drawn waves on film or disc were used to synthesize sound, and later versions were promised to experiment on musical intonations and temporal characteristics of live music performance, however not finished. Variophone is often referred as a forerunner of drawn sound system including ANS synthesizer and Oramics.
• Composer-Tron (1953) by Osmond Kendal—rhythmical sequences were controlled via marking cue on film, while timbre of note or envelope-shape of sound were defined via hand drawn shapes on a surface of CRT input device, drawn with a grease pencil.^[32]
• ANS synthesizer (1938-1958) by Evgeny Murzin—an earliest realtime additive synthesizer using 720 microtonal sine waves (1/6 semitones × 10 octaves) generated by five glas discs. Composers could control time evolution of amplitudes of each microtones via scratches on glass plate user interface covered with black mastic.
• Oramics (1957) by Daphne Oram—hand drawn contours on a set of ten sprocketed synchronized strips of 35 film were used to control various parameters of monophonic sound generator (frequency, timbre, amplitude and duration).^[33] Polyphonic sounds were obtained using multitrack recording technique.

Electro-mechanical sequencers

Wurlitzer Sideman (1959)

• Wall of Sound (mid-1940s–1950s) by Raymond Scott—early electro-mechanical sequencer developed by Raymond Scott to produce rhythmic patterns, consistent with stepping relays, solenoids, and tone generators^[14]
• Circle Machine (1959) by Raymond Scott—electro-optical rotary sequencer developed by Raymond Scott to generate arbitrary waveforms, consistent with dimmer bulbs arranged in a ring, and a rotating arm with photocell scanning over the ring^[16]
• Wurlitzer Sideman (1959)—first commercial drum machine; rhythm patterns were electro-mechanically generated by rotating disk switches, and drum sounds were electronically generated by vacuum-tube circuits^[34]

Analog sequencers

Analog sequencers with CV/Gate interface

Moog 960 Sequential Controller and 962 Sequential Switch

• Buchla 100's sequencer modules (1964/1966–)

  One of the earliest analog sequencer on the modular synthesizer era since 1960. Later, Robert Moog admired Buchla's unique works including it^[13]

• Moog 960 Sequential Controller^[35] / 961 Interface^[36] / 962 Sequential Switch^[37] (c.1968)^[38]

  A popular analog sequencer module for the Moog modular synthesizer system, following the earliest Buchla sequencer

• Doepfer Dark Time
• genoQs Octopus
• genoQs Nemo
• Korg SQ-10
• MFB Urzwerg / MFB Urzwerg Pro—CV/Gate step sequencer with 8steps/4tracks or 16steps/2tracks; also synchronizable with MIDI sequencer^[39][40]
• Serge Modular TKB
• Synthesizers.com Q119
• Synthesizers.com Q960—reissue of Moog 960
• Yamaha CS30 (1977)—monophonic synthesizer keyboard with built-in 8-step analog sequencer

Analog-style step sequencers

Analog-style MIDI step sequencers

Since the analog synthesizer revivals in the 1990s, newly designed MIDI sequencers with a series of knobs or slider similar to analog sequencer have appeared. These often equip CV/Gate and DIN sync interface along with MIDI, and even the patch memory for multiple sequence patterns and possibly song sequence. These analog-digital hybrid machines are often called "Analog-style MIDI step sequencer" or "MIDI analog sequencer", etc.

Quasimidi Polymorph (1999) has built-in step sequencer with a series of value knobs (bottom)

• Doepfer MAQ 16/3—MIDI analog sequencer, designed in cooperation with Kraftwerk
• Doepfer Regelwerk—MIDI analog sequencer with MIDI controller
• Frostwave Fat Controller
• Infection Music Phaedra
• Infection Music Zeit
• Latronic Notron
• Manikin Schrittmacher
• Quasimidi Polymorph (1999)—Four-part multitimbral tabletop synthesizer, with an analog-like step sequencer
• Roland EF-303—Multiple effects unit with 16-step modulation, also usable as the analog-style MIDI step sequencer^[41]
• Sequentix P3

Analog-style MIDI pattern sequencers

Several machines also provide the song mode to play the sequence of memoried patterns in specified order, as on drum machine.

• Doepfer Schaltwerk—MIDI pattern sequencer

Step sequencers (supported on)

Typical step sequencers are integrated on drum machines, bass machines, groove machines, music production machines, and these software versions. Often, these also support the semi-realtime recording mode, too.

• MFB Step 64—Standalone step sequencer dedicated for drum patterns (16steps/4tracks or 64steps/1tracks, 118program×4banks, 16song sequences, each with up to 128 sequences)^[42]

Embedded self-contained step sequencers

Casio VL-Tone VL-1

Casio Sampletone SK-1

Several tiny keyboards provide a step sequencer combined with an independent timing mode for recording and performance:

• Casio VL-Tone VL-1 (1979), Casiotone MT-70 (c.1984), Sampletone SK-1 (1986), etc.—Timings of musical notes stored on the step sequencer, can be designated by the two trigger buttons labeled "One Key Play", around the right hand position

Embedded CV/Gate step sequencers

Several machines have white and black chromatic keypads, to enter the musical phrases.

• Multivox / Firstman SQ-01 (1980)—a forerunner of TB-303
• Roland TB-303 (1981)
• Roland SH-101 (1982)—monophonic keytar synthesizer with sequencer
• Roland MC-202 (1983)—monophonic tabletop synthesizer with sequencer, similar to MC-101

Embedded MIDI step sequencers

Groovebox-type machines with white and black chromatic keypads, often support step recording mode along with realtime recording mode:

Korg Electribe series Roland Corporation MC series: MC-09 / MC-303 / MC-505 / MC-808 / MC-909

Yamaha RM1x Yamaha RS7000—Music Production Studio

Other groovebox-type machines (including several music production machines) also often support step recording mode, of course:

Linn 9000 (1984) Sequential Circuits Studio 440 (1986) E-mu SP-12 (1986) E-mu SP-1200 (1987) Akai MPC series (1988–)

Akai MPC Renaissance / Studio / Fly (2012)—Software with control surfaces Native Instruments Maschine (2009)—Software with control surface Roland MV-30 Roland MV-8000—Production Studio

Button-grid-style step sequencers

Recently emerging button-grid-style interfaces/instruments are naturally support step sequence. On these machines, one axis on grid means musical scale or sample to play, and another axis means timing of notes.

Tenori-on

• Akai APC40—interface for Ableton Live
• Arduinome—interface
• Bliptronics 5000—instrument
• Monome—interface
• Novation Launchpad—interface for Ableton Live
• Yamaha Tenori-on—instrument

In addition, newly designed hardware MIDI sequencers equipping a series of knobs/sliders similar to analog sequencers, are appeared. For details, see #Analog-style MIDI step sequencers.

Digital sequencers

CV/Gate

Also often support Gate clock and DIN sync interfaces.

EDP Spider (late 1970s)—supported LINK and CV/Gate EMS Sequencer series (1971) Max Mathews GROOVE system (1970) Multivox MX-8100 / Firstman SQ-10 (1979/1980)—supported V/Oct. and Hz/V Oberheim DS-2 (1974)

Roland CSQ-100 Roland CSQ-600 (1980)—it memories 600 notes for individual 4 tracks,[43] a buddy of TR-808 Roland MC-4 Microcomposer (1981) Roland MC-8 Microcomposer (1977)—also supporting DCB via OP-8 Sequential Circuits Model 800 (1977)

Proprietary digital interfaces (pre MIDI era)

• NED Synclavier series—CV/Gate interface and MIDI retrofit kit were available on Synclavier II. Also MIDI became standard feature on Synclavier PSMT^[44][45]
• Fairlight CMI series—CV/Gate interface was optionally available on Series II, and MIDI was supported on Series IIx and later models
• Oberheim DSX (Oberheim Parallel Bus)
• PPG Wave family (PPG Bus)
• Rhodes Chroma (Chroma Computer Interface)^[46]
• Roland JSQ-60 (Roland Digital Control Bus (DCB))
• Sequential Circuits PolySequencer 1005 (SCI Serial Bus)
• Yamaha CS70M (Key Code Interface)^[47]

Hardware MIDI sequencers

Standalone MIDI sequencers

Akai ASQ10 Alesis MMT-8—a buddy of HR-16 drum machine Korg SQD-1 Korg SQD-8 Kawai Q-80 Roland MC-327

Roland MC series: MC-50/MC-50MkII/MC-80/MC-300/MC-500 Microcomposer Roland MSQ-100 (1985) Roland MSQ-700 (1984)—one of the earliest multitrack MIDI sequencer (8tr),[48] a buddy of TR-909 Roland SB-55—SMF recorder Yamaha QX series: QX1/QX3/QX5/QX7/QX21

MIDI phrase sequencers

• Zyklus MPS

Embedded MIDI sequencers

• Sequential Circuits Six-Track (1984, see top), MultiTrak (1985), Split-8 / Pro-8 (1985)

MIDI sequencers with embedded sound module

• Yamaha TQ5—desktop version of EOS YS200 FM workstation
• Yamaha QY300—with embedded sound module
• Yamaha QY700—with embedded sound module

Palmtop MIDI sequencers

Yamaha QY70

• Korg SQ-8—palmtop sequencer
• Philips Micro Composer PMC100
• Roland PMA-5—palmtop sequencer with touch screen
• Yamaha Walkstation series: MU5/MU10/MU15/QY8/QY10/QY20/QY22/QY70/QY100—palmtop sequencer with embedded sound module

Accompaniment machines

Boss DR-5

Yamaha QR10

• Boss DR-5 Dr.Rhythm Section
• Yamaha QR10 Musical Accompaniment Player

Open-source hardware

• MIDIbox Sequencer modules—Analog-style MIDI step sequencer/MIDI effect processor modules of MIDIbox project

Software sequencers and DAWs with sequencing features

Free, open source

Scorewriters

• MuseScore—Linux, Windows, OS X

DAW with MIDI sequencers

• Ardour—Linux, OS X, FreeBSD
• LMMS—Linux, Windows
• MusE—Linux
• Qtractor—Linux
• Rosegarden—Linux
• Auxy: Beat Studio—iOS 7

Drum machines

• Hydrogen—Linux, OS X

Commercial

Software MIDI sequencers

• B-Step Sequencer from Monoplugs
• Master Tracks Pro from Passport Music Software

Loop-oriented DAWs with MIDI sequencers

• ACID Pro and Cinescore from Sony Creative Software
• Live from Ableton
• GarageBand from Apple
• REAPER from Cockos
• Tracktion from Mackie

Tracker-oriented DAWs with MIDI sequencers

• Renoise

DAWs with MIDI sequencers

• Ableton Live from Ableton
• Cubase and Nuendo from Steinberg
• Digital Performer from MOTU
• REAPER from Cockos
• FL Studio from Image Line Software
• Logic Pro and Logic Express from Apple
• Mixcraft from Acoustica
• Orion Platinum from Synapse Audio
• Pro Tools from Avid
• Samplitude, Sequoia, Music Maker and Music Studio from Magix
• Sonar and Home Studio from Cakewalk
• Studio One from PreSonus
• Podium from Zynewave (gratis)
• Z-Maestro from Z-Systems

Integrated software studio environments

• Reason and Record from Propellerhead
• Storm from Arturia

See also

• Groovebox
• Music workstation
• Tracker (music software)
• Combination action#Sequencers (for organs)
• List of music software

Notes

1. On WhatIs.com of TechTarget (whatis.techtarget.com), an author seems to define a term "Sequencer" as an abbreviation of "MIDI sequencer".
   • Margaret Rouse (April 2005). "Define sequencer". WhatIs.com (whatis.techtarget.com). TechTarget. In digital audio recording, a sequencer is a program in a computer or stand-alone keyboard unit that puts together a sound sequence from a series (or sequence) of Musical Instrument Digital Interface ( MIDI ) events (operations). The MIDI sequencer allows the user to record and edit a musical performance without using an audio-based input source. ...
2. Automation parameters on the DAW are often interoperable with MIDI messages (control changes (CC) or 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 Price 2006)
3. 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.

References

1. "Cubase 6 screenshot licensed under CC-BY-SA-3.0". Steinberg Media Technologies GmbH.
2. Rothstein, Joseph (1995). MIDI: A Comprehensive Introduction. Computer Music and Digital Audio Series 7. A-R Editions, Inc. pp. 77, 122. ISBN 978-0-89579-309-6.
3. Pinch, Trevor. J.; Trocco, Frank (2009). "Buchla's Box". Analog Days: The Invention and Impact of the Moog Synthesizer (reprint ed.). Harvard University Press. pp. 55-56. ISBN 978-0-674-04216-2.
   "Subotnick suggested that using a light source to control sound might be promising. ... Later he [Buchla] turned 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 recylce ..."
   Note: for a sequencer using a light source, see "Circle Machine" on #Analog sequencers and Raymond Scott#Electronics and research.
4. Price, Simon. "Using Mixer Automation In Reason - Reason Tips & Techniques". Technique: Reason Notes. Sound On Sound. No. September 2006.
   "Controller Data Vs. Automation / ... sequencer package such as Logic or Pro Tools, ... are akin to automation on professional hardware mixing consoles, ... This type of automation system is different to using MIDI Continuous Controller [Control Changes] (CC) data, ... In Reason, automation is MIDI Controller [Control Changes] data, but with some specialised tools for handling the data and playing it back. ...",
   "Recording Mixer Automation / As automation in Reason is MIDI CC data, it must be recorded on a sequencer track."
5. Pejrolo, Andrea (2011). "1.7.1 The Primary Goals You Want to Achieve with Your Audio Sequencer". Creative Sequencing Techniques for Music Production: A Practical Guide to Pro Tools, Logic, Digital Performer, and Cubase. Taylor & Francis. p. 48. ISBN 978-0-240-52216-6. (sub-section title contains the expression "Audio Sequencer")
6. Fowler, Charles B. (October 1967). "The Museum of Music: A History of Mechanical Instruments". Music Educators Journal (Music Educators Journal) 54 (2): 45–49. doi:10.2307/3391092. JSTOR 3391092.
7. Koetsier, Teun (2001). "On the prehistory of programmable machines: musical automata, looms, calculators". Mechanism and Machine Theory (Elsevier) 36 (5): 589–603. doi:10.1016/S0094-114X(01)00005-2.
8. Banu Musa (authors) (1979). Donald Routledge Hill (translator), ed. The book of ingenious devices (Kitāb al-ḥiyal). Springer. pp. 76–7. ISBN 9027708339.
9.  Chisholm, Hugh, ed. (1911). "Barrel-organ". Encyclopædia Britannica (11th ed.). Cambridge University Press.
10. "The RCA Synthesiser". 120 Years of Electronic Music (120years.net).—(PDF version is available)
11. "Das Siemens-Studio für elektronische Musik von Alexander Schaaf und Helmut Klein" (in German). Deutsches Museum.
12. Holmes, Thom (2012). "Early Synthesizers and Experimenters". Electronic and Experimental Music: Technology, Music, and Cluture (4th ed.). Routledge. pp. 190–192. ISBN 978-1-136-46895-7. (See also excerpt of pp. 157–160 from Holmes 2008)
13. Holmes, Thom (2008). Electronic and experimental music: technology, music, and culture (3rd ed.). Routledge. p. 222. ISBN 978-0-415-95781-6, ISBN 978-1-135-90617-7. Moog admired Buchla's work, recently stating that Buchla designed a system not only for "making new sounds but [for] making textures out of these sounds by specifying when these sounds could change and how regular those change would be."
14. "Wall of Sound (sequencer)". RaymondScott.com.
15. Robert Moog. "Memories of Raymond Scott". RaymondScott.com.
16. "Circle Machine". RaymondScott.com.—includes 2 sound files: Raymond Scott's demonstration, and commercial soundtrack for new batteries of Ford Motors.
17. Jörgen Städje (2012-10-06). "Andromatic, den automatiska andromedaren". International Data Group (IDG).
18. "EKO Computerhythm (1972)". Jarrography - The ultimate Jean Michel Jarre discography.
19. "EKO Computerhythm". SynthMaster.de.
20. "Multivox International". SYNRISE (in German). Archived from the original on 2003-04-20.
21. "CSIRAC: Australia's first computer". Australia: Commonwealth Scientific and Industrial Research Organisation (CSIRO). Retrieved 2007-12-21.
22. Fildes, Jonathan (2008-06-17). "'Oldest' computer music unveiled". BBC News Online. Retrieved 2008-06-18.—another oldest known recording of computer realized music played by the Ferranti Mark 1, captured by BBC in Autumn, 1951; the songs Baa Baa Black Sheep and In the Mood.
23. Hiller, Lejaren (Winter 1981). "Composing with Computer: A Progress Report". Computer Music Journal 5 (4).
    also available in Curtis Roads (ed.). The Music Machine: Selected Readings from Computer Music Journal. MIT Press (1989/1992). pp. 75. ISBN 978-0-262-68078-3.
24. Hinton, Graham (2001). "Synthi 100 (1971, formerly Digitana, aka the Delaware)". Electronic Music Studios (Cornwall).
25. Hinton, Graham (2001). "Synthi Sequencer 256 (1971, formerly Synthi Moog Sequencer)". Electronic Music Studios (Cornwall).
26. J.Michmerhuizen (Boston School of Electronic Music); Thomas E. Oberheim (Oberheim Electronics) (June 1974). DS-2 Digital Sequencer Instruction and Service Manual (PDF). Cite uses deprecated parameter |coauthor= (help)
27. "Model 800 Sequencer". SynthMuseum.com.
28. Russ, Martin (2008). Sound Synthesis and Sampling. Focal Press. p. 346. ISBN 0240521056. Retrieved 21 June 2011.
29. Gordon Reid. "The History Of Roland Part 1: 1930-1978". Sound On Sound (Nov 2004). Retrieved 2011-06-19.
30. "Synclavier Early History". Synclavier European Services.
31. Joel Chadabe (May 1, 2001). "The Electronic Century Part IV: The Seeds of the Future". Electronic Musician. In September 1977, I bought the first Synclavier, although mine came without the special keyboard and control panel ... (see Fig. 1 on the page).
32. "The Composer-Tron (1953)". 120 Years of Electronic Music (120years.net).
33. "Daphne Oram and 'Oramics' (1959)". 120 Years of Electronic Music (120years.net).
34. US patent 3,207,835, Howard E. Holman and Joseph H. Hearne (Wurlitzer Company), "Rhythm Device", issued 1965-09-21 
35. "Moog 960 Sequential Controller". MoogArchives.com.—3×8-step sequencer module
36. "Moog 961 Interface". MoogArchives.com.—interface module to convert several signal types including audio input, V-trigger (CV), and S-trigger (short-to-ground trigger for Envelope Controller)
37. "Moog 962 Sequential Switch". MoogArchives.com.—switching module for 960 to convert 3x8-step sequence into 1x24-step sequence, etc.
38. "Synthesizer 2C with optional 960 and 961 - 1968 Modular System "Synthesizer 2"". MoogArchives.com.—On the MoogArchives.com, the photograph with caption "Synthesizer 2C with optional 960 and 961" on this page seems to be the earliest record of Moog's sequencer module.
39. MFB-URZWERG, MFB Musik Elektronik
40. MFB-URZWERG Pro, MFB Musik Elektronik
41. Roland EF-303 Groove Effects - Owner's manual (PDF), Roland Corporation, pp. 48, 53, 54
42. Sequencer MFB-STEP64, MFB Musik Elektronik
43. "SM0600 Project - A Digital Sequencer - Rebuilding the Roland CSQ-700". Emulator Archive.
44. Brandon Amison (17 Jul 1999). "Yaking Cat Music Studios QAQA answers - Subject:0033 Re:Clothing ETC.". Yaking Cat Music Studios (Synclavier Assistance).
45. Furia, Steve De; Joe Scacciaferro (1986). The MIDI implementation book. Third Earth Pub. p. 25. ISBN 978-0-88188-558-3.—MIDI Implementation Chart of Synclavier MIDI Option v0.9 in 1985.
46. Williams, Tonny (January 24, 1984), Rhodes Keyboards Instruments Chroma Computer Interface Model 1611 Rev 5—Sequencer Manual (PDF), CBS Inc.
47. "External Key Code Interface Circuit", Yamaha CS70M Servicing Manual (PDF), Yamaha Corporation, October 1981, p. 24
48. "AM MSQ700 Nexus - MIDI Sequencer". Emulator Archive.

Further reading

List of papers sharing a similar perspective with this Wikipedia article:

• Arar, Raphael; Kapur, Ajay (2013). "A History of Sequencers: Interfaces for Organizing Pattern-Based Music" (PDF). Proceedings of the Sound and Music Computing Conference 2013 (SMC 2013), Stockholm, Sweden. Archived from the original (PDF) on 2015-04-02.
  Note: "Ace Tone FR-1 Rhythm Ace" emphasized on this conference paper is not a music sequencer nor first drum machine product.

External links

• "History of electronic musical instruments and sequencers". 120 Years of Electronic Music (120years.net).
• "Early sequencer controllers". Vintage Synth Explorer.
• Richmond, Leigh (11 November 1974). "Computer hums its own music". Evening Times (Melbourne, FL). p. A1. (1974 newspaper article about digital sequencer)