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. Some sequencers can also handle audio and automation data for digital audio workstations (DAWs) and plug-ins.
Overview
Modern sequencers
The advent of Musical Instrument Digital Interface (MIDI) 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. 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 (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. The market demand for standalone hardware MIDI sequencers 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 for MIDI sequencers CV/Gate data for analog sequencers Automation data for mixing-automation in DAWs, and software effect or instrument plug-ins for DAWs with sequencing features Audio data in audio sequencers including DAWs, loop-based music software, etc.; or phrase samplers including grooveboxes, etc. Also, a music sequencer can be categorized by its construction and supported modes.
Analog sequencer
Analog sequencers are typically implemented with analog electronics, and play the musical notes designated by a series of knobs or sliders for adjusting the note corresponding to each step in the sequence. It is designed for both composition and live performance; users can change the musical notes at any time without regard to recording mode. The time interval between each musical note (length of each step) may be independently adjustable. Typically, analog sequencers are used to generate 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 keypad, then select a step duration (or tie) from a group of length-buttons, sequentially. On the several home keyboards: in addition to the real-time sequencer, a pair of step trigger buttons is provided; using it, notes on the pre-recorded sequence can be triggered in arbitrary timings for the timing dedicated recordings or performances. In general, step mode, along with roughly quantized semi-realtime mode, is often supported on the drum machines, bass machines and several groove machines.
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, often punch in/out features originating in tape recording workflows are provided. This mode is widely supported on software sequencers, DAWs, and built-in hardware sequencers.
Software sequencer
A software sequencer is application software providing the functionality of a music sequencer, and often provided as one feature of the DAW or the integrated music authoring environments. The user may control the software sequencer either by using the graphical user interfaces or a specialized input devices, such as a MIDI controller.
Audio sequencer Alternative subsets of audio sequencers include:
History
Early sequencers
The early music sequencers were sound-producing devices such as 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. 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 as, among the four automated musicians, were two drummers. The drum machine used pegs on cams to bump into levers that operated the percussion. The drummers could be made to play different rhythms and different drum patterns if the pegs were moved around. 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.
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