Sequencing


The idea of recording a musical performance isn’t new. Fairground organs, orchestrions, player pianos and musical boxes used rolls, cards, drums and discs long before audio recording was invented. Despite modern technology, the principles remain unchanged: sequencing records a musician’s performance (the notes and their timing), not the actual sound of the music. Before the invention of the phonograph and the gramophone, this was the only way to record anything.

Mechanical Sequencers

Digital sequencing began with the clockwork musical box, a development of the striking clock. This usually contained a rotating cylinder whose tooled projections struck a comb-like metal plate. During the nineteenth century punched metal disks, paper rolls and cards were used extensively. Punched cards, for example, were used in weaving and lace-making. But the most popular application was the pianola or player piano, mainly because few people could actually play an instrument. Today, some of these rolls and cards constitute the only true record of how music was played in Victorian times.

Similar technology was used in the barrel-organ, containing a pin-studded cylinder turned by hand and coupled to mechanisms that opened organ pipes and struck metal tongues. This idea was further developed into the steam-powered fairground organ, which generated a huge range of sounds, whilst the orchestrion was designed to imitate the sounds of an entire orchestra. Unfortunately, nineteenth-century technology lacked electronics. This meant, for example, that Charles Babbage’s incredibly advanced calculating machines, although feasible in theory, couldn’t be created in practice.

Punched paper and cards were still used in computers of the sixties and seventies, some early mainframe machines being programmed via teletype machines and punched paper tape. Cards were frequently programmed by means of a crude form of hand-puncher, often involving obscure key combinations for certain characters. The most common card was the Hollerith card, as invented by Herman Hollerith (1860-1929) and originally used in the US census of 1890. In its modern form it eventually had 12 rows and 80 columns of possible hole locations. This heritage exists today, as text formatted with 80 characters per line. Hollerith’s company eventually became part of IBM.

Analogue Electronic Sequencers

The earliest sequencing device used in electronic music was the step sequencer, as used in conjunction with a voltage controlled synthesiser. It required the musician to enter both the pitch and duration of each note and then to step on to the next note. It worked, but couldn’t be described as ‘user friendly’.

In comparison, the Sequencer 256, as designed by EMS for the Synthi 100 synthesiser, was highly sophisticated. It recorded a real-time performance on three ‘layers’, each conveying a control voltage (CV), defining the note that had been played, and a gate signal, indicating how long the key had been held. Despite the limitations of a restricted memory (the composer had to compromise between timing accuracy and the length of a sequence), it vastly expanded the scope of the analogue synthesiser.

Ken Gale’s Wavemaker range of equipment included one of the first devices to work in the digital domain. His Digital Recording Module (DRM) took the output from a digital musical keyboard and recorded the performance on an audio tape recorder by means of frequency shift keying (FSK). The material could be ‘bounced’ from one track of the tape to another, whilst adding further performances.

The limitations of analogue synthesisers and their associated sequencers were apparent to anyone who used them. Most of these problems were solved by the arrival of devices containing microprocessors.

MIDI

In the early eighties, a group of interested parties issued a specification for the Musical Instrument Digital Interface (MIDI), a system that allowed universal communication between instruments, computers and other devices. The basis for this standard was purely commercial and within a few months of its introduction the floodgates were overwhelmed by new and affordable products.

One of the first MIDI sequencers was Yamaha’s QX1. This incorporated a single MIDI input for a keyboard and eight individual MIDI outputs for connecting to instruments. Unfortunately, all the sequencing operations had to be monitored through a small liquid crystal display (LCD) device.

But one machine was to do much more for MIDI and sequencing than anything so far. In January of 1984, Apple Computer unveiled its latest creation, the Macintosh desktop computer.

Computer Musicians

The use of the Macintosh computer was tentative at first. And early MIDI interfaces were very simple, conveying a single MIDI circuit over either or both serial ports of the computer. Pioneering software included Performer, a sequencing package by Mark of the Unicorn, and Composer, designed for working on a musical script. Sequencing software allowed the musician to record a real-time keyboard performance as a sequence in the computer. This could then be edited freely, saved onto disk in various versions, and finally employed to ‘play’ the synthesisers. The opportunities for editing were almost endless. For example, the length or pitch of any note could be changed, or sections of music could be reversed, repeated or inserted at another point, or the tempo could be changed.

The diagram below shows a typical MIDI installation, complete with an optional MIDI Thru box and MIDI merger. Although the ‘Thru’ outputs of most MIDI devices could be used to ‘loop’ a circuit to another device, a Thru box prevented the timing problems that could be caused by such a connection. A merger, on the other hand, simply combined MIDI data from the outputs of several devices.

The way the music was presented on the Mac’s screen varied with the sequencing application. And because of the complexity of musical score, a full script was rarely displayed. Instead, notes were shown either as bars (of varying lengths to match their duration) or simply as a list of MIDI ‘events’. Almost all sequencers could save a sequence on disk as a MIDI file. This kind of file contained no information to suit a particular sequencer, just pure MIDI data that described the sequence itself.

But MIDI could do so much more. In fact, it could automate an entire studio, especially since many effects devices could be controlled via MIDI. System Exclusive (Sysex) messages could tap into synthesisers and samplers, allowing sounds and samples to be manipulated and modified using a software editor. One very powerful device was the Yamaha DMP7, a MIDI-controlled 8-channel mixer. This used standard MIDI note and controller messages to gain access to every control, but also allowed the user to define a parameter list, assigning specific MIDI messages to particular controls.

These products and advanced sequencers pushed the Mac and MIDI interfaces to the limit. Faster machines, such as the Mac Quadra, appeared in the early nineties, along with multi-channel interfaces such as the Opcode Studio 5. These new computers had NuBus slots that accepted cards for on-board sampling and digital audio recording, either using the Mac’s own hard disk or a separate SCSI drive.

These developments led to a greater integration of the electronic music studio, with sounds recorded, edited and then ‘bolted into’ a MIDI sequence. The final result was ‘desktop composing’, as provocative to the music industry as desktop publishing was to printing. And, although MIDI is being pushed to the peripherals of such advances, its robust design assures it a challenging future.

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©Ray White 2001.