Sequencing - A Brief History

[Author's note: this article was actually written some years ago, when the technology in use was somewhat more... limited than it is today. One day I'll get around to producing a more up to date version, but in the meanwhile, please read its more quaint references as matters of history rather than current practise !]

The idea of sequencing is as old (if that adjective is an appropriate one) as the synthesiser itself, & has its roots in the fairground organs, piano rolls, & musical boxes of the late 19th & early 20th century, where the music was stored as a series of holes on a piece of paper which moves across a detector of some form, thus triggering the notes mechanically in the case of the pianola; or as a series of bumps upon a brass cylinder or disc, in the case of the musical box, which move across a series of tuned metal bars called 'tines' (whence the generic name of some synthesiser sounds) & physically twangs them into sounding.

The early synthesisers were 'analogue', using the flow of continuously changing voltages around circuits to work. Sound production in an analogue synthesiser is divided up into separate modules - typically a VCO (voltage controlled oscillator), which produces the initial 'sound', originally basic wave forms such as a square wave, a sawtooth (ramp) wave, or a triangle wave; next in the signal path is the VCF (voltage controlled filter), where the basic wave form is altered by filtering out certain frequencies according to whether it is a high, low, or mid pass filter, & certain frequencies are boosted by a given degree, known as resonance; lastly there is the VCA (voltage controlled amplifier) where 'shape' is given to the sound, parameters such as Attack time, Decay time, Sustain level, & Release time (the so - called ADSR, or Envelope) are set, & the sound is finally output to an amplifier so that it can be heard. All of these modules, of which they were more or less complex according to the sophistication of the synth, were connected together passing the information around in the form of the voltage.

The question is, how did the VCO know what note it was supposed to play ? Well, connected to it was a 'control voltage' producing device, either a keyboard, where the depression of each key output a different, specific voltage, or an analogue sequencer. The sequencer was so named because that is exactly what it did - stored 'sequences' of notes & caused the synthesiser it was connected to to play them back. Usually only 8 notes could be stored, or if you were very rich 16 notes, & there was no way of assigning note values to individual notes, so each note had to last for the same duration. The sequencer was 'programmed' in the same manner as the synth was - with a series of knobs (potentiometers / variable resistors) which you set according to what note you wished to sound at that point in the sequence chain; each note, rather than simply being a case of switching to 'c#', had to be tuned exactly; thus microtonal tuning was possible, & in some instances it was even mandatory on account of the dodgy electronics of the time ! The speed of the passing sequence was set using an LFO (low frequency oscillator). The limitations of these early sequencers led to quite a distinctive style of music in the early / mid 1970s, perhaps best exemplified by albums by the group Tangerine Dream from the time.

The major disadvantage with this system of connecting things together using a voltage system was that no 2 manufacturers had the same conventions as to how to split up the keyboard; 1 manufacturer (Korg) had its lowest note have a voltage of -6 V, & its highest note +6 V. Another maker, Roland, decided to have its range from 0 V to +12 V. To confuse matters further, just because 2 different synths might work from 0 - 12 V, how they actually divided the notes in between the ranges wasn't necessarily the same; 1 maker might follow a '1 volt per octave' rule, another might have the voltage directly proportional to the frequency of the note. The practical upshot of all this is if you had a Sequential Circuits synthesiser, you couldn't connect a Yamaha sequencer to it, or a Roland one, or a Korg one etc - at best the equipment wouldn't work & at worst you could have risked making a small explosion in your studio !

By the 1980s, & the onset of the so - called 'consumer electronics revolution', integrated circuit technology had advanced to the state where much of the earlier completely separate modules were now on one single chip, much of the operations of the synthesiser were now 'digitally' controlled (DCOs replacing VCOs etc), & early true digital synthesisers became available to a wider public. It was at this time that Sequential Circuits began to build synths with a digital interface in addition to the standard CV / Gate interface on the back. The head of Sequential Circuits, Dave Smith, had the idea that there was no reason why this interface could not connect to any other equipment, just as the RS-232C interface had become standard in the computer industry. He called a meeting with the heads of the other major synthesiser manufacturers, & after some development the consortium announced the new MIDI (musical instrument digital interface) standard. In addition to allowing synths & sequencers to connect to one & other regardless of race, religion, or nationality, it also encouraged the development of other ways of actually playing the instruments than with a keyboard, such as via a guitar (pioneered by Roland), by drum pads (from Simmons), & with an electronic wind instrument (as developed by Yamaha), which had existed previously, but not really been exploited; most importantly for our purposes now, though, it allowed the connection of synthesisers to the new personal computers which were appearing.

Optional MIDI interfaces became available for computers such as the Apple II, already the center of the Alpha Syntauri music computer system, & the first computers to actually have MIDI interfaces built in as standard were the Yamaha CX5M music computer (which itself was part of a similar attempt by the computer industry, the MSX standard, to rationalise different computer hardware & software), & the Sinclair ZX Spectrum 128. Unfortunately, the Yamaha computer was disadvantaged in that the only sequencing software which could access its MIDI ports was that which was hard coded into the machine (which also had a synth, the FB01, built in to its architecture), & the Spectrum never actually had any sequencing software that was noteworthy written for it, perhaps due to the non - standard shape of its MIDI sockets (which was always a problem generally for Sinclair computers) ! Luckily in 1986 Atari took the step of including standard MIDI ports with its new 16 bit ST machine, & encouraged the development of quality sequencing software for it such as Steinberg Pro - 24, & its successor Cubase which I use & has generally become the standard package in recording studios worldwide.

As we are here now, the market is in some what of a state of flux as regards software & hardware platforms, as the ST is virtually obsolute in the computer world, having been superceded by 32 bit high performance computers such as the Apple Macintosh, & computers using the Intel 486 processor & Microsoft's Windows operating system. The top end version of Cubase, Cubase Audio (which actually allows the recording of sounds in addition to MIDI information) is available for both, as are other packages such as Coda Finale which are more notation & score printing orientated than sequencing packages. As yet no clear market leader has emerged, though since they all conform to the MIDI standard, it could be argued - do we need or want a market leader ??