I suppose, to be strictly accurate, that ALL music that appears on CD, or on magnetic tape, or even on old fashioned phonographic records is electronic in some form. The grooves on a gramophone record aren't smooth or even, there are minute textures that are registered by the movement of the stylus and these textures are then, electronically, translated back into audible sound. Likewise recording onto tape creates fluctuations in the magnetic field strength and these fluctuations can be converted, electronically, back into sound.
Now, in the digital age, actual sound is sampled and converted into discrete binary numbers or pure data, the faster the sample rate, the higher the recording quality. It doesn't get more electronic than this.
But what I'm really talking about is music created by electronic means, not by striking a piano key, or hitting a snare drum or strumming a guitar string. The word synthesizer is often used as an umbrella to describe various electronic keyboards and gizmos, but synthesizers really just manipulate other sounds, and rarely create their own.
Brian Eno used a VCS3 on the early Roxy Music records. It was simply a box, carried in a medium sized suitcase that could change and distort any imput signal. Usually Phil Manzanera's guitar was fed into the VCS3 for Eno to play with. Frequently the guitar sound that emanated would be backwards, or treated to sound like a crashing plane. In the same way Andy Mackay's saxophone mic would be fed through Eno's synth to create the most other worldly sounds. The VCS3 had no keyboard and thus could not be 'played' as an instrument in it's own right, instead Eno had a series of knobs to twiddle to affect the sounds and would have to frantically switch the leads over when he wanted to switch from guitar to sax and from there to electric piano. One reviewer memorably compared him to a crazed telephone operator.
Of course at the same time synths were being created that did have their own keyboards or joysticks, meaning that analogue input wasn't always needed. Bob Moog set his tonal manipulators into smart wooden surrounds creating a keyboard that was more akin to a piece of furniture. At least it was fully electronic. Mellotrons, a mainstay of prog rock from the mid sixties onwards relied on samples of sound recorded onto short loops of tape, which could then be played in the same way as a conventional keyboard. The sustained strings sounds thus created were usually beautiful, but Mellotrons were liable to drift out of tune due to fluctuations in the power supply, or tapes that frequently stretched. Robert Fripp coined a number of helpful maxims for the various members of King Crimson, one of which runs simply 'Tuning a Mellotron doesn't.'
By the mid 1970s synths were portable enough, easier to control and genuinely play, and were capable of creating a huge variety of realistically musical sounds. Rock bands were generally wary of such new fangled devices, usually adopting the attitude that if you couldn't play guitar like Clapton, or drum like Bonham then you couldn't possibly be a 'real' musician. Even Pete Townshend was viewed with suspicion when he incorporated arpegiated synths into "Won't Get Fooled Again". Later in the mid 1970s Queen famously stated that their albums did not feature synthesiz, as if this was something to be admired.
So those who played electronic music started on the fringes. German bands loved the technological aspects of synths and fully utilised the wide range of sounds to found. Tangerine Dream initially created cosmic journies to the outer galaxies, before gradually switching to gently warm and inviting synth pop; NEU!, Cluster and Harmonia emphasized the rhythmic capabilities of the early percussion programmes, building complex melodies around an unwavering mechanised beat, and Kraftwerk took both aspects to create perhaps the most carefully crafted, ultra precise music ever heard, but somehow they were able to avoid their music sounding clinical and imbued it with a warmth and humanity that many other bands would struggle to achieve. For all their Man Machine pretensions the secret of Kraftwerk's success lay in the fact that the men fully controlled the machines. And men could make mistakes. And, for that matter, the machines were not 100% reliable either. These analogue machines had moving parts, valves, transistors, elements which could wear out, switches that could break or overheat, circuit boards that would change their performance depending on the humidity of the room, sounds that would fluctuate depending on the reliability of the electricity supply around the world. This was not cold, clinical unvarying music at all. The sounds created by the early synth musicians has all the vagaries of 'real' music, and thus it contains a genuine warmth and an emotional punch that later digital music cannot possess.
In the mid 1970s Brian Eno experimented with tape loops. He played a simple rising and falling motif on a keyboard and recorded on tape loops of varying length. When the loops were played back simultaneously, but at different speeds, the overlapping notes created a hypnotically calming effect. Eno would set this up and let it play for hours while he read, and then he decided to record a snapshot of this potentially endless music. Half an hour was released as Discreet Music in 1976. But what could have been very calculated and clinical is nothing of the sort, and perhaps surprisingly the whole piece has a strong emotional core. This is all down to movement. The tape loops physically move, and none can be absolutely precise. The combination of sounds they generate pushes the air around and this is captured on yet more tape, before being physically carved onto vinyl. Another potentially variable movement occurs when you play the record. This actual genuine movement surely contributes to what moves the listener emotionally. A digital version of this wouldn't have the same impact. In fact Eno once tried to digitally recreate Discreet Music. And he failed miserably. There was no way to recreate the effects of various tapes at different unstable speeds and pitches. The digital version wanted to correct all the wobbles and unevenness, although it's exactly these imperfections which that give the original it's power.
The differences between analogue and digital are clearly demonstrated by Jean-Michel Jarre. His pioneering albums Oxygene and Equinox are fabulous, with a warm buzzy sound to the analogue synths that is missing from most synth music once digital becomes the norm. By 1983 he'd converted to digital and sure enough all the warmth has gone. Zoolook still contains some cool tunes but it relies too heavily on technology which doesn't have the heart and soul of the old valve driven Moogs and ARPs that powered Oxygene.
One of the main problems with digital music is that it is generally so unwavering that it quickly becomes repetitive. Back in 1975 Brian Eno came up with some helpful aphorisms to overcome creative blocks. One of the most famous of these Oblique Strategies reads - "Repetition is a form of change". But this was coined before unwavering digital repetition which allows for no change at all. Repetition is only a form of change where there is a human and therefore unstable element in the equation. Which is why Kraftwerk continue to have such a large involvement in the controlling of their concerts. They don't simply turn up and press 'play' on their laptops; each concert is actually quite different as the four members take a very strong control over the programmes and samples that go to make up their music. And stuff often goes wrong. Without the human element the show would be very flat.
These sorts of problems are being recognised and there is a gradual movement back to analogue synths and moving part technology. Actually recording the music digitally is fine and allows for all sorts of improvements in storage and transfer, but it's become widely accepted that creating music digitally can lead to dullness and a cold unfriendly end result. Many synths are starting to have random elements built in, to replicate at least some of the variables of using tape. This is surely a good thing. Our human ears are not machines and our brains can cope with sounds that are not absolutely perfect. In fact our brains make the tinye adjustments needed to compensate for a dropped beat or a slightly out of tune note. If the music is so perfect, with little or no human variation then our brains actually switch off, as there is nothing for them to do. What ought to be active listening becomes something passive and therefore a fairly pointless exercise.
Music exists to played, not repeated by a machine. Music is something that humans have created, something that inspires us and moves us and involves us. Music needs to played by people - it doesn't matter what instruments are used, or whether it's a triangle or a violin or a complex synthesizer, what matters is the human involvement and the physical movement of the sound through the air molecules. That is music.
To perhaps a lesser degree the same applies to Kraftwerk. The sequencers and buzzes of The Man Machine album give it an organic, rich feel, but the Boings and Tschaks of Electric Cafe, fun and brilliantly constructed though they are, are much colder and less welcoming. It's only with very recent advances in technology that digital synths can give off that much needed warmer feel. But digital still can't give you that actual physical movement of sound created by moving parts in the machinery and the stylus scratching away at the vinyl...