If you were producing a musical album and, for some perverse reason, you actually wanted it to have a chequered history, chances are you'd choose to make a rock album. Rock musicians are temperamental, hard-living people whose egos and lifestyles are often at odds with the producer's primary objective of getting an album out of the studio and into the shops with the minimum of expense, fuss and bother.

Classical musicians are, on the whole, a different breed. To be fair they have the odd prima donna in their ranks but they generally turn up en masse to the recording hall, each one every inch the consummate professional and fiddle about for a day or two under the flawless supervision of their conductor, then go home. Very little untoward ever happens, before, during or after the recording. It's hard to imagine how to make a dog's dinner of a classical album.

Well, how about this: a record producer back in the 1960s decides that she is going to make an album of some of the most famous JS Bach pieces, something that had been done countless times beforehand. Except she decides to ditch the chamber orchestra and try out a novel and totally unproven electronic instrument. The instrument will only play one note at a time, so she hires a classical pianist who has to record every single part separately in a laborious process taking months. When eventually the album is finished, it is released to largely universal critical derision, but then goes on to be arguably the best selling classical album ever, going platinum (an almost unheard-of feat). In the aftermath, the pianist decides that she has had enough of pretending to be male and formally transitions to female. You couldn't make it up, really.

The Moog Synthesiser

Robert Moog¹ was born in Queens in New York in 1934. A bright child, he built a theremin at the age of 14, with which he probably made himself only slightly more popular with his parents than if he had bought himself a set of amplified bagpipes. The theremin is a 'musical' instrument, and the electronic equivalent of bowing a saw. In expert hands it sounds other-worldly; in the hands of all others, it sounds uniformly dreadful.

Moog was not just bright, he was also enterprising. He set up a company that produced theremins, R. A Moog and Co. He also published plans in an electronics journal describing how to make them and sold a kit of parts to prospective hobbyists. Moog managed to sell a thousand theremin kits from 1961 to 1963, then toyed with making a portable guitar amplifier.

It wasn't until he attended a convention in 1963 that he hit upon the idea of the synthesiser. The original Moog synthesiser was a completely analogue electronic instrument: there were no microchips or digital circuits. Instead, various modules, each with a specific function, were 'patched' together with cables. You fiddled with dials and cables, pressed a key and some sound came out of it, rather like the musical equivalent of an Enigma Machine.

Analogue synthesis was and remains a highly complex process. In the initial stages, pressing a key would output a fixed voltage which was then fed into a voltage controlled oscillator. This would generate a sine, square or saw-tooth waveform of audible frequency. The output of this circuit was then channelled into filters, envelope shapers and a variety of other circuits such as reverberation units before it actually got to a loudspeaker. Because the process was so complicated, Moog synthesisers were the very devil to set up properly and could only play one note at a time. Moreover, the voltage-controlled oscillators had a habit of drifting out of tune. Moog synthesisers hence spent most of their early years in the recording studio, not on the concert platform.

Genesis of the Album

Up until the late 1960s electronic classical music had remained the almost exclusive province of the avant garde. No doubt the conservatism of the musical establishment had a part to play in this, but so did the fact that a lot of it was widely regarded as atonal, self-indulgent intractable rubbish² - sounding like 'some obnoxious mating of a catfight and a garbage compactor', as one critic put it. There had been some attempts to meet the audience half-way, such as Terry Riley's A Rainbow in Curved Air, but most electronic composers wrote music for themselves first and others second. Schoenberg would have been very proud.

On the other hand, those musicians who simply wanted to adapt the canon of famous composers had, up to that point, simply used more modern acoustic instruments. Leopold Stokowski abandoned the chamber orchestra for the full modern version to great effect. His orchestral transcription of the Toccata and Fugue in D Minor remains the most famous of these adaptations, and was even used in the Disney film Fantasia³. Glenn Gould specialised in piano adaptations to great critical and popular acclaim as did others pianists such as Jacques Loussier⁴.

It was in the mid-1960s that Walter Carlos⁵, a physics and music graduate from two Ivy League universities and no mean pianist, struck up a professional relationship with Rachel Elkind, a record producer from CBS. Carlos, like most great pianists, had started out young and had been playing since the age of six. His formal musical education culminated at Columbia University where he was a student of Vladimir Ussachevsky, a pioneer of electronic music. On graduation, Carlos met Robert Moog and became one of his earliest customers for the (now antique) Moog 3P synthesiser⁶. Carlos reasoned that a synthesis of well-known and loved compositions with electronic instruments could help to set the whole genre free from its straitjacket of atonality. It would allow the classical music-loving public to at last appreciate what it had to offer. Moog agreed, and so Carlos set about recording the album. It's unclear as to who had the idea in the first place: Carlos or Elkind, but the latter certainly contributed a very great deal by way of her enthusiastic support for the project.

Because the synthesiser would only play one note at a time, Carlos had his work cut out with Bach's complex and layered music. He used a click track to provide a time signature to which he could perform and recorded each part separately on a custom eight-track tape machine. These recordings were then edited and transferred to stereo master tape. The process took months but Bach's music, with its heavy emphasis upon rhythm and structure was ideally suited to this incremental approach to music making.

How it turned out

At the end of it, Carlos had produced an album of ten of Bach's best known pieces:

• Sinfonia to Cantata #29
• Air on a G String
• Two Part Invention in F Major
• Two Part Invention in B-Flat Major
• Two Part Invention in D Minor
• Jesu, Joy of Man's Desiring
• Prelude and Fugue #7 in E-Flat Major (from Book I of The Well-Tempered Clavier)
• Prelude and Fugue #2 in C Minor (from Book I of The Well-Tempered Clavier)
• Chorale Prelude 'Wachet Auf'
• Brandenburg Concerto #3 in G Major
1. Allegro
2. Adagio
3. Allegro

The result was, by any standards, remarkable. Gone was the weedy voice of the harpsichord shouting to make itself heard over the string section. From the scintillating Sinfonia to Cantata #29, through the noble and religious Jesu, Joy of Man's Desiring, the frankly psychotic Prelude and Fugue in C Minor to the joyfully exuberant third movement of the Brandenburg #3, it was plain that Bach's music had found not just a fresh new voice but also a uniquely clear one. Every single note was audible, and Carlos' interpretations captured the spirit of each piece perfectly, alternating between bright and dark but always lyrical: muddy waters giving way to a sparkling spring.

Needless to say, the critics didn't see it that way. The album was mostly panned, supposedly for trivialising the work of the Greatest Composer that Ever Lived. There was even a revanchist⁷ response in the form of another CBS album, Switched-Off Bach, the same pieces played in the conventional manner by E Power Biggs, Glenn Gould and other notable interpreters of Bach's canon that had among the incredibly condescending liner notes (purportedly written in January 2268) the comments:

Electronic instruments have totally taken over music, and, this album is a museum piece played by virtuosos of a bygone era... music-making was most definitely circumscribed by the mechanical abilities of the instruments and by the technical abilities of the players... it is one bit of authenticity that, I fear, we will never be able to recapture. For no one yet has been able to program what the 20th Century called 'heart' into a machine.

Well, whatever the classical snobs thought, the public loved it. S-OB went platinum - a first for a classical album - and Robert Moog had musicians the world over beating his door down to get their hands on this remarkable new machine.

And Afterwards?

Thankfully, Carlos saw the negative response for what it was: musical Luddism masquerading as discernment. Carlos and Elkind went on to record several other albums, The Well-Tempered Synthesiser and Switched-On Brandenburgs being the most famous. Even the notoriously prickly Gould went on to say 'Carlos's realisation of the Fourth Brandenburg Concerto is, to put it bluntly, the finest performance of any of the Brandenburgs - live, canned, or intuited - I've ever heard.' Carlos also performed the high-octane soundtrack to A Clockwork Orange. Sometime during this period, Walter became Wendy, very privately and with little appetite for any subsequent public discussion. She now works and records music under this name. In particular, the Switched On series was remastered and reissued in 1999.

Time has been very kind to this brave experiment in classical music. Listening to Carlos' performances now, the intervening 35 years magnifies, not diminishes, the scale of her achievement when one considers the technologies available when she made the album. In an era when electronic adaptations of others' music are almost entirely restricted to ad-nauseam samplings of trite musical phrases, S-OB reminds us that virtuosity is neither guaranteed nor parameterised by the instrument, whether strings, woodwinds, or a pile of microchips and a CPU.