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Although FM synthesis has its roots in the sixties, the instruments that popularised it were to dominate the synth scene of the eighties. Gordon Reid uncovers the origins of FM and charts its rise to fame from its unlikely beginings in academic research in the USA.

For once, one of my retros does not begin with the sentence, "I remember the first time I saw a..." That's because it starts at the Bell Telephone Laboratories in the 1950s, some considerable time before I was born. This was where a gentleman by the name of Max Matthews began experimenting with digital computers, to see whether they could become a viable means for generating audio signals. Matthews was far ahead of his time, if only because he realised that -- unlike the primitive analogue signal generators of the time -- computer-generated digital audio could be consistent and controllable. In 1957 he wrote a program called MUSIC I, programmed in assembly code for an IBM 704 mainframe computer. You may think this unremarkable, but you should realise that the 704 was a vacuum-tube (valve) computer utterly incapable of executing the program in real time.

Understandably, MUSIC I was only capable of generating very basic sounds (it had a single triangle-wave digital oscillator) but Matthews continued his developments and, in 1958, wrote MUSIC II. This had four triangle oscillators and was capable of much more interesting sounds. Inevitably, MUSIC III followed. Completed in 1960, Matthews wrote the program for a more advanced (transistor) mainframe called the IBM 7094. Then there was MUSIC IV (1962), MUSIC IVF (written in 1965 by a man named Arthur Roberts) and MUSIC IV BF (1966/67).

Enter John Chowning

At this point we must change scene, to Stanford University's computer department, and observe two researchers named John Chowning and Leland Smith, without whom the music industry would be a very different place today. They were working on a new version of the programs developed by Matth
  FM Giant: The GS1 In More Detail  
  Even today, the GS1 is a remarkable instrument, weighing 90kg (a hair under 200lbs) and designed like a miniature grand piano. It's clear that Yamaha intended it for studio use. But don't let the 19th century looks deceive you. Its beautifully weighted 88-note keyboard is both velocity and poly-pressure sensitive, and -- with the exception of on-board editing -- it is everything you would expect from a top-of-the-range synth dating   
ews and his associates, which they called MUSIC V. At the same time, Chowning was experimenting with huge amounts of vibrato (amounts that you could never obtain without the use of electronics), applying this to the audio–frequency signals generated by the digital oscillators within the program. Apocrypha has it that he accidentally programmed a vibrato that was larger than even he intended, discovering that the result was not vibrato, but a unique tone unlike anything he had heard before.

Chowning was apparently unaware that he had stumbled across a common technique used to broadcast radio transmissions: Frequency Modulation of a carrier signal (an 'operator') by a modulator (another 'operator'). This is understandable: FM radio signals exist at frequencies around 100Mhz, and even exceptional human hearing is limited to about 25kHz, so nobody had fully appreciated the audible effect that the modulator could have. By accidentally modulating a signal in the audio band, Chowning became the first person to hear what we now call FM synthesis, and he discovered that it was a powerful way to create new sounds. Consequently, in 1966, he was the first person to compose and perform a piece of music using FM as the sound generator. Called Sabelithe, it predated commercial digital synthesis by more than a decade.

Meanwhile, development of the various MUSIC programs continued apace, and in 1968 Princeton released a much faster version for the IBM 360 mainframe. Even MIT got in on the act and, in 1973, a compact version, called MUSIC 11, was developed for the PDP 11 minicomputer. MUSIC 11 was a huge step forward. For one thing, the PDP 11 was much more compact than the huge IBM mainframes required by previous versions. Secondly, MUSIC 11 was the first 'mini' digital synthesis program to use a QWERTY keyboard and VDU.

Throughout the latter half of the sixties, Chowning continued to develop FM synthesis, adding functions that allowed him to control the evolution of the sounds he created. Then, in 1971, Matthews suggeste
d that he should create a range of recognisable sounds, such as organs or brass, to demonstrate that FM was musically useful and, therefore, a possible basis for a commercially viable product. Chowning did this and, with a view to licensing the technology, persuaded Stanford's Office of Technology Licensing to approach companies for him.

Yamaha Step In

Do you know the story of the A&R man at Decca who turned down The Beatles? Well, how do you think Hammond and Wurlitzer feel knowing that they turned down FM? As did all the other American manufacturers that the university approached. In desperation, Stanford contacted the Californian office of a well-known manufacturer of motorbikes, powerboat engines, and construction equipment. Yamaha duly despatched a young engineer named Ichimura who, after a brief evaluation, recommended that the company take out a licence on Chowning's system.

With understandable caution, Yamaha negotiated a one-year license that it believed would be sufficient to enable it to investigate FM and decide whether the technique was commercially viable. So it was that, in 1973, Yamaha's organ division (which, in 1974, would be responsible for the mighty GX1) began development of a prototype FM monosynth.

Despite the commercial development taking place elsewhere, Chowning was still an academic, and he continued working at Stanford on MUSIC 10 (yet another version, this time for the PDP 10). Unfortunately for him, the university failed to see the value of his work so, after a somewhat acrimonious parting of the ways, he moved to Europe to continue his research. This later proved to be a significant embarrassment for Stanford because, when Yamaha approached it to negotiate an exclusive commercial license for FM, Chowning was no longer a member of the faculty. The best that can be said of the university is that it knew when to eat humble pie, reinstating Chowning as Research Associate of its Center for Computer Research and Musical Acoustics (CCRMA). Chowning then assigned the copyright of FM to Stanford, which duly assigned the license to Yamaha.

Chowning was, of course, no fool, and he later received a royalty on the sale of all Yamaha's FM synthesizers. And, while his personal deal with Stanford has remained highly confidential, the university is rumoured to have collected more than $20 million in license fees. Whatever the exact figures, it's no coincidence that CCRMA was later re–housed in its own purpose-built facility.

Anyway, with the legal technicalities sorted out, it was time to begin serious commercial development of an FM synthesizer. So, in 1975, Yamaha built a prototype polyphonic FM synth. But first...

  back to 1981.  
  Setting one up is no mean feat. You have to tip the GS1 forward onto its front surface, so that you can bolt on the legs and the pedal unit. Then you have to get it upright again. I've managed to do this alone on two occasions, and my back still complains about it.

Once you've assembled the GS1, you can turn your attention to the sparse control panel situated immediately above and behind the keys themselves. At first this looks horribly limited. For example, there are only nine performance controls: vibrato and tremolo sections (each with speed and depth knobs), a 3-band EQ, a detune knob, and a master volume control. But these hide some superb performance capabilities. For example, the 'soft' pedal is actually a pressure-sensitive vibrato controller, while the centre 'sostenuto' pedal is a pressure-sensitive tremolo controller. (The damper, or 'sustain' pedal is exactly what it appears to be.) Likewise, the detune knob, far from being a simple detune, offers four settings: shallow and deep 'static' detune, and shallow and deep 'random' detune. It's remarkable how much life is injected into the sound by the random variations of the latter settings.

The only other control, aside from those that select and store voices, is the Ensemble On/Off switch. This introduces a real analogue delay line into the signal path, and makes the GS1 as swooshy and noisy as any analogue ensemble keyboard.

Finally, we come to the memories themselves. There are 16 of these, which you fill using Yamaha's preset voice library. To load a memory, you insert side 'A' of the small magnetic 'lollipop stick' in the card reader slot, then press one of the 16 location buttons to start the reading process. Once this is complete, you turn the magnetic stick over and load the information on side 'B'.

It's not obvious, but you've just loaded different voice data into two otherwise identical dual-operator/dual-carrier 16-voice synthesizers. This means that you can mix and match 'A' sides and 'B' sides from different patches, to create new, composite sounds in memory. Yamaha actually encouraged this, and the GS1 provides a 'Store' capability that allows you to record your new combinations onto single magnetic sticks.

You would probably be amazed at the expressive nature of the GS1. Even ignoring the polyphonic aftertouch control of both loudness and brightness, its sounds can be both digital -- in terms of clarity and brightness -- and very analogue in their warmth and depth. Indeed, had it weighed 80kg less, I would have been delighted to use one as my string ensemble of choice in the early 1980s. You won't hear me say that of any other FM synth! Nonetheless, the GS1 also pointed the way forward to the digital sounds of the '80s, with many of the FM pianos, harpsichords, and other plucked sounds that Yamaha would (almost) perfect in the DX7.

In 1984, Yamaha released a MIDI upgrade for the GS1. This fits inside the body of the instrument and has an interface/control panel that replaces one of the two radiator grilles on the underside. (Radiator grilles! I kid you not... The GS1 consumed 95W of power.) By modern standards, the MIDI specification added by the upgrade is incredibly primitive. The GS1 remains monotimbral, and communicates only on MIDI channel 1, 2 or 3. Furthermore, it only transmits and receives Note On/Off and Velocity messages. Oh yes, and it can't transmit and receive simultaneously. There is a switch to determine which it is doing at any given time!

Despite all the GS1's shortcomings, it was -- and remains -- a remarkable instrument, and a surprisingly satisfying one to play. Hmmm... maybe that's not so surprising, given that its 1981 price of £12,000 is equivalent to around £50,000 today.


The First FM Synths

Surprisingly, neither Yamaha's commercial work nor Chowning's academic efforts led directly to the world's first commercially produced digital synthesizer. Called the Synclavier, this was developed by NED (the New England Digital Corporation) and it was a polyphonic digital synth based upon 8-bit FM and additive synthesis.

Despite its famous name, it's highly unlikely that you have ever seen an original Synclavier. This is because they are incredibly rare. Released in 1978 or thereabouts, only 20 or so were made. The early Synclavier that some people recognise -- the one with the incredibly sexy five-octave keyboard spangled with little red buttons -- was, in fact, the second version. First appearing in 1980, NED called this, with remarkable logic, the Synclavier II. The instrument that most people recognise -- the huge black, weighted keyboard -- was the final version of the Synclavier. This soon became a mainstay of top professionals in the film and video industries, later spawning a powerful range of synth/sampling workstations, and nearly 20 years later it remains a favourite in post-production studios all over the world.

Yamaha, meanwhile, were in the synthesizer doldrums. Having scaled all the peaks with the GX1 and CS80, in 1975 and 1976 respectively, they had experienced a slow but inexorable slide from favour during the later years of the decade. The Prophet 5 and Oberheim OBX were cheaper and much lighter than the CS80, and the CS70M -- designed to replace the CS80 and cure some of its perceived deficiencies -- was a turkey of the first order. Similarly, the CS range of monosynths and the SK multi-keyboards failed to capture our hearts, souls, and wallets. Yamaha was floating into the backwaters of the professional keyboard world. Something had to be done.

It was not until 1981 that Yamaha unveiled their first commercial FM synthesizers, trailing NED by three years. Named the GS1 and the GS2, these abandoned recognisable synth facilities such as oscillators and filters, in favour of frightening new things such as multi-operator equation generators, 30kHz data rates, and digital-to-analogue converters. What's more, despite offering just two-operator algorithms, the operation of these monstrously expensive machines (the GS1 retailed for £12,000) was a complete mystery to all but the most mathematically orientated. Not that this mattered, as neither machine offered editing, each being (more or less) a preset instrument, capable of playing only the 500-odd voices supplied by Yamaha on little magnetic 'lollipop' sticks. Yet the GSs were, for a couple of years, reasonably successful. Toto, for example, layered nearly a dozen tracks of GS1 on million-selling hits such as 'Rosanna' and 'Africa', and used two of them in their live shows.

There was a good reason for this success. The sound quality and playability of the GS1 was exceptional (and the GS2 wasn't too shoddy either). But, in an otherwise pre-digital world, for most players these were hyper-expensive oddities. It's thus no surprise that Yamaha sold only around 100 or so GS1s and, in all likelihood, few more GS2s.

Then, in 1982, Yamaha demonstrated a keyboard with 'six-operator equation generators' that you could edit. It was never released in its original form, but this instrument was to be the progenitor of one of the most important synthesizers ever created. It would cost a fraction of the price of its predecessors. Moreover, it would weigh far less, would offer an unprecedented 16-note polyphony, and would incorporate velocity and pressure sensitivity. Furthermore, using a radical new technology called 'storage cartridges', it would be able to store and access thousands of new sounds. But before that, there were the CE20 and CE25 Combo Ensembles.

The First Affordable FM Synths

I remember seeing a second-hand CE20 for sale in the late '80s. It looked like one of those 'diddly-bop' four-octave home keyboards that Yamaha and Casio seemed to churn out with frightening frequency, and I duly ignored it. Had I known its significance, I'm sure I would have forked out the £60 or so that the seller wanted.

With 14 preset monophonic voices and six preset, eight-note polyphonic voices, this was undoubtedly the first affordable FM keyboard on the planet. Yet, like the heavyweight GS1, it offered vibrato, 'symphonic' (ensemble chorus), and programmable velocity and pressure sensitivity, at the time unknown on cheap polyphonic keyboards. That the aftertouch offered control over tone, volume and vibrato depth was just astounding. Another neat trick was offered by the portamento provided on the monophonic voices, which only created its glide effect when both the initial and the destination notes were depressed simultaneously. Later copied by a handful of esoteric synths such as the Crumar Spirit, and more recently the Alesis Andromeda, this feature allowed you to use playing technique (rather than knobs or wheels) to create portamento and pitch-bend effects.

Despite its groundbreaking price/performance ratio, the CE20 was clearly aimed squarely at the home-organ market. Its solo voices comprised five woodwind, three brass, four strings, and two electric-bass imitat
  The GS2 In Brief  
  The GS2 offers only one of the 2x2-operator synthesizers found in its bigger brother, and this limits you to simpler sounds comprising just side 'A' of a voice card. This may seem like a huge restriction, but given how radical FM synthesis was in 1981, and how bright and percussive FM voices seemed to a generation brought up on fat, splodgy analogue synths, it wasn't a problem.

Unfortunately, there are a couple of other deficiencies in the GS2's specification. On the electronic side, the GS2 loses the random modes of detune that add so much to some GS1 sounds. More significantly, it also loses the beautiful 88-note velocity and poly-pressure sensitive keyboard, which is replaced with an equally beautiful (but only velocity-sensitive) 73-note keyboard. This is the real difference. Whereas the GS1 is a wonderful instrument to play, the GS2 is merely streets ahead of anything else that was available back in 1981. Once you had played the GS1, nothing else would do.

Surprisingly, the GS2 is only 18kg lighter than its big brother, so you gain little benefit from its lesser specification. I suspect this is why -- despite its much lower retail price -- the GS2 sold little better than the GS1.

ions, while the polyphonic voices included such 'classics' as polyphonic brass, horn, organ, electric piano, harpsichord and strings. Of course, none of these -- by today's standards -- sounded much like the real thing, but when you consider the alternatives available in 1982, they were remarkable.

The CE25 was a somewhat different beast, with 20 polyphonic voices -- five brass, three strings, two organs, two poly-leads, two poly-bass, and six percussive -- so it lacked the CE20's monophonic portamento. By way of compensation, it offered a slider that controlled the depth of the ensemble effect. This allowed players to add just a hint of depth to voices that would have suffered had 100 percent of the effect been applied to them.

Whichever way you look at them, the CE20 and CE25 were revolutionary keyboards that should have created far more of a stir at the time, and should have carved a far deeper niche in synthesizer history than they have. The reason that they did not is, perhaps, that they were completely overshadowed by what was to come...

The World's Most Popular Synth

In retrospect, it seems clear that, just as the GX1 had been used to prototype technology for the CS50, CS60 and CS80, the GS1 and GS2 were test-beds for the DX series. Likewise, I suspect that the CE20 and CE25 were little more than market-testers for Yamaha, designed to ascertain whether the public was interested in the sound of FM. Yet, despite their decade-long gestation, finalising the first batch of DX7s proved to be a bit of a problem because, just as they entered production, Sequential Circuits launched the Prophet 600 -- the world's first MIDI synth. The prototype DX7 had no MIDI, so Yamaha quickly upgraded the electronics to allow the instruments to transmit and receive on MIDI Channel 1. Unfortunately, the cases had already been manufactured, so you can recognise the earliest DX7s by the silk-screening of the word 'MIDI' on their control panels. The word was added later and, apparently, it's a slightly different colour from the other legends.

Despite these teething troubles, the DX7 was an instant sensation. Its six-operator, 32-algorithm FM synthesis allowed programmers to create sounds of unprecedented complexity and/or subtlety. Its 16–voice polyphony made a mockery of the five-note Prophet 5 and the eight-note Oberheims and Jupiter 8. It offered 32 patch memories, and you could use ROM and RAM cartridges to expand the number of sounds available at any given moment. Furthermore, breath control augmented the velocity and aftertouch sensitivity. This was an unparalleled specification for the time.

Then there was the price... at under £1500, the DX7 was not only the most highly specified of professional synthesizers, it was by far the most affordable. It lacked the sonic depth of its analogue competitors, but it more than made up for this by providing a breathtaking new palette of sounds, many of which remain classics to this day. Of these, the now clichéd DX7 piano patch is probably the most (in)famous, and 18 years later it still shows no sign of disappearing. Indeed, so successful was this sound that it later became impossible to buy a synthesizer -- analogue or digital -- without an imitative patch named 'DX Piano', or something simil
  Sine Of The Times: A Bit About FM Synthesis  
  FM synthesizers create complex sounds by arranging and combining the outputs of digital sine–wave generators ('Operators') in different ways ('Algorithms').

The interactions of the Operators within the Algorithm determine the nature of the sound. Each Operator can act in two ways: as a Carrier, or as a Modulator. In simple terms, a Carrier is acted upon, whereas a Modulator acts upon. To be precise, a Modulator can also be 'acted upon' by another Modulator, but this is not the place to discuss FM in that much depth. Simply remember this: (i) the more Operators that can interact, the more complex the sound can be, and (ii) the more Algorithms there are, the more varied the range of sounds can be.

The GS1 has eight operators per voice (which is a lot) but these are arranged as four modulator/carrier pairs (which is extremely primitive). The GS2 is even worse: it sports just two modulator/carrier pairs per voice. In contrast, the DX7 has six operators per voice, but offers 32 algorithms that allow programmers to design sounds that take advantage of far more complex interactions between the operators. In this light, it's amazing that the two GS keyboards sounded as rich and engaging as they did.

For a full explanation of FM synthesis, take a look back at parts 12 and 13 of our epic synthesis series, Synth Secrets (see SOS April 2000 and May 2000; also available on the SOS web site at

ar. Even sampled pianos and Roland's SAS (modelled) pianos offered DX imitations alongside their emulations of acoustic and electric pianos.

It soon became clear that the DX7's forté was percussive instruments, and anything that sounded like two bits of metal being banged against each other. Furthermore, it excelled at orchestral imitations such as brass and woodwind. Taking the untreated sound from its single output and adding a little chorus and reverb proved highly successful, adding a realism that no analogue synth had ever approached. I even became a surprise beneficiary of this when, in 1984, Robert John Godfrey of the Enid (a band then famous for its huge rig of analogue synths) bought a DX7 and gave me his 'redundant' ARP Odyssey!

In stark contrast to its wide-ranging capabilities, the DX7 looked surprisingly conservative. At a time when many American instruments sported multi–coloured control panels, graphic affectations such as blue pin-stripes, and large blocks of wood on either end, Yamaha had given the DX7 a slim, sober, and professional appearance. This proved to be a master stroke. In 1983, the world was poised on the brink of the digital revolution. Large turntables with granite bases were out, and compact disc players were in; huge, mainframe computers were out, and tiny 'home' computers were in; large, knobby analogue synthesizers were out, and sleek digital synthesizers were very much in.

But just as the DX7 had great strengths, it had huge weaknesses. As we now know, it proved completely unable to create the warm pads that are meat and drink to any self-respecting analogue polysynth. It was also incapable of the characteristic filter sweeps that dominate so much of popular music in the 21st century. Likewise, its achievements in the field of lead synthesis are (to be polite) less than memorable.

It also had functional disabilities. It wasn't long before players started to notice the hiss generated by the 14-bit DACs used in the early models. In addition, it was a MIDI imbecile, and suffered from the most obnoxious operating system ever devised for a commercial keyboard. And, even ignoring the woefully inadequate screen and horribly abbreviated parameter names, FM synthesis was simply too much science for players brought up on VCOs, VCFs and VCAs. Far from being, as Yamaha claimed, "an easier synthesiser to program than ever before", it precluded most players from all but the most serendipitous twiddling. Indeed, the vast majority of players never reached first base in programming the DX7, electing instead to use it as a preset instrument. Consequently, a whole industry was built on players' needs for more sounds on ROM, more RAM packs (both internal and external) and even computer-based patch editors for the brave.

Of the third-party products, perhaps the most important was the Grey Matter E! board, which increased the number of on–board memories from 32 to 320 (each with independent MIDI parameters) and added patch layering, plus limited EQ. Two French developers named Dan Armandy and Alain Seghir produced the less well-known but superior SuperMax. Like E!, this added more memories, layering, and enhanced MIDI controller capabilities, but also offered arpeggios, MIDI echo and delay, velocity cross-switching, and more.

But perhaps the strangest add-on (being about as large as the DX7 itself) was the Jellinghaus DX Programmer, a large blue control surface that offered dedicated knobs for all the important FM parameters. I only ever saw one of these, at Rogue Music in New York, and was sorely tempted to buy it. Unfortunately, I dithered an hour too long, and by the time I went back for it, it was gone.

If the DX7 took the world by storm (and it did), the same can not be said of its less-than-impressive littlebrother, the DX9. This lacked the DX7's velocity and pressure sensitivity and offered an emasculated eight-algorithm, four-operator-per-voice version of FM with just 20 patch memories. It was a strange sibling for the DX7. Whereas big brother almost single-handedly redefined the synthesizer world, little brother was -- to be blunt -- a complete turkey. Of course, Yamaha may be a lot sneakier than people realise. If ever there was an incentive to spend a bit more to get a DX7, the DX9 was it!

More successful was the TX7, a desktop MIDI module that contained the guts of a DX7, but offered no on-board editing. Then, in 1984, the monstrous TXn16 appeared. This was a 19–inch rackmount frame that housed up to eight TF1 modules, each of which was, in essence, a DX7. These came configured as the TX216 (with two TF1s) to the truly monstrous TX816 -- a 128-note polyphonic, eight-part multitimbral device equivalent to no fewer than eight DX7s in a single cabinet.

But none of these modules captured the public's imagination as had the original DX7. That honour was left to another of Yamaha's monster synths with the number '1' in its name. It was time for the DX1.

Gordon Reid recalls FM's finest hour, and describes the heyday of what was perhaps the most successful family of synthesizers ever developed:

In the first part of this history of FM synthesis, last issue, I mentioned that 1982 saw Yamaha demonstrating a prototype keyboard with "six-operator equation generators" that you could edit. Appearing a year before the launch of the first DX7 (covered last month), the prototype I mention was nonetheless a true 'DX', with all the functions and attributes we now associate with this famous family of synthesizers.

I know of only one mention of it to appear in print. In the International Musician and Recording World Electronic Musical Instrument Guide 1983/4, there's a picture of an otherwise unknown synth. It featured nine programming sliders and an intriguing flip-up panel to the right of its enormous control surface but, in all other respects, this huge, six–octave keyboard looked identical to the instrument it would eventually become. Despite sporting Yamaha's famous, analogue 'CS' series prefix, it would evolve into the biggest and best DX of them all. The Yamaha CSDX was destined to become the Yamaha DX1.

The DX1

I remember the first time I saw a DX1. (You just knew I was going to say that, didn't you?) It was March 1984, and I was walking past a music store in a neon-infested street in Osaka, Japan. I even remember thinking that, if Yamaha's GX1 analogue megasynth (retro–reviewed in the February 2000 SOS) looked like the helm from the original starship Enterprise, the DX1 looked like... well, a more modern version of the helm from the original starship Enterprise. (Remember, this was five years before Jean-Luc Picard first pointed his index finger at the camera and said "Engage".) Anyway, this DX1 was large, flat, beautiful, and had enough red LEDs to compete with the street outside. It also had a price to match -- ¥3,500,000, which was somewhat over £10,000 in 1984 (somewhere between £30,000 and £40,000 at today's values).

Everything about the DX1 spoke of quality: its physical size, its weight, its 73-note wooden keyboard, and, of course, its price. And, although in theory a DX1 should have sounded no better than two DX7s costing a mere £3000, most players privileged enough to play one agreed that this wasn't the case -- it sounded better. You might be forgiven for suspecting that the reasons for this were as much psychological as sonic, but the DX1 genuinely did sound better because Yamaha hand-picked the components for its flagship instrument, leading to a noticeably quieter and cleaner-sounding output. But even this was to miss the point of the DX1. Its ostentatious control surface was more than mere decoration; it was the breakthrough that finally made FM accessible.

Since we're here to praise Caesar rather than bury him, let's take a good look at what made the DX1 special. We'll start at the top left of the panel. It's here that, under a long perspex window, you'll find the graphic representations of the 32 algorithms that the DX1 shares with its little brother, the DX7. To the immediate right of this, there are no fewer than 13 LED windows that -- depending upon the algorithm chos
  Links On The Web  
  As you might expect, there are dozens of sites on the Web that support the DX and TX series. A quick search for "Yamaha DX7" using Yahoo, Google or one of the other major engines will reveal hundreds of pages, many of which are very informative. You should be able to find patch editors and librarians for a number of platforms, thousands of patches, technical advice, book lists, and even programs that – for example -- allow you to tune the DX7/IIs to any scale you wish. There are interviews with John Chowning, discussions of Bessel functions (not for those of a nervous disposition) and much more besides.

en -- show the positions and relationships of the operators. There are even small LED bars that link the windows together so that the algorithm is represented in all its glory. Next to this, there's another pair of LED windows to display the algorithm number and the amount of feedback (if any) for the appropriate oscillator. It's a remarkable section, and all the more showy because, with the exception of the feedback amount, all the information represented is available in the simple graphics found alongside.

But this is far from the end of the story. Moving to the right again, the next section has further LED windows that show the frequency ratio (or, if selected, the fixed frequency) and the detune amount of the currently chosen operator. Then there's the biggie... the collection of eight numeric LEDs (00 to 99) and four 16-segment LEDs that depict the amplitude rates and levels (or, if selected, the pitch-change rates and levels) of the currently selected operator. If you've ever torn your hair out when trying to puzzle out a sound on a DX7, you'll appreciate just how marvellous this on-board representation of the envelopes can be.

Next, there's the Keyboard Scaling panel, which offers more LED windows showing the break point, depths, and selected curves for the chosen operator. Finally, yet more LED windows display the velocity sensitivity, amplitude modulation, and output level for that operator.

As you can imagine, all of this takes up a significant chunk of real estate, but there's no question that it's space well used. Indeed, the only way to make it more useful would be to display all six operators simultaneously. Unfortunately, this would make the DX1 about five feet deep!

You control all of the pretty lights using a control panel that requires more than double the space occupied by the displays themselves. This features yet another innovation that comes as a very welcome surprise: real buttons. Whereas the DX7 had horrid membrane switches (sure, they kept the price dow
  The Yamaha FX1  
  Lest you think that (other than the DX1) all FM synthesizers were small, neat affairs, let me tell you about the FX1. This was a huge three-manual beast very much in the mould of the GX1, but based entirely on FM synthesis. If you've never heard of it, I'm not surprised. Costing £36,000 in 1986, there's only one working example in the UK, and not many more elsewhere.

Yamaha sold Britain's only FX1 to the Blackpool Beach 'Sandcastle', where it was to be used for recitals by organists such as Glyn Madden and Harry Stoneham -- names that will be very familiar to lovers of large Wurlitzers and the Blackpool Tower Ballroom. Unfortunately, the Sandcastle was not a long-term commercial success so, in 1995, the FX1 was sold off to an organist living in the town. By this time it was in a bit of a sad state but, with Yamaha's assistance, the new owner restored it to something close to its original condition.

Now, I bet that you didn't know that I occasionally play at the Grand Hotel, Lytham St Annes. Well, I do... and the organist in question is a colleague of the guitarist with whom I play these gigs. So I eventually got to see and play the FX1, and what a beast it is. Most impressive of all are the motorised edit faders that jump into position whenever you recall a patch. Now that's what I call clear and intuitive FM programming!

Let's not forget the FX1's smaller brethren, the FX3, the FX10 and FX20. You've never seen one of these? Don't worry about it. Neither have I.

n, but they were still horrid), the DX1 had firm momentary switches that emitted a satisfying click each time you pressed one. What's more, most of them incorporated yet more LEDs, so there was never any doubt what was selected, and what was not. With six dedicated switches for operator selection, another six for operator on/off, more for algorithm and feedback selection, operator mode and tuning, individual buttons for the rates and levels (I could go on, but I'm sure you get the picture), the DX1 was useable.

Of course, much of what I've outlined so far describes merely a sexier DX7, and it's not until you search for the patch–selector buttons that you discover the next, huge difference between the DX7 and the DX1. Where the DX7's 32 membrane switches doubled as patch selectors, the DX1 offered two sections -- 'A' and 'B' -- each with four banks of eight patches, for a total of 64 patches in all. Oh yes, and don't forget the dual ROM/RAM cartridge slots; one each for the 'A' and 'B' banks, thus making 128 patches available at any given time. Not bad for 1984!

And we're still not finished, because alongside the 24 patch-selector buttons lie a further 16 multi-function buttons and a 40-character x 2-line LCD. If you are playing (as opposed to editing) the synth, these take you from 'Single' mode to 'Dual' mode, acting as eight banks of eight memories that access the 64 dual-patch performances. In Edit mode, eight of them act as LFO editors (it's quite an LFO section in a DX1!) while two others allow you to transpose and name patches. Then there's Function mode...

This has an associated Function Job Table silk–screened into the area occupied by the flip-up panel on the CSDX, which lists no fewer than 47 additional parameters, sub-divided into Tuning, Performance Memory Parameters, Memory Management and MIDI Control sections. When you see that, for example, nine of these parameters control the poly-aftertouch control of individual operators, it all looks hideously esoteric, but I can tell you from experience that -- once mastered -- it all works remarkably quickly and simply.

Returning to the right of the panel, there are four faders and two buttons where the nine faders of the CSDX once resided. These control the master volume, the A/B balance between the two sections, portamento time, and data entry (either by up/down buttons or continuous controller). All of this sits behind the Minimoog-style pitch and modulation wheels that, like everything else on the DX1, are beautifully weighted and positive in action. Oh yes, and speaking of weighting, how does a 73-note piano-weighted keyboard with polyphonic aftertouch grab you?

At the back of the DX1 you'll find 13 inputs and outputs. These include the now ubiquitous MIDI In/Out/Thru sockets, continuous controller inputs for volume and modulation amount, and momentary pedal inputs for sustain and portamento on/off. But it's the six audio outputs that interest me most. In truth, there are just three outputs because they are presented in both balanced (XLR) and unbalanced (quarter-inch jack) format. Nonetheless, they offer individual 'A' and 'B' outputs, as well as a single, mixed output. You might ask why I put so much emphasis on these. Well, if you're wrinkly or crumbly enough, think back to 1984 and ask yourself how many other instruments of the era offered two fully–functional 16-voice MIDI synthesizers in a single (albeit very heavy) case. The Prophet 10? Sure, it had two engines, but it was merely 10-voice polyphonic and was pre-MIDI.Likewise, the eight-voice Roland Jupiter 8 and Yamaha's own CS80. It wasn't until much later that the two-synths-in-a-box concept really caught on, and only Roland -- with the dual-JX8P Super JX10 -- came anywhere close to competing with Yamaha in this area.

Now imagine super-clean versions of, for example, the classic FM pianos, layered with equally excellent brass and woodwind sounds, Clavinets, or the DX's trademark percussion patches. You could even create some remarkably lush ensemble performances by directing different string and brass sounds to each output, and treating them externally with the effects units of your choice. I know it's fashionable to believe that FM was incapable of producing warm analogue pads, but just try a DX1 hooked up to a couple of Dimension Ds, a Lexicon or -- better still -- an Eventide effects processor. I guarantee that you'll question your preconceptions.

Of course, the DX1 is not what you could call a convenient synthesizer and, given its size and weight, it was inevitable that most of them would end up living in studios of one sort or another. Consequently, it came as no surprise when, a year later, Yamaha announced the DX5. With a superb 76-note semi-weighted keyboard, this offered channel aftertouch rather than poly–aftertouch, lacked all the LED screens, and provided fewer buttons, but functionally it was an otherwise perfect substitute for the DX1.

Indeed, many players preferred the DX5 to the DX1, because the DX1's keyboard is perhaps the heaviest you'll ever encounter on a synth. To quote my mate Blue Weaver (The Strawbs, The Bee Gees, and the chap who played for the Pet Shop Boys what was later to become my DX1), "You can shred your fingers playing glissandos".

In short, the DX5 was slim, manageable, and a delight to use. And, at around £3000, it cost just 30 percent of the ten grand demanded for its almost identical bigger brother. It's true that neither the DX1 nor the DX5 were the most powerful examples of their generation of FM synths, offering just a quarter of the eight-part multitimbrality and 128-note polyphony of the TX816. But that wasn't the point. The DX1 and the DX5 were superb performance synthesizers, and they remain so to this day.

  The Key FM Synths & Modules  
The following table lists all the mainstream FM synthesizers covered in this two-part retro. It's far from a comprehensive list of FM instruments, lacking dozens of PSS- and PSR- home keyboards, as well as PF-series pianos, EMT- modules, HS-series, HE-series and a host of other organs.
* The First Generation (sine-wave operators and 14-bit D-A converters)
These were the first of Yamaha's commercial FM synthesizers. You couldn't edit them, although, in the cases of the GS1 and GS2, you could load new voices from Yamaha's preset patch library. (See part one of this retro, last month, for more details.)
Year Name Operators Polyphony
1981: GS14 pairs
16 GS2 2 pairs 16
1982: CE20 2 pairs? 9
CE25 2 pairs? 9
* The Second Generation (sine-wave operators and 14-bit D-A converters)
Ranging from the tiny DX100 to the monstrous DX1, these instruments totally dominated the synthesizer market of the mid-'80s.
Year Name Operators Polyphony
1983: DX7 6 16
DX9 4 16
TX7 6 16
1984: TX816 6 up to 128
DX1 6 32
1985: DX5 6 32
1986: DX21 4 8
DX27 4 8
DX100 4 8
FB01 4 8
* The Third Generation (sine-wave operators, and 16-bit D-A converters)
Designed to replace the second generation of FM synths, these failed to achieve the same success. That's a shame, because the DX7/IIFD and TX802 are fine synthesizers.
Year Name Operators Polyphony
1987: DX7/IID 6 16
DX7/IIFD 6 16
DX7S 6 16
TX802 6 16
* The Fourth Generation (eight waveforms as operators, 16-bit D-A converters)
Very much a swansong that allowed Yamaha to capitalise further on the FM system. With the exception of the TX81Z, these failed to make any real impression in serious musical circles.
Year Name Operators Polyphony
1987: TX81Z 4 8
1988: DX11 4 8
YS100 4 8
YS200 4 8
1989: V50 4 16
TQ5 4 8

A Large And Unruly Family

Throughout the mid-'80s, Yamaha flooded the market with a plethora of low-cost FM synths. These used the truncated four-operator/eight-algorithm FM architecture of the DX9, so they were not compatible with the DX7, the DX1 or the DX5.

The DX27 was the basic model. With just 8-note polyphony and a 61-note keyboard that was neither velocity- nor pressure- sensitive, this was, in retrospect, a particularly poor instrument. Nevertheless, the combination of 192 preset patches, 24 user memories, aggressive pricing and the magic FM cachet ensured that the DX27 was a commercial success. There was even a DX27S, with built-in speakers and a chorus effect. This was no doubt aimed at the 'home' synthesist, but I suspect that Yamaha sold very few.

Then there was the DX100. This was in many ways identical to the DX27 but was fitted with a 49–note mini-keyboard and strap pegs. Designed for Howard Jones-style posing, this was perhaps the most successful of all the four-op machines. Certainly, it was instrumental in introducing a whole generation of younger players to the joys (or not) of FM synthesis. And let's not forget the FB01, an eight-voice, eight-part multitimbral version of the DX27 and DX100 in a half-rack box designed to complement the home organ of your choice. You couldn't edit it from its front panel, but that didn't stop Yamaha from selling bucketfuls of them.

Slightly better than any of these, the DX21 featured a basic split/layer capability, thus making it capable of more interesting sounds than either the DX27 or the DX100. It also offered a handful of extra voicing capabilities, such as the ability to bend a single note within a chord -- great for acoustic guitar impersonations. If you're ever tempted to buy one of these cheapo four-op instruments, this is the one to get.

The Third Generation

With around 200,000 units sold, the DXs and TXs dominated the mid-'80s music scene in a way that no other keyboards or modules had done before, nor have done since. Indeed, FM dominated all forms of electronic music, and a huge family of home keyboards, keyboard expanders, electronic pianos, multi-keyboards and console organs used one or another form of FM sound generation. There were even FM synthesizers produced by other manufacturers -- specifically Korg and Elka -- to whom Yamaha had sub-licensed the technology. But, in 1987, Yamaha replaced the second generation of FM synthesizers with a third.

Yamaha sought to capitalise on earlier successes by calling all the new models the DX7 'something or other'. The DX7/IID was the basic model, and this was to be the direct replacement for the DX7. It retained the 'pure' six-op FM programming system of earlier DXs, but addressed many of the problems of the originals and proved to be a huge improvement over its predecessors. For example, the hissy output of the DX7 was eliminated by the simple expedient of replacing its 14-bit D-A converters with CD-quality 16-bit, 44.1kHz DACs. As you will appreciate, this also increased the frequency response and dynamic range of the synth, and eliminated much of the aliasing that plagued higher-pitched notes on the original. There were many other notable improvements. Yamaha improved the hardware and programming interface, added assignable sliders, doubled the number of patch memories, introduced micro-tuning, added a bigger screen, and significantly extended the storage capabilities of the RAM cartridges. The new synth's FM voicing system was also upgraded, with subtle (but important) enhancements to the level scaling, LFOs, and pitch envelope generators. There was even a Random pitch parameter that introduced subtle inconsistencies to the tuning of each note as you played. Now known as 'analogue feel', this is almost ubiquitous in 2001, but was a revelation in 1987. Perhaps the most significant change was the introduction of a true stereo sound generator, which made the DX7/IID bi-timbral, and capable of two-part splits and layers (performances). Then there was the aftertouch-controlled pitch bending, a hugely improved MIDI specification, and more.

All in all, the DX7/IID was an excellent synth, but its enhanced sibling, the DX7II/FD, was even better, because it added a 3.5-inch DSDD floppy drive to the standard specification. At a time when only a handful of expensive synths and samplers offered drives, this was a huge benefit that made backing up, saving, and loading
  The Latter Days Of FM Synthesis  
  FM didn't die when Yamaha discontinued production of its DX-, TX-, and YS-series synthesizers. However, it metamorphosed into something called AFM (Advanced FM) that offered multiple waveforms as operators, and could use PCM samples as modulators. The SY77 was the first instrument to offer this system and, although it received merely lukewarm applause upon its release in 1990, the '77 has recently enjoyed a resurgence of 'retro' interest and respect.

The SY22 Vector Synthesizer was another post–FM instrument that incorporated aspects of FM synthesis. Combining FM, AWM (Yamaha's name for PCM-based synthesis) and the vector technology developed by Sequential Circuits, this was truly a hybrid of sounds and styles, as was its successor, the SY35.

Yamaha released one last, large AFM synth -- the SY99 -- before it ditched the system to concentrate almost exclusively on AWM. But even then FM didn't die. The FS1R Formant Synthesiser (1998) is closely related to the second generation of FM synths. Indeed, if you ignore most of the advanced features of this superb rackmount module (such as its 88 FM algorithms) you'll find that its patches are fully compatible with those of the original DX7. And, most recently, a 'groovebox'-style instrument, the DX200, became the latest Yamaha synth to use FM synthesis, with the addition of easy-edit knobs and step–sequencing facilities, plus a free software editor for more in-depth control.

simpler and cheaper than it had ever been before.

The baby of the range, the DX7S, lost the bi-timbral split/layer capabilities of its bigger brothers, as well as the improved LCD, but in all other respects it was a true DX7/II.

But perhaps the most attractive synthesizer of this generation wasn't a keyboard at all. The TX802 was a 2U rackmount module. Essentially an 8-part multitimbral DX7/II in a box, it was the canine's hindquarters and, at current prices, I reckon it remains a little gem, even in 2001.

Clearly, Yamaha intended for the DX7/IID, the DX7/IIFD, the DX7S and the TX802 to take over from the original DX7, and to continue its domination of the professional synthesizer market. But after four years the keyboard world was ready for something new. To be fair, the DX7/IID and FD were reasonably well received, but for some reason they simply didn't have the appeal of the original DX7. As for the 'S', it was a turkey of the first order. Yamaha's reign was well and truly over.

The Fourth Generation

By the time the tail end of 1987 rolled around, FM synthesis was beginning to look decidedly old hat. The lustre had gone, and when Roland released the D50, players everywhere snapped it up in preference to the Yamahas of the day. With its PCM capabilities, built-in effects and ethereal sounds, there seemed no doubt that the D50's was the sound of the future.

But Yamaha had a couple of throws of the FM dice left, and in 1987 it launched the TX81Z, an eight-voice, 1U rackmount module that offered a new type of FM synthesis -- one that allowed you to select from eight waveforms for each of its four operators. What's more, the TX81Z was cheap and multitimbral, so it soon proved very popular as a low-cost expander.

The following year, the DX11 appeared. This was the first truly multitimbral FM keyboard synthesizer but, because it was modelled closely on the TX81Z, it too was based on just four-op FM. However, the DX11 also offered copious memories and presets, and introduced a simplified editing system called Quick Edit FM that made FM more approachable than ever before, so it proved to be a reasonable success. The same was not true of its technological siblings, the home-keyboard style YS100 (which added an effects processor to the DX11 architecture), the YS200 (which added a basic sequencer), and the TQ5, the desktop module of the YS200. Yamaha's last 'pure' FM synth was the V50, again more of a home keyboard than a serious instrument, and with its demise in 1990, a line of great synthesizers finally died.


If this month's retrospective has concentrated on the DX1, there's a good reason. With the exception of the hyper-expensive rarity that is the FX1 (see 'Yamaha FX1' box on page 258) it was the king of the FM synthesizers. Even today, sitting behind 10 grand's worth of hand-finished keyboard is enough to m
  Grey Matter Response  
  Like the DX7, the DX7IID and its derivatives spawned a successful industry that provided sounds, memory cards, and add-ons for the basic synths. Of these, the 'E!' enhancement board (see last month's instalment) remains the most significant.

The original E! board for the DX7 had added extra memories, patch mapping, bi-timbrality, layering, and master controller functions to the original synth, so manufacturer Grey Matter Response must have been mightily dismayed when Yamaha incorporated all these facilities into the DX7IID.

However, as is so often the case, the eventual winner was the customer, because the re-engineered E! for the DX7IID and FD offered eight-part multitimbrality, sequencing, and MIDI monitoring. A top-of-the-range DX7II/FD with E! is therefore a powerful instrument, and one that remains desirable to this day. Unfortunately, Grey Matter Response no longer has E!s in stock, and has ceased production. Shame.

If you require more information about E! you can approach Grey Matter Response directly. The company still supplies manuals and other documentation.

Grey Matter Response Inc, Suite C,
4340 Scotts Valley Drive, Scotts Valley,
CA 95066, USA.


ake any player feel good. The sheer range of controls is spectacular, and if you've never had the opportunity to edit a DX1, you've missed out on one of electronic music's great pleasures. Unfortunately, it appears that just 20 of them were delivered to the UK, thus it's highly unlikely that you will ever have the opportunity to buy one.

Despite the fact that Yamaha have produced some superb instruments over the past 17 years, most synthesizer aficionados claim that FM was a blind alley, and that the CS80 was the last great Yamaha synth. I'm sure that John Chowning would think them wrong, as do I. Here's why.

The CSDX (which, if you remember the start of this retro, became the DX1) took the poly-aftertouch of the CS80, and incorporated it into a bigger, beautifully weighted keyboard. It took the dual voicing of the CS80, and adopted the same voicing philosophy for its 'performance' mode. It even took the real-time control of analogue synthesis and transformed this into a real-time digital editing system with multiple displays and relatively simple control capabilities. (That the DX1 lost the nine control faders of the prototype CSDX is a shame, but in my view it's irrelevant, because the DX1 remains to this day the only true FM synthesizer that you can programme quickly and easily from its own control panel.)

So if you're looking for a later Yamaha synth that still qualifies for the tag 'great', look no further: the DX1, a true successor to the CS80.


I would like to thank Richard Clews for alerting me to the photo of the CSDX in International Musician and Recording World magazine, and for his thought-provoking views on the history of FM synthesis.


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