A digital synthesizer introduced by Yamaha in 1983. The DX7 was the first mass-produced synthesizer to use frequency modulation extensively, and the first digital synthesizer to sell in large quantities. It defined the direction of Yamaha's entire keyboard line for the next seven years after its introduction. At over 100,000 units sold, it still stands as by far the best-selling synthesizer ever produced.
The DX7 story begins with music composer and researcher John Chowning. While working at Stanford University in the late 1960s, he begin experimenting with digital FM synthesis methods. Running on the slow computers of the era, he developed means of computing FM timbres to emulate real instruments such as bells and pitched percussion instruments, without needing inordinate amounts of CPU time to compute the sounds. Through Stanford, he obtained patents on the applications of FM to music synthesis.
In 1973, Chowning and Stanford licensed these patents to Yamaha. It took another eight years for CPU development to get to the point where the technique could be incorporated into a reasonable-sized musical instrument. In 1981, Yamaha introduced its first instrument to use FM, the GS1 organ/synth. The GS1 was a large and costly instrument intended for institutional customers; only a handful were sold, and the FM features mystified the few performers who tried to use it.
So Yamaha pulled out the FM circuits and built a synth around them -- the DX7. A key feature of the DX7 was its well-executed factory patches, which provided ear-pleasing renditions of grand pianos and Rhodes pianos, as well as brass sounds. Introduced in 1983, within two years the DX7 had crushed most of its competition. Further models added more patch memory, improved processing circuitry, additional sounds, and floppy disk storage for patch data.
The DX7's dominance changed the synthesizer market in several ways, not all of them good. Yamaha had realized that many players would be intimidated by the complexity of the FM synthesis method, plus the number of parameters would make for a very cluttered and expensive-to-produce panel if every parameter was given its own control. So Yamaha minimized the user interface, with a set of buttons that stepped through menus to select editing parameters on a small alphanumeric display, and a single knob to set the value of whatever parameter was selected -- the now familiar one-knob interface. They guessed right; a large number of DX7 players did little or no patch editing, perferring to either buy sound banks or just play the factory patches. In fact, the DX7 was the first synth to be purchased in large volume by performers who had no interest in it as a synth; they simply wanted to use it as a substitute for a piano, with the additional ability to cover organ and brass sounds. Meanwhile, the DX7's popularity pushed many other synths off the market; by creating a demand for realism in synthesis, it forced out the early-80s analog synthesizer designs that couldn't produce accurate-sounding piano sounds. Patch design began to be thought of as a speciality job, rather than something that most synth players should do for themselves. And anybody who did want to design their own sounds was pushed back by the DX7's minimal and user-unfriendly interface. Some parties tried to improve this situation; the famous Jellinghaus DX7 programmer consisted of a knob-laden box that edited parameters via the DX7's MIDI interface. And interestingly, Yamaha itself offered up the CX5m music computer with a software cartridge that turned it into a graphical DX7 patch editor. But none of these sold well; most DX7 customers were simply not interested in patch editing.
Yamaha rode the crest of this wave for about five years. Unfortunately for them, during this time memory was getting cheaper, and by the late '80s, romplers were capable of beating the DX7 at the realism game, and providing traditional instrument sounds that FM couldn't easily produce. Yamaha itself started to move away, first introducing synths that combined FM with sample playback, and then moving away from FM and into physical modelling. The last version of the DX7, the IIFD, went out of production in 1991.
All of this tends to disguise the fact that the DX7 was a very good and capable synth. It contained 8 voices, each with six "operators", or individual sine wave oscillators that could be made to modulate each other in various ways. (Yamaha later reduced a four-operator version to a small chip set, and this was used as the basis for several low-cost FM synths, as well as sold for use in video games and computer sound cards.) The keyboard was velocity and aftertouch sensitive, and the DX7 was one of the first synths equipped with MIDI from the factory. A huge variety of startling and unusual sounds was available to the patient programmer; Brian Eno programmed his extensively. And of course its sound was startlingly different from the analog synths that dominiated the market at the time.
Today, because of the sheer number produced, the DX7 can be had cheaply on the collector market. The patch editing problem is largely solved with modern computer editors. In fact, Native Instruments' soft synth emulation, FM8, can actually exchange patch data with a DX7.
A question that is often asked: Is it true that the DX7 didn't really do FM? Technically, yes it's true. Because microprocessors were still pretty limited in 1983, the DX7 internally uses a related computation known as phase modulation, which requires less CPU power. The trick: frequency modulation and phase modulation produce the exact same result, provided that the modulating waveform is a pure sine wave. That's why the DX7, and most other FM synths, didn't offer waveforms other than sine waves from the operators.