Yamaha's FM synthesis was designed by John Chowning: Dx was the first true commercial release implementing this new concept.
The FM revolution changed the sound forever and killed analog synthesizers from the eighties.
KEYBOARD (15 Kg weight) 61 keys with Velocity range 0-99 (not really 127) featuring Aftertouch and editable Velocity Curves.
The main panel features a 16*2 lines display with no backlight,2 sliders for Volume gain and data entry + 42 buttons for programming purposes. On the left side there are two assignable wheels for Pitch and Modulation (value ranges are adjustable for both) and below a headphones connector plus a Yamaha Breath controller Input.
Rear panel terminal connectors: mono jack out for Volume, a
the Midi interface, double footswitch inputs for Sustain and Portamento and finally another double Foot controller Inputs for Volume and Modulation.
Power supply is internal.
VOICES main core 8-bit CPU Hitachi HD63A03X manages 16 FM digital voices;
The YM2128 generates 6 syncable digital oscillators sinusoidal waveform called Operator each with individual volume settings and Pitch Detune-Coarse. These operators can be chained into
32 different combinations Algorithms with Frequency ratio or Fixed frequency and the output is fed back to its input with 7 different levels feedback; as general rule, high values Feedback results in high Harmonic contents.
are 6 Sinewaves operators organized as Algorithms depending on the function as Carrier
or Modulator, linked between them on different
ways, interacting on their harmonic contents, mostly depending on the
Strength Feedback. The Carrier sets the Amplitude and the Spectral Frequency while the Modulator mainly sets the sound timbre and the relative harmonic contents.
HISTORY typical eighties FM mellows Rhodes heard in tons of mellow hit records or typical digital bell. FM can do this and much more like crystal sounds with lush strings or even complicated noises.
FM principle always come back soon or later, even decades after it has been re-implemented in newer machines like excellent workstation Yamaha Sy99, a DJ groovebox Dx-200 or most sophisticated formant Fs1R. Nevertheless the DX7 still shines for its sounds maybe for the raw dynamic at 13 bits resolution. DX7 Vs DX7II sonic test differences
LFO two digital modulators with Frequency, adjustable Start Delay and 2 destinations: the PMD modulates Pitch, while the AMD modulates Amplitude. Both LFO have 6 waveforms (Sinusoidal, Triangle, SawUP, SawDown, Square, Sample & Hold) and the special Sync function allows to continue the modulation effect between notes or retriggers the modulation from beginning.
EDIT main functions values are done using a single data entry slider on tiny display, which sounds rather basic! but it results functional after a while - anyway there are lots of computer editors available on the market or just for free.
ENVELOPE the YM2819 generates a total of 7 envelopes: 1 EG pitch + 1 EG per Operators (six) and all EG have a 4 segments structure +4 different time levels. Another important
function is the Scaling Level - a very precise key follower with 4 linear or exponential curves and Depth.
EFFECTS NONE! in later 4OP FM engines Yamaha used some kind of pseudo reverbs tricks like TX81z.
MEMORY holds 32 patch backup with soldered CR-2032 lithium battery + 32 extra sounds on external cartridge data slot - of course you can still dump your data by Midi Sysex exclusives.
E! BOARD EXPANSION Standard Dx7 mk1 is monotimbral with some flaws like Velocity on keyboard that later Yamaha corrected later on the successor DX7 mkII including also a better DAC at 16 bits resolution. Nevertheless some people
still prefer the mk1 for the distinctive fatter and dirtier sound! so If you are in love with this model there are ways to fix some of the irritating original defects by hardware modifications. Third party companies build custom upgrades, and one the best board is the E! from Grey Matter Response. Grey matter CARD it is not easy to find and requires a Dx7 with one the latest OS (only upgradable by EPROM) and requires some skills on soldering and cutting and re-routing circuit tracks.
Upgraded Dx7 E! is multitimbral with ten time more RAM slots, a neat Monophonic Mode with up to 8 voices
Stack and adjustable Random Detune (variable range set) a user-friendly TX programmability, Midi out Channel, controller
Remap and much more.
OP6 DX FAMILY After one year Yamaha released the super deluxe version Dx1 that later became the cheaper DX5. There' s also an expander module Tx7, then the huge TX816 a pretty impressive rack modular version! The Tx802 is a DX7 II (mk2) rackmount versions.
Below a little DX Sum-up: