The Dx7 was the first affordable synthesizer implementing FM synthesis, designed by John Chowning.
The FM revolution changed the sound forever.
KEYBOARD (weight: 15 Kg) 61 keys with velocity and aftertouch.
The main panel features a 16*2 lines, 42 buttons, 2 sliders for volume and data entry.
On the left side there are 2 wheels for pitch and modulation and right below a headphones out with a breath controller input.
Rear panel terminal connectors: mono out, Midi interface, two footswitch inputs for sustain and portamento and finally 2 pedal 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 sinewave oscillators or "Operator" each with individual volume settings and detune.
Operators can be chained into
32 different combinations Algorithms with frequency ratio or fixed frequency: the output is fed back to its input with 7 different levels feedback.
As general rule, high values feedback results in rich harmonic contents.
are 6 sinewave operators organized as algorithms, assigned as carrier
or modulator and linked between them on different
pathways interacting on their harmonic contents depending on the
feedback strength. - carrier: defines the amplitude and the spectral frequency - modulator: sets the sound timbre and the relative harmonic contents.
DX7 MK2 the second DX7 version offers some update and sounds a bit different, mainly for the different DAC with higher resolution.
I made a little comparison test:DX7 Vs DX7II
LFO there are 2 digital modulators with adjustable start delay and sync retrigger:
1- PMD modulates pitch
2- AMD processes the amplitude
Both LFO offers 6 waveforms : sine, triangle, saw up/down, square and sample & hold.
ENVELOPE the YM2819 generates 7 envelopes:
- 1 EG pitch: 4-segments structure + 4 time levels.
1 EG for each operators: 4-segments structure + 4 time levels.
The Scaling Level is a very precise key follower with 4 linear / exponential curves.
EFFECTS none: in later 4-OP FM lines Yamaha implemented some pseudo reverbs by Midi tricks like TX81z.
MEMORY holds 32 patch backup, doubled if a cartridge RAM1 is present.
The backup memory works with a CR-2032 lithium battery soldered to the board, just be aware that there is no ROM factory recall so it is necessary to use Midi exclusives data for this job.
E! BOARD EXPANSION This special board can be fitted to upgrade to machine to new functions and features:
- ten times RAM slots,
- monophonic with 8 voices
adjustable random detune (variable range set)
a user-friendly TX programmability
much more on the Dx7 E grey matter PDF manual.
INSTALL board requires a Dx7 with latest OS (only upgradable by EPROM) and requires some advanced skills for soldering and cutting circuit tracks.
EDIT the Dx7 is not famous for easy and real-time edit functions! if you are lucky enough, you can try the mega-rare Jellinghaus DX Programmer (worth 2000€).
A cheaper way are the computer programmers, some of the first were available for Atari ST like Dx-android, Dx expert or caged ST, then PC-based programs like Soundiver, Midiquest, DX-manager, Synlib and others.
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.