Yamaha DX7

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Yamaha DX7

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W × H × D (mm)	101.8 × 10.2 × 32.9
Weight	14.2kg
Type	6 operator FM Synthesizer
Keyboard	61 Keys with initial and aftertouch sensitivity
Manufacturer	Yamaha
Release date	1983
Parts	1 (Monotimbral)
Max polyphony	16
Normal presets	32
Expansion	DX7 Voice Cartridge
Power delivery	Hard-wired Region-specific (Applicable to all DX7 models and variants)
Backup battery	3v CR2032

The Yamaha DX7 is a 61-key 6 operator FM synthesizer keyboard created by Yamaha in 1983. It's one of the most famous synthesizers ever made. It was incredibly successful and especially popular in the 1980's. Many of its tones appearing in popular music and productions of the time. Many of its sounds (Such as the unique glassy rhodes tone, its very distinctively harsh digital bass sounds, and many more) to this day are still production staples, having been sampled in countless sample-based synthesizers and most notably in the General MIDI spec, as the Electric Piano 2 voice.

It employs 6 operator FM synthesis as its main source of sound generation, with 32 algorithms. The DX7 comes with 2 sound cartridges, with the first 32 preset voices of the first one loaded in internal memory.

FM Synthesis

Contrary to a lot of marketing, the DX7 actually implements phase modulation synthesis; rather than modulating the frequency of each oscillator, it modulates its phase instead. For DX7's implementation, where only sine wave-based operators can be used, this is perfectly equivalent to frequency modulation, however later Yamaha FM synths that use non-sine wave based oscillators (such as the TX81Z) would have a slightly different sound compared to FM implementations.

Regardless of such, FM synthesis provides a very different paradigm compared to more traditional subtractive synthesis - rather than having a sound that you can use a filter to remove parts of the sound, you are provided with many different "operators", which can rapidly sweep the pitch (or phase) at audible rates to create harmonically rich sounds. When tuned precisely to ratios (such as 2x, 3x and so on), this can create very sharp and bright sounds, uncharacteristic of typical subtractive synthesis, especially of its era which employed much simpler sawtooth or pulse waveforms. The user also had the choice to run these operators at a "fixed" frequency, which did not scale with the frequency played, to create harsher sounds.

32 algorithms are provided to the user, which link up the operators in different ways. The operators that actually output audio are referred to as carriers, while an operator that links to one or more operators are referred to as modulators. It is worth noting that modulators can feed into other modulators, however the relationship of this is dependant on the algorithm chosen. One operator has access to a "feedback" parameter, which lets it modulate itself, regardless of whether it is a carrier or modulator.

Yamaha's implementation of FM synthesis on the DX7 employs the use of two chips: The Yamaha YM2128 (OPS) for generating the operator sounds, and the Yamaha YM2129 (EGS) for the envelope generation. Later revisions of the DX7, such as the DX7 II, employed revisions with the same base feature sets - The Yamaha YM2604 (OPS2) for operators, and Yamaha YM3609 (EGM) for the envelopes instead.

Revisions & Variants

Yamaha DX9

The Yamaha DX9, released in 1983, is a DX7 with a modified firmware, which reduces the number of available operators from 6 to 4, and reduces the algorithm count from 32 to 8, among other cost-reducing factors.. The 8 algorithms are the same as those featured on later 4-operator Yamaha offerings, such as the DX21/100/200 and the TX81Z.

There is firmware available online to restore some of the missing functionality, making the DX9 behave more like a real DX7, but ultimately the DX9 and DX7 are designed differently enough where this isn't fully feasible - differences in available RAM, the key bed not supporting aftertouch or velocity sensitivity, and lack of enough front panel controls have made it challenging, if not impossible, to make the keyboard "be" a real DX7.

Yamaha TX7

The Yamaha TX7 is a desktop version of the DX7. It is not a rack mounted synthesizer. It otherwise employs the same features as the DX7.

Yamaha DX7s

Released in 1987, the DX7s is a redesign of the DX7 to get it looking more in-line with the DX7ii which released the same year. It employs the same feature set as the DX7.

Yamaha DX7iiD / Yamaha DX7iiFD / Yamaha DX7ii Centennial

Released in 1987 (1988 for the Centennial edition), these are all upgrades over the base DX7 that provide double the polyphony, bi-timbral operation, stereo output, as well as a new design to make editing easier. Because it is bi-timbral, one can employ proper "split" patches (as opposed to using the level scale feature to create faux-splits on previous units), or simply employ 2 FM voices per note for more elaborate sound design (such as layering a marimba and brass sound together, as an example).

The DX7ii Centennial further upgrades the DX7 by featuring a 76-note keyboard instead of the more typical 61, and also being featured in a silver-y white finish rather than the dark greys or browns of the previous units.

Available Firmware

As the DX7 was a hugely popular synthesizer, it is relatively common practice for people to upgrade the firmware to add features not present on the original synthesizers. [need to find info about firmware history and revisions]

Emulations and recreations

As the DX7 is quite a popular synthesizer, and because the sound production method isn't strictly tied to including an entire bank of ROM waveforms, there are quite a lot of emulations and recreations available, either as free open-source software or as paid software, or even hardware.

Dexed

By far the most popular recreation. It is available as a free VST and standalone program, and has the ability to interface with a real DX7, acting as a librarian. It is also fully open-source and has an interface that allows for full patch editing. It is regarded as difficult to use for patch creation by some.

Chipsynth OPS7

This is a modern recreation that tries to accurately recreate all the quirks of the DX7, from some of its software quirks to the compander-based DAC. It can also act as a librarian, but also implements a number of features not available on the DX7, such as a dual voice system reminiscent of the DX5 and DX1, or the later DX7ii, extra waveforms taken from the TX81Z, the YMF262, or even the AFM engine from the SY77. The interface is easier to use than Dexed's and offers a similar user interface to Chipsynth MD. It is available as a one-time paid purchase from Plogue's storefront.

Arturia DX7 V

This is another modern recreation. It implements SysEX support, but cannot act as a librarian. Many extra waveforms are implemented, as well as a wealth of new features, a modulation matrix, and a nice graphical interface. It also has a built-in velocity scaling feature, allowing the user to either use the full 0-127 velocity range, or limit it to 0-99 as per the original DX7 key bed. It can be acquired from Arturia's storefront either on its own or as part of the "V Collection" bundle.

Korg Volca FM & Volca FM 2

This is a compact hardware unit with a built-in sequencer, it has 3-voice polyphony, it can load DX7 SysEx files. The Volca FM 2 doubles this to 6-voice polyphony.

Oddities

• The DX7 was made very early on when the MIDI protocol was still new, so its implementation has quite a few oddities and quirks such as:
  • On the original models, it can only transmit velocity up to 100, though all DX7s can receive up to the normal 127. As the original set of patches was designed to be used with the limited-velocity keyboard, they may sound weird at louder velocities if they are velocity sensitive (or, depending on how the DX7 was used, the opposite can also be true).
  • It can only transmit on Channel 1 (but can still receive on any channel).
  • Aftertouch was a CC parameter rather than a controller type of its own (this was since corrected in later firmware).

• The DX7 Manual has an error on page 1 that states the keyboard is expandable up to 128 preset voices when it can only interface with up to 96 when considering the 32 Voice Preset Internal memory and an external 64 Voice cartridge.

External Links

• DX7 Operating Manual + MIDI DATA Format
• DX7 Voice Library with Performance Notes
• Brochure