The Roland JD-990 is a module version of Roland JD-800

Roland JD-800

The JD-800 was a digital synthesizer released by Roland in 1991. The synthesizer featured many knobs and sliders for patch editing and performance control - features which some manufacturers, including Roland, had been omitting in the name of 'streamlining' since the inception of Yamaha's DX-7...

 synthesizer with expanded capabilities. JD-990 is a multitimbral synthesizer utilizing wave-table synthesis technology. It is equipped with 6 Mb of ROM containing wave-table, four sets of stereo outputs that are assignable to individual, internal, instruments, and standard MIDI in/out/through ports. JD-990 has a large LCD display and programming takes place through a keypad on the front panel of the unit. The unit can generate multitimbral sounds reminiscent of the vintage analog synthesizers but is also capable of generation of modern digital textures. There are several expansion boards available for JD-990 that can be installed in the provided expansion slot in the chassis of the unit.

The JD-990, also known as Super-JD, had the following features which were not available on the JD-800:

1. Expanded wave ROM
   Read-only memory
   Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
   
    (6 MB vs. 4 MB)
2. Ability to use a 8 MB expansion board
3. 4 additional outputs
4. True stereo engine
5. Oscillator sync
   Oscillator sync
   Oscillator sync is a feature in some synthesizers with two or more VCOs . One oscillator will restart the period of another oscillator, so that they will have the same base frequency...
   
   
6. Cross-modulation (FXM)
   Frequency modulation
   In telecommunications and signal processing, frequency modulation conveys information over a carrier wave by varying its instantaneous frequency. This contrasts with amplitude modulation, in which the amplitude of the carrier is varied while its frequency remains constant...
   
   
7. Oscillator structures that allow ring modulation
   Ring modulation
   Ring modulation is a signal-processing effect in electronics, an implementation of amplitude modulation or frequency mixing, performed by multiplying two signals, where one is typically a sine-wave or another simple waveform. It is referred to as "ring" modulation because the analog circuit of...
   
    and serial dual filters
8. Additional LFO waveforms
9. MIDI CC control of parameters
10. Tempo
    Tempo
    In musical terminology, tempo is the speed or pace of a given piece. Tempo is a crucial element of any musical composition, as it can affect the mood and difficulty of a piece.-Measuring tempo:...
    
     sync
    Synchronization
    Synchronization is timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time....
    
     delay
    Delay (audio effect)
    Delay is an audio effect which records an input signal to an audio storage medium, and then plays it back after a period of time. The delayed signal may either be played back multiple times, or played back into the recording again, to create the sound of a repeating, decaying echo.-Early delay...
    
    
11. Polyphonic portamento
    Portamento
    Portamento is a musical term originated from the Italian expression "portamento della voce" , denoting from the beginning of the 17th century a vocal slide between two pitches and its emulation by members of the violin family and certain wind instruments, and is sometimes used...
    
    
12. Performance memories
13. Additional multitimbral
    Multitimbral
    Monotimbral is usually used in reference to electronic synthesisers which can produce a single timbre at a given pitch upon pressing a single or multiple keys .An electronic musical instrument may be...
    
     slots
14. One patch can keep full effects in multi mode

Factory Sounds

The Factory presets of the JD-990 were created by Eric Persing

Eric Persing

Eric Persing is a professional synthesist and producer in Los Angeles, California. He is best known as the Founder and Creative Director of the leading music software and virtual instrument company Spectrasonics...

and Adrian Scott.