The Roland JD-990 was a sophisticated digital synthesiser that built upon the architecture of its predecessor, the Roland JD-800, while significantly expanding its sonic capabilities and memory capacity. At the heart of the instrument was a wave memory containing 195 waveforms, which included all 108 waveforms from the JD-800 along with 87 additional acoustic instrument and drum/percussion sounds.
These waveforms were sampled at 44.1kHz and processed through 18-bit D/A conversion, providing audio quality that exceeded CD fidelity. The unit offered substantial expandability, allowing users to increase the wave memory to 16 MB by combining an SR-JV80 Series 8MB expansion board with 2 MB SL-JD80 or SO-PCM1 Series PCM cards. Furthermore, the Roland JD-990 supported PN-JD80 Series data cards, enabling the convert-loading of JV-80/880 patch data onto the instrument, thereby facilitating the use of parameter data from optional M-256E memory cards.
The synthesis engine of the Roland JD-990 provided several advanced functions for creative sound design. The Wave Generator featured FXM (Frequency Cross Modulation), which allowed users to add a raw, distorted texture to sounds, and Oscillator Sync, which enabled the creation of new waveforms by locking the default oscillator period to the frequency of any of the four Tones in a Patch. This function allowed the initial waveform to return to its starting point in time, producing a fat, shimmering richness.
Additionally, the Tone Delay function controlled the time lag between the note-on event and the actual sound for each Tone, offering a delay of up to five seconds. The instrument also incorporated a high-performance digital Time Variant Filter (TVF) with high-, low- and band-pass modes. The TVF featured resonance settings capable of achieving true self-oscillation and a four-stage envelope that allowed for precise waveform shaping. Velocity and key follow settings could also be applied to the TVF.
The Time Variant Amplifier (TVA) complemented the filter with its own four-stage envelope and two LFO settings. A key follow feature known as Bias allowed users to change the balance between several layered Tones according to the key range, adding depth to the performance. The Roland JD-990 included two Low Frequency Oscillators (LFOs) that could be programmed independently for each Tone, resulting in up to eight LFOs per Patch. These LFOs offered a choice of modulation waveforms, including triangle, sine, sawtooth, square, trapezoid, sample & hold, random, and chaos. These modulation sources could be assigned to the Wave Generator, TVF, and TVA sections to create complex movement and texture.
Patch assembly on the Roland JD-990 involved using up to four completed Tones, which could be arranged using six different Structures. These Structures allowed the Tones to interact in ways similar to a modular synthesiser. Some Structures utilised Ring Modulation, which merged Tones to create new frequencies with non-integer overtones, resulting in an unpitched metallic-sounding resonance effect.
The Structures also permitted the use of the Roland JD-990’s powerful filters in serial arrangements, enabling incredible sweeping effects. The editing interface was designed for ease of use, featuring a large 320 x 80 dot LCD with clear parameter graphics. This display allowed for easy confirmation of related parameters, facilitating quick and smooth editing. The system offered both absolute and relative editing, enabling users to change a parameter for one Tone while maintaining values on the remaining Tones, or to change the parameter globally for all Tones.
The user interface included convenient features such as the Effects On/Off and Utility menus, which were displayed in windows for instant access from any other screen. The Utility menu provided functions such as data copy and write. A Preview function allowed users to audition a sound as they edited it by pressing the Volume knob. The Roland JD-990 also featured a comprehensive onboard effects processing system utilising a newly developed high-performance Digital Signal Processor.
Users could set on/off settings individually for each of the seven effects or combine them in any order. Group A effects, which processed the original sound, included Distortion with seven different types ranging from mellow tube amp overdrive to fuzz tone; Phaser with Manual, Rate, Depth, Resonance, and Mix controls; Spectrum, a band-pass filter working on six frequencies for drastic tonal changes; and Enhancer, which emphasised brightness and clarity by processing only the harmonics of the sound.
Group B effects added various effects to the original sound. The Chorus effect offered variable delay time for creating a wide range of effects, from doubling to flanging. The Delay effect was a 3-tap delay that allowed localising sounds with different delay times at left, centre, and right, with delay times up to 3 seconds. It included a tap mode for setting delay time with a footswitch or front panel button and synchronised to MIDI Clock.
The Reverb effect provided ten types, including Room, Hall, Gate, and Reverse, with reverb times up to 20 seconds. Additionally, the Roland JD-990 featured a 3-band Parametric EQ with bands for low (200Hz–400Hz), mid (200Hz–8kHz) with flexible Q setting, and high (4kHz–8kHz). Each EQ band could be boosted or cut by ±15dB, and the settings could be stored to each Patch.
The instrument operated in three versatile modes: Patch Mode, Rhythm Mode, and Performance Mode. Patch Mode was designed for solo performance, allowing the user to play one Patch consisting of four Tones with both Group A and B effects applied. Rhythm Mode allowed the recall and playback of a rhythm set with specific rhythm tones assigned to each note.
Performance Mode utilised the Roland JD-990 as an eight-Part multitimbral sound module, consisting of six Synth parts, a Super Synth Part, and a Rhythm Part. In this mode, both Group A and B effects could be used on the Synth Part, and parameters such as level, pan, MIDI receive channel, and effects send level could be set for each Part. The Super Synth Part, one of the eight multitimbral parts, could be used with all seven effects simultaneously, plus the 3-band parametric EQ.
Realtime performance control was a significant feature of the Roland JD-990, offering expressive control over tone parameters. The instrument allowed the use of two control sources for controlling four parameters for each of the four Tones in a Patch, providing control over up to 32 parameters per Patch. Control sources included pitch bender, modulation, aftertouch, expression, breath, and foot.
Controllable parameters included WG Pitch, TVF Cutoff and Resonance, TVA Level, and LFO 1/2 Pitch depth, TVF depth, and TVF rate. In Patch Mode, two control sources could be used for each Patch, each controlling a single effect parameter, such as controlling distortion drive with an expression pedal and chorus rate with the modulation lever. In Performance mode, Group A effect parameters of the Super Synth Part could be controlled.
The Roland JD-990 featured multiple outputs for flexible routing. It had four Stereo Out pairs: Mix Out, Direct Out 1, Direct Out 2, and Direct Out 3. This allowed users to independently assign an individual Part to each output for effects processing and mixing with external units. Audio output from the Mix Out could be EQ’ed with Bass, Mid, and Treble controls. Since an instrument in the Rhythm Part could be assigned to each output, each rhythm instrument could be individually processed with external effects, similar to sophisticated rhythm machines.
The Roland JD-990 also offered full MIDI control, including a Part Information function that allowed users to confirm incoming MIDI information such as program changes and pitch bend for each Part on the display. Many parameters were compatible with those of the JD-800, allowing users to create sounds on the JD-990 using the sliders of a connected JD-800, although Roland JD-990-only parameters could not be controlled by the JD-800 sliders.
Memory and connectivity were robust, with the JD-990 capable of storing 16 Performances, 64 Patches, and one Rhythm Set of user-defined data in its internal memory. The same amount of data could be saved to an M-256E Memory Card, effectively doubling the user memory. The Stack function allowed up to eight JD-990s to be connected for intelligent MIDI overflow, catering to applications requiring a large amount of polyphony.
The Roland JD-990 was housed in an EIA-2U rack format and measured 88mm in height, 482mm in width, and 281mm in depth, weighing 5.1kg. Optional accessories included SL-JD80 Series Sound Library Cards, SO-PCM1 Series PCM Cards, PN-JD80 Series Data Cards, SR-JV80 Series Expansion Boards, M-256E Memory Cards, and RH-20/80/120 Stereo Headphones.
Features
- Wave Generator with FXM (Frequency Cross Modulation), Oscillator Sync and individual Tone Delay of up to five seconds.
- Wave-memory expansion using SR-JV80 Series expansion boards and compatible PCM cards; PN-JD80 data-card support and convert-loading of JV-80/880 patch data.
- Time Variant Filter with high-pass, low-pass and band-pass modes, resonance capable of self-oscillation, a four-stage envelope, velocity response and key follow.
- Time Variant Amplifier with a four-stage envelope and Bias key follow for changing the balance of layered Tones across the key range.
- Two independently programmable LFOs per Tone, with triangle, sine, sawtooth, square, trapezoid, sample & hold, random and chaos waveforms; assignment to Wave Generator, TVF and TVA sections.
- Up to four Tones per Patch and six Structures, including Ring Modulation and serial filter arrangements.
- Graphical editing with detailed Edit Screens, Palette Screens, selectable display fonts, absolute and relative editing, and global parameter changes across all Tones.
- Effects On/Off and Utility windows accessible from other screens, with write, copy, initialize, card, bulk dump and protect facilities.
- Preview function for auditioning sounds by pressing the Volume knob.
- Seven onboard effects with individual on/off settings and configurable effect order: Distortion, Phaser, Spectrum, Enhancer, Chorus, Delay and Reverb.