Roland JD-990 Super JD: A Powerhouse of Digital Synthesis
Released in 1993 by the Roland Corporation, the Roland JD-990 Super JD stands as a sophisticated evolution of the JD-800. While it may appear to be a simple module version of its predecessor, the JD-990 is a significantly expanded instrument with enhanced capabilities, making it a distinct entity in the world of digital synthesis.
The JD-990 utilizes PCM sample-based subtractive synthesis, a method where pre-recorded digital waveforms (PCM) are shaped using filters and envelopes to create a wide array of sounds. This allows the unit to bridge the gap between the warmth of vintage analogue synthesizers and the precision of modern digital textures.
[ไม่มีภาพประกอบ]Key Facts
- Production Years: 1993–1996.
- Synthesis Engine: Digital Sample-based Subtractive.
- Polyphony: 24 voices.
- Timbrality: 7 parts plus 1 dedicated drum part.
- Memory: 6MB of PCM ROM (expandable to 16MB).
- Connectivity: Four assignable stereo outputs and standard MIDI I/O.
Technical Architecture and Sound Generation
At the heart of the JD-990 is its oscillator system, featuring 6MB of PCM ROM containing 195 waveforms. Each patch can utilize up to four waveforms (tones), allowing for complex, layered sounds. For those seeking more variety, the chassis includes an expansion slot to increase the ROM to 16MB.
Filtering and Modulation
The instrument employs a Time Variant Filter (TVF), which provides lowpass, bandpass, and highpass filtering options with adjustable resonance. To shape the evolution of the sound, the JD-990 uses TVA (Time Variant Amplifier) envelopes, TVF envelopes, and pitch envelopes. Modulation is further enhanced by two LFOs (Low Frequency Oscillators) per patch, while velocity and aftertouch expression allow performers to add dynamic nuance to their playing.
Effects and Storage
To polish the raw synthesis, the JD-990 includes a comprehensive suite of built-in effects, including Chorus, Reverb, Delay, Phaser, Spectrum, Enhancer, Distortion, and EQ. Users can store their creations in three banks of 64 patches (which are expandable) and access three drum kits containing 61 sounds.
[ไม่มีภาพประกอบ]Hardware and Interface
Unlike the JD-800, the JD-990 is a rack-mount module without a built-in keyboard. Programming is handled via a front-panel keypad and a large LCD screen. Its multitimbral nature is supported by four sets of stereo outputs, which can be assigned to individual internal instruments, providing greater flexibility during mixing.
| Feature | Specification |
|---|---|
| Manufacturer | Roland |
| Release Period | 1993-1996 |
| Original Price | $2,195 (US) / £1,445 (UK) |
| Polyphony | 24 Voices |
| Waveforms | 195 PCM waveforms (6MB to 16MB) |
| Timbrality | 7 + 1 Drum part |
| Filter Types | Lowpass, Bandpass, Highpass |
Frequently Asked Questions
Is the Roland JD-990 compatible with JD-800 presets?
No. Because the JD-990 features expanded capabilities and different internal architecture, it is not compatible with JD-800 presets when exchanging data.
What is the maximum memory capacity of the JD-990?
The unit comes with 6MB of PCM ROM, but it can be expanded to 16MB using available expansion boards installed in the chassis slot.
How many sounds can the JD-990 play simultaneously?
The JD-990 has a polyphony of 24 voices and is multitimbral, supporting 7 instrument parts plus 1 drum part.
What types of filters are available on the JD-990?
The Time Variant Filter (TVF) allows users to choose between lowpass, bandpass, and highpass filters, all of which include resonance controls.
Does the JD-990 have a built-in keyboard?
No, the JD-990 is a synthesizer module. It is controlled via MIDI and programmed using the keypad and LCD on its front panel.