TECH main core is a Hitachi H8/532 (at IC36) which manages up to 24 voice or digital oscillators polyphony - DAC based on a 18 bits Burr Brown PCM61P.
single JD patch is based on pure rompler system, composed by up to 4 PCM oscillator (a sample) layer generated by the "WG" wave generator.
Each layer with individual parameters such as:
- level mix
- pitch coarse and fine
- pitch random amount
- key follow modes.
WAVETABLE internal 4 MB ROM contains 108 PCM waveforms, further PCM can be added using EXPANSION cards.
The internal waveforms are organized into 10 categorie:
|Fast attack (one shot)
EXPANSION extra waveforms can be added with external JV PCM cards (SO-PCM1 series) compatible with earlier JV series like Roland JV-1080 or JV-880*
SL-JD80 SERIES there are 8 sets of 2 cards "SL-JD80" series (PCM+ DATA) officialy released by Roland purposely made for the JD-800:
the JD-800 is not able to the 2 mb cards, up to 1mb max - but rackmount JD-990 does.
FILTER a multimode (lowpass / highpass / bandpass) digital resonant filter TVF is assigned for each PCM layer.
HEAR low pass with resonance
ENVELOPE 3 EGs for each PCM layer:
- EG pitch: 3 segments level + 3 times
- EG filter (TVF) : 4 segments + 4 times
- EG amplitude (TVA) 4 segments + 4 times
All EGs offers a Keyfollow tracker mode.
Above - click for TVA/TVF EG board
LFO up to 2 delayed, bipolar
and interchangeable modulators with variable depth and note retrig mode with fade IN time. LFO shapes:triangle, saw, square, sample & hold and random with variable phase attack.
LFO Destinations are:
- LFO to amplitude
- LFO to filter cutoff
- LFO to oscillator pitch.
HEAR all LFO waves on pitch
Above - click for LFo 1 + LFo2 board
PERFORMANCE each PCM layer can be controlled as an independent multipart section, in fact there are several parameters for each of them:
key zone range
- monophonic mode
- legato mode with portamento
split / dual mode
- upper / lower Midi channel assignment
- bender range assignment
- key transpose (1 oct)
- modwheel assignable to LFO1/ LFO2/ both
- aftertouch can be assigned to TVF / TVA / WG pitch
- breath can be assigned to volume / amplitude / modulation aftertouch
NOTE: the fifth part is dedicated to drum kit and percussions.
EFFECT FX DSP is split into 2 groups: A (mono) + B (stereophonic) + 3 bands EQ with shelving while Midband has peak. Effects from A-B can be chained in different combination order:
|- 7 distortions models with drive amount
- phaser with depth / rate
- dynamic enhancer
- a 6 bands spectrum enhancer
|- stereo delay up to 600 Ms
- chorus with rate, depth and feedback
HEAR reverb from dry to wet
MIDI some basic CC# including:
hold / sustain.
TECH: Full Sysex implementation transmits all slider movements to program another JD-800 or JD-990 unit but unit IDs must be matched.
64 RAM patches
Memory doubled if card model M-256 E or D (also 512) is fitted / M-128 is NOT compatible.
Battery replacement: JD memory system works with a lithium 3V Cr-2032.
Note: JD-990 is compatible with JD-800 but not the contrary.
MAINTENANCE JD800 is a machine plagued by common technical issues:
- red resin under the keys drips over mainboard sticking the key circuit switch creating dead contacts
- sliders with random values
- like Roland U-20 and D-70 contact rubbers are quite fragile and may need new board stripes.
Check the guide video below:
Restoring and fixing a Jd-800
can be a long and expensive job by technical center...
(BELOW) Disgusting red resin (glue)
... instead follow this DIY video guide
- Repair video guide
EDITOR there are some third-part computer software for quick editing:
Soundquest (PC/MAC $$)
VST panel for CTRLR (Linux, MAC, PC - open source)
||JD-990 the rackmount expansion features great improvements (roland jd800 vs jd990):
- 2 more ROM MB
- true multitimbric (8 parts)
- 8 analog outs
- panning position
- matrix modulation
- polyphonic portamento
- Sr-Jv slot expansion (20 cards)
- 3 new LFO shapes: sinewave, trapezoid, chaos
- waveform sync
- frequency cross modulation FXM
- 5 more algorithms structures
- longer delay time and Midi syncable
JD800 cannot read more than 1mb PCM
- JD990 lacks hold pedal and expression pedals.
- Jd990 lacks real time controls
||Roland JX-XA analog digital crossover synthesizer. Should be the Jd800 sucessor. Not tried yet.
VST PLUGIN / SAMPLED VERSION there are some free and commercial samples set: