This page is read from MIDI Instrument Definitions, a Python library used in the author's other projects, in which every number is traced to a document its maker published. Its source is on GitHub.

Roland JX-08 MIDI implementation

The MIDI implementation of the Roland JX-08: what it answers to, and the 49 controls it offers, on firmware 1.03.

At a glance

Firmware

This page describes firmware 1.03.

MIDI channel

Any one of 1 to 16.

Parts

Part, 2 of them: each on a MIDI channel of its own, taking notes, controls, and program changes.
System: on a MIDI channel of its own, taking notes and program changes.

MIDI mode

3: omni off, poly.

Voices

Not recorded.

Note range

0 to 127: C-1 to G9, counting middle C as C4.

Velocity

Sent and received. Release velocity is ignored.

Aftertouch

Polyphonic, a value for each key. It sends none.

Pitch bend

How far it bends is not recorded, and the range can be changed.

Program change

Received and sent, with 256 presets.

MIDI clock

Sent and received.

Start and stop

Sent and received.

Control change

49 controls, in the tables below.

NRPN

None.

System exclusive

None.

Controls

In the order the definition gives them, by part and group. Under each control is the name a program calls it by, once pymidiinstrumentdefs.load("roland/jx_08") has loaded them.

Part

LFO

DCO-1/DCO-2

Mixer

VCF

VCA

Envelope-1/2

Portamento

Effects

Without a group

Where these facts come from

Source documents

• JX-08 Owner’s Manual, eng01, dated June 2022, its user manual, read on 8 October 2026 (the file read).
• JX-08 Reference Manual (HTML): MIDI Implementation Chart (Part), its MIDI implementation, read on 8 October 2026 (the file read).
• JX-08 Quick Start, eng01, dated June 2021, its user manual, read on 8 October 2026 (the file read).
• Roland - Support - JX-08 - Owner's Manuals, its download page, read on 8 October 2026.
• Roland - Support - JX-08 - Updates & Drivers, its download page, read on 8 October 2026.
• JX-08 System Program ( Ver.1.03 ), Ver.1.03, dated November 2025, its release notes, read on 8 October 2026 (the file read).

How they were read

The manual Roland lists as the JX-08 Reference Manual, which calls itself "JX-08 Owner’s Manual" (reference p. 66) on its back, edition 1.00, 66 pages: the panel at pp. 3 to 14, patches and parts at pp. 16 to 20, the sound modes at pp. 22 and 23, patterns at p. 26, the sequencer's motion recording and settings at pp. 33 and 34, the part, keyboard, MIDI and system settings at pp. 38 to 42, the factory patches at pp. 59 to 61, the Part chart at pp. 62 and 63, the System chart at p. 64 and the specifications at p. 65. The HTML edition's Part chart, read against the PDF's. The Quick Start, read for an absence. And Roland's Owner's Manuals and Updates & Drivers pages for the JX-08, with the system program's own page.

THE SURVEY BEHIND THIS CORPUS SAID ROLAND PUBLISHES NO MIDI IMPLEMENTATION CHART FOR THE JX-08, AND ITS MANUAL CARRIES TWO, BEFORE ITS SPECIFICATIONS, AS THE JD-08'S DOES. "MIDI Implementation Chart (Part)" (reference p. 62) and "MIDI Implementation Chart (System)" (reference p. 64), each Date: Oct. 13, 2021 and Version: 1.00. The Owner's Manuals page lists seven Quick Starts and the Reference Manual twice, as PDF and as HTML, and no separate MIDI implementation (manuals_page); JX-08_reference_eng02_W.pdf and every other name tried answered 403. The HTML edition's Part chart has the same 49 controller rows as the PDF's, number, marks and name (chart_html).

TWO PARTS AND A SYSTEM CHANNEL, EACH WITH A CHANNEL OF ITS OWN. "The JX-08 features two sound generator parts" (reference p. 18), and "You can select separate patches for parts A and B." (reference p. 16); they sound together in DUAL mode, or on either side of a split point in SPLIT mode (reference pp. 19 and 20), and no page says whether either mode applies to notes that arrive over MIDI. "Sets the MIDI transmitting/receiving channel for PART A." (reference p. 41), and the same for PART B, each 1 to 16; and the system's, 1 to 16 or OFF, where the parts have no OFF: "Pattern selection (program change messages) is output using this channel." (reference p. 41). The system channel is also the one an external keyboard plays on: "Use the MIDI channel you set here when using an external MIDI keyboard in place of the K-25m." (reference p. 41), and another setting names the connector it arrives at - off, MIDI or USB - which "Normally you will leave this “OFF.”" (reference p. 41). Such a keyboard can play the arpeggio: "To play chords using an external MIDI keyboard connected to this unit, set the MIDI receive and transmit channels beforehand." (reference p. 25). MIDI travels at the MIDI connectors and at the USB port, of which the manual says "This is used to transfer USB MIDI and USB audio." (reference p. 14), and which needs a driver: "You must install the USB driver if you want to connect this unit to your computer." (reference p. 14). The Part chart, by its title, covers the two parts. The System chart takes no control change, selects a pattern by program change, "Selects the step sequencer pattern." (reference p. 64), and passes notes, velocity and aftertouch on: "Transmits/receives between the selected part and the system." (reference p. 64). It also recognises pitch bend, and no page says what that bends. No page gives a factory channel for any of the three, or says what the system channel's OFF does. The manual calls middle C C4 (reference p. 8), and no page gives its note number.

FORTY-NINE CONTROLLERS: 42 BOTH WAYS AND 7 RECEIVED ONLY. The seven received only are the modulation wheel on 1, portamento time on 5, PATTERN PART LEVEL on 7, expression on 11, BEND PITCH on 41, the hold pedal on 64 and the reverb's send level on 91 (reference pp. 62 and 63); none is sent only. The specifications list no pedal jack among the connectors (reference p. 65), so expression and the hold pedal arrive only as MIDI. What the manual says goes out on a part's channel is what is played and the patch chosen: "What you play on the keyboard for PART A (note and control change messages) as well as patch selections (program change messages) are output using this channel." (reference p. 41); no page says whether the sequencer's, the arpeggio's or the step buttons' notes go out too. A pattern can hold the panel's movements, "The movement of the knobs and sliders (MOTION) can also be recorded in the pattern." (reference p. 33), and a sequencer setting, CC, decides whether they are played out: "When this is on, the unit outputs the control change messages (MOTION) recorded in a pattern." (reference p. 34), on a channel no page names. No page says that moving a knob or slider sends its controller, though 42 of the 49 are marked as sent. The part's level has a setting of its own, "Adjusts the part volume." (reference p. 38), which "You can adjust this parameter for each pattern." (reference p. 38), and no page pairs it with 7. There is no controller for the part's pan, "Sets the pan position for each part." (reference p. 38), and 10 is not on the chart.

EVERY CONTROL BELOW NAMES THE PART, BECAUSE THE PARTS' CHANNELS ARE THE ONLY ONES THAT TAKE CONTROL CHANGE. No channel derives from a base - the system's and each part's are set on their own (reference p. 41) - so a control naming no part would mean a channel the JX-08 does not have. All forty-nine numbers are on the Part chart, which by its title covers the parts, and the System chart crosses control change in both columns (reference p. 64): so by the two charts an external keyboard, which plays on the system channel, reaches no part with its controllers. The chart treats the two parts alike, so each control is written once.

TWO NAMES ARE PRINTED TWICE, AND ONE SOUND CONTROL, DCO-1'S TUNE, HAS NO ROW. The chart prints DCO-1 RANGE against 20 and 47, and PORTAMENTO TIME against 5 and 117 (reference pp. 62 and 63), and the HTML edition prints the same (chart_html). The DCO section's picture shows DCO-1 with an LFO slider, a TUNE knob, a RANGE switch and a WAVE FORM switch (reference p. 6), and no row is named for DCO-1's TUNE; DCO-2's TUNE knob, whose scale runs -1OCT to +1OCT (reference p. 6), is the nearest match for 87, DCO-2 COARSE 1OCT. No page says what either of 20 and 47 is, so both are kept under the chart's name, as dco1_range_20 and dco1_range_47. Of the portamento pair, 5 is received only and 117 travels both ways (reference pp. 62 and 63), and the panel has one portamento knob (reference p. 11); they are portamento_time_5 and portamento_time_117. The effects' buttons, which "Turns the chorus effects I, II on and off." (reference p. 12) and "Turns reverb on/off." (reference p. 12), and the two buttons that choose which envelope the sliders edit (reference p. 10) have no row either.

THE ENVELOPE SECTION'S TABLE LEAVES OUT A SLIDER ITS PICTURE SHOWS. The table lists ATTACK, DECAY and RELEASE sliders and a KEY FOLLOW switch (reference p. 10), and the picture above it shows a SUSTAIN slider between DECAY and RELEASE; the chart has a sustain for each envelope, 85 and 102 (reference pp. 62 and 63). The two envelopes share the section's sliders, chosen with two buttons: "Selects the envelope to edit." (reference p. 10).

NO RANGE IS PRINTED FOR ANY CONTROLLER, AND NO PAGE SAYS HOW A VALUE MAPS ONTO ITS PARAMETER. The chart gives numbers and names only (reference pp. 62 and 63), so those that set a choice are left continuous here, their states named only on the panel's pages - among them the LFO's three waveforms (reference p. 5), the DCOs' ranges, waveforms, cross modulation and envelope mode (reference p. 6), the mixer's envelope choice (reference p. 7), the HPF slider's 0 to 3 and the VCF's envelope mode (reference p. 8), the VCA's two modes (reference p. 9), the envelopes' key follow, 0 to 3 (reference p. 10), the portamento button (reference p. 11) and the sound modes. Those are four, Unison solo (reference p. 23) among them, where 119's name, SOLO/POLY/UNISON, gives three, as the page before them does (reference p. 22). The depths the part settings give modulation and aftertouch each run -63 to 63 (reference p. 39), and no controller is named for any of them. The labels are the chart's Remarks with trailing spaces removed; its spelling DCO-1 ENEV MOD is kept.

PROGRAM CHANGE REACHES 256 PATCHES, BY BANK. "letting you save a total of 4 x 8 x 8 = 256 patches." (reference p. 16), in groups A to D, banks 1 to 8 and numbers 1 to 8, all of them user memories (reference p. 65); the factory filled 143, A.11 to C.27: "This is a list of the patches stored in this unit by factory default." (reference p. 59). The Part chart gives LSB 0, MSB 0–1 and PC 0–127 both ways (reference p. 63), so a bank select of 0 or 1 and a program of 0 to 127 reach them - but no page maps a number to a group, bank and patch. Bank select is given only there: 0 and 32 are not among the chart's controllers (reference pp. 62 and 63). The system channel's program change instead selects one of 128 patterns (reference pp. 26 and 64), and "A pattern can contain patch numbers for parts A and B, as well as the recorded sequence data." (reference p. 26).

CLOCK AND TRANSPORT BOTH WAYS, AND NO SONG POSITION. On the System chart Clock, Start and Stop are circled both ways and Continue is received only: "Works the same as “start.”" (reference p. 64). The Part chart circles Clock and Commands both ways without that distinction, and Song Position is crossed both ways on both charts (reference pp. 63 and 64). Which port the sequencer follows is a MIDI setting - automatic, internal, MIDI or USB - and which port sends clock another - off, MIDI, USB or all (reference p. 41); neither has a default stated, and the automatic choice "Automatically detects the signal inputted to the jack." (reference p. 41) without naming the jack. The EXT CLK IN jack takes pulses: "You can make the steps of the sequencer advance in sync with the clock (pulse) that’s inputted." (reference p. 13). A soft thru setting re-sends what arrives at MIDI IN "as-is from the MIDI OUT connector." (reference p. 41).

PITCH BEND AND AFTERTOUCH ARE RECEIVED, NOT SENT. Pitch bend and polyphonic aftertouch are crossed as transmitted and circled as recognised, and channel aftertouch crossed both ways, on both charts (reference pp. 62 and 64). The bend range is a part setting of 2, 3, 4 or 7 semitones, "Sets the variable pitch range for the pitch bend." (reference p. 39), with no default stated, and no page says whether 41, BEND PITCH, sets it. Three part settings send aftertouch to the LFO, the low-pass filter and what the page calls the tone, each "only enabled when a product featuring aftertouch is connected" (reference p. 39), and no page names such a product. Another part setting "Adjusts the depth of the modulation effect." (reference p. 39), and no page pairs it with 1.

MODE 3, AND THREE OF THE FOUR MODE MESSAGES ARE ALL NOTES OFF ON A PART'S CHANNEL. Mode 3 is the default both ways on both charts (reference pp. 62 and 64). On a part's channel, omni off, omni on and mono "Works the same as “all notes off.”" (reference p. 63), poly is crossed both ways, and all sound off, reset all controllers and all notes off are received. Mono is also circled as transmitted (reference p. 63), the one mode message the chart marks as sent, and no page says when it is. The system channel takes none of them (reference p. 64). Local control is crossed. Active sensing is circled both ways on both charts.

SYSTEM EXCLUSIVE IS CROSSED BOTH WAYS ON BOTH CHARTS (reference pp. 63 and 64), and no other page mentions it, so it is recorded as absent, as roland/jd_08's is.

FIVE MORE FAULTS, NONE IN A FIELD, ALL FOUND BY THE BLIND SECOND READER. The System chart's aftertouch row carries the remark "Transmits/receives between the selected part and the system." (reference p. 64) over a cross for transmitted, as the JD-08's does. The DCO section's table describes one LFO slider, one TUNE knob and one RANGE switch for both oscillators - "Sets the octave for DCO-1 and DCO-2." (reference p. 6) - where its picture gives each oscillator its own. The same table calls the waveform selector a knob, "This knob sets the waveform." (reference p. 6), where the picture shows a switch on each oscillator. The VCA's LEVEL slider is printed 0–100 (reference p. 9), where its picture's scale runs 0 to 10 as its neighbours' do. And a part setting expands VCO CUTOFF FREQ (reference p. 38) on an instrument with DCOs and a VCF.

NOT RECORDED, AND WHY:

• the polyphony, which no page states for the sound generator - the one figure, "8 notes (Polyphonic)" (reference p. 65), sits in the specifications' Step Sequencer row beneath 64 steps, and the page does not say whose figure it is;
• the voicing, a choice of solo, poly, unison and unison solo with no count for any (reference p. 23);
• and a default bend range.

The Quick Start holds no MIDI map at all (quick_start).