Jupiters: the Promars (MRS-2)

bcox commented

2026-10-12 21:15:26 +00:00

Owner

Ben asked on 2026-10-12 which instruments of the families already here were missed, and for an issue a family. Everything below is from recollection, with no manual read; issue #20's list was wrong in several places for the same reason, so read the manuals first and correct this. Each is to be an extension of the existing instrument, as the Jupiters and the JX family are, never a "model" switch.

Promars Compuphonic (MRS-2), 1979: recalled as a one-voice Jupiter-4 with a second VCO beside the first, detuned. Expected to be nearly all settings of mini-JP: voice.count 1, the sub oscillator, and whatever its second VCO really is.

First in Ben's order of work.

Ben asked on 2026-10-12 which instruments of the families already here were missed, and for an issue a family. **Everything below is from recollection, with no manual read**; issue #20's list was wrong in several places for the same reason, so read the manuals first and correct this. Each is to be an extension of the existing instrument, as the Jupiters and the JX family are, never a "model" switch. - **Promars Compuphonic (MRS-2)**, 1979: recalled as a one-voice Jupiter-4 with a second VCO beside the first, detuned. Expected to be nearly all settings of mini-JP: `voice.count` 1, the sub oscillator, and whatever its second VCO really is. First in Ben's order of work.

bcox commented

2026-10-12 21:38:18 +00:00

Author

Owner

Done on the family-extensions branch (not pushed), by Claude, with no one to ask. The issue is left open.

What was read. Roland's service notes for the MRS-2 (first edition, 31 January 1980, a July 1982 printing), from archive.org. The owner's manual was not found: Roland's archive has the other Jupiters' and none for the Promars. docs/references.md has both facts.

Against the recollection ("a one-voice Jupiter-4 with a second VCO beside the first, detuned"): borne out, with more to it.

The second VCO is a second board, VCO-9, "just as the same" as the VCO on the module board, with a sub oscillator of its own. The panel has one DUAL VCO section: one range, modulation depth, pulse width, waveform and SUB switch for both, and one NOISE switch.
VCO-2's only controls are two tune knobs, A and B, each "greater than ±1 octave", and a three-position switch between them. Its middle, read from the VCO-9 control board's schematic, switches VCO-2 off.
37 keys, one voice, the Jupiter-4's filter, envelopes, LFO and figures, and the Jupiter-4's processor program. No ensemble and no arpeggio. Every key struck retriggers the envelopes.

What was built. A Promars is settings of mini-JP: voice.count 1, zone.assign 0, mixer.balance 0.5, VCO-2 given VCO-1's waveform and range. Two things could not be set and were added, each at nothing until asked for:

vco2.sub: a sub oscillator under the second VCO, which goes with it in the mixer.
vco2.tune_b and vco2.b: B TUNE in semitones, and the tune switch at B, where B takes the place of vco2.tune and vco2.detune (which are A).

Nothing in engine/ changed. All tests pass.

Wants Ben's word (listed under "Open decisions" in CLAUDE.md):

Which key sounds when several are held: not known without the owner's manual or the key board's schematic traced. Left at the latest.
A level each for the two sub oscillators, where the hardware has one switch.
Whether B TUNE and its switch are wanted at all, their names, and B's reach of two octaves.
Levels: everything is at half with the mixer in the middle.
Left out: LFO BEND with NORM/WIDE, HOLD, BRILLIANCE, the jacks.
The bench moved a little. Run on the Pi before and after, twice, beside another session's miniomnid: voices that do not use the new sub oscillator cost a tenth to six tenths of a percent of a core more (eight voices' sawtooth 10.8% to 11.0%, thirty-two with everything 72.2% to 72.8%). One Promars voice with everything on is 2.4%.

It has not been played or heard.

Done on the `family-extensions` branch (not pushed), by Claude, with no one to ask. The issue is left open. **What was read.** Roland's service notes for the MRS-2 (first edition, 31 January 1980, a July 1982 printing), from archive.org. **The owner's manual was not found**: Roland's archive has the other Jupiters' and none for the Promars. `docs/references.md` has both facts. **Against the recollection** ("a one-voice Jupiter-4 with a second VCO beside the first, detuned"): borne out, with more to it. - The second VCO is a second board, VCO-9, "just as the same" as the VCO on the module board, **with a sub oscillator of its own**. The panel has one DUAL VCO section: one range, modulation depth, pulse width, waveform and SUB switch for both, and one NOISE switch. - VCO-2's only controls are **two tune knobs, A and B**, each "greater than ±1 octave", and a three-position switch between them. Its middle, read from the VCO-9 control board's schematic, switches VCO-2 off. - 37 keys, one voice, the Jupiter-4's filter, envelopes, LFO and figures, and the Jupiter-4's processor program. No ensemble and no arpeggio. Every key struck retriggers the envelopes. **What was built.** A Promars is settings of mini-JP: `voice.count` 1, `zone.assign` 0, `mixer.balance` 0.5, VCO-2 given VCO-1's waveform and range. Two things could not be set and were added, each at nothing until asked for: - `vco2.sub`: a sub oscillator under the second VCO, which goes with it in the mixer. - `vco2.tune_b` and `vco2.b`: B TUNE in semitones, and the tune switch at B, where B takes the place of `vco2.tune` and `vco2.detune` (which are A). Nothing in `engine/` changed. All tests pass. **Wants Ben's word** (listed under "Open decisions" in CLAUDE.md): - Which key sounds when several are held: not known without the owner's manual or the key board's schematic traced. Left at the latest. - A level each for the two sub oscillators, where the hardware has one switch. - Whether B TUNE and its switch are wanted at all, their names, and B's reach of two octaves. - Levels: everything is at half with the mixer in the middle. - Left out: LFO BEND with NORM/WIDE, HOLD, BRILLIANCE, the jacks. - **The bench moved a little.** Run on the Pi before and after, twice, beside another session's `miniomnid`: voices that do not use the new sub oscillator cost a tenth to six tenths of a percent of a core more (eight voices' sawtooth 10.8% to 11.0%, thirty-two with everything 72.2% to 72.8%). One Promars voice with everything on is 2.4%. It has not been played or heard.

bcox commented

2026-10-13 01:27:31 +00:00

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Owner

Closed by Ben's word on 2026-10-12. The work is on the branch family-extensions, not yet merged.

Closed by Ben's word on 2026-10-12. The work is on the branch `family-extensions`, not yet merged.

bcox closed this issue

2026-10-13 01:27:31 +00:00

bcox referenced this issue from a commit

2026-10-13 01:34:35 +00:00

Add the Promars to the Jupiters: a second sub oscillator and a B tune

bcox referenced this issue

2026-10-13 01:44:30 +00:00

Omni family: the String Ensemble (Solina) and the Quadra #36

bcox commented

2026-10-13 04:27:03 +00:00

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Owner

Ben played it on his laptop on the night of 2026-10-12, set as a Promars with both sub oscillators on, and found it good to go. He confirmed the second sub oscillator's own level, A TUNE and B TUNE as they are, and that the few tenths of a percent it costs voices that do not use it are not worth a second copy of the voice's loop. Which key sounds still wants its owner's manual, which was not found; that is under "Open decisions" in CLAUDE.md. Everything said here is on main, pushed, on the night of 2026-10-12. What was heard was heard on Ben's laptop, not on the Pi.

Ben played it on his laptop on the night of 2026-10-12, set as a Promars with both sub oscillators on, and found it good to go. He confirmed the second sub oscillator's own level, A TUNE and B TUNE as they are, and that the few tenths of a percent it costs voices that do not use it are not worth a second copy of the voice's loop. Which key sounds still wants its owner's manual, which was not found; that is under "Open decisions" in CLAUDE.md. Everything said here is on `main`, pushed, on the night of 2026-10-12. What was heard was heard on Ben's laptop, not on the Pi.

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Jupiters: the Promars (MRS-2) #32