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A new instrument: Moog's small two-VCO synthesizers (Prodigy, Rogue, Concertmate MG-1, Liberation, Source, Taurus, Sonic Six) #52

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opened 2026-10-12 23:32:36 +00:00 by bcox · 2 comments
bcox commented 2026-10-12 23:32:36 +00:00
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Ben decided on 2026-10-12, on #26, that the Moogs up to the Memorymoog are wanted, with variants combined where that fits, and asked for an issue for each instrument that makes. This is one of five; the others are linked from #26. Not started.

Everything below is from recollection and a quick look at encyclopedia and shop pages, with no manual read; issue #20's list was wrong in several places for the same reason. Find and read Moog's owner's and service manuals before designing anything, put them in docs/references.md, and correct this.

What it covers

One instrument: one voice of two VCOs into the ladder filter, and every small Moog that is that voice with things added or left off.

  • Prodigy (1979). Two VCOs, each a sawtooth, a triangle or a pulse, an octave switch each, the second with an interval knob and able to be synchronized to the first; no noise; the ladder filter; two contours of attack, decay and sustain, one for the filter and one for the amplifier, the decay also the release; an LFO giving a triangle or a square, to the oscillators and the filter by the wheel.
  • Rogue (1981). A cut-down Prodigy: two VCOs with fewer waveforms (sawtooth and a square or pulse; no triangle), sync, noise, a mixer that overdrives, the ladder filter, and one contour shared by the filter and the amplifier. Its LFO adds a sample and hold. Pitch and modulation wheels.
  • Realistic Concertmate MG-1 (1981). Made by Moog for Radio Shack beside the Rogue, on much the same voice: two "tone sources" with sync and detune, noise, the ladder filter, one contour for both. Where it differs: it has a polyphonic section, a divide-down organ tone on every key with its own level, and a ring modulator, called "bell tone"; and it has no wheels.
  • Taurus II (1981). Bass pedals, recalled as the Rogue's voice on a stand.
  • Liberation (1980). Worn on a strap. Recalled as the Prodigy's panel with noise, a ring modulator and a polyphonic section added to the mixer, two contours, and a keyboard that feels pressure, with a ribbon on the neck.
  • Source (1981). Two VCOs (sawtooth, triangle, a pulse of variable width), sync, noise, the ladder filter, two full ADSR contours, an LFO with a sample and hold. It is known for its memory and for one knob that edits everything, neither of which is of interest here; its voice is this family's fullest.
  • Taurus (1975), the first pedals. Two sawtooth VCOs with a beat control, the ladder filter, simple contours and a glide. Three fixed sounds and one that can be set.
  • Sonic Six (1972). Two VCOs, two LFOs that can be mixed, a ring modulator, white or pink noise, a filter, one simple contour, and a keyboard that is duophonic, one VCO on the lowest key and the other on the highest. It came from another company's design and is the loosest fit here.

The Rogue against the Prodigy, which Ben asked about: the same idea at two prices. The Prodigy has a contour each for the filter and the amplifier, a triangle wave, and a waveform and octave switch for each VCO; the Rogue has one contour for both and less choice of waveform, and has what the Prodigy lacks, noise and a sample and hold. Neither is the other with a part taken out, but both are settings of one voice that has two contours, noise and the sample and hold.

The MG-1 against the Rogue, which Ben asked about too: siblings, built at the same time on the same voice, neither a patch on the other. The MG-1 is the Rogue's voice plus the polyphonic section and the ring modulator, less the wheels. With the Liberation wanting the same two additions, they are parts of this instrument and not of one model.

So the voice is the Source's and the Liberation's between them: two VCOs with three waveforms and a variable pulse, sync, noise, a ring modulator, the polyphonic section, the ladder filter, two contours that can be tied together as one, an LFO with a sample and hold; and each model is that with things at nothing.

To find out

  • The Sonic Six and the Source are here, and Ben found the grouping fine on 2026-10-12. The Sonic Six's two LFOs and its duophony are more than settings of the others; the duophony is what #22 wants for the Odyssey. Whether its filter is Moog's ladder wants its manual.
  • Whether #53 becomes part of this. By Ben's word on 2026-10-12: if adding a waveshape knob is all it takes to cover the Micromoog's line, #53 merges into this instrument; otherwise it depends on how much the two overlap. The two issues stay separate until one of them has been built, and whichever is built first should be built with the other in mind.
  • The polyphonic section: what its tone is, whether it goes through the filter and the contour, and whether each key has a gate of its own. engine/divide_down.h, written for the Omni, should be what makes it.
  • The ring modulator: which two signals it multiplies on each model.
  • The contours. The Rogue's and MG-1's one contour has a switch for its modes; what each does wants the manual.
  • The first Taurus. Its oscillators are said not to track as the others do, and its sound is held to be its own. As settings it is two sawtooths and a filter; the rest is #4.
  • Pressure and the ribbon on the Liberation: engine/midi.h passes key and channel pressure already.

What it does not cover

The Source's memory, its arpeggiator (engine/arpeggiator.h stands for it) and its two sequencers, which would be an issue of their own. The Taurus's and Taurus II's being pedals: they are played from MIDI like anything else. The Sonic Six's speaker.

Nothing from the Phattys: Ben ruled them out on 2026-10-12, as a line that began after about 2000.

What is already here to build on

  • engine/analog_vco.h and engine/four_pole_filter.h, as for the Minimoog; the ladder's saturation and the Rogue's overdrive are #4.
  • The SH-5's voice.h has a ring modulator and a sample and hold in one voice already.
  • engine/divide_down.h for the polyphonic section.
  • engine/key_assign.h, engine/portamento.h, the shared arpeggiator and effects. The SH-101's way of having more than one voice, off by default, would serve here too.

Provenance

  • The Source has a processor and patch memory. Rule 3: no firmware disassembly. Rule 4: none of its programs.
  • The first Taurus's three fixed sounds are wired in, not stored. Ben decided on 2026-10-12, on #26: what is wired into a circuit, such as resistor values, and can be seen on a published schematic is fair game; what needs a ROM, stored factory patches included, is another matter and stays under rules 3 and 4. So they may be had, read from the published schematic and from nowhere else, with a comment naming it (rule 5). The Source's programs are stored and may not.
  • Rule 2: nothing from an emulator's code.
  • The names. "Moog" and the model names are trademarks that are actively used and defended. Ben said on 2026-10-12 to use Moog's own names for now, so that he can tell what each is, the repository being private; nearly every instrument's name here will have to change before anything is sold, and these with them. So, say, instruments/prodigy/ and programs named miniprodigy.
Ben decided on 2026-10-12, on #26, that the Moogs up to the Memorymoog are wanted, with variants combined where that fits, and asked for an issue for each instrument that makes. This is one of five; the others are linked from #26. Not started. **Everything below is from recollection and a quick look at encyclopedia and shop pages, with no manual read**; issue #20's list was wrong in several places for the same reason. Find and read Moog's owner's and service manuals before designing anything, put them in `docs/references.md`, and correct this. ## What it covers One instrument: one voice of two VCOs into the ladder filter, and every small Moog that is that voice with things added or left off. - **Prodigy** (1979). Two VCOs, each a sawtooth, a triangle or a pulse, an octave switch each, the second with an interval knob and able to be synchronized to the first; no noise; the ladder filter; **two** contours of attack, decay and sustain, one for the filter and one for the amplifier, the decay also the release; an LFO giving a triangle or a square, to the oscillators and the filter by the wheel. - **Rogue** (1981). A cut-down Prodigy: two VCOs with fewer waveforms (sawtooth and a square or pulse; no triangle), sync, noise, a mixer that overdrives, the ladder filter, and **one** contour shared by the filter and the amplifier. Its LFO adds a sample and hold. Pitch and modulation wheels. - **Realistic Concertmate MG-1** (1981). Made by Moog for Radio Shack beside the Rogue, on much the same voice: two "tone sources" with sync and detune, noise, the ladder filter, one contour for both. Where it differs: it has **a polyphonic section**, a divide-down organ tone on every key with its own level, and **a ring modulator**, called "bell tone"; and it has no wheels. - **Taurus II** (1981). Bass pedals, recalled as the Rogue's voice on a stand. - **Liberation** (1980). Worn on a strap. Recalled as the Prodigy's panel with noise, a ring modulator and a polyphonic section added to the mixer, two contours, and a keyboard that feels pressure, with a ribbon on the neck. - **Source** (1981). Two VCOs (sawtooth, triangle, a pulse of variable width), sync, noise, the ladder filter, two full ADSR contours, an LFO with a sample and hold. It is known for its memory and for one knob that edits everything, neither of which is of interest here; its voice is this family's fullest. - **Taurus** (1975), the first pedals. Two sawtooth VCOs with a beat control, the ladder filter, simple contours and a glide. Three fixed sounds and one that can be set. - **Sonic Six** (1972). Two VCOs, **two LFOs** that can be mixed, a ring modulator, white or pink noise, a filter, one simple contour, and a keyboard that is duophonic, one VCO on the lowest key and the other on the highest. It came from another company's design and is the loosest fit here. **The Rogue against the Prodigy**, which Ben asked about: the same idea at two prices. The Prodigy has a contour each for the filter and the amplifier, a triangle wave, and a waveform and octave switch for each VCO; the Rogue has one contour for both and less choice of waveform, and has what the Prodigy lacks, noise and a sample and hold. Neither is the other with a part taken out, but both are settings of one voice that has two contours, noise and the sample and hold. **The MG-1 against the Rogue**, which Ben asked about too: siblings, built at the same time on the same voice, neither a patch on the other. The MG-1 is the Rogue's voice plus the polyphonic section and the ring modulator, less the wheels. With the Liberation wanting the same two additions, they are parts of this instrument and not of one model. So the voice is the Source's and the Liberation's between them: two VCOs with three waveforms and a variable pulse, sync, noise, a ring modulator, the polyphonic section, the ladder filter, two contours that can be tied together as one, an LFO with a sample and hold; and each model is that with things at nothing. ## To find out - **The Sonic Six and the Source are here**, and Ben found the grouping fine on 2026-10-12. The Sonic Six's two LFOs and its duophony are more than settings of the others; the duophony is what #22 wants for the Odyssey. Whether its filter is Moog's ladder wants its manual. - **Whether #53 becomes part of this.** By Ben's word on 2026-10-12: if adding a waveshape knob is all it takes to cover the Micromoog's line, #53 merges into this instrument; otherwise it depends on how much the two overlap. The two issues stay separate until one of them has been built, and whichever is built first should be built with the other in mind. - **The polyphonic section**: what its tone is, whether it goes through the filter and the contour, and whether each key has a gate of its own. `engine/divide_down.h`, written for the Omni, should be what makes it. - **The ring modulator**: which two signals it multiplies on each model. - **The contours.** The Rogue's and MG-1's one contour has a switch for its modes; what each does wants the manual. - **The first Taurus.** Its oscillators are said not to track as the others do, and its sound is held to be its own. As settings it is two sawtooths and a filter; the rest is #4. - **Pressure and the ribbon** on the Liberation: `engine/midi.h` passes key and channel pressure already. ## What it does not cover The Source's memory, its arpeggiator (`engine/arpeggiator.h` stands for it) and its two sequencers, which would be an issue of their own. The Taurus's and Taurus II's being pedals: they are played from MIDI like anything else. The Sonic Six's speaker. Nothing from the Phattys: Ben ruled them out on 2026-10-12, as a line that began after about 2000. ## What is already here to build on - `engine/analog_vco.h` and `engine/four_pole_filter.h`, as for the Minimoog; the ladder's saturation and the Rogue's overdrive are #4. - The SH-5's `voice.h` has a ring modulator and a sample and hold in one voice already. - `engine/divide_down.h` for the polyphonic section. - `engine/key_assign.h`, `engine/portamento.h`, the shared arpeggiator and effects. The SH-101's way of having more than one voice, off by default, would serve here too. ## Provenance - The Source has a processor and patch memory. Rule 3: no firmware disassembly. Rule 4: none of its programs. - **The first Taurus's three fixed sounds** are wired in, not stored. Ben decided on 2026-10-12, on #26: what is wired into a circuit, such as resistor values, and can be seen on a published schematic is fair game; what needs a ROM, stored factory patches included, is another matter and stays under rules 3 and 4. So they may be had, read from the published schematic and from nowhere else, with a comment naming it (rule 5). The Source's programs are stored and may not. - Rule 2: nothing from an emulator's code. - **The names.** "Moog" and the model names are trademarks that are actively used and defended. Ben said on 2026-10-12 to use Moog's own names for now, so that he can tell what each is, the repository being private; nearly every instrument's name here will have to change before anything is sold, and these with them. So, say, `instruments/prodigy/` and programs named `miniprodigy`.
bcox commented 2026-10-17 03:10:25 +00:00
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Built as mini-PRD (instruments/prodigy/, programs miniprd*, .mprd, port 8817) in 7fa9705, with Ben away; every choice is Claude's and is listed in CLAUDE.md under the instrument's section and "Open decisions".

One voice of two VCOs (sawtooth, triangle and a pulse of any width at levels; 32' to 2'; hard sync; the first moving the second at audio rate; contour to each pitch), noise white or pink, a ring modulator (exclusive-OR, or multiplying with ring.multiply), the MG-1's and Liberation's polyphonic section on engine/divide_down.h, the ladder, two ADSR contours that can be one (env.single), the release following the decay as on the Prodigy, VCA contoured/keyed/bypassed, two modulation oscillators (triangle, square, sample and hold, sine), the Sonic Six's duophonic keyboard, pressure, and up to 16 voices, off as it comes. No model switch; it starts as a Prodigy. In the suite and the CLAP plugins. No modulation matrix.

What the manuals corrected:

  • The Prodigy has no pulse width control: VCO 1 is a fixed 10% pulse at 32'-8', VCO 2 a square at 16'-4'. Its square LFO goes upward only, and reaches the VCOs and filter only through the wheel.
  • The Rogue's VCOs are saw/50% square and saw/85% pulse, with a SYNC CONTOURED mode; its VCA is keyed, contoured or bypassed; it has AUTO TRIG.
  • The MG-1 and the Liberation play the highest key; their ring modulator is an exclusive-OR, not a multiplier; the poly section is squares keyed on/off with no envelope, through the same filter and VCA.
  • The Source and the Taurus play the lowest key (stated). The Prodigy's and Rogue's priority is not stated; taken as lowest.
  • The Sonic Six has no sync, its VCA is before its filter, its ring modulator multiplies.
  • No Rogue owner's manual, no MG-1 or Liberation owner's manual, and nothing at all on the Taurus II was found; the Taurus II is played as a Rogue.

Left out: the Taurus's three fixed sounds (four of their resistors are select-on-test and unprinted on the schematic), the Source's memory and sequencers, overdrive/saturation (#4), external inputs (#17). For #53: the waveshape knob is already a VCO's saw/pulse levels and width here; doubling and the VCO on the filter at audio rate are not built.

Bench on the Pi (suite idle beside it): one voice 1.8% of a core, everything 4.3% (5.6% with effects), 16 voices of everything 45.3% (46.7%). Nobody has played it yet.

Built as **mini-PRD** (`instruments/prodigy/`, programs `miniprd*`, `.mprd`, port 8817) in 7fa9705, with Ben away; every choice is Claude's and is listed in CLAUDE.md under the instrument's section and "Open decisions". One voice of two VCOs (sawtooth, triangle and a pulse of any width at levels; 32' to 2'; hard sync; the first moving the second at audio rate; contour to each pitch), noise white or pink, a ring modulator (exclusive-OR, or multiplying with `ring.multiply`), the MG-1's and Liberation's polyphonic section on `engine/divide_down.h`, the ladder, two ADSR contours that can be one (`env.single`), the release following the decay as on the Prodigy, VCA contoured/keyed/bypassed, two modulation oscillators (triangle, square, sample and hold, sine), the Sonic Six's duophonic keyboard, pressure, and up to 16 voices, off as it comes. No model switch; it starts as a Prodigy. In the suite and the CLAP plugins. No modulation matrix. What the manuals corrected: - The Prodigy has no pulse width control: VCO 1 is a fixed 10% pulse at 32'-8', VCO 2 a square at 16'-4'. Its square LFO goes upward only, and reaches the VCOs and filter only through the wheel. - The Rogue's VCOs are saw/50% square and saw/85% pulse, with a SYNC CONTOURED mode; its VCA is keyed, contoured or bypassed; it has AUTO TRIG. - The MG-1 and the Liberation play the **highest** key; their ring modulator is an exclusive-OR, not a multiplier; the poly section is squares keyed on/off with no envelope, through the same filter and VCA. - The Source and the Taurus play the lowest key (stated). The Prodigy's and Rogue's priority is not stated; taken as lowest. - The Sonic Six has no sync, its VCA is before its filter, its ring modulator multiplies. - No Rogue owner's manual, no MG-1 or Liberation owner's manual, and nothing at all on the Taurus II was found; the Taurus II is played as a Rogue. Left out: the Taurus's three fixed sounds (four of their resistors are select-on-test and unprinted on the schematic), the Source's memory and sequencers, overdrive/saturation (#4), external inputs (#17). For #53: the waveshape knob is already a VCO's saw/pulse levels and width here; doubling and the VCO on the filter at audio rate are not built. Bench on the Pi (suite idle beside it): one voice 1.8% of a core, everything 4.3% (5.6% with effects), 16 voices of everything 45.3% (46.7%). Nobody has played it yet.
bcox commented 2026-10-17 03:53:09 +00:00
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Closed by Ben on 2026-10-16 after playing mini-PRD on the Pi through minisuited, with the Sonic Six's scale knob, contour on the modulation rate and contour timer added (564487d), and the voice limit back at 16.

Left as they are: the Taurus's three fixed sounds (unprinted select-on-test resistors), the Taurus II (no documents), saturation and the Rogue's overdrive (#4), external inputs (#17), the Liberation's force sensor switch, the MG-1's keys loading each other, and the unconfirmed plain choices listed in CLAUDE.md. #53 may become parameters of mini-PRD.

Closed by Ben on 2026-10-16 after playing mini-PRD on the Pi through minisuited, with the Sonic Six's scale knob, contour on the modulation rate and contour timer added (564487d), and the voice limit back at 16. Left as they are: the Taurus's three fixed sounds (unprinted select-on-test resistors), the Taurus II (no documents), saturation and the Rogue's overdrive (#4), external inputs (#17), the Liberation's force sensor switch, the MG-1's keys loading each other, and the unconfirmed plain choices listed in CLAUDE.md. #53 may become parameters of mini-PRD.
bcox closed this issue 2026-10-17 03:53:09 +00:00
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