AMSynths Roland 100M (2020s–Present)
A Eurorack revival of Roland's unbuilt modular designs, with prototype circuits finally made real
Overview
The AMSynths Roland 100M line is built from Roland's unrealized 1978 prototypes. These are not plain clones or reissues. They are made with careful accuracy and just enough modern refinement to keep them stable. The original System 100M was legendary, sure, but these modules cover the what-ifs: the 141 envelope generator with gate delay, the dual portamento, the CV mixers that never made it past the drawing board. They now come in 16HP Eurorack format, built to sit alongside the classics.
AMSynths did not just copy Roland's old schematics. They hunted down surviving prototypes, worked with collectors like Alex Ball who own these ghost modules, and reverse-engineered them from photos, service notes, and surviving components. The family stays true to the 100M, quirks included. The AM8141 is the exact circuit layout of the 141 prototype, a dual ADSR with the gate delay that later reappeared in the 172. The AM8165 is a faithful replica of the rare 165 Dual Portamento, a module so elusive that even full 100M systems rarely included one. Then there are the hybrids, like the AM8120, which fuses the Jupiter-8's 24dB OTA filter with the 130's VCA. It gives you that Roland resonance with modern Q compensation and self-oscillation.
What’s striking is how these modules don’t just mimic the past; they extend it. The original 130 Dual VCA was AC-coupled, which meant it couldn’t handle CV signals—fine in 1978, but a real limitation today. AMSynths fixed that with the AM8133, a DC-coupled version that lets you modulate modulation, opening up complex feedback patches that the original system could only dream of. Same with the AM8132 CV Mixer, a reissue of the 132 that was useful in its day but now feels essential in a modern Eurorack context where voltage manipulation is half the fun. These aren’t museum pieces; they’re tools built for today’s modular workflows, but with the soul of late-’70s Roland engineering. And yes, they look the part—black panels, silver knobs, that distinct Roland font—so they blend seamlessly with Behringer’s System 100 modules or stand proudly on their own.
Specifications
| Manufacturer | AMSynths |
| Production Years | 2020s–Present |
| Module Format | Eurorack |
| HP Width | 16HP (standard for most modules) |
| Depth | Varies by module (typically 30–40mm) |
| Current Draw | +12V: 60–100mA, -12V: 20–40mA (varies by module) |
| Audio Inputs | 3.5mm or 1/4" (module-dependent) |
| CV Inputs | 3.5mm, typically 1V/octave |
| Outputs | 3.5mm or 1/4" (module-dependent) |
| Voltage Control | Most modules support exponential and linear response |
| Filter Types | OTA-based 24dB/oct low-pass, 12dB/oct modes, Q compensation |
| Envelope Generators | ADSR with invert, manual gate, CV control |
| LFOs | Multiple waveforms, switchable ranges (x1, x1/10) |
| Mixing Capabilities | Audio and CV mixing, panning, multiple inputs |
| Special Features | Gate delay, sample & hold with lag, portamento control, DC coupling (AM8133) |
| Weight | Approx. 200–300g per module |
| Construction | Steel front panel, PCB-mounted jacks, rotary encoders |
| Compatibility | Fully compatible with standard Eurorack power and patching |
Key Features
The Ghost Modules Made Real
The real magic of the AMSynths Roland 100M series lies in its resurrection of circuits that never officially existed. The 141 envelope generator, for instance, was a prototype in 1978 but never entered production—until now. The AM8141 brings it to life with dual ADSRs, gate delay, and an invert/adder circuit that lets you flip and sum control voltages on the fly. This isn’t just a convenience; it’s a compositional tool. You can create staggered envelopes, reverse-trigger effects, or complex rhythmic gating that would’ve required multiple utility modules in other systems. Similarly, the AM8165 Dual Portamento isn’t just a glide control—it’s a voltage-controllable portamento with CV input, letting you modulate the glide time from an LFO or sequencer. That kind of expressiveness was rare even in high-end modulars of the era, and having it in a compact Eurorack format is a game-changer.
Modernized Classics with a Purpose
AMSynths did not stop at replication. The original 130 Dual VCA was a workhorse, but its AC coupling meant it couldn't pass DC signals, which limited its use in modulation routing. The AM8133 fixes that with full DC coupling, making it useful for CV mixing, offset generation, or even low-frequency waveform shaping. The AM8120 takes a different approach. Instead of cloning the 121 VCF, it reworks it with the Jupiter-8's filter topology, adding 12dB/oct mode, Q compensation, and smoother resonance control. The filter sounds like Roland, with more flexibility and stability than the original OTA designs. It is not a replacement for the original.
Integration and Expandability
The line plays well with others. The modules use standard 3.5mm jacks, run on standard Eurorack power, and respond to 1V/octave scaling, so they work with Behringer's System 100 modules, Roland's System-500, or any other modern setup. The AM8171 Sequential Switch is a four-channel analog gate that can be stepped manually or via CV, good for rhythmic switching or sample-and-hold-style randomness. Pair it with the AM8176 Triple Resonator, a vactrol-based filter bank with independent resonance and modulation, and you get a sound design engine that would have surprised Roland's engineers in 1979.
Historical Context
The original Roland System 100M was born in 1978, when modular synthesis was already being eclipsed by preset-based polysynths. Roland doubled down on modularity anyway, offering a flexible, semi-normalled system that was more accessible than the System-700 but far more powerful than the semi-modular System-100. It found favor with experimental musicians, film composers, and Japanese hobbyists during a synth boom fueled by a thriving electronics culture. Even as it succeeded, Roland was developing prototypes like the 141 and 165 that never made it to production, either due to cost, complexity, or shifting priorities. For decades they remained footnotes in synth history, known only through schematics and rumors. AMSynths changed that, using modern manufacturing, digital documentation, and a passionate collector community.
Collectibility & Value
These are modern production modules, so they aren't "collectible" in the traditional sense, but they are highly sought after, especially the rarer prototypes like the AM8141 and AM8165. New units typically sell for between £250 and £350 depending on the module, with the AM8120 and AM8133 slightly more common and thus easier to find. Used prices hover around 70-80% of retail, and there's little evidence of scalping or artificial scarcity. AMSynths seems to produce in reasonable batches. If you're building a full 100M-style system in Eurorack, these modules are worth prioritizing over third-party alternatives because of their circuit accuracy. They're also reliable: no aging capacitors, no failing connectors, no need for recap. The only real failure risk is availability, since some modules are released in limited runs. There's no degradation over time, no maintenance beyond standard dusting, and no compatibility issues with modern cases. For anyone who loves the 100M but can't afford or house a full vintage system, this is the closest you'll get to owning the real thing, without the fire hazard.
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