ALM MCO MKII (2024–)

A 6HP Eurorack module covering the digital sounds of the '90s and 2000s, with polyphony, presets and seven synthesis engines.

Overview

The ALM MCO MKII is a full voice module. It fits seven distinct synthesis engines into 6HP. Each one points at a different era of digital synthesis: the super-saws of a JP-8000, the gritty talkbox rasp of a vintage vocoder, the squelchy pulse of a SID chip, and the textures of additive synthesis that could pass for SND or Gabor Lazar patches. It's a desktop workstation sound set with Eurorack immediacy.

The interface is the same one ALM has been using for a while. It has a high-resolution color display and a single encoder/button combo, familiar from Pam's PRO Workout and the MFX. Long-press for settings, short-press to dive in, twist to scroll, click to select. The UI is visual, responsive and forgiving, so you don't need a cheat sheet to get through the menus. Many compact digital modules give up tactile feedback to save space. This one doesn't feel that way. You edit a 12-operator additive engine with the same control scheme you use to set a clock divider, which is a little funny when you think about it.

Each engine behaves like its own instrument. The DigiWave engine builds on the original MCO's wavetable foundation and adds user-uploadable tables via USB-C. You can load custom or community-made wavetables, or pull them from vintage synths if you have the data. The ToneSum additive engine allows per-harmonic detune, spread and amplitude modulation, which gives evolving, inharmonic textures that go well past glassy pads. The BC8000 mode covers the Roland digital sound: supersaws with chorus depth, unison stacks that thicken with a twist, and the bright, cutting leads of trance and progressive house. Sylon is the vocoder engine. It's a full 16-band vocoder with internal carrier, external carrier input and modulator sidechain, and it handles everything from robotic speech effects to lush formant sweeps.

Specifications

Key Features

A Synthesis Engine for Every Era

The MCO MKII doesn’t just dabble in different synthesis methods—it commits. The DigiWave engine resurrects the original MCO’s multidimensional wavetable approach but adds stereo output options and a newly introduced multi-mode filter, letting you sculpt the raw digital output with resonance and slope. ToneSum, the additive engine, is unexpectedly deep: with 12 operators (harmonics), each with independent amplitude and detune, it can generate anything from pure sine stacks to metallic bell tones and evolving drones. The BC8000 mode doesn’t merely imitate the JP-8000; it expands on it, offering multiple unison types, spread controls, and the ability to modulate the supersaw width at audio rate. And then there’s Oomph—the bass engine—which isn’t just another sub oscillator. It’s tuned for punchy kicks, sub-bass layers, and percussive thumps, with internal envelope shaping that can stand in for a dedicated drum module. The inclusion of the SID GUTs engine—a faithful port of ALM’s discontinued SID chip module—is a nostalgia bomb for C64 fans, delivering authentic 8-bit grit, ring modulation, and filter sweeps that scream “Commodore.”

Polyphony and Chords in a 6HP Slot

Four-voice polyphony in a 6HP module is impressive. The MCO MKII manages it by treating chords as a main feature. Each engine can trigger pre-defined chords (major, minor, diminished, 7ths, 9ths) with options for inversions and user-defined voicings. Send a single CV into the pitch input and the module outputs evolving harmonies without any external logic. The chords respond to glide, envelopes and LFOs just like monophonic lines. That makes it possible to build pads that breathe, arpeggios that swell, and basslines that shift tonality on the fly. The chords are stored per preset, so a single preset change switches between a solo virtual analog lead and a four-note vocoder chord, with no patching.

USB-C and Expandability: The Modern Modular Touch

The USB-C port handles firmware updates by drag and drop. You can also upload custom wavetables and back up your entire configuration, including user presets and CV assignments, with a single click. ALM keeps updating the firmware. Version 106 added a multi-mode filter to DigiWave, and Version 105 introduced the AEIOU formant engine. Axon expander support adds up to four more CV inputs via AXON-1 or AXON-2. That lets you modulate vocoder band levels from a second sequencer, or assign additional LFOs to additive harmonics.

Historical Context

The MCO MKII arrives when Eurorack is crowded with oscillators, including endless variations on VCOs, LFOs and waveshapers, but short on modules that offer complete sonic experiences without bloating the rack. ALM is known for utility modules with deep functionality (Pam's PRO Workout, the MFX), and it has applied that approach to sound generation. The module draws heavily from the 1990s and 2000s, the years when digital synthesis went mainstream, when Roland, Korg and Yamaha packed entire sound engines into single chips, and when presets became part of the creative process. It brings the preset-driven workflow of the JD-800 into a modular, where patching and modulation come first.

Competitors like Mutable Instruments' Plaits (now discontinued) or the newer STG Soundlabs DUSG offered digital versatility, but none matched the MCO MKII's blend of polyphony, presets and engine diversity in such a small footprint. Plaits focused on morphing between synthesis types in real time. The MCO MKII lets you stay in one mode and go deep. It also embraces presets, which many modular purists still eye with suspicion. ALM's view is that inspiration often starts with a sound, not a blank patch.

Collectibility & Value

As a 2024 release, the MCO MKII isn't "vintage" in the traditional sense, but it's already positioned as a modern classic. It's priced at £230 (around $290 USD), which is not cheap for 6HP. New units sell quickly through authorized dealers like SchneidersLaden and Perfect Circuit, and resale prices remain close to MSRP, indicating strong demand and low churn. There are no known hardware failures at this stage. Service technicians note that the USB-C port and display are the most sensitive components, so avoid forcing cables or exposing the module to excessive moisture. The firmware is actively maintained, with updates adding features like the AEIOU engine and smoother modulation curves.

For buyers, the main consideration is workflow fit rather than reliability. The MCO MKII suits small or travel racks, live setups, and systems where space is tight. It's less ideal for modularists who want a dedicated knob for every parameter. This is a module for people who don't mind menu diving. Used units in good condition typically sell for 15-20% below MSRP, but mint units with original packaging and firmware up to date can fetch full price. Collectors are already holding onto them as "future classics," especially given ALM's reputation for long-term support and firmware evolution. If you're considering one, check the firmware version (106 or later recommended), test all CV inputs with an expander if possible, and verify that the display has no dead pixels or ghosting. A VCV Rack version exists and mirrors the hardware exactly, so you can audition the module before purchase.

eBay Listings

ALM BUSY CIRCUITS MCO MKII : NEW : [DETROIT MODULAR]

$300

ALM BUSY CIRCUITS MMMIDI MKII : NEW : [DETROIT MODULAR]

$210

ALM Busy Circuits MCO MKII Digital Oscillator EURORACK - NEW

$300

ALM Busy Circuits mmMIDI mkII MIDI to CV EURORACK - NEW - PE

$200

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