ADDAC 222 (2016–Present)

Turn four CV lines into eight-note polyphonic chaos—or precision—with one of Eurorack’s most misunderstood MIDI brains.

Overview

The ADDAC 222 doesn't make sound and doesn't process it. It sits in your system and lets an analog sequencer drive a vintage Jupiter-6, a DAW and a rack of digital synths at once, polyphonically. It's a CV-to-MIDI converter, but it also negotiates between protocols. It has four independent CV inputs, and each one can generate up to six-note polyphonic MIDI streams. Your modular's control voltages come out as full MIDI performances over USB or DIN MIDI to external gear. It's precise, as long as you calibrate it properly. This isn't plug-and-play. Expect to plug, tweak, recalibrate, swear and update firmware before it behaves.

Polyphonic voice management is what sets the 222 apart from other CV-to-MIDI solutions. Most converters force you into monophonic mode or simple chord triggers. The 222 lets each CV input stack up to six voices in a wraparound buffer. If you send step changes from a sequencer, the module doesn't just play the latest note. It holds the previous five and cycles them out as new voltages arrive. This is old-school polyphony logic, the kind found in vintage synths like the Prophet-5 or Juno-106, and it works well with polyphonic MIDI instruments. It only works if your target device can handle polyphony per MIDI channel, though. Send six-note chords to a monosynth and you'll get either one note or a MIDI traffic jam.

The module sits in the middle of ADDAC's MIDI Series as the polyphonic counterpart to the more basic 221. The 221 handles one CV input and simpler note conversion. The 222 is the full-featured one, built for setups where several external synths need to be driven at the same time. It's not the cheapest option, nor the smallest, but it packs a lot of control into 16 HP. Each input has its own octave transpose switch, MIDI channel and bank selection, and a trimmer for fine-tuning CV scaling, since not every oscillator tracks perfectly.

The catch is that the 222 demands precision. It uses the 1V/oct standard, and if your CV source drifts, even slightly, you'll get wrong notes, missed triggers or ghosting. One user on a popular forum described trying to control it with a Sweet Sixteen and getting inconsistent results. The issue wasn't the 222. It was the difficulty of dialing in exact voltages by hand. The 222 assumes calibrated gear, not wobbly knobs and drifting LFOs. If your system isn't stable, the 222 will expose it. That's why each input has its own ADJ.x trimmer.

Specifications

Manufacturer	ADDAC System
Production Years	2016–Present
Original Price	$425 USD
HP	16
Current Draw +12V	70 mA
Current Draw -12V	30 mA
Current Draw 5V	0 mA
CV Inputs	4 (1V/oct)
MIDI Outputs	USB MIDI, 5-pin DIN MIDI
MIDI Inputs	5-pin DIN MIDI (pass-through to USB and MIDI OUT)
MIDI Channels	9 (3 banks × 3 channels)
Polyphony per Input	Up to 6 voices
Operation Modes	Continuous, Triggered, Gate Follower with Sustain
Octave Transpose	+1 to +2 octaves per input (extendable via C1-C2 OFFSET knob)
Calibration	Individual ADJ.x trimmers per CV input
Control Inputs	Gate inputs for Note Off and All Notes Off per channel
Firmware Updates	Supported via Teensy loader (latest: B_7, April 30, 2021)
Weight	Approx. 250g
Dimensions	80.8mm depth, 16HP width

Key Features

Polyphonic Voice Management That Feels Analog

Voice allocation on the 222 isn't random or velocity-based. It's sequential and deterministic, like an old analog polyphonic synth. In 3- or 6-voice mode, it treats incoming CV changes as note events and cycles through a buffer. First voltage change is note one, second is note two, and by the sixth you have a full chord. The seventh replaces the first, and so on. This wraparound behavior suits step sequencers, since you can build evolving pads or arpeggios without external logic. Live performers also use it to layer multiple synth lines from a single sequencer run, sending different CV streams to different MIDI channels. The one limitation is that your target device must accept multiple simultaneous notes on a single channel. If it doesn't, use 1-voice mode.

Three Distinct Trigger Modes for Any Workflow

The 222 offers three modes for interpreting CV. In continuous mode, it fires a new note every time the CV changes, which suits live knob tweaks or slow LFOs. In triggered mode, it waits for a gate signal before sending a note, which suits tight, sequenced playing. The third is Gate Follower with Sustain, a firmware addition that lets the note follow the gate input directly. Its sustain function holds active notes even after the gate drops. It works well for expressive playing, especially with a keyboard or ribbon controller. These modes were refined over several firmware updates, including fixes for note-holding bugs.

Deep MIDI Routing and Pass-Through Flexibility

The 222 also routes MIDI. USB MIDI data is passed to the DIN MIDI OUT, and incoming DIN MIDI is mirrored to both USB and the output jack. That makes it a passive MIDI hub, so you can daisy-chain other MIDI devices without extra interfaces. You can sync your modular clock to Ableton while also sending note data to a Prophet. Nine MIDI channels are available across three banks (A: 1-3, B: 4-6, C: 7-9), so each CV input can go to a different synth without overlap. To put CV Input 1 on MIDI Ch 4, set it to Bank B, Channel 1. It isn't intuitive at first, but the mapping is easy to memorize.

Historical Context

The ADDAC 222 launched in 2016. Eurorack was already deep into its golden age, but MIDI integration was still a pain point. Most CV-to-MIDI solutions were monophonic, unreliable, or required a computer in the middle. The 222 arrived as part of ADDAC's MIDI Series, a set of modules designed to bridge the analog-digital divide without giving up hands-on control. It wasn't the first CV-to-MIDI converter, but it was one of the first to offer true polyphony in a modular format. Digital synths like the Elektron Digitone and Waldorf Quantum were gaining traction at the time, and the 222 let modular users control them with the same hardware they used for analog sound generation. Competitors like the Kenton Pro Solo or Doepfer MSY2 existed, but they were often rack-mounted, less flexible, or lacked polyphonic voice management. The 222 found its niche by being patchable, voltage-controllable and firmware-upgradable. It also arrived alongside the ADDAC 221, which handled simpler, single-channel conversion, making the 222 the premium option for complex setups.

Collectibility & Value

The ADDAC 222 isn't vintage in the traditional sense. It's still in production, and ADDAC still supports it with firmware updates. It's collectible anyway. Modules with proven reliability and deep functionality gain cult status in the modular world, and the 222 is quietly becoming one of them. On the used market, prices range from $350 to $450, depending on condition and whether it includes the original TRS-to-MIDI cables. New units from dealers like Perfect Circuit or Reverb list for $509.

Not much breaks, but there are quirks. Firmware updates require a physical button press between the PCBs. That's easy to miss if you don't have a plastic tool ready, since metal can short pins. Some early users reported issues with note-off timing when changing MIDI channels. These were resolved in firmware B_3 and later. The most common "failure" is user error. Misunderstanding the voice wraparound logic or misconfiguring the bank/channel mapping leads to frustration, not malfunction. Buyers should test each CV input with a stable source, verify MIDI output on multiple devices, and confirm the firmware is up to date. The module ships with a black panel, but ADDAC offers custom colors (red, blue, bronze, etc.) for an extra fee. These are rare and sometimes resell at a premium.

Maintenance is minimal. There are no moving parts and no audio circuitry to degrade. Keep the firmware updated and make sure your CV sources are stable. A hybrid setup, with a modular controlling digital synths or DAW instruments, is where the 222 makes sense. If you only run analog gear, you might not need it.