ADDAC 221 (2016–)

A 16HP gateway between your modular’s squelches and the digital world’s control—turning CV into MIDI CC messages with surgical precision and zero fluff.

Overview

Say a slow LFO is modulating a filter cutoff, and you want that same motion to change the reverb decay on a DAW plugin. That is the job of the ADDAC 221. It makes no sound. It takes 10 channels of CV and converts them into MIDI Control Change messages, sent out over both USB and 5-pin DIN MIDI, so the modular can control soft synths, effects or DAW parameters without a pile of converters and code.

And it’s not just a dumb converter. The 221 is smart enough to let you map each CV input to any CC number and MIDI channel, store presets, and even offset or invert the signal before conversion. That means you can set up one configuration for tweaking a granular synth’s grain size and density, another for automating a filter bank in a plugin, and switch between them in seconds. It’s the kind of module that makes your system feel less like a lab experiment and more like a real instrument. The front panel is clean, industrial black with white labels and chunky knobs—nothing showy, but built like it’s meant to survive a tour. And at 16HP, it’s not the skinniest utility module out there, but you’re not going to weep over the space it takes.

ADDAC is not a company chasing digital wizardry or flashy interfaces. They are deep into the analog side - warm preamps, vintage-style clipping, tactile control - but they are not allergic to modern connectivity. The 221 digitizes your control, not your sound.

Specifications

Key Features

CV to MIDI CC Conversion with Preset Intelligence

Most CV-to-MIDI converters do one thing: translate voltage into data. The 221 does that, but it also remembers your settings. It has eight user-configurable presets, and each one saves a full control mapping, say CV 1 to CC 74 (filter cutoff) on MIDI channel 3, and CV 2 to CC 1 (mod wheel) on channel 1. That saves repatching and reprogramming when you switch setups. The presets are managed in a standalone app (Windows and macOS), which sets CC numbers, MIDI channels and scaling for each input. It is not browser-based and not cloud-synced. Because the module stores the presets locally, you don't need your computer running to use them.

Flexible Signal Conditioning

The first eight channels each have a large white knob and a small pot. The big knob is a manual offset, a bias control that sets the baseline CV level before conversion. The small pot is an attenuverter, so it scales the incoming CV up or down and can flip its polarity. That matters with bipolar LFOs or envelopes that swing positive and negative, when the target parameter only responds to 0-127. The toggle switch next to each input forces the signal to unipolar (positive only), which suits gates and triggers. All of this reshapes your CV before it ever becomes MIDI.

Dual MIDI I/O with Thru Functionality

The 221 routes MIDI as well as sending it. USB MIDI data is passed to the 5-pin DIN output, and incoming DIN MIDI is passed to both the USB port and the DIN output. You can daisy-chain MIDI devices through the 221, or use it as a passive MIDI thru box. It can send the modular's clock to a drum machine while also controlling a plugin, or merge MIDI from a keyboard into the modular's MIDI stream. It is not a full MIDI merger or processor.

Historical Context

The ADDAC 221 launched in 2016. Most CV-to-MIDI solutions then were either clunky external boxes or modules with limited functionality, while modular users were relying more and more on DAWs, VSTs and digital effects. ADDAC didn't invent CV-to-MIDI. They packed preset storage, bidirectional MIDI routing and per-channel configuration into a single module. It wasn't the first, but it was one of the first to feel like a complete solution.

Its closest competitors at the time were modules like the Kenton Pro Solo or the Expert Sleepers FH-2, but those were often more complex or required deeper technical knowledge. The 221 was accessible enough for beginners and deep enough for pros. It also reflected a shift in modular design: utility modules could be just as important as sound generators.

Collectibility & Value

The ADDAC 221 isn't a rare bird, but it isn't disposable either. It has been built since 2016 with ongoing firmware updates, so it is a modern module by vintage standards, and it has already earned a reputation as a reliable workhorse. On the used market it typically sells for $300 - $380, depending on condition and whether it includes the original cables. Units with custom faceplates (available in colors like red, blue, or bronze) sometimes fetch a small premium, but most buyers care more about functionality than looks.

Failures are rare, but when they happen, it's usually the Teensy microcontroller or the USB port. Firmware updates require physically pressing a button on the internal board, so you have to pull the module from your case. That is annoying, but not a dealbreaker. The rotary switches for preset selection were changed from 9-position to 8-position in 2020 due to component shortages, so early units have one more preset slot. It isn't a major functional difference, but collectors might note it.

If you're buying used, check that all knobs turn smoothly, the USB connection is solid, and the MIDI outputs trigger external devices reliably. Test each CV input with a known source and verify that the CC messages are sent correctly. Some users report stuck values if the firmware is outdated, and a quick update usually fixes it. Overall the 221 is low-risk: no electrolytic caps to dry out and no analog circuitry to drift, just solid-state logic.

eBay Listings

ADDAC ADDAC221 CV to CC Converter Modular EURORACK - NEW - P

$489

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