ADDAC System ADDAC213A (2017–)

Two cases, one clean ribbon cable, and suddenly your modular setup stops looking like a bowl of tangled spaghetti.

Overview

It starts with the cables—too many of them, snaking across your desk, getting stepped on at gigs, shorting out when you shift a module. You tell yourself it’s part of the charm, but really, it’s just stress. Then you see someone with a pair of ADDAC213A modules, and they plug in a single ribbon cable between two cases like it’s nothing. Eight CV or audio signals, cleanly routed, no patching required. It feels like magic, but it’s just smart engineering. The ADDAC213A isn’t flashy. It doesn’t make sound. It doesn’t sequence, filter, or modulate. But if you’ve ever cursed while trying to sync a second Eurorack case, this thing is your quiet savior.

Designed in Lisbon by ADDAC System, a boutique modular outfit with a knack for solving real-world problems, the 213A launched around 2017 as the first piece of their Eurorack Bridge system. It’s a passive utility module—no power draw, no active circuitry—just a robust interface that lets you send and receive up to eight signals between cases over a single ribbon cable. The idea is simple: pair two 213As (one in each case), connect them with the included 100cm cable, and you’ve got a dedicated bridge. Need more channels? You can expand the system by adding ADDAC213B modules to each 213A, stacking up to 24 total signals. That’s enough to carry full stereo audio, clock, gate, pitch CV, and mod wheel data from a remote controller case to your main rig without a single patch cable in sight.

What makes it elegant isn’t just the function, but the fit. At 6 HP wide and only 2.4 cm deep, it tucks neatly into even the most cramped skiff. The ribbon cable connector is on the back, so the front panel stays clean. And because the module can be mounted in either normal or 180-degree orientation, you can adapt it to any case layout—top row, bottom row, angled build, it doesn’t matter. It’s the kind of module you don’t know you need until you use it, and then you wonder how you ever lived without it.

Specifications

Key Features

No Power, No Problem

The ADDAC213A doesn’t need power, which is both its greatest strength and a subtle revelation. Most utility modules eat +12V and -12V like snacks, but this one just sits there, doing its job silently, without loading your power supply. That’s a big deal if you’re running a dense case on a limited PSU. It also means fewer points of failure—no voltage regulators to blow, no power LEDs to flicker. The signal path is direct, passive, and reliable. What you send in is what comes out, with minimal loss or crosstalk, assuming your ribbon cable is in good shape.

Expandable to 24 Channels

While the base pair handles eight signals, the real flexibility comes from the ADDAC213B expansion modules. Each 213B adds another eight channels and connects directly to the back of the 213A. You can run one or two per 213A, letting you scale from a modest bridge to a full inter-case nervous system. This is where the system shines for live performers or studio users with multiple cases—one cable carries everything from a remote keyboard skiff to your main synth brain. It’s not just about convenience; it’s about stability. Fewer patch cables mean fewer accidental disconnects, fewer noise issues, and a cleaner setup when you’re under lights or on a moving stage.

Skiff-Friendly and Reversible Mounting

At 2.4 cm deep, the 213A clears even the shallowest skiff designs. And the ability to mount it upside-down (180 degrees) is more than a gimmick—it’s a thoughtful design choice for cases where rear access is tight or where cable strain might be an issue. Whether you’re building a travel rig or a permanent studio setup, that kind of flexibility matters. The front panel is cleanly labeled, with channel numbers and signal direction indicators, so you’re never guessing which pin goes where.

Historical Context

When the ADDAC213A arrived, Eurorack was already deep into the era of modular sprawl. What started as compact experimental systems had ballooned into multi-case rigs, often cobbled together from different manufacturers, power supplies, and form factors. The problem of inter-case connectivity wasn’t new, but most solutions were either janky (DIY breakout boxes) or overly complex (MIDI-to-CV bridges, digital multiplexers). ADDAC’s approach was refreshingly analog and pragmatic: use a standard ribbon cable, keep it passive, and make it modular-native. They weren’t the first to try this—some DIY builders had been doing similar things for years—but they were among the first to package it as a polished, commercially available module with proper support and documentation.

The 213A also reflects a broader trend in the modular world: the rise of utility as an art form. As synthesisers became more digital and patching more complex, the demand grew for tools that simplified, organized, and optimized the physical experience. The 213A sits in that lineage—not a sound generator, but a quality-of-life upgrade that makes the whole system feel more coherent. It’s the kind of module that doesn’t show up in demo videos, but it’s there in the background, letting the artist focus on playing instead of patching.

Collectibility & Value

The ADDAC213A has never been rare, but it’s consistently in demand. Priced at €105 for a pair when new (plus shipping from Portugal), it’s not cheap for a passive module, but most owners report it pays for itself in reduced frustration. On the used market, pairs typically sell between $80 and $120, depending on condition and whether the original ribbon cable is included. Because it’s passive, there’s almost nothing to break—no ICs, no capacitors to degrade. The main failure points are mechanical: bent pins on the ribbon connector, damaged mounting tabs, or frayed cables. None are catastrophic, but they’re worth checking before buying used.

One quirk: ADDAC offers custom front panels in colors like red, blue, silver gray, or bronze, often at a premium and with a lead time of 4–6 weeks. These limited-run versions occasionally surface on eBay or Reverb, usually priced 20–30% higher. For most users, the standard black panel is plenty, but the option adds a touch of personalization that collectors appreciate.

If you’re considering the DIY kit (€73, excluding VAT), it’s a solid choice if you’re comfortable with basic soldering. The assembly guide is thorough, and the parts are standard. But unless you’re on a tight budget or enjoy building, the pre-assembled version is worth the extra cost—especially since misaligned pins or cold solder joints can cause intermittent signal issues.

eBay Listings

As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.

Related Models

• ADDAC System 712 Vintage Pre
• ADDAC System 712
• ADDAC System 800X
• ADDAC System 801
• ADDAC System 802
• 4ms Ping
• ADC 27
• 2hp LPG V2
• ALM AXON-2
• AMS DMX 2000