ADDAC System ADDAC213B (2017–)

A silent workhorse that untangles your patch with surgical precision—no power, no fuss, just clean signal routing that feels like magic.

Overview

You don’t hear the ADDAC213B, but you feel its absence the second it’s gone—like losing a favorite screwdriver you didn’t realize you used every day. It’s not a sound generator, not a processor, not something that warps or modulates. It’s a bridge. A quiet, passive, brilliantly simple solution to one of Eurorack’s most persistent headaches: cable spaghetti. When your modular system sprawls across multiple cases or even just deep within a single 104HP skiff, patching a clock from the back row to a sequencer up front means either a jungle of cables or nothing at all. The ADDAC213B fixes that—not with flashy circuitry, but with clever engineering and a ribbon cable the color of printer innards.

Born in the mid-2010s, when Eurorack was exploding in size and complexity, the ADDAC213B arrived as part of a larger ecosystem: the Eurorack Bridge system. While the ADDAC213A handles inter-case communication with a single cable linking two full systems, the 213B is its expandable sidekick—both a standalone tool and an add-on. Use a pair inside one case to route eight signals from top to bottom without a single patch cable crossing the front panel. Or, strap two 213Bs onto a pair of 213As and suddenly you’ve got 24 channels bridging two cases. That kind of scalability was rare at the time, and still counts for something in a world where most manufacturers stop at “one cable, eight signals” and call it a day.

And here’s the kicker: it draws zero power. No +12V, no -12V, no 5V witchcraft—just passive headers on the back, a ribbon cable, and eight clean signal paths. That means you can install it in any case, any power setup, even the most power-starved skiff, and it won’t blink. It’s the kind of module that makes you wonder why more companies don’t build these. Because while everyone’s chasing the next granular oscillator or AI-powered sequencer, someone still has to wire the damn thing together. The 213B is the electrician in the back room, keeping the lights on while the rock stars play solos.

Specifications

Manufacturer	ADDAC System
Production Years	2017–
Original Price	90.00 € (pair, excluding VAT)
Format	Eurorack
Width	3 HP
Depth	2.5 cm
Power Requirements	None (passive module)
Signal Channels	8 CV/audio signals (bidirectional)
Installation Orientation	Normal or 180-degree inverted
Ribbon Cable Included	Two 50 cm cables (one used for standalone, both for expansion)
Expansion Capability	Up to two ADDAC213B pairs per ADDAC213A pair
Total Expansion Channels	24 (with two 213Bs on a 213A)
Module Pair Requirement	Always sold and used in pairs
DIY Kit Available	Yes (61 €, excluding VAT)
Custom Panel Options	Red, Green, Blue, White, Silver Gray, Yellowed Silver, Dark/Light Bronze (custom order)
Print Color Options	Black, White, Red, Yellow, Blue, Green (dependent on panel color)
Lead Time (Custom Panels)	4–6 weeks
Assembly Guide	Available as PDF (ADDAC213B_DIYkit.pdf)

Key Features

Passive Signal Routing That Just Works

The brilliance of the ADDAC213B is in its silence. No power, no noise, no crosstalk—just eight clean, passive signal paths between two modules. Each pair connects via a 50cm ribbon cable (with a 100cm option available), linking two 213Bs installed anywhere in the same case. Once connected, you can route clocks, gates, audio, or CV from one end of your system to the other without a single patch cable. Want to send a modulation source from your lower row to a filter on the top? Done. Need to loop a trigger into a sequencer three rows down? No spaghetti, no clutter. The modules themselves are 3 HP each—slim enough to tuck into forgotten corners—and can be mounted in either direction, so you can route signals vertically or horizontally depending on your case layout. It’s not flashy, but it’s transformative.

Expandable Bridge Architecture

Where the 213B really flexes is as an expansion to the ADDAC213A. While the 213A pair gives you 8-channel inter-case bridging out of the box, each 213B connected to the back of a 213A adds another 8 channels. Two 213Bs per 213A means you can scale up to 24 total channels between cases—critical for large, multi-case systems where you’re syncing sequencers, sharing audio, or distributing master clocks across multiple frames. This kind of modular expandability was ahead of its time. Most bridge systems are fixed: 8 channels, period. But ADDAC built in headroom, letting users grow their setup without replacing core infrastructure. It’s the kind of forward thinking that makes technicians and touring artists breathe easier.

DIY-Friendly and Customizable

ADDAC didn’t just sell a module—they sold access. The 213B is available as a DIY kit for 61€ (excluding VAT), complete with a detailed assembly guide. For a passive device, the build is straightforward: no soldering of ICs, no delicate op-amps, just headers, connectors, and mechanical assembly. It’s a perfect intro to DIY for newcomers, and a cost-saving option for veterans. And if you’re the type who matches your modules to your mood, ADDAC offers custom panel colors—red, green, blue, white, silver, bronze, even yellowed silver—with matching print colors. It’s a small touch, but in a world of black-anodized uniformity, a splash of copper or cobalt on your case backplane feels like rebellion.

Historical Context

The ADDAC213B didn’t emerge in a vacuum. It arrived in 2017, right as Eurorack was shifting from boutique curiosity to mainstream fixture. Modular wasn’t just for noise artists and academics anymore—it was in pop studios, film scoring stages, and touring rigs. And with that growth came complexity. Systems were no longer single 60HP cases; they were sprawling, multi-rack beasts with dozens of modules, multiple power supplies, and tangled nests of patch cables. The industry responded with more oscillators, more filters, more everything—but few addressed the physical logistics of managing it all.

ADDAC, a Portuguese company with a knack for hybrid analog-digital design, saw the gap. While others chased sonic novelty, they built utility: tools that made modular *work* better. The Eurorack Bridge system—anchored by the 213A and expanded by the 213B—was a direct answer to the cable chaos. It wasn’t the first signal bridge (Intellijel’s Link did something similar), but it was among the first to offer expandable, multi-channel, bidirectional routing with passive simplicity. In an era when modules were getting smarter, faster, and more power-hungry, the 213B stood out by getting dumber—by design. It didn’t compute. It didn’t process. It just moved signals. And in doing so, it solved a problem everyone had but no one wanted to talk about.

Collectibility & Value

The ADDAC213B isn’t a collector’s grail. You won’t find people flipping them for profit or hunting serial numbers. But that doesn’t mean it’s not valuable—quite the opposite. On the secondhand market, a pair typically sells for $90–$130, depending on condition and whether it includes both ribbon cables. The DIY kit, when available, trades for around $70. Prices have remained stable, not because of scarcity, but because of utility. People buy 213Bs to *use*, not to hoard.

Failures are rare—astonishingly so for a passive module. There are no components to degrade, no power rails to fry. The only real risk is physical: bent pins on the rear headers, or a damaged ribbon cable. But even then, replacements are easy. The ribbon cables are standard 10-pin, so off-the-shelf versions work fine. And since the module doesn’t draw power, there’s no risk of reverse polarity damage or voltage spikes. It’s about as low-maintenance as a Eurorack module can get.

That said, buyers should check two things before purchasing: first, confirm it’s a genuine ADDAC213B pair—some listings mislabel 213As as 213Bs, which are functionally different. Second, inspect the rear connectors. If the pins are bent or the solder joints look cold, walk away. While repairable, it’s not worth the hassle when new units are still in production. And if you’re eyeing a custom panel version, expect a premium—those don’t come up often, and the 4–6 week lead time means most owners keep them.

For long-term ownership, the 213B is a keeper. It doesn’t age, doesn’t drift, doesn’t need recalibration. It’s the kind of module you install once and forget—until you power down your case and realize, with mild panic, that half your patches don’t make sense anymore. That’s when you remember: the 213B was working in the dark the whole time.