ADDAC System ADDAC213B (2017–)

A passive module that cuts down patch cable clutter with clean signal routing.

Overview

The ADDAC213B makes no sound. It isn't a sound generator or a processor, and it doesn't warp or modulate anything. It's a bridge, and a passive one. It goes after one of Eurorack's most persistent headaches: cable spaghetti. When a modular system sprawls across multiple cases, or sits deep inside a single 104HP skiff, patching a clock from the back row to a sequencer up front means a jungle of cables or nothing at all. The ADDAC213B fixes that with a ribbon cable and no flashy circuitry.

The ADDAC213B was born in the mid-2010s, when Eurorack was growing fast in size and complexity. It arrived as part of a larger ecosystem, the Eurorack Bridge system. The ADDAC213A handles inter-case communication with a single cable linking two full systems. The 213B is its expandable sidekick, and it works both standalone and as 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 you've got 24 channels bridging two cases. That kind of scalability was rare at the time, and most manufacturers stop at "one cable, eight signals."

It draws zero power. No +12V, no -12V, no 5V. It has passive headers on the back, a ribbon cable, and eight clean signal paths. You can install it in any case with any power setup, even the most power-starved skiff. Someone still has to wire the whole rig together, and the 213B does that job.

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 213B is silent. There's no power, no noise and no crosstalk, just eight 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 patch cable. That covers sending a modulation source from your lower row to a filter on the top, or looping a trigger into a sequencer three rows down. The modules 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.

Expandable Bridge Architecture

The 213B also works as an expansion to the ADDAC213A. The 213A pair gives you 8-channel inter-case bridging out of the box, and 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. That helps in large, multi-case systems where you're syncing sequencers, sharing audio, or distributing master clocks across multiple frames. Most bridge systems are fixed at 8 channels. ADDAC built in headroom, so users can grow their setup without replacing core infrastructure.

DIY-Friendly and Customizable

The 213B is available as a DIY kit for 61€ (excluding VAT), complete with a detailed assembly guide. The build is straightforward for a passive device: no soldering of ICs, no delicate op-amps, just headers, connectors, and mechanical assembly. That makes it a good intro to DIY for newcomers, and a cost-saving option for veterans. ADDAC also offers custom panel colors - red, green, blue, white, silver, bronze, even yellowed silver - with matching print colors.

Historical Context

The ADDAC213B 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. With that growth came complexity. Systems were no longer single 60HP cases. They were sprawling, multi-rack builds with dozens of modules, multiple power supplies, and tangled nests of patch cables. The industry responded with more oscillators and more filters, but few addressed the physical logistics of managing it all.

ADDAC is a Portuguese company with a knack for hybrid analog-digital design. 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 went the other way. It didn't compute. It didn't process. It just moved signals.

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. There are no components to degrade and no power rails to fry. The only real risk is physical: bent pins on the rear headers, or a damaged ribbon cable. 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.

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. It's repairable, but new units are still in production. A custom panel version costs a premium, and with a 4-6 week lead time, those don't come up often.

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.