ADDAC System ADDAC213A (2017–)
Two cases, one clean ribbon cable, and the tangle of patch cords between them is gone.
Overview
Cables pile up. They snake across the desk, get stepped on at gigs, and shake loose when you move a module. Two ADDAC213A modules fix part of that. A single ribbon cable runs between two cases and carries eight CV or audio signals with no patching. The ADDAC213A isn't flashy. It doesn't make sound. It doesn't sequence, filter, or modulate. It just links a second Eurorack case to the first.
ADDAC System designed it in Lisbon, and the 213A launched around 2017 as the first piece of their Eurorack Bridge system. It's a passive utility module with no power draw and no active circuitry. It sends and receives up to eight signals between cases over a single ribbon cable. You pair two 213As, one in each case, and connect them with the included 100cm cable. Need more channels? Add ADDAC213B modules to each 213A, for 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.
The module is 6 HP wide and only 2.4 cm deep, so it fits even a cramped skiff. The ribbon cable connector is on the back, which keeps the front panel clean. You can mount the module in either normal or 180-degree orientation, so it adapts to any case layout - top row, bottom row, angled build.
Specifications
| Manufacturer | ADDAC System |
| Production Years | 2017– |
| Original Price | €105 (pair) |
| Format | Eurorack |
| Width | 6 HP |
| Depth | 2.4 cm |
| Power Draw | Passive (no current draw) |
| Signal Channels | 8 CV/audio signals (per pair) |
| Expansion | Up to two ADDAC213B modules per ADDAC213A |
| Max Channels with Expansion | 24 |
| Ribbon Cable Length | 100 cm (standard), custom lengths available |
| Mounting Options | Normal or 180-degree orientation |
| Availability | Pre-built or DIY kit (€73, excl. VAT) |
| Weight | Approx. 100 g per module |
| Panel Color | Black (standard), custom colors available |
| Assembly | DIY kit includes full assembly guide |
Key Features
No Power, No Problem
The ADDAC213A needs no power. Most utility modules draw +12V and -12V, but this one loads nothing on your power supply. That helps 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 and passive. 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
The base pair handles eight signals. The ADDAC213B expansion modules add more. Each 213B adds another eight channels and connects directly to the back of the 213A. You can run one or two per 213A. Live performers and studio users with multiple cases can run one cable from a remote keyboard skiff to the main synth. Fewer patch cables also mean fewer accidental disconnects and fewer noise issues.
Skiff-Friendly and Reversible Mounting
At 2.4 cm deep, the 213A clears even the shallowest skiff designs. You can also mount it upside-down (180 degrees), which helps in cases where rear access is tight or cable strain might be an issue. The front panel is labeled with channel numbers and signal direction indicators, so there's no guessing which pin goes where.
Historical Context
When the ADDAC213A arrived, Eurorack was already deep into modular sprawl. Compact experimental systems had grown into multi-case rigs, often put together from different manufacturers, power supplies, and form factors. Inter-case connectivity wasn't a new problem, but most solutions were either janky (DIY breakout boxes) or overly complex (MIDI-to-CV bridges, digital multiplexers). ADDAC's approach was analog and pragmatic: use a standard ribbon cable, keep it passive, and make it modular-native. They weren't the first to try this, since 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 fits a broader trend in the modular world: utility modules. As synthesisers became more digital and patching more complex, demand grew for tools that simplified, organized, and optimized the physical experience. The 213A isn't a sound generator. It's a quality-of-life upgrade that makes the whole system feel more coherent. It doesn't show up much in demo videos.
Collectibility & Value
The ADDAC213A has never been rare, but it's consistently in demand. It cost €105 for a pair when new (plus shipping from Portugal). That'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 check for them 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. The standard panel is black.
The DIY kit costs €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. Unless you're on a tight budget or enjoy building, the pre-assembled version is worth the extra cost, since misaligned pins or cold solder joints can cause intermittent signal issues.
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