ADDAC System 203 (2010–Present)

A quiet workhorse in black FR4, the 203 slips into your rack like a utility knife - unassuming and always sharp when you need it.

Overview

You don’t buy the ADDAC System 203 for glamour. You buy it because at 3 a.m., halfway through a patch that’s spiraling into chaos, you realize your LFO is screaming at +8V when your filter cutoff only wants a gentle nudge of +2V, and you don’t have time to rebuild the whole thing. That’s when the 203 earns its keep. It’s not a sound generator, not a modulator with character—this is voltage plumbing. Dual channels of offset and attenuversion, each with its own input, output, gain knob, and offset knob, all packed into a svelte 6 HP. The front panel is stark black FR4, no flashy graphics, just clean white silkscreen telling you exactly what does what. It looks like a module that knows its job and intends to do it without fuss.

The gain section is an attenuverter. You can scale a CV down or flip its polarity entirely, which is what you need when you want a rising envelope to close a filter instead of open it. After that, the offset stage slides the whole signal up or down by ±5V. That sounds modest until you need to shift a bipolar LFO into unipolar territory to modulate something that only accepts positive voltages. There are no CV inputs on the first rev, but the Rev.02 adds an offset CV input, which allows dynamic remapping on the fly. Patch an envelope into it and your pitch CV can drift higher as your sequence progresses. Or use it to change how much an inverted envelope affects your panner.

First introduced around 2010 as one of ADDAC's earliest Eurorack modules, the 203 has stuck around because it never needed reinventing. The circuit is straightforward analog utility: passive scaling, active offset, solid op-amp buffering. It draws a modest 40mA on both +12V and -12V rails, fits in shallow skiffs at just 25mm deep, and uses a standard Doepfer-style power cable. No exotic chips, no firmware, no hidden modes.

Specifications

Manufacturer	ADDAC System
Production Years	2010–Present
Original Price	€97 (kit), ~$163 (assembled)
Format	Eurorack
Width	6 HP
Depth	25 mm
Power Supply	±12V
Current Draw +12V	40 mA
Current Draw -12V	40 mA
Bus Board Cable	8×2 IDC (Doepfer style)
Channels	2
CV Input Range	±10V
CV Output Range	±10V
Attenuverter Range	0 to ±10V (adjustable via jumper to x1 or x10 max gain)
Offset Range	±5V
Offset CV Input	Yes (Rev.02)
Panel Material	Black FR4
Assembly Option	DIY kit (SMD pre-soldered)

Key Features

Dual-Channel Voltage Taming

Each of the two channels on the ADDAC203 is a complete CV scaler and shifter. The signal enters, hits the attenuverter, which can reduce amplitude or flip polarity, then passes through the offset stage, where a knob adds a fixed DC voltage between -5V and +5V. That repositions whole control voltages into usable ranges. A slow LFO that swings from -5V to +5V can be offset to 0V to +10V, which suits a VCA that expects unipolar CV. Or you can knock a +10V envelope down to +3V to nudge a filter without slamming it open. With two channels you can handle two signals at once, say scaling a random voltage for pitch while offsetting an envelope for amplitude. There's no normalization between channels, so they stay independent.

Offset CV Input (Rev.02)

The original 203 was purely manual - set your offset and leave it. The Rev.02 upgrade added a CV input for the offset stage, which turns the module from a static scaler into a dynamic mapper. Instead of a fixed offset, you can modulate the offset itself. Patch an envelope into the CV input and your LFO's center point rises over time. Feed in a sequencer step and each note's modulation baseline shifts. That makes the 203 a kind of "CV transformer," able to produce evolving control voltage behavior without a microprocessor or patch memory.

DIY-Friendly Build

ADDAC released the 203 as a DIY kit. All surface-mount components come pre-soldered. Users only need to attach through-hole parts like jacks, pots, and the power cable. The build is rated "easy/medium," so intermediate builders can handle it. The FR4 panel doubles as the circuit board, a space-saving and cost-effective design common in early Eurorack but now rare. Documentation is clear, and the simple circuit means fewer points of failure during assembly. There's also a jumper to set the maximum gain to either x1 (unity) or x10, so you can pick subtle scaling or extreme attenuation/inversion.

Historical Context

When ADDAC System launched the 203 around 2010, Eurorack was still a niche within a niche. The format had escaped its boutique origins but hadn't yet become the crowded, trend-driven market it is today. Modules were simpler, often designed by engineers for engineers, and utility functions like voltage scaling were frequently left to the user to patch together with op-amps or repurpose from other modules. ADDAC, founded in 2009 with a focus on bridging analog and digital synthesis, saw a gap for a dedicated, reliable module for CV manipulation. The 203 wasn't revolutionary. It echoed functions found in Doepfer's A-183 or Intellijel's uScale. But it was a clean, compact, and affordable solution at a time when such tools weren't standardized. Its release coincided with a growing demand for "patch essentials," as more musicians moved from desktop synths to modular systems and needed infrastructure to keep their patches coherent. It became a staple in early ADDAC adopters' racks. Later, as ADDAC expanded into more complex modules like the Vintage Clip and Vintage Pre, the 203 stayed in the lineup.

Collectibility & Value

The ADDAC203 isn't a collector's item in the traditional sense. It doesn't appreciate, it has no rare revisions with mythical sound qualities, and you won't find people hunting for "NOS" units on forums. New assembled units sell for around $160 - $180, while the DIY kit goes for about €97. Used prices hover between $80 and $120, depending on condition and whether it's assembled. It's a passive utility module with no moving parts beyond the pots, so failure points are minimal. The most common issues are dirty or scratchy potentiometers, which can usually be cleaned with contact cleaner, or cold solder joints on the power cable, especially in user-assembled kits. The FR4 panel is durable but can crack if over-tightened, so check the mounting screws when buying used. The circuit is so simple that repairs are straightforward for anyone with basic soldering skills. There's no obsolescence risk, with no chips to go out of production and no firmware to update. A working 203 from 2012 will perform exactly like a new one, so it's not worth chasing "new old stock" or paying a premium for early versions. For a skiff or a travel system, the 25mm depth and 6 HP width make it easy to fit.