ADDAC System ADDAC203 (2010–2023)

A Eurorack utility for taming and shaping control voltages.

Overview

The ADDAC203 CV Mapping module has no blinking lights and no presets stored in memory. It is knobs, jacks and analog circuitry, and it shapes control voltages. Originally released in 2010, it is a dual-channel offset and attenuverter that lets you compress, invert and shift CV signals. In a system where one out-of-range envelope can wreck a patch, a voltage wrangler like this is a good pair of pliers: nobody notices it until it's missing.

The module changed over time. The REV.02 update shrank it from 4HP to a more compact 6HP footprint, which is a odd way to say it got smaller, but the jacks were repositioned and a CV input for offset control was added. That revision also introduced a jumper on the back to cap gain at either unity (x1) or x10, so builders and tech-savvy users can tailor the response to their system. Each channel handles input, attenuation (with phase inversion) and offset. You can map erratic LFOs into usable pitch ranges, scale down gate voltages, or offset random voltages to sit in a desired octave. A sequencer output clipping a VCO's CV input is the classic case where you suddenly need one.

Specifications

Manufacturer	ADDAC System
Production Years	2010–2023
Original Price	100€ (assembled), 74€ (DIY kit)
Format	Eurorack
Width	6 HP (REV.02)
Depth	2.5 cm (REV.02), 3 cm (original)
Power Supply	±12V or ±15V compatible
Current Draw	40mA +12V, 40mA -12V (REV.02)
Bus Board Connector	8×2 IDC (Doepfer style)
Channels	2
Input Voltage	±10V
Output Voltage	±10V
Gain Control	Attenuverter with selectable max gain (x1 or x10 via back jumper)
Offset Range	-5V to +5V
Offset CV Input	Yes (REV.02)
Normalled Inputs	No
DIY Availability	Yes (full kit available)
Custom Panel Options	Yes (Red, Green, Blue, White, Silver Gray, Yellow, Gold)

Key Features

Dual-Channel Voltage Sculpting

The two channels on the ADDAC203 operate independently, so you get two separate CV paths. Signal flow is straightforward: input, gain (via attenuverter), then offset. The attenuverter doesn't only reduce signal amplitude. It can also flip the polarity, which you need to invert an envelope or reverse an LFO's sweep. That lets you do things like make a rising envelope close a filter instead of opening it. The offset knob shifts the whole signal up or down between -5V and +5V, handy for tuning a pitch CV to the right octave or biasing a modulation source into a desired range. With nothing patched in, the offset control alone generates a steady DC voltage, so each channel works as a simple offset generator.

CV-Controlled Offset (REV.02)

The REV.02 update added a CV input for the offset stage. Instead of a static offset, you can modulate the DC bias with another CV source, such as an LFO to slowly drift a pitch over time, or a sequencer to shift modulation depth step by step. To sweep a filter's cutoff across octaves with a slow sine wave, patch the LFO into the offset CV input and dial in the range with the offset knob. The addition also reflects ADDAC's responsiveness to user feedback, and it was a refinement based on how people actually use these modules in practice.

Gain Jumper and DIY Flexibility

On the back of the PCB, a small jumper sets the maximum gain to either x1 (unity) or x10. System builders can use it to fine-tune the module's behavior: x1 keeps things predictable for precise scaling, while x10 boosts weak signals or exaggerates modulation depth. More adventurous users can modify the gain by swapping resistors for custom calibration. ADDAC also offers a full DIY kit. The assembly guide is detailed and well-illustrated, which makes it accessible even to intermediate solderers. Custom front panels in colors like gold, red or silver gray are available too, which is rare for utility gear.

Historical Context

The ADDAC203 emerged during the early 2010s Eurorack renaissance, when modular synthesis was shifting from boutique curiosity to widespread adoption. Many manufacturers were focused on flashy sound generators or complex sequencers, but ADDAC System staked its claim in the utility space with modules that don't make sound. The 203 was part of their 200 Series, dedicated to analog CV utilities, and it filled a gap in voltage scaling and offsetting. Not all modules in a modular system speak the same voltage language. A sequencer might output 0-8V, but a VCO expects 1V/octave. An LFO might swing ±8V, but a filter only wants ±5V. Without proper mapping, you get unstable tuning, clipped modulation or unpredictable behavior. The ADDAC203 gave users a reliable dual-channel solution. It wasn't the only attenuverter on the market, but its clean layout, dual functionality and ADDAC's growing reputation for solid build quality made it a go-to choice.

Collectibility & Value

The ADDAC203 isn't a rare unicorn, but it's not generic either. Original 4HP versions from the early 2010s occasionally surface on the used market, but most collectors are focused on the REV.02, which is the definitive version. Prices for used REV.02 modules typically range from €80 to €120, depending on condition and whether it includes the original packaging or DIY kit materials. Assembled units in good working order hold their value well, especially with custom panels, which can add €20 - €30 in resale value. The DIY kit, originally €74, is still sought after by builders and often sells secondhand for similar prices, sometimes more if rare panel colors are included.

Failures are rare, but not unheard of. The most common issue is misaligned potentiometers. Early ADDAC modules, including the first 203s, had attenuverter knobs that felt "backwards" to some users (fully counter-clockwise = full signal). REV.02 didn't reverse the taper, but the updated layout and labeling make it less confusing. More serious issues usually come from incorrect power connection or DIY assembly errors, so always check the jumper setting and make sure the module is getting proper ±12V or ±15V. There's no firmware and there are no digital components, so once it's built right, it should last indefinitely. When buying used, test both channels for smooth pot response and verify that the offset CV input modulates cleanly. There are no LEDs or calibration routines to check.