ADDAC System ADDAC203 REV.02 (2023)

A compact dual-channel CV tamer that turns unruly voltages into precision tools—simple, essential, and built for real patching life.

Overview

The ADDAC203 REV.02 is a dual-channel CV processor that handles gain and offset in 6HP of Eurorack space. It isn't flashy. Control voltages can run wild coming off sequencers, sensors or errant LFOs, and this module keeps them in line. Patch it between a temperamental external controller and your VCO, or use it to scale a modulation source to just the right depth.

The ADDAC203 was originally introduced in 2010 and has been refined over time. This REV.02 is the most practical version yet. Some sources get the width wrong, so to be clear: ADDAC System's own product page lists the REV.02 as 6HP. The older ADDAC203 was 4HP, and this revision trades some panel density for added functionality. The extra space buys an offset CV input per channel, so you can modulate the offset itself instead of only setting it by hand. That turns a static utility into a dynamic one. A slow LFO on the offset can sweep a filter's cutoff across octaves, or morph between tuning ranges in real time.

Each channel has an input, an output, a gain attenuverter (it can reduce the signal or flip its polarity), and an offset knob that shifts the voltage range up or down between -5V and +5V. With no input patched, the offset control alone makes each channel a fixed voltage source, handy for tuning oscillators or biasing other modules. A rear-mounted jumper caps the maximum gain at either x1 (unity) or x10. DIY tinkerers can also modify resistor values for more customization, though most users will find the stock configuration more than sufficient.

Specifications

Manufacturer	ADDAC System
Production Years	2023
Original Price	100€ (assembled), 74€ (DIY kit, excl. VAT)
Format	Eurorack
Width	6HP
Depth	2.5 cm
Power Supply	±12V or ±15V compatible
Current Draw	40mA +12V, 40mA -12V
Bus Board Connector	8×2 IDC (Doepfer style)
Channels	2
Gain Control	Attenuverter with polarity inversion
Gain Range	Selectable max gain: x1 or x10 via back jumper
Offset Range	-5V to +5V
Offset CV Input	Yes, per channel
Input Voltage Range	±10V
Output Voltage Range	±10V
DIY Availability	Yes, full kit available
Custom Panel Options	Red, Green, Blue, White, Silver Gray, Yellow, Gold (custom order)

Key Features

Dual-Channel Flexibility with Real-Time Offset Modulation

Most dual attenuverters stop at gain control. The ADDAC203 REV.02 adds a CV input for the offset on each channel, so the voltage shift can be modulated instead of just set. Patch an LFO into the offset CV to glide a drone from sub-bass to soprano. Modulate the offset with an envelope to dynamically re-center a random voltage source. The module becomes an active part of the modulation matrix instead of a passive scaler. That matters most in generative or experimental setups where voltage landscapes shift over time.

Compact Design with Thoughtful Engineering

At 6HP, it's not the smallest module out there, but it packs in a lot for the space. The 2.5 cm depth fits shallow cases, which is a real concern for desktop or travel-friendly systems. It uses standard Doepfer-style power connectors, so no adapter cables are needed, and it works with ±12V/±15V supplies. The front panel is black with white labeling, and the knobs are sturdy, with clear detents for repeatable settings. There's no color coding or backlighting. It's a tool, not a spectacle.

DIY-Friendly with Room for Tinkerers

ADDAC System has always embraced the DIY ethos, and the ADDAC203 REV.02 keeps it up. The DIY kit costs 74€ (excl. VAT), and a detailed assembly guide is available online. The circuit is straightforward - op-amps, resistors, jacks - so even novice builders can complete it. The fun for tinkerers is the back jumper that sets gain scaling. Swapping resistors to alter gain curves or modifying the offset range is entirely feasible, and the documentation encourages experimentation. There are no obscure ICs and no surface-mount parts, which makes it a good first look at analog signal processing for educators or modular newcomers.

Historical Context

The ADDAC203 traces its roots to 2010, when ADDAC System was still finding its identity in the early wave of Eurorack expansion outside Germany. Utility modules were often afterthoughts then - cheap, bare-bones and functionally limited. ADDAC's original 203 stood out by offering dual channels with both attenuation and offset in a compact form. As modular synthesis matured and patches grew more complex, demand for precise CV manipulation increased. Modules like the Intellijel Quad VCA or Mutable Instruments Levels offered more features, but at higher cost and complexity. The REV.02 update, released in 2023, is a refinement and not a reinvention. It adds CV control where it mattered most, slims the footprint slightly, and improves build quality.

Competitors like the Make Noise Dual Offset & Attenuator or the ALM Busy Circuits SBG offer similar functionality, but often at higher price points or with less modularity. The ADDAC203 REV.02 sits between them on affordability, DIY access and expanded control. It's not a Swiss Army knife. It's a no-nonsense scalpel for voltage shaping. Some modules cost more than entire starter cases, and this one doesn't.

Collectibility & Value

As a 2023 module, the ADDAC203 REV.02 isn't "vintage" in the traditional sense, but it's already a staple in modern Eurorack builds. Its value lies in utility, not rarity. It rarely gets sold, since once you have one you tend to want a second. New units retail for 100€ (excl. VAT), with DIY kits at 74€, which makes it one of the more affordable dual-channel CV processors on the market. On the used market, expect to pay between €60 and €85 depending on condition and whether it includes the original packaging or custom panel.

Failures are rare. The most common issues stem from power connections, so check the IDC cable for bent pins before installation. The jacks are standard 3.5mm, durable but not gold-plated, so oxidation can occur in humid environments. The rear jumper for gain scaling is a small surface-mount solder point. If you're buying used, verify that it hasn't been tampered with unless you want a modified gain curve. Custom panels add collectible appeal, especially the gold or silver gray options, but they're primarily aesthetic. Functionally, all versions are identical.

For buyers, the biggest question is whether you need the CV-controllable offset. If you're just attenuating triggers or scaling static control voltages, a simpler (and cheaper) attenuverter might suffice. For complex modulation routing, live performance patching or experimental sound design, the REV.02's added flexibility is worth every euro.