ADDAC System ADDAC204 (2023–)
A quiet powerhouse for sculpting control voltages with voltage-controlled precision—this is the module that makes your CV do backflips on command.
Overview
You don't plug audio into the ADDAC204 and expect fireworks. It isn't a filter, oscillator, or distortion box. It lives in the background of a patch. It's a voltage-controlled CV mapper, and the work happens behind the scenes: turning a slow LFO into a snappy gate, warping an envelope into a wobbly pitch source, or morphing one control signal into a mirrored, inverted, or blended version of itself. All of it happens in real time, with CV control over the transformation.
At first glance the ADDAC204 looks simple. It's a red 6HP Eurorack module with a handful of knobs, three outputs, and a clean layout. But it doesn't just scale and offset CV like a basic attenuverter. It has voltage control over the offset, which means you can modulate the entire operating range of a control voltage on the fly. Want to sweep a filter's cutoff from sub-bass to ultrasonic using a single LFO, but have the center point drift up and down with another envelope? The ADDAC204 can do that. Need to morph between a normal CV signal and its inverted counterpart using a sequencer? It does that too.
It slots into the ADDAC200 series, modules focused on analog CV utilities, and it's a direct evolution of the ADDAC203 CV Mapping module. The upgrade is voltage control over the offset parameter. In practice that turns the module from a static utility into a dynamic modulation engine. It lacks audio-rate performance, so don't expect clean waveshaping here. What it does well is generate complex, evolving control signals that make other modules downstream behave in ways they weren't designed for.
Specifications
| Manufacturer | ADDAC System |
| Production Years | 2023– |
| Original Price | 190.00 € |
| Format | Eurorack |
| Width | 6 HP |
| Depth | 2 cm |
| Power Supply | ±12V or ±15V |
| Current Draw | 40mA |
| Bus Board Connector | 8×2 IDC (Doepfer style) |
| CV Input Range | ±10V |
| CV Output Range | ±10V |
| Inputs | CV Input (with attenuator), Offset CV Input (with attenuator) |
| Outputs | Normal, Inverted, Morphed |
| Controls | Input attenuator knob, Offset CV attenuator knob, Morph knob |
| Custom Panel Options | Black, Green, Blue, White, Silver Gray, Yellowed Silver, Dark Bronze, Light Bronze |
| Print Color Options | Black, White, Red, Yellow, Blue, Green |
Key Features
Voltage-Controlled Offset: The Game Changer
The defining feature is voltage control over the offset. Most modules let you set an offset by hand, but here you can modulate that offset with another CV source. For example, you could use an envelope to shift the entire range of a sequencer's output over time, so each pass through the sequence starts at a higher or lower voltage. Or use an LFO to make a filter's modulation depth drift cyclically. The offset CV input has its own attenuator, so you're not stuck with full modulation swings. You can dial in subtle nudges or wild sweeps.
Three-Output Morphing Architecture
There are three outputs: normal, inverted, and morphed. The normal output gives you the processed CV signal, scaled and offset. The inverted output flips it 180 degrees, turning positive voltages negative and vice versa. The morph output blends between the normal and inverted signals based on the position of the morph knob. That knob can be overridden with a CV input (though the input itself isn't voltage-controlled), so you can sweep through the blend by hand or with a gate, sequencer, or envelope. That's handy for dynamic inversions, like flipping the direction of a modulation on every other beat, or gradually inverting an LFO to reverse its effect over time.
Compact Utility with No Compromises
At 6HP, the ADDAC204 doesn't take much space, and its 2cm depth fits even the shallowest skiffs. The design is plain: no LEDs, no extra switches, no digital trickery, just analog signal processing. The build quality is consistent with ADDAC's reputation: sturdy PCB, reliable jacks, and a front panel that feels solid. The lack of audio-rate performance keeps it focused on its intended role.
Historical Context
The ADDAC204 arrived in 2023. Early modular systems treated CV processing as a secondary concern, handled by mixers, attenuators, and inverters. Modern Eurorack asks for more, and as patches grow more complex, dynamic CV manipulation has become critical. The ADDAC204 sits alongside modules like the Intellijel Lin/Exp converter, the Mutable Instruments Shades, and the ALM Busy Circuits STM-003. Those modules often focus on signal distribution or shaping, while the ADDAC204 specializes in transformation, changing not just the level of a CV but its behavior.
ADDAC System, based in Lisbon, has built a reputation for thoughtful, musician-first design, often drawing inspiration from vintage gear without relying on nostalgia. The 200 series reflects a philosophy of "analog intelligence": using simple circuits to achieve complex results. The ADDAC204 needs no microcontrollers or firmware updates. It does its job with op-amps and resistors, which makes it as future-proof as any analog circuit can be.
Collectibility & Value
As of 2026, the ADDAC204 is still in production and available from ADDAC's website and authorized dealers, at a price of €190 (excluding VAT). It hasn't entered the vintage market, so there's no secondhand premium or scarcity to speak of. Its utility and build quality suggest it will hold value well among modular enthusiasts who prioritize function over flash. It contains no rare components or complex firmware, so it's unlikely to become a "holy grail" module, but it's also not the kind of piece that will be discarded or replaced quickly.
Failures are rare. The most common issues would stem from the power connector or input/output jacks, which are standard wear points for any Eurorack module. No design flaws or batch issues have been reported in user communities. The only maintenance consideration is the custom front panel option: custom colors require a 4-6 week lead time and are made to order, so replacements won't be readily available. For buyers, the main advice is to verify the module powers up correctly and that all knobs and jacks function smoothly. There's little else that can go wrong.
The ADDAC204 is a strong candidate for a compact or travel-friendly system. It's not a must-have for everyone, but patchers who rely on evolving, generative sequences or complex modulation routing will get the most from it. Its value isn't in rarity or resale potential.
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