ADDAC System 805 (2018–present)

A tiny 4HP crossfader, and an updated 8HP module that shares its name and does a lot more.

Overview

You might pick up the ADDAC805 thinking you're getting a simple voltage-controlled crossfader for your Eurorack rig, and technically, you are—but which 805 you're holding changes everything. There are two distinct modules here masquerading under the same model number, and confusing them could mean the difference between a neat utility and a centerpiece of your patching workflow. The original ADDAC805 is a compact 4HP module designed purely as a dual-channel VC panner or crossfader, clean and minimal. But the version that collectors and seasoned modular users actually talk about—the one that shows up in deep-dive demos and gets modded on forums—is the ADDAC805.VS2, an evolved 8HP stereo signal router that turns crossfading into a compositional tool. It’s not just a mixer; it’s a dynamic routing matrix for audio and CV, capable of morphing between four sources in real time, acting as a stereo VCA, or even a six-channel mono summing hub. If the 4HP version is a pocket knife, the VS2 is a modular workshop in a panel.

The VS2 borrows from the waveform mixing section of the ADDAC701 VCO, then pushes the idea further. It has two independent X-faders, each with a manual control, CV input, and attenuverter. You blend two pairs of signals, say two oscillators on the left and two noise sources on the right. Then you route those outputs through a master stereo VCA that doubles as a third crossfader. Use the master channel to crossfade between the left and right outputs and you have a four-quadrant mixer. Patch four LFOs into the inputs, modulate the X-faders with sequencers, and you are evolving textures in stereo space instead of just switching waveforms. The module handles audio and CV equally well, so you can crossfade modulation sources as easily as sound sources. That makes it a favorite for generative patches and evolving drones.

It is fully analog, with high-quality VCAs that keep noise low and signal integrity high. That matters when you route delicate CV or quiet audio through multiple stages. The build is solid, and the nutless jacks give the panel an uninterrupted look. The included signal flow diagram is a patching roadmap as well as documentation. The labeling is small, almost shy.

Specifications

Key Features

Three X-Faders, One Sonic Chameleon

The core of the 805.VS2 is its three voltage-controlled crossfaders: two dedicated channels and a master stereo VCA that can be repurposed as a third. That is layered control, not redundancy. You can set the left and right channels to blend two pairs of signals independently, then use the master to crossfade between those blended outputs. That gives you four-quadrant mixing: four sources, any-to-any crossfading, all in stereo. You could morph from a sine wave on the far left to a square wave on the far right while a triangle and sawtooth orbit around them. Patch them in, assign CVs, and let the module handle the transitions. The exponential response of the VCAs gives smooth, musical sweeps. Early units showed slight channel imbalance, though, and some owners modded their modules with matched capacitors for tighter tracking.

More Than a Mixer: A Routing Brain

The 805.VS2 works best as a dynamic router. You can send signals directly to the outputs or through the master VCA, which opens up parallel and serial signal paths within a single module. For example, send a dry signal straight to the output while routing a wet, effected version through the master for real-time dry/wet blending. Or use the direct stereo inputs to bring in external audio and modulate its presence in the mix via CV. The mono sum output combines left and right into a single channel. That makes the module an unconventional six-input mono mixer, handy for summing modulation sources or collapsing a stereo field into a control voltage for further manipulation.

DIY-Friendly Design with Real Engineering

ADDAC offered the 805.VS2 as a DIY kit. The included assembly guide and signal flow diagram are detailed enough that intermediate builders can learn from the process. The SMD-Kit-2 includes both surface-mount and through-hole components. The module is also DC-coupled, so it handles control voltages as cleanly as audio. That lets it work in both modulation and sound-shaping roles.

Historical Context

The ADDAC805.VS2 emerged in 2018 as part of a shift in Eurorack toward the "multi-role utility." Users wanted modules that did more than one thing well, with analog integrity. The VS2 offered the flexibility of digital routing with the warmth and immediacy of analog VCAs. It arrived alongside similar innovations from MakeNoise, Mutable Instruments, and Intellijel, but it focused on crossfading, a function often treated as an afterthought in modular systems. ADDAC made it the centerpiece, which suited a growing interest in morphing, evolving textures and stereo spatialization, particularly in ambient, experimental, and generative music. The original 4HP 805 was a simpler response to demand for compact, affordable VC panners, a role many other manufacturers filled.

Collectibility & Value

The ADDAC805's collectibility depends entirely on which version you mean. The original 4HP model, priced at just 80€, is a budget option for basic VC panning. It is not rare, not sought after, and doesn't command a premium. The 805.VS2 is a different story. At 170€ new, it is not cheap for a utility module, but its versatility justifies the cost for many users. On the secondhand market, used VS2 units typically sell between €120 and €160, depending on condition and whether they include the original packaging or documentation. The DIY kit version, priced at 129€ (excl. VAT), is popular among builders and often sells out quickly through distributors like Exploding Shed.

One known issue affects early production runs of the VS2: inconsistent gain response between the left and right X-fader channels. Some units have a steeper slope on the right side, which gives uneven crossfading. ADDAC acknowledged the issue and provided a fix for affected users, which means replacing specific capacitors. Test for it when buying used. Owners report that the problem doesn't cause distortion or damage, but it can undermine precise stereo imaging. Check for balanced output levels when testing. Beyond that, the module has no widespread failure points. The nutless jacks are durable, and field reports show no signs of common cold solder joints or power-related damage on the PCB.

If you are considering a purchase, pick the VS2 over the original 4HP model unless space is at an absolute premium. The extra 4HP buys you exponential flexibility. Verify which version you are buying, since some listings blur the distinction, and the VS2's full capabilities aren't obvious from photos alone.

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