ADDAC 702 VCF (2015–)

A dual-filter module that snarls like a rewired MS-20 and works in stereo.

Overview

Flip the switch and the ADDAC 702 wakes up with a guttural hum. It isn't clean and it isn't polite. It's two filters in one module, one high-pass and one low-pass, each with its own distortion circuit that can turn a sine wave into a chain-saw buzz with a flick of a toggle. It takes up 16HP of Eurorack space. Born in 2015 as ADDAC's first foray into voltage-controlled filtering, the 702 wears its Korg MS-20 inspiration openly, but it's not a clone. It's a reimagining, built for the modern modular world, where patching is everything and subtlety is optional.

What sets the 702 apart is how the two filters talk to each other. You can run them completely independent, processing two separate signals. Or stack them in series, high-pass feeding into low-pass, for a classic band-pass sweep that carves out vocal-like formants or tightens up a muddy drone. There's also a coupling mode inspired by the obscure Oscar synthesizer, where the low-pass cutoff tracks the high-pass with an offset. That lets you sweep a resonant window across the spectrum with a single control. For stereo processing, the voltage-controlled mix output blends the HP and LP outputs dynamically, so a single CV morphs both space and tone.

Then there's the dirt. Both filters have their own post-filter distortion stage, switchable between clean, diode clipping, and LED clipping, so the grit comes after the filtering. Run a resonant sweep into it and it doesn't just get louder. It tears and growls. The distortion isn't an afterthought; it sits in the signal path. Add the phase inversion switches on each output and you can cancel some parts of the sound and reinforce others, building textures that shift around. It rewards deep patching, and it can turn a simple oscillator into something unrecognizable.

Specifications

Key Features

A Dual-Channel Mindset

Most filter modules give you one flavor and expect you to work with it. The 702 has two. The high-pass and low-pass aren't mirror images; they work as partners. You can route a kick through the LP and a hi-hat through the HP, then sweep both with linked CVs for a dynamic filter gate effect. Or feed a single drone into both and use the mix control to crossfade between spectral extremes. The architecture assumes you'll patch creatively rather than just insert it into a signal chain. The CV inputs are separate for each filter, each with its own attenuverter. It's a filter system, and it wants to sit at the center of your patches.

Resonance with a Bite

Turn up the resonance and the 702 doesn't just whistle. It bites back. The resonance circuit is modeled after the MS-20's famously aggressive filter, but ADDAC added a three-position switch that changes how the resonance clips. In "diodes" mode it's warm and snarling, like a tube amp pushed into breakup. "LEDs" adds a sharper, more chaotic edge, good for industrial textures. "None" gives clean resonance for when you want precision. The switch changes the behavior of the filter under high resonance, so resonance works as a timbral tool and not just a parameter. Resonance is also voltage-controllable, so with some clever logic patched in you can modulate not just how much resonance you get, but what kind.

Smoother Than It Looks

A tiny switch on the panel is labeled "Smooth," and it's one of the 702's secret weapons. Engage it and the cutoff control takes on a soft, vactrol-like glide that smooths out stepped CVs and turns sharp envelopes into slow sweeps. It's not a dedicated slew generator. It's part of the filter's response, so it feels organic rather than processed. It helps with sequencers or digital LFOs that sound too precise, since the Smooth circuit puts back a bit of analog slop. That lets the 702 sit comfortably in patches that mix digital and analog sources.

Historical Context

The ADDAC 702 arrived in 2015, right when Eurorack was shifting from boutique curiosity to mainstream staple. Modules were getting smarter and more complex, but a lot of them were also getting cleaner, more digital and more precise. Against that backdrop, the 702 was raw and unpredictable. It tapped into the same nostalgia that fueled the MS-20 reissues and Behringer's clones, but it built on the past instead of rehashing it. The MS-20 filter was legendary for its aggression, but it was also limited: single filter, no CV control over resonance, no stereo operation. The 702 kept the attitude and added full voltage control, a patchable topology, and a dual-channel design.

It also arrived when modular users were starting to treat effects and processors as instruments in their own right, not just add-ons. The 702 wasn't for cleaning up signals. It was for mangling them, turning simple waveforms into evolving soundscapes. Competitors like the Mutable Ripples or Intellijel Morgasmatron offered more polished, refined filtering, but they didn't have the 702's punk-rock edge. This was a module for people who wanted their synths to sound like they'd been dragged through a junkyard and lit on fire. It also fit with ADDAC's reputation for bold, expressive design, as seen in the 604 Quad LFO and the 712 Vintage Pre.

Collectibility & Value

The ADDAC 702 has never been rare. ADDAC kept production steady, and it's still available new. It has become a cult favorite, the kind of module that shows up in high-end racks and DIY skiffs alike. On the used market, prices hover between €250 and €320 depending on condition and whether it's the original silver panel or one of the limited dark or custom-colored versions. The dark panel variant, with its black finish and red accents, tends to fetch a slight premium, not because it sounds different, but because it looks like it belongs in a horror movie synth lab.

Condition is key. These units are generally sturdy, with no delicate pots and no flaky jacks, but the toggle switches, especially the phase and distortion toggles, can get noisy over time if not cleaned. The LEDs are also known to dim or fail after years of use, though that's more cosmetic than functional. The biggest red flag is any sign of overvoltage damage. The 702 draws a fair bit of current, and if a user plugged it into a poorly regulated power supply, the filter cores can get fried. There's no user-serviceable repair for that, only a full board replacement. So when buying used, ask for a demo video showing all modes, all outputs, and both filters under a resonance sweep.

Maintenance is relatively straightforward. The distortion circuits are passive, just diodes and LEDs, so they're unlikely to fail. The vactrols in the smooth circuit can degrade over decades, but it hasn't come to that yet, and most units from 2015 are still behaving. Recapping isn't a common need, but if you're restoring one that's been in a hot rack for years, fresh electrolytics won't hurt. The real cost isn't in repair. At nearly 16HP, the 702 isn't small, and in a crowded system that's a trade-off.

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