ADDAC 702 Dual Voltage Controlled Filter (2015–)

A dual-filter Eurorack beast that doesn’t just shape sound—it growls, grinds, and rewrites the patch with its own analog attitude.

Overview

Plug in the ADDAC 702 and you’re not just adding a filter—you’re inviting a temperamental, gloriously unpredictable analog personality into your rack. It doesn’t whisper; it argues. One minute it’s sculpting a smooth, vactrol-softened sweep that melts into vintage warmth, the next it’s snarling through diode clipping with the kind of harmonic aggression that makes modular heads turn and mutter, “What the hell is that?” Built around two completely independent filters—a high-pass and a low-pass—this 16HP module doesn’t just offer flexibility, it demands interaction. You don’t dial in a sound so much as negotiate with it. And that’s exactly why it’s earned its cult status among Eurorack users who’ve grown tired of pristine, predictable filtering.

The 702 isn’t a clean room tool. It’s a garage experiment gone right. Inspired by the raw, unapologetic character of the Korg MS-20 filter, ADDAC didn’t just clone it—they rewired its brain. The high-pass and low-pass filters each have their own audio input and output, sure, but the real magic happens in the voltage-controlled mix path that lets you blend them dynamically. Want to sweep from a subby growl to a needle-sharp whistle with a single CV? Done. Want to invert the phase of the mix output and create hollow, phase-cancelled textures that seem to disappear into the walls? Also done. This is a module that doesn’t just respond to your patch—it suggests new ones.

And then there’s the dirt. Oh, the dirt. Each filter has its own post-filter distortion/fuzz circuit, which isn’t just an afterthought—it’s baked into the architecture. Flip the switch and your clean resonance spike turns into a sputtering, overdriven beast. It’s not digital grit; it’s analog saturation with weight, texture, and unpredictability. Crank it and the 702 doesn’t just distort—it fights back, adding layers of harmonic complexity that feel more like overdriving a tube amp than running a signal through a module. It’s the kind of character that makes you reach for it not because you need filtering, but because you need *character*.

Specifications

Key Features

The Dual-Filter Duality: HP, LP, and Everything Between

Most dual-filter modules offer symmetry—two of the same thing, maybe with a little cross-modulation. The 702 laughs at symmetry. It gives you a high-pass and a low-pass filter, each fully independent, each with its own personality. You can run them in parallel for complex spectral shaping, stack them in series to create a resonant band-pass effect, or engage the coupling switch—inspired by the rare Oscar synthesizer—that ties the low-pass cutoff to the high-pass, using the LP knob as an offset. This isn’t just a technical feature; it’s a compositional tool. It lets you create moving band-pass zones that shift in width and center frequency with a single control, perfect for evolving pads or rhythmic sweeps that feel organic rather than sequenced.

But the real innovation is the voltage-controlled mix output. Instead of just summing the two filters externally, the 702 blends them internally with a CV-controllable fader. This means you can automate the balance between the high and low ends of your sound in real time—say, morphing from a subby drone to a glassy harmonic sheen with an LFO or envelope. It’s a level of integration that feels more like a miniature mixing console than a filter module.

Resonance with Bite: Clipping Paths and Character

Turn up the resonance on most filters and you get a smooth sine wave howl. Turn it up on the 702 and you get a choice: clean feedback, diode clipping, or LED saturation. That three-position switch on the front panel isn’t just for show—it radically alters the character of the resonance peak. In “no clipping” mode, it behaves like a classic analog filter, resonant but controlled. Flip it to “diodes” and the peak distorts early, adding a gritty, aggressive edge that’s perfect for industrial textures or overdriven leads. Switch to “LEDs” and you get a softer, more rounded clipping—still saturated, but with a vintage warmth reminiscent of old synth circuits pushing their limits.

This isn’t just about distortion for distortion’s sake. It’s about giving the filter its own voice. In a system full of clean VCFs, the 702 stands out because it *ages* like analog gear—warm, slightly unpredictable, and full of character. The resonance clipping interacts with the post-filter fuzz circuit, creating cascading layers of saturation that can turn a simple sine wave into a roaring, harmonically rich monster.

Phase, Fuzz, and the Art of Controlled Chaos

The 702 doesn’t just filter—it transforms. Each of the three audio outputs (HP, LP, Mix) has a phase inversion switch, letting you flip the polarity on the fly. This isn’t just useful for live mixing; it opens up wild possibilities for phase cancellation when routing multiple outputs to a mixer. Send both HP and LP to separate channels, invert one, and suddenly your full-range sound develops a hollow, metallic center that feels like it’s being eaten from the inside. Combine that with the mix output and you’ve got a three-way spectral war happening in real time.

And then there’s the fuzz. Each filter has its own post-filter distortion stage, which can be engaged independently. This means you can fuzz the high end while keeping the low end clean, or vice versa. It’s not a subtle effect—it’s in-your-face, with a gnarly, almost speaker-rattling aggression when pushed. But it’s also musical. The distortion doesn’t obliterate the source; it enhances it, adding upper harmonics that make pads shimmer and drums punch through a mix. It’s the kind of circuit that makes you reach for sources you’d normally avoid filtering—noise, FM, even vocals—just to hear what the 702 will do to them.

Historical Context

The ADDAC 702 arrived in 2015, right when Eurorack was shifting from boutique curiosity to mainstream modular dominance. At the time, many new modules were chasing digital precision, clean signal paths, and sterile usability. The 702 was a middle finger to that trend. It didn’t pretend to be transparent. It didn’t hide its quirks. Instead, it leaned into the analog ethos—imperfection, unpredictability, and character. By drawing inspiration from the Korg MS-20, a synth legendary for its raw, unfiltered sound, ADDAC positioned the 702 as a tool for sonic rebellion.

It also arrived alongside a wave of “vintage-inspired” modules that used DSP to simulate analog warmth. The 702 stood apart because it didn’t simulate—it *was*. Built with discrete analog circuitry, it didn’t rely on algorithms to create grit. The distortion came from real diodes and LEDs, the filtering from real capacitors and transistors. In a world increasingly dominated by digital emulations, the 702 was a reminder that analog isn’t just a sound—it’s a behavior.

Competitors like the Doepfer MS-20 filter clones offered similar inspiration, but the 702 differentiated itself with its dual-filter topology and integrated mix path. It wasn’t just a filter—it was a mini-synth processor, capable of reshaping entire patches in ways that required multiple modules elsewhere. It shared DNA with the Make Noise QPAS or the Intellijel Metropolis, but with a rawness those modules often polished away.

Collectibility & Value

The ADDAC 702 has never been a budget module, and it hasn’t gotten cheaper. New units still list around €385–$405 direct from ADDAC, and custom-colored panels add a premium with a 4–6 week lead time. On the used market, prices vary widely based on condition and panel color. Standard black panels typically sell for €250–€320 in good condition, while rare custom colors (like bronze or silver gray) can fetch €350 or more from collectors who value the aesthetic as much as the audio.

But here’s the catch: the 702 is not a plug-and-play relic. It’s a living, breathing analog circuit, and like any such device, it can develop issues. The most common failure points are the toggle switches—especially the resonance clipping and phase inversion switches—which can become scratchy or intermittent with heavy use. The potentiometers, while high-quality, can also degrade over time, particularly if the module is frequently adjusted in a live setting. The distortion circuits, while robust, draw significant current and can stress power supplies if the bus board isn’t properly regulated.

Owners report that the module is generally reliable, but it rewards maintenance. Cleaning the switches and pots every few years keeps it running smoothly. The LEDs, while useful for monitoring output levels, are not critical to function and can be replaced if they fail. There are no known design flaws that make the 702 prone to catastrophic failure—no capacitors known to leak, no ICs that routinely die—but it’s not indestructible. Keep it in a well-ventilated case, avoid overloading the inputs, and it should last for decades.

For buyers, the key is to test every switch and pot before purchasing. Ask for a demo video showing the mix CV in action, the resonance sweep with and without clipping, and the phase inversion on all three outputs. If the seller can’t provide that, walk away. The 702 is too nuanced to buy blind. And while it’s tempting to go for a rare panel color, remember: the sound doesn’t change. The black panel sounds just as ferocious as the bronze.

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