ADDAC System 705 Stinggy Filter (2010s)

A jagged little filter that bites back when you push it. It's the Wasp filter's feral cousin.

Overview

Plug in a clean sine wave, turn up the resonance, and within seconds the module is arguing with you. The ADDAC 705 Stinggy Filter is a compact Eurorack multimode filter, born in the early 2010s, when Eurorack was shedding its niche skin and charging into the mainstream. It wasn't built as a polite utility. It has the DNA of the EMS Wasp synth's famously raw filter, stretched, distorted, and stuffed into 8HP of 3U real estate. It doesn't smooth edges. It gnaws on them.

The 705 leans into imperfection. A state-variable filter (SVF) from Make Noise or Intellijel is surgical. The Stinggy Filter keeps its quirks. The resonance warbles, howls, and sometimes seems to modulate itself when pushed into self-oscillation. That's the point. Owners report that at high Q settings the filter develops a kind of "juicy warble," a harmonic instability that feels alive and almost unpredictable. Add the onboard distortion circuit and the whole thing starts to fray.

Despite its compact size, the 705 has four independent filter outputs - low-pass, band-pass, notch, and high-pass - each with its own dedicated jack. That makes it a routing powerhouse, since you can split and process different frequency bands in parallel. The main output has a four-position switch that selects the final filter type, plus a dedicated distortion/fuzz circuit that adds harmonic grit. The distortion is baked into the signal path, not slapped on at the end. It can be subtle, adding warmth and presence, or cranked into full-on fuzz, turning even a simple sequence into something that sounds like it's being eaten by a robot.

Then there's the clipping circuit. One switch chooses between no clipping and diode clipping for the resonance path, and another sets resonance depth (high or low). These change how the filter behaves under pressure. With diode clipping engaged, the resonance gets a snarling edge, good for industrial textures or aggressive leads. Without it, the filter cleans up slightly, though "clean" is relative here. This module still prefers drama over diplomacy.

It's not a filter for every patch. If you want transparent filtering, silky sweeps, or precise frequency sculpting, look elsewhere. If you want a filter that *performs* - one that reacts, bites, and surprises - the 705 fits. Simply inserting it and twisting a few knobs can make you rethink patches you thought were finished. Many owners describe it as "versatile," because of its character and not despite it.

Specifications

Key Features

The Wasp Filter Reimagined

The EMS Wasp synth's filter, designed in the late 1970s, was never known for neutrality. It was raw, aggressive, and prone to self-oscillation, which made it beloved by experimental musicians and despised by purists. ADDAC didn't just clone it. They amplified its personality. The 705 keeps the Wasp's core topology but adds voltage control over cutoff (with attenuverter), which makes it far more flexible in a modern Eurorack context. The original Wasp filter required external circuitry to reach self-oscillation. The 705 gets there on its own, turning into a shrieking oscillator when resonance is maxed. It's a sound source in its own right, capable of unstable, organic tones.

Distortion as a Design Philosophy

Most filters treat distortion as an afterthought, an overdrive circuit tacked onto the output. The 705 treats it as a core feature. The distortion/fuzz on the main output isn't a separate effect. It's part of the filter's voice. When engaged, it interacts dynamically with the resonance and input gain, creating harmonics that feed back into the filtering process. The distortion colors the input, which then gets filtered, which then distorts again. The sound evolves as you tweak it and never quite settles. Service technicians observe that the distortion circuit uses silicon diodes and op-amp overdrive stages, allowing for multiple flavors of saturation, from soft clipping to full-on fuzz, depending on input level and distortion knob position.

Four Outputs, One Identity

Independent outputs for each filter type open up complex patching. You can send the low-pass to a reverb, the band-pass to a delay, and the high-pass to a compressor, all from a single source. This kind of parallel processing was rare in 8HP modules at the time. The main output, selected via a 4-position switch, acts as the "final mix" of the filter, complete with distortion and phase inversion. The phase switch is subtle, but it can be crucial when layering multiple filters or syncing with external gear. Sometimes flipping polarity is all it takes to make a patch click.

Historical Context

The 705 arrived during Eurorack's explosive growth phase, when the format was shifting from DIY curiosity to professional studio tool. Many manufacturers leaned toward refinement: clean designs, precise tracking, transparent sound. ADDAC went the opposite direction. The 705 wasn't trying to be the most accurate filter. It was trying to be the most *interesting*. It shared shelf space with modules like the Mutable Instruments Ripples and the Make Noise QPAS, both of which offered smoother, more controllable filtering. The 705 stood out by embracing its roots in the lo-fi, punk ethos of the EMS Wasp, a synth that was itself a product of economic constraint and creative necessity.

At the time, there was a quiet rebellion against the idea that analog meant "warm" or "smooth." Modules like the 705, the Intellijel Diode Filter, and the Tiptop Audio Z4000 Filter Frenzy went for the gnarly, the unstable, and the unpredictable. The 705 offered a kind of controlled chaos in a market increasingly dominated by digital precision. It also reflected ADDAC's broader approach: hybrid instruments that blurred the line between analog and digital, between utility and expression.

Collectibility & Value

The ADDAC 705 Stinggy Filter has a quiet but devoted following. It's not a "hype" module, but it's not obscure either. On the used market, assembled units typically sell between $180 and $250, depending on condition. Units described as "excellent" with original packaging and accessories can fetch the higher end, while those with cosmetic wear ("mild rack rash") or untested status dip closer to $160. The DIY kit, originally priced at €119, occasionally appears on eBay or Reverb for $100-$140, though many buyers prefer the assembled version because of the module's SMD components.

Reliability is one of the 705's strengths. Documentation shows a straightforward analog design with no known systemic failures. Some vintage filters suffer from capacitor drift or op-amp degradation, but service technicians report few issues with the 705 beyond standard cleaning and recalibration. The knobs are noted for their resistance, similar to Doepfer's, which makes fine adjustments easier but fast sweeps slightly stiff. This is generally seen as a positive, given how sensitive the resonance and distortion controls are.

Buyers should check a few things before purchasing. First, verify that all four filter outputs are functioning, as cold solder joints on the output jacks have been reported in early production runs. Second, test the distortion circuit with a clean input signal to make sure it responds smoothly across its range. Third, confirm that the resonance reaches self-oscillation. Some units may have a slightly lower threshold due to component tolerances. Finally, if buying a kit, make sure all SMD components are present and undamaged, as replacements can be hard to source.

The 705 isn’t a module that will skyrocket in value—it’s too recent, too niche. But it’s also not going to fade into obscurity. For players who value character over conformity, it’s a keeper. It’s the kind of module that, once installed, rarely gets removed. And in a format where modules rotate in and out like seasons, that’s high praise.

eBay Listings

ADDAC ADDAC705 Stinggy Filter Modular EURORACK - NEW - PERFE

$329

ADDAC ADDAC705 Stinggy Filter Modular EURORACK - DEMO - PERF

$249

ADDAC ADDAC705 Stinggy Filter Modular EURORACK - USED - PERF

$269

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