ADDAC System ADDAC705 (2023–Present)

A tiny 8HP filter that punches like a modular heavyweight, resurrecting the raw, snarling character of the EDP Wasp in modern Eurorack format

Overview

Plug in the ADDAC705 and twist the cutoff with your hand near the resonance—before you even touch a cable, you can feel it: this thing breathes. It doesn’t just filter, it reacts. Based on the cult-classic filter from the 1978 EDP Wasp, a synth so quirky it looked like a space heater designed by a punk band, the ADDAC705 captures that same anarchic spirit in a module barely wider than a thumb. It’s not polished. It’s not neutral. It’s alive, with a bite that cuts through dense patches and a warmth that makes digital oscillators sound like they’ve been left out in the sun. For a format that often prizes precision, the 705 is a welcome shove off the grid—a reminder that filters can be instruments in their own right, not just tone shapers.

What makes the 705 special isn’t just its heritage, but how faithfully ADDAC System resurrects the Wasp’s chaotic charm without turning it into a museum piece. It offers four filter types—low-pass, band-pass, notch, and high-pass—each with its own dedicated output, letting you route multiple timbral flavors from a single source. The main output isn’t just filtered; it’s weaponized, with a built-in distortion/fuzz circuit that can push signals into snarling, harmonically rich overdrive. Switches let you toggle between diode clipping or none at all, and choose between high or low resonance depth, giving you control over just how unhinged it gets. And because it’s Eurorack, you can modulate the cutoff voltage with CV, complete with an attenuverter so you can fine-tune how much wobble you want—whether it’s a slow, seasick undulation or a rapid, resonant scream.

Sit it next to a clean, modern filter like a Mutable Instruments Ripples or a Make Noise QPAS, and the contrast is immediate. Those modules are surgeons; the 705 is a chainsaw artist. It doesn’t aim for transparency—it wants to leave marks. But that’s the point. In a system full of pristine wavefolders and digital morphing filters, the 705 is the one you reach for when you need something to growl, to distort, to surprise you. It’s not always the “right” tool, but it’s often the most fun one.

Specifications

Manufacturer	ADDAC System
Production Years	2023–Present
Original Price	€230
Format	Eurorack
Width	8 HP
Depth	3 cm
Max Current +12V	60 mA
Max Current -12V	30 mA
Bus Board Cable	8 × 2 IDC (Doepfer style)
Filter Types	Low-Pass, Band-Pass, Notch, High-Pass
Main Output Filter Selection	4-position switch
Resonance Clipping Options	No clipping, Diode clipping
Resonance Depth	High / Low switch
Cutoff CV Input	Yes, with attenuverter
Distortion/Fuzz Circuit	On main output
Phase Switch	Yes, for main output polarity
Signal LED	On main output
DIY Kit Available	Yes (€91, excluding VAT)

Key Features

Wasp DNA, Reborn

The EDP Wasp was never a commercial hit, but its filter became legendary—crude, unpredictable, and full of character. ADDAC didn’t just model it; they recreated its topology, capturing the way it distorts when pushed, how resonance interacts with input gain, and how it can oscillate into a sine wave when cranked. The 705 doesn’t simulate that behavior—it lives it. The diode clipping switch engages the same kind of soft saturation that made the Wasp sound “dirty” in the best way, adding even-order harmonics that warm up cold waveforms. Flip it to “no clipping,” and the filter cleans up slightly, though it’s never truly sterile—there’s still a slight grit, like tube amp breakup at low volume. It’s not a clean slate; it’s a character actor.

Four Flavors, One Core

Having dedicated outputs for low-pass, band-pass, notch, and high-pass isn’t just convenient—it’s compositional. You can send a single oscillator through the 705 and split its filtered versions to different VCAs, modulators, or effects. Imagine a bass sequence filtered low-pass to one channel, while the same source, high-passed, triggers a reverb on another. Or use the notch output to create phasing effects without an LFO. The 4-position switch on the main output lets you select which mode dominates, but the individual outs mean you’re never locked in. This flexibility is rare in such a compact module, and it turns the 705 into a timbral hub, not just a filter.

Distortion as a Design Feature

Most filters treat distortion as a byproduct. The 705 treats it as a feature. The built-in distortion/fuzz circuit on the main output can be engaged independently, letting you add grit without affecting the other filter outputs. This means you can have a clean low-pass on one channel and a fuzzed-out band-pass on another—ideal for parallel processing. The amount of saturation is controlled by input level and resonance, so it’s responsive, not static. Feed it a hot signal, crank the resonance, and it’ll start to break up like a vintage guitar pedal. It’s not subtle, but subtlety isn’t the goal. This is the sound of a synth that wants to be heard, even in a mix.

Historical Context

The EDP Wasp, released in 1978, was a product of British DIY synth culture—built from off-the-shelf parts, housed in a plastic case that looked like a child’s toy, and powered by a filter circuit that no one expected to become iconic. It was cheap, unreliable, and sonically unique. Decades later, that filter became the stuff of legend, sampled, cloned, and reverse-engineered by boutique builders. ADDAC System’s decision to resurrect it as a Eurorack module in 2023 wasn’t just nostalgia—it was a statement. At a time when modular synthesis is increasingly dominated by digital brains and algorithmic sound design, the 705 says analog chaos still matters. It joins a wave of “vintage circuit” modules from brands like 4ms, Industrial Music Electronics, and Tip Top Audio, all digging into forgotten or obscure designs to bring back raw, unfiltered (pun intended) character. Compared to contemporaries like the 4ms RCD or the ALM Bush-1, which also explore chaotic filtering, the 705 stands out for its compactness and direct lineage. It’s not a reinterpretation—it’s a revival.

Collectibility & Value

The ADDAC705 is too new to be “vintage” in the traditional sense, but it’s already gaining cult status among modular enthusiasts who prize character over convenience. New units sell for €230 directly from ADDAC, with dealers often listing them for $250–$280. Used prices hover around $200–$230 depending on condition, with little fluctuation—there’s no artificial scarcity, but demand remains steady. The DIY kit, priced at €91 (excluding VAT), is a rare bargain for a module of this complexity, making it accessible to builders who want to learn about analog filter design. However, sourcing the front panel separately isn’t possible—custom colors must be ordered through ADDAC, with a 4–6 week lead time and a premium cost.

Failure points are minimal. The PCB is well-laid out, and the through-hole components used in the DIY version are robust. The most common issue reported is intermittent connection on the resonance switch if the module is rack-mounted too tightly, due to the 3cm depth—owners suggest leaving breathing room or using spacers. The diode clipping circuit, while authentic, can introduce noise at high gain settings, but this is considered part of the character, not a defect. No firmware updates or recalls have been issued, and ADDAC’s documentation, including a detailed assembly guide, is thorough. For collectors, the black panel is standard; custom colors are a personalization, not a rarity. If you want one, buy it new—there’s no investment angle here, just sonic value.