ADDAC System 106 (2020–)

Four channels of gritty, noise-based percussion in 8HP—this module doesn’t simulate drums, it invents them.

Overview

Plug in the ADDAC 106 and you’re not getting a TR-808 or a DMX clone—you’re stepping into a back-alley drum lab where snares are built from filtered noise bursts, hi-hats are carved from high-passed crackle, and kicks growl up from post-VCA resonance. This isn’t a drum module that panders to realism; it’s a percussion engine for people who want their beats to sound like they were ripped from a decaying tape found in a Lisbon subway station. The moment you flip the “dirt” switch on the summing output, the whole thing snarls to life, adding a layer of harmonic grit that makes even the simplest sequence feel like it’s been run through a tube amp left on for three days straight.

Part of ADDAC’s T-Networks series—named for the vintage passive filter topology that shaped early drum machines—the 106 is the final and most focused installment. It’s a 4-voice analog noise synthesizer, each voice built around a T-network filter that shapes white noise into percussive transients. Voices 1 through 3 are nearly identical: frequency and decay knobs, a timbre switch labeled “Hat/Snare,” and an input mode selector. The fourth voice breaks the mold with a three-position range switch (Low, Mid, High) and a different signal path—post-VCA filtering—which gives it a deeper, more resonant character perfect for kicks, toms, or subby thumps. The entire module is manual-only: no CV control over frequency or decay, no voltage-controlled muting. What you set is what you get, unless you patch creatively. And that’s kind of the point: this is a “hands-on, tweak-as-you-go” module, not a set-and-forget drum brain.

The summing mix output is where the 106 really earns its keep. It’s not just a passive combiner—it’s got a volume knob and a “Normal/Dirt” toggle that routes the mixed signal through a distortion stage. Flip it to “Dirt” and suddenly your clean hi-hats turn into sizzling static, your snare gets a second harmonic life, and your kick punches through like it’s been overdriven in a ’70s studio limiter. It’s not subtle, but it’s musical—never fizzy or harsh, just warm, saturated, and alive. And because each voice has its own output, you can send individual elements to external processors, compressors, or delays while still keeping the dirty mix as a parallel layer. That kind of flexibility makes it a standout in a genre (Eurorack percussion) that often leans toward either sterile digital emulation or overly complex modular drum systems.

Specifications

Key Features

T-Network Filtering with Character

The heart of the 106 lies in its use of T-network filters—passive RC circuits once used in vintage drum machines to shape noise into recognizable percussive tones. ADDAC doesn’t just simulate this; they implement it in analog hardware, giving each voice a distinct, slightly unpredictable timbre. Voices 1–3 use a pre-VCA configuration, meaning the noise is filtered before being gated. This results in a cleaner, more immediate attack—perfect for sharp hats and snappy snares. Voice 4 flips the script: the noise is gated first, then filtered. This post-VCA setup allows for a more resonant, “blooming” decay that feels more organic and less clicky. It’s a subtle difference on paper, but in practice, it gives the module a real sense of depth. You’re not just changing pitch and decay—you’re changing the physics of how the sound is generated.

Hat/Snare Timbre Switching

The “Hat/Snare” switch on the first three voices isn’t just a label—it’s a functional high-pass filter. In “Snare” mode, the full frequency range of the filtered noise passes through. Flip it to “Hat,” and a high-pass filter kicks in, cutting the mids and lows to leave only the crisp, metallic top end. It’s a simple trick, but it works brilliantly. You can set one voice to a deep snare tone, then flip the switch to turn it into an open hat, all without touching the frequency knob. And because the three voices are slightly detuned from each other at the circuit level, you get natural variation even when they’re set to the same frequency—no randomization needed. It’s a smart, hands-on way to get variety without CV modulation.

Summed Output with Grit

Most drum modules treat the mix output as an afterthought—a simple passive combiner with no character. The 106 treats it like an instrument. The summing section includes a volume knob and a “Normal/Dirt” toggle that routes the mixed signal through an overdriven stage. In “Dirt” mode, the entire kit gets a warm, harmonically rich saturation that glues the elements together. It’s not distortion in the harsh sense—it’s more like running your drums through a tube preamp with the gain cranked. This feature alone makes the 106 feel more “finished” than other DIY-style percussion modules. You don’t need to patch in an external saturator to make your beats cut through a mix; it’s built in, and it’s effective.

Historical Context

The ADDAC 106 arrived in 2020 as the final piece of the T-Networks series, a line of Eurorack modules that paid homage to the analog drum circuits of the 1970s and 1980s. At a time when modular percussion was dominated by digital samplers, FM synthesis, or complex algorithmic engines, ADDAC took a step back—toward the raw, component-level design of early rhythm boxes. The T-network filter, once a cost-effective way to shape noise in machines like the Roland TR-606 or Korg KR-55, became the star of the show. Rather than chasing authenticity, ADDAC leaned into the quirks: the slight detuning, the non-linear response, the way the circuits interact when pushed. The 106 wasn’t trying to replace a drum machine; it was offering a new way to think about noise-based rhythm in a modular context. It arrived alongside other boutique analog percussion modules like the Intellijel Rainmaker and the ALM Squid Salmple, but stood out for its simplicity, hands-on playability, and lack of digital processing. In a format increasingly dominated by complex, menu-dense modules, the 106 was a refreshingly tactile, immediate tool.

Collectibility & Value

The ADDAC 106 isn’t a rare module, but it’s not generic either. Assembled units typically sell for €170–€200, with DIY kits going for around €110. Used prices hover between €130–€160 depending on condition, and because it’s a simple analog design with no firmware or complex ICs, it’s extremely reliable. Failures are rare, but when they happen, they’re usually related to power—either reversed polarity during installation or a damaged regulator. The module runs at 40mA on both rails, so it’s not a power hog, but it’s worth checking the PSU if you experience dropouts or noise. There’s no battery backup, no memory, no software—just resistors, capacitors, and op-amps. That makes it a low-maintenance addition to any system.

What to watch for when buying: check the switches. The input mode and timbre switches get a lot of use, and while they’re sturdy, repeated toggling can lead to crackle or intermittent connection. The pots are standard alpha units—replaceable if needed, but rarely fail. The DIY kit is well-documented and beginner-friendly, with a full assembly guide available online. If you’re handy with a soldering iron, it’s a great way to save money and learn about T-network filtering firsthand. Custom front panels are a fun bonus—ADDAC offers a range of colors and print options—but they don’t affect value significantly. The module’s real collectibility lies in its role as the closing chapter of the T-Networks series. It’s not likely to become a “holy grail,” but it’s a cult favorite among modular drum builders and noise enthusiasts. For under €200, it’s one of the most characterful ways to add analog percussion to a rack.

eBay Listings

ADDAC System ADDAC106 T-Noiseworks (Black) EURORACK - NEW -

$229

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