ADDAC System 106 (2020–)

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

Overview

The ADDAC 106 is not a TR-808 or a DMX clone. Snares are built from filtered noise bursts, hi-hats come from high-passed crackle, and kicks growl up from post-VCA resonance. It doesn't chase realism. It sounds like a decaying tape found in a Lisbon subway station. Flip the "dirt" switch on the summing output and it adds a layer of harmonic grit that makes even the simplest sequence sound like it's been run through a tube amp left on for three days straight.

The 106 is part of ADDAC's T-Networks series, named for the vintage passive filter topology that shaped early drum machines, and it is the final and most focused installment. It's a 4-voice analog noise synthesizer. Each voice is 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. That gives it a deeper, more resonant character for kicks, toms, or subby thumps. The whole module is manual-only. There's no CV control over frequency or decay and no voltage-controlled muting. What you set is what you get, unless you patch creatively. It's a "hands-on, tweak-as-you-go" module, not a set-and-forget drum brain.

The summing mix output is where the 106 earns its keep. It's more than a passive combiner. It has a volume knob and a "Normal/Dirt" toggle that routes the mixed signal through a distortion stage. In "Dirt," clean hi-hats turn into sizzling static, the snare picks up a second harmonic layer, and the kick punches through like it's been overdriven in a '70s studio limiter. It isn't subtle, but it stays warm and saturated rather than fizzy or harsh. Each voice also has its own output, so you can send individual elements to external processors, compressors, or delays while keeping the dirty mix as a parallel layer. That sets it apart in Eurorack percussion, which often leans toward either sterile digital emulation or overly complex modular drum systems.

Specifications

Key Features

T-Network Filtering with Character

The 106 is built on T-network filters, passive RC circuits once used in vintage drum machines to shape noise into recognizable percussive tones. ADDAC implements them in analog hardware instead of simulating them, and each voice ends up with a distinct, slightly unpredictable timbre. Voices 1-3 use a pre-VCA configuration, so the noise is filtered before it's gated. The attack is cleaner and more immediate, which suits sharp hats and snappy snares. Voice 4 reverses the order: the noise is gated first, then filtered. This post-VCA setup gives a more resonant, "blooming" decay that feels more organic and less clicky. It's a subtle difference on paper, but in practice it adds depth. The knobs change more than pitch and decay. They change how the sound is generated.

Hat/Snare Timbre Switching

The "Hat/Snare" switch on the first three voices is a functional high-pass filter, not just a label. In "Snare" mode, the full frequency range of the filtered noise passes through. In "Hat," a high-pass filter cuts the mids and lows and leaves the crisp, metallic top end. You can set one voice to a deep snare tone, then flip the switch to turn it into an open hat without touching the frequency knob. The three voices are also slightly detuned from each other at the circuit level, so you get natural variation even when they're set to the same frequency. No randomization needed.

Summed Output with Grit

Most drum modules treat the mix output as an afterthought, a simple passive combiner. The 106 gives it real controls. The summing section has 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 less harsh distortion and more like running your drums through a tube preamp with the gain cranked. That makes the 106 feel more "finished" than other DIY-style percussion modules. You don't need an external saturator to make your beats cut through a mix.

Historical Context

The ADDAC 106 arrived in 2020 as the final piece of the T-Networks series, a line of Eurorack modules based on the analog drum circuits of the 1970s and 1980s. Modular percussion was then dominated by digital samplers, FM synthesis, and complex algorithmic engines, and ADDAC went back to 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, is the centerpiece. ADDAC kept the quirks: the slight detuning, the non-linear response, the way the circuits interact when pushed. The 106 wasn't meant to replace a drum machine. It offered a new way to approach noise-based rhythm in a modular context. It arrived alongside other boutique analog percussion modules like the Intellijel Rainmaker and the ALM Squid Salmple, and stood out for its simplicity, hands-on playability, and lack of digital processing. Many modules in the format were menu-dense, and the 106 was tactile and immediate.

Collectibility & Value

The ADDAC 106 isn't rare, but it isn't 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. It's a simple analog design with no firmware or complex ICs, so it's extremely reliable. Failures are rare. 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 check the PSU if you get dropouts or noise. There's no battery backup, no memory, no software, just resistors, capacitors, and op-amps. That makes it low-maintenance.

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. They're 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 saves money and teaches you T-network filtering firsthand. Custom front panels are a bonus, since 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. It costs under €200.

eBay Listings

ADDAC106 T-Noiseworks Noise Percussion Synth Module Used 4-V

$415

ADDAC106 T-Noiseworks Noise 4-Voice Percussion Synth Module

$302

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

$249

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