ADDAC103 T-Networks ()

Four voices of raw, tunable analog percussion that hit like circuit-bent thunder—simple, unpredictable, and full of character.

Overview

If you’ve ever wished your Eurorack could cough up a set of analog toms that sound like they were pulled from a half-dead drum machine buried in a ’70s studio floor, the ADDAC103 T-Networks might be your kind of chaos. It’s not a drum module that pretends to be musical; it’s a percussion source that leans into its own weirdness, built around the kind of Twin T-Networks circuits that once gave classic machines their punch and unpredictability. Four voices, each with its own personality, let you dial in everything from subby kicks to wooden clacks and metallic zaps—all without a single sample or digital trick in sight.

ADDAC System didn’t overthink it: this is a straight-ahead analog percussion module, no frills, no MIDI, no CV quantization. Each voice has a frequency knob and a range switch—Low, Mod, High—so you can jump between registers fast. The top two channels are biased toward higher frequencies, great for snappy toms or clave-like tones, while the bottom two dig deeper, capable of earthy, rounded kicks. You get individual outputs for each voice, which means you can process them separately, pan them around, or feed them into other modules for mangling. There’s also a summed mix output with its own volume knob, so you can throw all four voices out at once if you’re building a rhythm stack live.

What’s interesting—and a little sneaky—is that the T-Networks isn’t just a sound generator. Feed an audio signal into one of the trigger inputs, and the voice starts acting like a brutal, resonant filter. It’s not clean, it’s not precise, but it’s definitely musical in that “let’s see what happens” way that Eurorack thrives on. Owners report using it as a kind of destructive filter bank, especially when driven with signals near or above audio rate. That gate-to-trigger converter at each input means you don’t need pristine gate sources—anything from a sequencer, an envelope, or even a random pulse will fire it up.

It’s not trying to be a Roland TR-808 or a LinnDrum clone. It’s more like a cousin to those old circuits—inspired by them, sure, but not beholden. And while it lacks 1v/octave CV control (a limitation some users note), that’s kind of the point: this is about immediacy, not precision. You turn knobs, you hit triggers, you get sound. Fast.

Specifications

Key Features

Inspired by Twin T-Networks circuits used in many legendary drum machines

The ADDAC103 doesn’t hide its roots. It’s built around the same kind of Twin T-Networks topology that powered the guts of vintage drum machines—machines known for their punchy, resonant, and slightly unstable character. These circuits don’t generate waveforms in the traditional sense; they use feedback and resonance to create percussive bursts that decay naturally. That’s why the T-Networks doesn’t just *sound* analog—it feels alive, with a slight unpredictability in how each hit blooms and fades. It’s not a simulation; it’s a spiritual descendant.

At each voice input there’s a gate to trigger converter so any input source is possible

You don’t need a perfectly timed gate signal to make this thing bark. Each trigger input includes a gate-to-trigger converter, meaning even messy or slow-rising signals can fire up a voice. That opens the door to using all kinds of sources—envelopes, LFOs, random voltages, or even audio-rate signals—as triggers. It’s forgiving in a system that often demands precision, and that flexibility makes it a great companion for experimental patches.

Audio inputs can also be used as an input; each voice can be used as very destructive filters

This is where the T-Networks stops being just a drum module and starts becoming a sound mangler. Feed an external audio signal into a trigger input, and the voice’s internal circuit starts resonating in response—effectively turning each voice into a resonant, self-oscillating filter. It’s not a 24dB synth filter with a smooth sweep; it’s more like a circuit pushed into screaming feedback, capable of creating metallic howls, ringing artifacts, or chewed-up textures. Perfect for transitions, glitches, or adding a layer of controlled destruction to a mix.

It accepts signals well into audio rate and can behave as a weird filter of sorts

Owners report pushing the module beyond its intended use, feeding in signals at or above audio rate and getting unpredictable, often musical results. The interaction between the input signal and the T-Network’s resonance creates complex overtones and intermodulation—something that feels more like circuit bending than synthesis. It’s not for every track, but when you need a sound that cuts through with character, this is the kind of module that delivers.

The module has "4 sounds" that are "each tunable with individual outs."

Each of the four voices is fully independent, with its own frequency control and output. That means you’re not stuck with a summed drum mix—you can route each voice to different effects, mixers, or processors. One user noted they use it for “low earthy kicks, analog toms x4, or wood block clave type sounds,” which sums up its versatility. You’re not just getting four copies of the same sound; you’re getting four distinct sonic slots, each with its own tuning range and character.

It has "LMH frequency switches."

The Low/Mid/High (LMH) range switches on each voice let you jump between broad frequency bands instantly. This is crucial for live performance or quick sound design—instead of turning a knob through a massive range, you can flip a switch and go from sub-kick to high-tom in a heartbeat. One user admitted they were “a little put off at first that the LMH frequency switches didn’t work how I expected,” but quickly adapted. It’s not a linear sweep; it’s a coarse selector that changes the operating point of the oscillator, giving each range a different flavor.

Collectibility & Value

The ADDAC103 T-Networks currently trades in a tight range: $112 to $149 on Reverb, $119.80 on eBay, and €142.00 at Exploding Shed. At its original price of 110.00 € (excl. VAT) for the assembled version, it was already a budget-friendly option for analog percussion. The DIY kit, priced at 77€ (excl. VAT), offers even more value—but comes with a caveat. The kit requires assembly with both SMD and through-hole components, meaning you’ll need solid soldering skills and proper testing equipment. There’s no hand-holding; if you build it wrong, it’s on you.

It’s currently sold out at several retailers, including Exploding Shed, which suggests steady demand despite its niche appeal. With an average rating of Ø 4.27 from 11 votes on ModularGrid, it’s well-regarded but not universally loved—some users question whether it’s “rich enough for kick purpose” or if it leans more toward toms. That’s a fair critique: while it can do kicks, they’re not the deep, rounded thump of a dedicated kick module. They’re tighter, more mid-focused, with a snap that suits lo-fi or industrial styles better than dancefloor punch.

Shipping has been a sore point for some. One user noted that paying “30E for a 100E module seems.. rather excessive for shipping,” highlighting the cost burden of importing from Europe to places like the US. With no confirmed production years or original launch pricing beyond the current retail figures, it’s hard to judge its long-term collectibility—but as a compact, characterful percussion module with a cult following, it’s likely to remain a sought-after utility in Eurorack setups.

eBay Listings

ADDAC System 103 T-Networks (Black) Modular EURORACK - NEW -

$149

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