ADDAC103 T-Networks ()
Four voices of raw, tunable analog percussion. Simple and unpredictable.
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 kept it simple. This is a straight-ahead analog percussion module with no MIDI and 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, good for snappy toms or clave-like tones. The bottom two go deeper and can do earthy, rounded kicks. Each voice has its own output, so you can process them separately, pan them around, or feed them into other modules. There's also a summed mix output with its own volume knob, for throwing all four voices out at once.
The T-Networks is also more than 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 and it's not precise. Owners report using it as a destructive filter bank, especially when driven with signals near or above audio rate. Each input has a gate-to-trigger converter, so you don't need pristine gate sources. A sequencer, an envelope or even a random pulse will fire it.
It isn't a Roland TR-808 or a LinnDrum clone. It's closer to a cousin of those old circuits, inspired by them but not bound to them. It lacks 1v/octave CV control, which some users note as a limitation. The module is about immediacy: you turn knobs, hit triggers and get sound.
Specifications
| Manufacturer | ADDAC System |
| Dimensions (HP) | 6 HP |
| Depth | 25 mm |
| Current Draw | 40 mA +12V, 40 mA -12V, 0 mA 5V |
| Number of voices | 4 |
| Controls per voice | Frequency control, Frequency Range Switch (Low/Mod/High) |
| Inputs per voice | Trigger Input |
| Outputs per voice | Audio Output |
| Additional output | Summing Mix output with Volume control |
| Top 2 channels feature a higher frequency range, bottom 2 channels feature a lower frequency range. | Yes |
| CV inputs are not calibrated to 1v/octave. | Yes |
| Configuration options | Factory Kit, Factory Assembled |
| Price (assembled module) | 110.00 € (Excl. VAT) |
| Price (DIY Kit) | 77€ (Excl. VAT) |
Key Features
Inspired by Twin T-Networks circuits used in many legendary drum machines
The ADDAC103 is built around the same kind of Twin T-Networks topology that powered vintage drum machines, known for punchy, resonant and slightly unstable sounds. These circuits don't generate waveforms in the traditional sense. They use feedback and resonance to create percussive bursts that decay naturally. Each hit blooms and fades with a slight unpredictability. It's not a simulation.
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, so even messy or slow-rising signals can fire a voice. Envelopes, LFOs, random voltages and audio-rate signals all work as triggers. That's forgiving in a system that often demands precision, and it suits experimental patches.
Audio inputs can also be used as an input; each voice can be used as very destructive filters
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 closer to a circuit pushed into screaming feedback, with metallic howls, ringing artifacts and chewed-up textures. It suits transitions, glitches, or a layer of controlled destruction in 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 input signal and the T-Network's resonance interact to make complex overtones and intermodulation, which feels more like circuit bending than synthesis.
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. You're not stuck with a summed drum mix, so 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.” Each voice is its own sonic slot with its own tuning range.
It has "LMH frequency switches."
The Low/Mid/High (LMH) range switches on each voice jump between broad frequency bands instantly. That helps in live performance or quick sound design, since you can flip a switch and go from sub-kick to high-tom instead of turning a knob through a massive range. 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. Its original price was 110.00 € (excl. VAT) for the assembled version, already a budget-friendly option for analog percussion. The DIY kit costs 77€ (excl. VAT) but has a catch. It requires assembly with both SMD and through-hole components, so 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. It has an average rating of Ø 4.27 from 11 votes on ModularGrid. Some users question whether it's “rich enough for kick purpose” or if it leans more toward toms. That's a fair critique. It can do kicks, but they're tighter and more mid-focused than the deep, rounded thump of a dedicated kick module, 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,” pointing to the cost of importing from Europe to places like the US. There are no confirmed production years or original launch pricing beyond the current retail figures.
eBay Listings
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