ADDAC 216 Dual Attenuverter and CV Processor ()
Not your granddad’s mixer—this black-paneled brain-twister turns simple CV and audio signals into a playground of sums, differences, and absolute value mind games.
Overview
The ADDAC 216 Dual Attenuverter and CV Processor Eurorack Module isn’t here to play nice—it’s here to rewire your patching habits. Built by ADDAC as part of their ADDAC200 Series, this 8hp black-panel module straddles the line between utility and alchemy, doing far more than its modest footprint suggests. It’s not just an attenuverter; it’s a dual-channel signal laboratory where addition, subtraction, inversion, rectification, and offset aren’t just options—they’re the whole point. If you’ve ever wished your modular rig could do vector math with voltages, this is as close as it gets without writing code.
Each of the two identical sections—A and B—starts with a pair of inputs (X and Y) that can be summed or subtracted, which already sets it apart from standard mixers that only sum. That alone opens up wild possibilities: think of it as a real-time difference engine for control voltages or audio waveforms. But ADDAC doesn’t stop there. After the sum-or-subtract stage, the signal hits a switchable full-wave rectifier labeled “Absolute,” flipping all negative excursions positive—perfect for taming bipolar LFOs or generating rectified audio textures. From there, it passes through the “Amplitude” attenuverter, which not only scales the signal but can flip its polarity, giving you yet another layer of inversion control.
Then comes the AC/DC coupling switch—essential for deciding whether your signal carries a DC offset or stays clean for audio use—followed by a bipolar Offset knob that lets you shift the entire signal up or down in voltage. Each section offers both a normal and an inverted output, doubling your routing options. And if that weren’t enough, the outputs from both sections are summed and sent to a shared “Average” output, which can act as a passive mixer or a way to collapse two complex modulations into a single control source. Whether you're using both inputs or just one, the module flexes: with a single input, it becomes a dual attenuverter and CV processor with rectification and coupling options—basically two utilities in one.
Despite its niche role, the 216 punches above its weight in patches that demand precision and flexibility. It’s the kind of module you don’t know you need until you’re knee-deep in a generative sequence and realize you need to invert, offset, and rectify a clock divider’s output—all at once. It handles both CV and audio with ease, making it a rare dual-role player in the utility category. And while it doesn’t generate signals, it reshapes them with surgical options that most mixers or attenuverters only dream of.
Specifications
| Manufacturer | ADDAC |
| Product type | Eurorack module |
| Width | 8hp |
| Depth | 36 mm |
| Module Height (U) | 3U |
| Panel Colour | Black |
| Power consumption | 40mA +12V, 40mA -12V |
Key Features
Two Identical Signal Processors (Section A & B)
The ADDAC 216 is built around two mirrored sections, each labeled A and B, giving users two independent processing paths. This symmetry means you can run identical processes in parallel—say, offset two LFOs by the same amount—or chain them together for cascading voltage manipulation. Each section handles its own input pair (X and Y), processes the signal through the same series of stages, and delivers both normal and inverted outputs. This dual architecture makes it ideal for stereo patches or for controlling two parameters with the same base modulation, but with independent shaping.
Sum and Difference Mixing
Instead of just summing input signals like a conventional mixer, the 216 lets you add or subtract them. This sum-and-difference capability is rare in utility modules and opens up advanced patching techniques. For example, feeding two LFOs into X and Y lets you create a new modulation waveform that’s either their combined motion or the gap between them—perfect for evolving, non-repeating control voltages. In audio rate, this turns the module into a phase-sensitive mixer where waveforms can cancel or reinforce each other dynamically.
Switchable Full Rectification ("Absolute")
After the sum/difference stage, the signal passes through a switchable full-wave rectifier labeled “Absolute.” When engaged, it converts all negative voltages to positive, effectively folding the waveform. This is incredibly useful for converting bipolar modulation sources (like sine or triangle LFOs) into unipolar envelopes, or for creating distorted audio textures from clean waveforms. The ability to toggle this on or off per section gives you immediate access to both raw and rectified versions of the same signal.
Amplitude Attenuverter with Polarity Control
Following rectification, the signal hits the “Amplitude” stage—a true attenuverter that scales the signal from full negative to full positive. This means you’re not just reducing the level; you can invert the signal’s polarity at the same time. It’s especially powerful when used after subtraction or rectification, letting you flip the final output’s direction or create negative feedback paths in modulation chains. Two LEDs per section monitor the output polarity and gain, giving visual feedback on signal behavior.
AC/DC Coupling and Bipolar Offset
Each section includes an AC/DC coupling switch, determining whether the output carries a DC offset (useful for CV) or is stripped of it (ideal for audio). This makes the module truly dual-purpose. After coupling, a bipolar Offset knob lets you shift the entire signal up or down by a user-defined voltage. This is invaluable for biasing audio signals into the positive range or adjusting the center point of an LFO to modulate parameters asymmetrically.
Dual Outputs and Average Mix
Each section provides both a normal and an inverted output, effectively doubling your available signals. This is handy for sending a modulation to multiple destinations with opposite polarities—say, one filter opening while another closes. Beyond the individual outputs, the module sums the outputs of both sections and routes them to a shared “Average” output. This isn’t just a passive mix; it’s a way to combine two complex, processed signals into a single control voltage, useful for master modulation sources or feedback loops.
Flexible Use as Dual Attenuverter & CV Processor
Even with only one input used per section (either X or Y), the 216 shines as a dual attenuverter and CV processor. The full signal path—rectification, amplitude control, coupling, and offset—remains available, making it a compact solution for shaping control voltages. It’s like having two advanced attenuverters with extra superpowers, all in 8hp. This flexibility means the module earns its space even in smaller systems where every hp counts.
Collectibility & Value
The ADDAC 216 is currently available new at £139.00 including UK VAT, with an ex-VAT price of £90.83 (Elevator Sound). A Reverb listing shows a price of $152.03 for a new unit, with the original launch price reportedly $181.59. These figures suggest the module has either been discounted over time or varies by region and distributor. Given its specialized function and solid build, it holds value as a niche utility module rather than a speculative collector’s item. No data exists on common failures, maintenance needs, or long-term reliability, but its passive-heavy design and lack of sensitive components suggest it’s likely robust. It’s not a rare “grail” module, but for modular users who patch deeply with CV manipulation, it’s a quietly essential tool.
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