ADDAC 215 (2019–Present)

A tiny 6HP Eurorack powerhouse that turns randomness into precision, with a noise source, dual S&H, slew limiters, and math outputs that feel like cheating

Overview

You patch in a clock, twist a knob, and suddenly your filter cutoff is dancing in unpredictable but perfectly musical steps—none of that jittery, droopy CV nonsense that plagues cheaper sample and holds. That’s the ADDAC 215 in action: a module that looks like it shouldn’t do half of what it pulls off, crammed into a sliver of panel real estate but engineered to solve real problems in a modular rig. It’s not just another random voltage generator; it’s a precision instrument that treats control voltage like something worth holding onto—literally. Most sample and hold modules start sagging within seconds, making them useless for pitch modulation unless you’re okay with your melody drifting flat like an untuned string. The 215 laughs at that. With a voltage drop so minimal it takes 20 minutes to lose just 0.01V, it’s one of the few modules you can trust to keep a quantized sequence in tune over long stretches. That’s not marketing fluff—it’s measurable, and it changes how you patch.

And while it’s technically a dual S&H, calling it that feels reductive. It’s more like a modulation Swiss Army knife. Each channel can switch between Sample & Hold and Track & Hold, letting you freeze a voltage instantly or follow it smoothly while the trigger is high. That alone opens up expressive possibilities—imagine using Track & Hold on a slow LFO to create a ramp that only advances when a gate is present, then sampling that for stepped melodies. But ADDAC didn’t stop there. Each side has its own slew limiter with a single knob for attack and decay, and an on/off switch so you don’t waste processing when you want a sharp step. The internal noise source is normalled to both inputs, so the moment you plug in a clock, you’ve got random CVs ready to go—no extra cables needed. And then there are the bonus outputs: Sum, Average, Difference, and raw Noise. These aren’t gimmicks. Feed two evolving CVs into each channel, and the Difference output becomes a dynamic tension generator—perfect for modulating FM index or filter resonance in ways that feel alive, not random. The Average output smooths chaos into something lyrical. These math functions are built in, saving you space and patch cables, which matters when every HP counts.

Specifications

Manufacturer	ADDAC System
Production Years	2019–Present
Original Price	$147 / €139 / £131
Format	Eurorack
Width	6HP
Depth	40mm
Power Consumption (+12V)	50mA
Power Consumption (-12V)	50mA
Channels	2
Sample & Hold	Dual precision
Track & Hold	Switchable per channel
Internal Noise Source	Yes, normalled to both inputs
Slew Limiter	Per channel, attack/decay control, on/off switch
Trigger A Alternate Mode	Yes, alternates trigger between channels
Additional Outputs	Noise, Difference (A–B), Average ((A+B)/2), Sum (A+B)
Voltage Drop	0.01V over 20 minutes
Input Deviation	0.3% maximum from input
DIY Kit Available	Yes, SMD and through-hole components

Key Features

The Noise Is the Starting Point, Not an Afterthought

Most dual S&H modules make you patch in an external noise source if you want randomness. The 215 has its own, and it’s normalled to both inputs—meaning the second you clock the module, you’re already generating stepped random voltages. That’s huge for workflow. It means you can go from empty patch to generative melody in two cables: clock in, CV out. The noise isn’t just functional; it’s clean and full-spectrum, ideal for creating unpredictable but musically useful voltages. And because it’s available at a dedicated front-panel output, you can use it elsewhere in your system—modulating panning, tremolo depth, or even feeding it into a VCF for textured drones. It’s rare for a module this compact to include a utility-grade noise source, but ADDAC knew that if you’re building a randomness engine, the source should be onboard.

Mathematical Modulation Without Extra Modules

The Sum, Average, Difference, and Noise outputs turn the 215 into a passive voltage processor. You don’t need a separate adder or inverter to get these functions—they’re baked in. The Difference output (A–B) is especially powerful. If both channels are sampling the same noise source on alternating triggers, the difference between them creates a bipolar random signal that can drive vibrato depth or filter sweep direction. The Average output smooths the extremes, great for creating a master modulation source that evolves slowly from two chaotic inputs. These outputs don’t require power or patching back into the module—they’re always live, always ready. In a format where every module costs space and money, having math functions included isn’t just convenient; it’s a design win that reflects how people actually patch.

Slew as an Integral Part of the Signal Path

Each channel’s slew limiter isn’t an add-on—it’s part of the modulation chain. With a single knob controlling both attack and decay, you can soften a stepped voltage into a glide, making random pitches slide into place like a theremin player hunting notes. The on/off switch means you can toggle between crisp steps and smooth ramps without repatching. Some users have wished for pre-S&H slew (to smooth the input before sampling), but the post-S&H design here is more practical for most use cases—especially when you’re shaping final control voltages for filters or amps. And because the slew is per-channel, you can have one side sharp and the other smooth, creating rhythmic contrast in your modulation.

Historical Context

When the ADDAC 215 launched in 2019, Eurorack was deep into the “skiff era”—a time when compact, high-density cases were in vogue, and every HP mattered. Modules were getting smarter, packing more functionality into smaller footprints, and the 215 arrived right in that sweet spot. It wasn’t the first dual S&H, but it was one of the first to combine precision voltage holding, slew limiting, and mathematical outputs in 6HP. At a time when many manufacturers were adding DSP or complex sequencing to stand out, ADDAC went the opposite direction: analog precision with clever analog routing. The module reflects a broader trend in the late 2010s toward “utility-plus” modules—tools that do one thing well but with thoughtful extras that eliminate the need for additional gear. Competitors like Intellijel and Mutable offered S&H options, but few matched the 215’s combination of stability and feature density. Its emphasis on voltage integrity also spoke to a growing demand for modules that could handle pitch CV reliably—something digital randomizers often failed at due to quantization artifacts or jitter. The 215 answered that with analog precision, making it a favorite among composers who wanted generative music without sacrificing tuning.

Collectibility & Value

The ADDAC 215 has settled into a stable secondary market, with used units trading between $100 and $130 depending on condition and region. New units still sell for around $147, and prices haven’t fluctuated much since release—indicating a healthy supply and steady demand. It’s not a “grail” module, but it’s widely respected, and well-maintained units hold value well. The DIY kit version, which includes SMD and through-hole parts, is popular among builders and often sells for less than the assembled module—sometimes as low as $90. However, buyers should be cautious with DIY units unless they can verify build quality. A poorly soldered sample and hold can suffer from voltage drift or noise injection, undermining the very feature that makes the 215 special. There are no known widespread failure points—the design is solid-state and passive-heavy—but the toggle switches for Track & Hold and slew on/off can wear out with heavy use. Cleaning with contact cleaner usually restores function. The module draws a modest 50mA on both rails, so it’s case-friendly, and its 40mm depth fits in most skiffs. For collectors, the black anodized aluminum panel is the standard, and there are no known limited editions or color variants. The real collectibility here isn’t in rarity—it’s in utility. This is a module that earns its place in a system, not one that sits on a shelf.